Financial Incentives for Homeless Smokers: A Community-based RCT
Phase: NA
Conditions: Tobacco Smoking
Sponsor: Massachusetts General Hospital

ClinicalTrials.gov: NCT04445662 
TITLE: Financial incentives for homeless smokers: A community-based RCT 
PRINCIPAL INVESTIGATOR: Travis P. Baggett, MD, MPH 
GRANT NUMBER: R01 CA235617 (National Cancer Institute, National Institutes of Health) 
VERSION DATE: December 7th, 2023 
 
I. BACKGROUND AND SIGNIFICANCE 
A. Historical background 
An estimated 68-80% of homeless adults are cigarette smokers1-6, in contrast to the 18% 
prevalence in the U.S. general population.7 The health impact of this disparity is substantial. 
Obstructive lung disease is more than twice as prevalent among homeless individuals than in 
the US general population,3 contributing to higher rates of death due to COPD and other 
respiratory causes.8-10 Heart disease is a major cause of death among homeless adults,11, 12 and 
several studies have shown higher rates of mortality due to circulatory system diseases among 
homeless persons in comparison to non-homeless counterparts.8-10, 12, 13 In a series of 
epidemiologic studies of 28,033 homeless adults in Boston, we found that one-third of incident 
cancers in this cohort were smoking-attributable, and the age-adjusted lung cancer incidence 
and mortality rates were over 2-fold higher than in Massachusetts adults.14 These findings 
contributed to 3- to 5-fold higher rates of death due to any tobacco-attributable cause relative to 
rates in the Massachusetts general population.15  
Homeless smokers are interested in quitting.2, 16-19 In 2002, Butler et al. reported that 56% of 
homeless smokers were contemplative about quitting and 17% were in preparation to quit; the 
level of interest in smoking cessation programs was not significantly different from that seen in 
low-income non-homeless smokers.16 In the same year, Connor et al. found that 37% of 
homeless smokers were ready to quit within the next 6 months.2 In 2004, Arnsten et al. reported 
that 44% of homeless smokers were somewhat or very interested in smoking cessation 
counseling, and 19% were either preparing or trying to quit.18 In a nationwide study of homeless 
and non-homeless community health center patients in the United States, we found that 
currently and formerly homeless smokers did not differ from never-homeless smokers in their 
past-year desire to stop smoking.19 In a 2014 survey of 306 homeless smokers at Boston Health 
Care for the Homeless Program (BHCHP), 62% of participants had intentionally quit smoking for 
at least 24 hours in the past year and 85% planned to quit smoking in the future, including 24% 
who planned to do so in the next month. 
Despite their interest, few homeless smokers are able to quit and self-efficacy for quitting may 
be low.18  Baggett and Rigotti found a quit ratio (the proportion of ever-smokers who are former 
smokers) of 9% in a national sample of homeless adults,1  a figure one-fifth of that observed in 
the US general population.20 The pervasiveness and social acceptability of smoking in the 
setting of homelessness17, 21 may be one explanation for the low success rate. Homeless 
smokers are continuously confronted with social cues to smoke. In a survey of homeless 
smokers in Dallas, participants reported contact with a mean of 43 other smokers each day.22  
Additionally, homeless smokers are a vulnerable subset of homeless individuals; they are more 
likely to have histories of childhood adversity, physical or sexual assault, and alcohol or drug 
use problems.1 In comparison to non-homeless smokers, homeless smokers begin smoking at 

is an FDA-approved prescription smoking cessation medication33 that acts as a partial 
agonist/antagonist at nicotinic receptors, easing withdrawal symptoms while also blocking the 
rewarding effects of nicotine from cigarettes.18 Varenicline is now strongly recommended as a 
first-line smoking cessation medication in virtually all patient populations.34 Research suggests 
that varenicline is superior in producing short-term and long-term abstinence compared to 
bupropion35 while also producing higher continuous abstinence rates than NRT.36 When paired 
with counseling, varenicline is the most effective smoking cessation medication available.37 
Varenicline has also been shown to be safe and effective in at-risk populations, including those 
with comorbid psychiatric conditions,38 alcohol use disorder 39 and substance use disorders.40, 41 
To date there has been limited research on the use of varenicline in homeless populations.42 
Therefore, the results of the current study may provide further insight on the uptake of and 
adherence to varenicline in a homeless population. 
 
II. SPECIFIC AIMS 
To address the above gaps in evidence, we will conduct a community-based RCT of financial 
incentives for smoking abstinence among adult smokers at BHCHP. Recognized as a leader in 
homeless health care, BHCHP serves 12,000 currently and formerly homeless patients annually 
throughout greater Boston.43 We will randomize 180 participants recruited from 3 BHCHP sites: 
a shelter clinic, a day center clinic, and a medical center clinic. All participants will be offered 12 
weeks of varenicline, 5 sessions of tobacco coaching, and 10 cotinine monitoring visits over a 
12-week period. Participants randomized to the financial incentives arm (n=90) will receive 
escalating debit card payments (range $25-$70) at each monitoring visit for saliva cotinine 
levels <30 ng/ml. Control arm participants (n=90) will receive a fixed payment ($10) at each 
monitoring visit regardless of their saliva cotinine level. We will use an embedded-experiment 
mixed methods design,44 where qualitative (‘qual’) data collection is embedded within a larger 
quantitative (‘QUAN’) RCT with the following specific aims: 
Aim 1. (QUAN) To determine the effect of the financial incentives intervention on cotinine-
verified 7-day smoking abstinence at A) the end of treatment (12 weeks) and B) 12 weeks after 
treatment (24 weeks). 
    Hypotheses: Incentive arm participants will have significantly greater cotinine-verified 7-day 
smoking abstinence than control arm participants at A) 12 weeks and B) 24 weeks. 
Aim 2. (qual) To assess why, how, and under what circumstances homeless smokers A) 
achieve abstinence in response to financial incentives and B) maintain abstinence after 
incentives are stopped. 
    Interviews with participants at A) 12 weeks (N=30) and B) 24 weeks (N=20) will examine 
cognitive (‘why?’), procedural (‘how?’), and contextual (‘under what circumstances?’) 
dimensions of their response to financial incentives to generate hypotheses about potential 
mechanisms for on-treatment and post-treatment effects and to inform modifications of the 
intervention for future use. 
 
III. SUBJECT SELECTION 

A. Inclusion and exclusion criteria 
To be eligible to participate, individuals must meet all of the following criteria: 
1) Aged ≥18 years old, assessed by self-report and verified by date of birth. 
Rationale: We wish to focus only on adult smokers since adolescent smokers present 
unique issues that merit separate consideration.  
2) Lifetime smoker of ≥100 cigarettes with current daily smoking of ≥5 cigarettes/day, 
verified by a saliva cotinine level ≥30 ng/mL.28  
Rationale: In order to document smoking abstinence via saliva cotinine levels, trial 
participants must smoke a sufficient number of cigarettes per day at baseline to be 
above the accepted threshold of 30 ng/ml for determining smoke exposure. 
3) Ready to try to quit smoking within the next 3 months, assessed by self-report. 
Rationale: We wish to focus on smokers interested in quitting in the near future in order 
to better isolate a treatment effect. 
4) Proficient in English, assessed with items asking about native language and self-
reported comfort communicating in English among non-native speakers. 
Rationale: We do not have the resources to develop study materials or conduct in-
person counseling in languages other than English. 
5) Currently or formerly homeless, assessed by self-report and defined as having ever 
stayed in an emergency shelter, transitional shelter, abandoned building, place of 
business, car or other vehicle, church or mission, hotel or motel, or anywhere outside, or 
having ever stayed in somebody else’s house, apartment/condominium, or room due to 
not having their own place to stay. 
Rationale: BHCHP and most HCH programs nationally continue to serve patients after 
they have gained housing. Additionally, currently and formerly homeless people smoke 
at similarly high rates,19 and our epidemiologic analysis of tobacco-attributable cancer 
and mortality disparities experienced by BHCHP patients included both currently and 
formerly homeless individuals.15, 45  
6) Have a primary care provider (PCP) within the BHCHP system. 
Rationale: This will help ensure that we can communicate efficiently with participants’ 
PCPs via secure, EHR-based messaging systems regarding the safe use of varenicline 
for smoking cessation.  
 
Individuals will be excluded if they meet any of the following criteria: 
1) Unable to provide informed consent, assessed with knowledge questions about the 
material presented during the informed consent process that individuals must correctly 
answer before providing consent to participate.  
Rationale: Participants must have a clear understanding of what is involved in the study 
prior to enrolling. 
2) Report a history of an allergic reaction to varenicline.  
Rationale: Varenicline is a treatment component in both study arms. 
3) Currently pregnant, planning to become pregnant, or breastfeeding. 
Rationale: There is limited information on the safety of varenicline in pregnant women. 
46,47 

4) Past-month suicidal ideation with plan or intent, or past 12-month history of suicidal 
behaviors or attempts, based on the primary care screening version of the Columbia 
Suicide Severity Rating Scale (C-SSRS).48 
Rationale: Due to past reports of suicidal ideation in patients taking varenicline and 
limited research on the safety of prescribing varenicline to individuals with recent suicidal 
ideation or behaviors,49, 50 we do not believe it is appropriate for these patients to 
participate in the study.  
5) Self-reported psychiatric hospitalization in the past 3 months. 
Rationale: Varenicline carries a caution label for neuropsychiatric events. There is also 
limited research on the use of varenicline in patients with unstable mental illness. Hence, 
we do not feel that it is appropriate to include patients with a recent psychiatric 
hospitalization in the study.41, 49, 51 
 
We will not exclude individuals who use alcohol or other drugs, as long as they meet all of the 
above eligibility criteria. This decision was made because our prior survey of homeless smokers 
in Boston suggested that limiting the trial to individuals who do not use other drugs or alcohol 
would considerably narrow the pool of potentially eligible participants and would severely limit 
the generalizability of our findings. Concomitant drug and/or alcohol use is common among 
homeless smokers,1 and smoking interventions for this population must contend with that reality 
in order to be applicable. In our pilot RCT, we found that drug and alcohol use, assessed serially 
over 8 weeks, did not change among participants assigned to receive financial incentives for 
smoking abstinence. Furthermore, evidence suggests varenicline is both safe and effective in 
patients with a history of substance use disorder.40,38, 40 Because of the potential importance of 
this issue, we again plan to assess drug and alcohol use with a validated instrument at the 
beginning, middle, and end of the trial, and to conduct interaction analyses to determine 
whether drug and alcohol use severity modify the effect of the intervention. 
B. Source of subjects and recruitment methods 
This study will be registered with ClinicalTrials.gov prior to the recruitment and enrollment of 
human subjects. All participants will be recruited from BHCHP clinical sites. BHCHP does not 
have its own IRB but instead will rely on the Mass General Brigham Human Research 
Committee for IRB review through a reliance agreement initiated through SMART IRB. In 
addition to being a faculty physician-investigator at Massachusetts General Hospital and 
Harvard Medical School, the study PI has over 20 years of clinical experience with homeless 
patients and more than 13 years of research experience relating to the health of homeless 
people. He has been a staff physician at BHCHP since 2008 and was named the Director of 
Research at BHCHP in 2017. 
Recruitment of study participants will occur at up to 3 venues; however, initial efforts will focus 
on the first of these sites: 
a) Medical center venue: Jean Yawkey Place, adjacent to Boston Medical Center, is the BHCHP 
headquarters facility where medical, behavioral health, and dental clinics operate 5 days per 
week with an on-site pharmacy and medical respite unit. Compared to other BHCHP locations, 
Jean Yawkey Place has the highest volume of patients, the most space, and the greatest 
flexibility in space configuration. This will allow study personnel to conduct in-person participant 
recruitment while practicing COVID-appropriate social distancing and prioritizing the health and 
well-being of both participants and study staff. 

Depending on the status of the COVID-19 pandemic, recruitment may later expand to two 
additional locations when safe to do so: 
b) Shelter venue: Pine Street Inn is a 470-bed shelter serving both men and women where 
BHCHP operates a medical clinic 7 days per week in the men’s shelter and 6 days per week in 
the women’s shelter. 
c) Day center venue: St. Francis House is a multiservice day center for homeless people where 
BHCHP operates a medical clinic 5 days per week. 
Study participants will be recruited through five methods:  
a) Self-referral: Study staff will be stationed in heavily trafficked areas within the recruitment 
sites at prespecified times each week. We anticipate that a general awareness of the study due 
to study staff presence and word-of-mouth will encourage prospective participants to approach 
study staff and undergo eligibility screening if interested. 
b) Proactive outreach: BHCHP has a comprehensive EHR system (Epic) that prompts providers 
to assess tobacco use at every clinical encounter, facilitating determination of smoking history 
and current smoking status. Individuals with a BHCHP PCP who have been seen in a BHCHP 
clinic in the past year and who were current smokers at the time of their most recent clinical 
encounter will be approached in person at BHCHP clinical sites if they have a scheduled 
appointment or contacted proactively via phone (if they have listed contact information) by a 
research coordinator and screened for eligibility to participate. The BHCHP Chief Medical 
Officer has approved this recruitment strategy on behalf of all primary care providers at BHCHP 
clinical sites, who will in turn be notified about this recruitment approach (see attached letter of 
approval).  
c) Referrals from Boston Health Care for the Homeless Program (BHCHP) clinical staff: 
Physicians, advanced practitioners, nurses, and other clinical staff at each BHCHP site routinely 
screen all patients for tobacco use. We will inform BHCHP staff about the RCT through 
program-wide presentations and emails and encourage them to refer all current smokers for 
eligibility screening at one of the recruitment sites and/or securely message study staff about 
potentially eligible patients who may be good candidates for outreach screening as described in 
section (b). 
d) Recruitment flyers: We will post and distribute study advertisements at BHCHP sites to 
facilitate patient self-referrals for eligibility screening. 
e) Rescreening of previously screened participants: Participants who have previously been 
screened have also consented to letting study staff keep their data. Participants who were 
previously screened and ineligible due to time-varying factors such as not having seen their 
PCP in the past year, or participants who previously screened as eligible but did not enroll within 
two weeks of screening (see section V.A.2) will be periodically recontacted and invited to screen 
again to determine eligibility if they granted study staff permission to be contacted again. We will 
not contact participants who had previously told study staff that they did not wish to be 
contacted.  
Following screening, eligible individuals will be invited to attend a study enrollment visit to 
complete written informed consent and a baseline survey. 

 
IV. SUBJECT ENROLLMENT 
A. Methods of enrollment 
Participant screening, enrollment, and randomization will take place over the course of 3 visits: 
1) Screening visit: Individuals recruited through the above methods will be screened for study 
eligibility. Prospective participants who approach study staff during prespecified open-screening 
sessions at clinic sites will complete the entire eligibility screen in-person. Prospective 
participants who call study staff directly or who are proactively contacted for recruitment over 
the phone will be given the option to complete the eligibility screener questions over the phone 
and then complete the saliva cotinine test in-person at JYP (see section V.A.). We anticipate 
screening up to 1000 people in order to reach our target of 180 randomized participants. 
2) Enrollment visit: Individuals who are eligible for the study will be invited to attend a study 
enrollment visit for written informed consent, collection of demographic and contact information 
and assessment of baseline measures.  
3) Randomization and baseline clinician visit: Individuals who complete the enrollment visit and 
baseline survey will be asked to return for a baseline clinical evaluation by the study clinician. 
The study clinician will evaluate participants to determine if a varenicline prescription is 
appropriate and will provide the initial prescription for varenicline in most cases (see section 
V.A. for details). Concurrently, participants will be randomized to the control arm (N=90) or 
financial incentives arm (N=90). Randomization will be stratified by housing status (currently 
homeless vs. currently housed). Following randomization, staff will set up a brief introductory 
video on a tablet to orient participants to their study arm. Participants without a mobile phone 
will be provided one with a prepaid voice and text plan to facilitate communication and follow-up 
(see section V.C. for details).  
B. Informed consent procedures 
Informed consent will be obtained in person by a research staff person working under the 
direction of the PI. During the consent process, study staff will ask all potential participants if 
they would like to speak with a physician. If the participant chooses to speak with a physician, 
study staff will immediately send a secure message to the PI, Dr. Travis Baggett, who will 
respond to talk with the participants as soon as possible (within 30 minutes). To ensure that 
participants have an adequate understanding of the potential risks associated with study 
participation, all participants will be informed of these risks in plain language on a written 
informed consent document that will be read aloud to each participant, making no assumption of 
literacy.  
Participants will be informed of the option of not participating in the study and that their decision 
regarding study participation will in no way impact their ability to receive future services at 
BHCHP. Following a practice we established in our prior survey work involving homeless 
smokers and further refined in our pilot RCT for homeless smokers, we will confirm individuals’ 
understanding of the consent materials with basic knowledge questions about the consent 
document content to ensure that they have the capacity to provide informed consent. Individuals 
who are able to correctly answer these questions will be asked to sign the paper consent form if 

they wish to enroll in the trial. A signed copy will be retained by study staff and a second signed 
copy of the consent form will be given to participants for their own records. 
C. Treatment assignment 
Participants will be randomized 1:1 to the control arm (n=90) or the financial incentives arm 
(n=90). Randomization will be stratified by housing status to ensure balanced representation of 
housed and homeless individuals across the 2 study arms. The attached Study Schema 
provides an integrated summary of the screening, enrollment, and randomization procedures 
along with the components of each study arm and the principal study outcomes. 
The 2 study arms are as follows: 
    1) Control arm (n=90): Participants in this arm will be offered 12 weeks of varenicline and 5 
sessions of tobacco coaching. As an attention control to help ensure a similar level of contact to 
the financial incentives arm, control arm participants will have the option to attend 10 cotinine 
monitoring visits over 12 weeks during which they would submit saliva samples for cotinine 
testing and receive a fixed debit card payment, irrespective of the result.  
    2) Financial incentives arm (n=90): Participants in this arm will be offered 12 weeks of 
varenicline and 5 sessions of tobacco coaching in a manner identical to the control arm. These 
participants will also have 10 cotinine monitoring visits over a 12-week period where they will 
receive debit card payments for saliva cotinine levels <30 ng/ml. 
 
V. STUDY PROCEDURES 
A. Study visits and measurements 
A complete timeline of study activities is depicted in Figure 3 below. In total, this study will 
involve a screening visit, an enrollment visit, a randomization and baseline clinician visit, 2 
additional clinician visits, 5 tobacco coaching sessions, 10 on-treatment monitoring visits over 
12 weeks, and a post-treatment outcome assessment visit at 24 weeks. Participants must 
complete their enrollment visit within 2 weeks of their screening visit. The randomization and 
baseline clinician visit must be completed within 4 weeks of enrollment. During this visit, 
participants will be encouraged to set a quit date for the following week. Participants who are 
prescribed varenicline by the clinician will attend 2 follow-up clinician visits at weeks 3 and 7 (+/- 
1 week). The first tobacco coaching session will occur on participants’ quit date and the 
remaining 4 sessions will coincide with on-treatment monitoring visits at 2, 4, 8 and 12 weeks 
(or within one week after each of these time points). On-treatment monitoring visits will begin 1 
week after the quit date. Selected participants will additionally be asked to participate in 
qualitative interviews at the end of treatment (12 weeks) and at the end of follow-up (24 weeks). 
The content and measurements involved in each of these visits are described below.  
 
Figure 3. Study activities timeline 

 
Depending on space availability, participant preference, and the safety of having in-person 
interactions based on the status of the COVID-19 pandemic, study participants may complete 
surveys, coaching sessions, clinician visits, and qualitative interviews in the following ways: A) 
On-site in-person: Staff may administer the surveys/provide coaching in-person at a private 
area in the clinic space while adhering to physical distancing guidelines. B) On-site virtual: 
Study staff will set up a tablet in a separate on-site room for participants and administer the 
survey/provide coaching via Microsoft Teams or Enterprise Zoom. C) Remote and virtual: 
Participants with access to a phone, smartphone, or computer can complete the surveys, 
coaching sessions, clinician visits, and/or interviews virtually with study staff via phone call, 
Microsoft Teams, or Enterprise Zoom. 
Regardless of how participants complete study visits, the PI, Dr. Travis Baggett, and/or the 
study clinician will be available to advise study staff and speak with participants as needed. Any 
questions or concerns raised during the consent or enrollment phase in addition to any issues 
unrelated to varenicline raised throughout the study will be directed to the PI. Any questions or 
concerns related to varenicline raised throughout the study will be directed first to the study 
clinician, with the PI serving as back-up.  
1) Screening visit: Participants will be screened for study eligibility through measurement of 
the specific data variables listed in section VI.A. Participants who are proactively contacted for 
recruitment or who contact study staff directly will be offered the option to complete the eligibility 
screener questions over the phone. If their responses to the questions suggest that they are 
eligible to participate, they will be invited to meet with study staff in person at JYP to confirm 
their eligibility with a saliva test for cotinine. If the cotinine saliva test is consistent with current 
smoking, participants will be able to proceed with enrollment procedures. Both the eligibility 
screener saliva test and all enrollment procedures need to occur within 2 weeks after the 
participant answered the eligibility screener questions. Eligible participants who complete all 
components of the eligibility screening in-person during open screening hours will be asked to 
come back at a later time to complete enrollment procedures (also within 2 weeks). 
2) Enrollment visit: The enrollment visit will occur within 2 weeks after completing the 
screening visit. If more than 2 weeks has elapsed since screening, participants will need to be 
rescreened before proceeding to enrollment. During the enrollment visit, eligible participants will 
provide written informed consent. Enrolled participants will then complete a baseline 
assessment that includes measurement of the specific data variables listed in section VI.A and 
a demographics/contact form that includes data variables listed in section VI.A. Participants will 
also be provided with their CT Payer cards (listed below in section XI.A) during this visit upon 
completion of the baseline assessment survey. Participants will receive $25 for completing the 

baseline survey. Prior to randomization visits, CRCs will look up enrolled participants in the 
BHCHP electronic health record (EHR) and will complete a chart review form (data variables to 
collect listed in section VI.A). Enrolled participants will then be randomized to a study arm in the 
manner described above. 
3) Randomization and baseline clinician visit: The randomization and baseline clinician visit 
will occur within 4 weeks after completing the enrollment visit. If more than 4 weeks has passed 
since enrollment, participants will first need to undergo repeat screening to confirm their 
continued eligibility, followed by reassessment of baseline survey measures to inform 
randomization and identify conditions relevant to varenicline use (see below), before being 
allowed to proceed to randomization. During the randomization visit, study staff will reveal the 
participant’s group assignment and set up the introductory video which will explain the study 
components and the study schedule. After the introductory video, staff will provide participants 
with a study cell phone if applicable (see section V.C.). The participant will then be seen by the 
study clinician, as described in more detail below. During this visit, participants will be 
encouraged to set a quit date for the following week.52 Participants will receive $10 for attending 
this visit.  
4) Clinician visits: Participants who are enrolled and interested in varenicline will meet with the 
study clinician for a maximum of 3 visits. The first visit will occur at the time of randomization, as 
described above. At the first visit, the clinician will assess health conditions relevant to 
participants’ use of varenicline based on their responses on the baseline survey, their health 
history as documented in the BHCHP electronic health record, and their self-reported health 
history discussed during the visit. The clinician will use this information to follow a risk-based 
varenicline prescribing protocol detailed in section V.B. If the participant is undecided on 
whether they would like to try varenicline or if approval is needed from the participant’s PCP and 
is still pending, the clinician may delay writing the varenicline prescription for up to 2 weeks 
following the initial clinician visit. Participants prescribed varenicline at the start of the study will 
attend 2 on-treatment follow-up clinician visits in conjunction with monitoring visits at on-
treatment weeks 3 and 7 (or within 1 week pre or post these timepoints). During these visits, 
participants will meet with the clinician to discuss varenicline adherence and side effects, as well 
as to have their prescription refilled, adjusted, or stopped depending on participants’ 
preferences and degree of response and tolerance to the medication. During the week 7 visit, 
the clinician will also encourage the participant to think about whether they are interested in 
remaining on varenicline after they finish with their study prescription after 12 weeks. 
Varenicline will only be prescribed for 12 weeks in this study but can be safely prescribed for up 
to 24 weeks to increase the chances of long-term abstinences for those who have quit smoking 
or to further increase chances of quitting.52 If participants are interested in remaining on 
varenicline after completing 12 weeks, they will be encouraged to talk to their PCP to determine 
if continuing varenicline is appropriate for them. 
5) Tobacco coaching sessions: Coaching sessions will occur on the participants’ quit date 
and at monitoring visit weeks 2, 4, 8, and 12. To enhance uptake of these services and 
acknowledge the competing life priorities53-56 of homeless smokers, participants will receive $15 
for each coaching session they attend. Participants can complete coaching sessions up to 1 
week after the scheduled date. 
a) Session 1: A 30-minute baseline session will coincide with the participants planned quit date. 
During this session, the coach will assess participants’ readiness to quit, deliver a brief smoking 

cessation intervention using the “5 A’s” approach (Ask, Advise, Assess, Assist, and Arrange),57 
provide motivational interviewing on the use of varenicline, and introduce the “3-sided triangle” 
of tobacco addiction.  
b) Sessions 2-4: 20-minute follow-up sessions at 2, 4, and 8 weeks will review skills for quitting 
smoking. The counseling content of these visits will be based on the counseling protocol used in 
our pilot RCT, which incorporated elements of motivational interviewing and cognitive behavioral 
therapy, both applied in practical and concrete ways, to help homeless smokers overcome 
ambivalence about quitting and establish goals for behavior change. The protocol was 
structured around the American Lung Association Freedom from Smoking program theme of 
addressing the 3 parts of tobacco addiction: physical, mental, and social.58 Each session 
includes brief psycho-education in combination with skills-building and practical tips for coping 
with cravings, emotional triggers, and high-risk social situations, with content tailored to the 
unique circumstances of homeless people. 
c) Session 5: A final 30-minute session at 12 weeks will focus on identifying treatment needs 
following the study. For participants who have achieved abstinence at 12 weeks, this visit will 
focus on relapse prevention skills in addition to contingency planning for lapse or relapse. For 
non-abstinent participants, this visit will focus on motivational enhancement strategies. 
6) On-treatment monitoring visits: 10 cotinine monitoring visits will occur over 12 weeks. 
Monitoring visits will begin 1 week after the quit date and occur weekly through week 8, followed 
by every other week through week 12. These visits serve 2 purposes: a) to assess self-reported 
smoking behavior, varenicline use and side effects, and selected other measures (section VI.A), 
and b) to objectively verify smoking status through measurement of saliva cotinine. Cotinine is 
the major metabolite of nicotine, and saliva cotinine is widely used to verify smoking abstinence 
in research settings because it can be measured reliably, rapidly, inexpensively, and with 
minimal invasiveness using saliva collection devices and cotinine detection kits at the point of 
care.28 These qualities make the measurement of saliva cotinine a useful tool for verifying 
smoking abstinence in contingency management setting since contingent rewards are most 
effective when delivered immediately.59, 60 Frequent objective verification of smoking status 
provides frequent opportunities for abstinence-contingent financial rewards for incentive arm 
participants and serves as an attention control for control arm participants. 
Point-of-care saliva cotinine testing will be conducted using commercially available, 
professional-grade kits with documented performance characteristics and a cut-off level of 30 
ng/ml. Current examples include the Alere iScreen OFD cotinine oral fluid screening device and 
the Jant Accutest Saliva Cotinine Test, although other tests with similar performance 
characteristics may be used depending upon availability and supply chain considerations. 
Instructions and procedures provided by the manufacturer will be carefully followed during 
collection. Collected saliva samples will be discarded immediately upon reading the results and 
will be handled as if they were potential biohazards. No identifying information will be affixed to 
the samples. For participants in the financial incentives arm, payments will be based exclusively 
on having a negative point-of-care saliva cotinine test and will not rely on self-report.30 Payments 
for negative cotinine levels will begin at $25 and increase by $5 for each successive abstinent 
measurement up to a maximum of $70. Non-abstinent measurements, or failure to provide a 
saliva sample for cotinine measurement, will result in no payment and will reset the subsequent 
payment for an abstinent test back to the starting value of $25. An exception to this reset 
procedure will be made for participants who miss a monitoring visit due to COVID-related 

isolation or quarantine requirements (described in section G). These individuals will not have 
their incentive payment schedule reset to the starting value for a COVID-related absence, but 
rather will resume payments at the value following where they left off prior to the 
isolation/quarantine period. A similar exception will be made if the saliva cotinine test produces 
an invalid result. If this occurs during an intervention arm monitoring visit, the participant will be 
offered the chance to repeat the test for a 2nd and 3rd time on the same day and up to 3 times on 
the next business day. If invalid results persist on repeat testing, or if a participant refuses to 
attempt repeat testing, they will not be paid for the monitoring visit, but their incentive payment 
will not reset to the starting value and will remain at the value where they left off during their 
previous monitoring visit.   
To facilitate equivalent levels of contact for the incentive and control arm conditions, control arm 
participants will also have the opportunity to undergo cotinine monitoring visits according to the 
same schedule used for incentive arm participants. Control arm participants will receive a fixed 
amount of $10 for completing each monitoring visit, irrespective of their saliva cotinine levels. If 
a control arm participant has an invalid saliva cotinine test result, they will be offered the 
opportunity to repeat the test up to two more times during that visit, but they will still be paid $10 
for attending the monitoring visit and attempting to complete at least one saliva test even if no 
valid results are produced. In addition to verifying abstinence through the above point-of-care 
measurements, we will also formally assess the primary study outcome at the week 12 
monitoring visit. This will involve collecting a second saliva sample for send-out cotinine testing 
at a contracted laboratory that provides a more precise quantitative result using a 
chemiluminescence immunoassay or gas chromatography/mass spectrometry.61 We currently 
plan for J2 Laboratories to conduct this testing, although other laboratories offering assays with 
equivalent performance characteristics may be engaged if circumstances dictate doing so. For 
these tests, participants will be asked to hold a saliva collection sponge in their mouths for about 
5 minutes. When the sponge is completely wet, it will be placed back into the collection tube. 
The tube will be sealed and labeled with the participant’s study ID number so that no personal 
information is associated with the saliva sample. Instructions and procedures provided by the 
contracted laboratory will be carefully followed during collection. Samples will be batch mailed to 
the contracted laboratory, where saliva cotinine levels will be quantified. Sample results will be 
reported to research staff via password protected email exchange.  
During the week 12 visit, we will also administer a follow-up survey to reassess several of the 
baseline data variables (listed below in section VI.A). Participants who miss their 12-week 
monitoring visit will be able to complete the outcome cotinine saliva test and follow-up survey 
within 2 weeks. 
7) Post-treatment outcome assessment visit: A post-treatment visit will occur at 24 weeks. 
The purpose of this visit is to assess and verify smoking abstinence following the removal of all 
study treatments. Abstinence testing at this timepoint will be similar to the strategy outlined 
above for assessing on-treatment abstinence at week 12. Smoking abstinence will be assessed 
for all participants using the quantitative laboratory saliva cotinine test. In addition, smoking 
abstinence will be assessed by the point-of-care saliva cotinine test to allow staff to immediately 
categorize participants for potential qualitative interviews as described below. We will also 
administer a follow-up survey to reassess several of the baseline variables (listed below in 
section VI.A.) at each of these post-treatment assessment visits. Participants who miss their 24-
week outcome testing visit will be able to complete the outcome cotinine saliva tests and follow-
up surveys within 2 weeks of this timepoint.   

8) Qualitative interviews: We will conduct qualitative interviews with a purposively-selected 
sample of incentive arm participants to better understand why, how, and under what 
circumstances they A) achieve (or not) abstinence in response to financial incentives and B) 
maintain (or not) abstinence after incentives are stopped. Information gathered during these 
interviews will help generate hypotheses about potential mechanisms for on-treatment and post-
treatment effects and inform future modifications of the intervention.  
To address part A of this aim, we will purposively sample incentive arm participants at 12 weeks 
according to their on-treatment abstinence profile, categorized as follows:  
1) Non-responders (N=10): Earned <5 abstinence-contingent reward payments and divided 
into 2 subgroups a) concordant reporters (N=5): showed concordance between self-
reported and biochemically-verified abstinence and b) non-concordant reporters (N=5): 
showed non-concordance between self-reported and biochemically-verified abstinence 
throughout the trial.   
2) Partial responders (N=10): Earned ≥5 abstinence-contingent reward payments but was 
non-abstinent at the 12-week outcome assessment. 
3) Responders (N=10): earned ≥5 abstinence-contingent reward payments and was 
abstinent at the 12-week outcome assessment.   
Abstinence at the 12-week outcome assessment will be based on participant’s point-of-care 
saliva cotinine level. To account for a potential treatment effect of these interviews44 on 
subsequent 24-week smoking outcomes, we will interview 30 control arm participants at 12 
weeks about their general experience with attempting to quit smoking in the setting of 
homelessness. To attempt to achieve balance on abstinence profile, we will aim to recruit 20 
control arm participants who were non-abstinent at 12 weeks and 10 who were abstinent at 12 
weeks based on point-of-care salivary cotinine testing.  
To address part B of this aim, at 24 weeks we will purposively sample from 2 strata of incentive 
arm participants who achieved abstinent cotinine levels at 12 weeks:  
1) Sustained responders (N=10): Abstinent cotinine levels at 12 and 24 weeks 
2) Non-sustained responders (N=10): Abstinent cotinine level at 12 weeks but not at 24 
weeks.  
Abstinent cotinine levels will be determined by a negative laboratory saliva cotinine result at 12 
weeks and a negative point-of-care saliva test at 24 weeks. The point-of-care cotinine test will 
be used at the 24-week timepoint to ensure that interviews can be scheduled and completed 
within 2 weeks (since it may take up to 30 days for the laboratory cotinine test result to return).  
Actual sample sizes for each response profile may be adjusted until thematic saturation is 
reached. This sampling approach will ensure a diverse set of experiences with the financial 
incentives intervention and will aid in understanding the factors underpinning variability in 
treatment responsiveness. Part A participants will be recruited by study staff within 2 weeks of 
their 12-week follow-up visit. Part B participants will be recruited by study staff within 2 weeks of 
their 24-week follow-up visit. Audiotaped interviews lasting up to 60 minutes will be conducted 
by trained study staff following semi-structured interview guides addressing the content areas 
described below in section VI.A. Participants will receive $30 in remuneration on their study-
issued debit card for participating in these interviews. 

B. Drugs 
Participants in both study arms will be offered a prescription for varenicline, an FDA-approved, 
first-line smoking cessation medication33 that has been shown to be safe and effective in at-risk 
populations, including those with comorbid psychiatric conditions,38 alcohol use disorder 39 and 
substance use disorders.40, 41 In general, varenicline prescriptions will be issued by the study 
clinician who will meet with participants at the randomization visit to assess their health history 
and relevant comorbid conditions. In most cases, participants will receive a 1-month prescription 
for varenicline from the study clinician according to the recommended 7-day loading procedure 
of 0.5 mg daily on days 1-3 then 0.5 mg twice daily on days 4-7 before reaching the target dose 
of 1 mg twice daily on day 8.52  
After the completion of the enrollment visit, study staff will contact the participant’s PCP to 
inform them of their patient’s enrollment in a stop smoking study in which varenicline will be 
offered. Unless the participant reports a history of specific comorbidities, PCP permission will 
not be required before the study clinician meets with the participant and prescribes varenicline 
at the typical dosage. However, PCPs will be invited to respond to study staff messages to 
express any questions or concerns, and if the PCP recommends that varenicline is not 
prescribed, the study clinician will follow this recommendation. For participants with selected 
comorbidities, including seizure history, chronic kidney disease, or higher-risk mental states, we 
will follow a systematic algorithm to ensure safe varenicline prescribing (Appendix 2). 
Comorbidities will be assessed in various ways, including a) participants’ responses to the 
eligibility screener and baseline survey items related to chronic medical conditions and mental 
health symptoms, b) review of documented comorbidities within participants’ EHR, and c) 
baseline clinical assessment by the study clinician. The action plans in response to specific 
comorbidities (as visualized in Appendix 2) are explained further below: 
1) Seizures: During the baseline survey, participants will be asked if they have a lifetime 
history of seizures, and if yes, whether they had a seizure in the past year. If the 
participant has had a seizure within the past year, study staff will send the participant’s 
PCP a direct message via Epic on the same day as the enrollment visit informing them 
of their patient’s enrollment in the study and requesting input from the PCP regarding 
whether a prescription for varenicline is appropriate. The study clinician will not prescribe 
varenicline to such a participant until explicit permission from the PCP is granted. If the 
participant has not had a seizure within the past year, study staff will still send the 
participant’s PCP a direct message informing them of their patient’s enrollment in the 
study and invite their input if they have any questions or concerns; however, the clinician 
will proceed with prescribing varenicline unless the PCP directly expresses that the 
participant should not take varenicline. 
2) Chronic kidney disease (CKD): For participants with a history of CKD, our varenicline 
prescribing protocols are based on past research on varenicline use in patients with 
renal impairments and the recommendations listed on the Pfizer varenicline packet 
insert.52, 62 During the baseline survey, participants will be asked if they have a lifetime 
history of CKD, and if yes, whether they are currently on dialysis. For participants on 
dialysis, the clinician will prescribe varenicline at a maximum dose of 0.5 mg once daily 
(a quarter of the typical maximum dose). For participants who are not on dialysis, the 
clinician will recommend that the participant completes lab testing to ascertain current 
serum eGFR levels. If the participant refuses new labs, the clinician will prescribe 

varenicline at a maximum dose of 0.5 mg twice per day (half the maximum typical dose), 
which is the recommended dose for patients with severe renal impairment (eGFR < 30). 
Participants who agree to have labs drawn will be prescribed varenicline according to 
their eGFR results. If the participant’s eGFR is <30, the clinician will prescribe 
varenicline at a maximum dose of 0.5 mg twice per day. If the participant’s eGFR is ≥30, 
the clinician will up-titrate varenicline to the typical maximum dose of 1.0 mg twice per 
day. In all cases, study staff will send an Epic message to the PCPs of participants with 
any degree of CKD to inform them of their patient’s enrollment in the study; however, the 
clinician will proceed with prescribing varenicline according to the above well-defined 
clinical protocols unless the PCP directly recommends otherwise. 
3) Higher-risk mental health states: Participant suicidality will be assessed during the 
eligibility screener, and other mental health symptoms will be assessed during the 
baseline survey using multiple assessments, as described in section VI.A. If the 
participant reports vague suicidal ideation but is otherwise found to be at low risk of 
suicide based on the C-SSRS primary care screening instrument (patients with  high risk 
will be excluded) or if the participant is considered moderate risk of suicide only due to 
suicidal behavior over 12 months ago, study staff will send the participant’s PCP a direct 
message via Epic on the same day as the enrollment/baseline survey study visit 
informing them of their patient’s enrollment in the study and requesting input regarding 
whether prescribing varenicline is appropriate. The same procedure will occur for 
participants with high scores on standardized mental health symptom instruments 
administered during the baseline survey (see Appendix 2). The study clinician will not 
prescribe varenicline to the patient until explicit permission from the PCP is granted.   
At the time of the baseline clinician visit, the participant may be undecided on whether they want 
to try varenicline, or final approval from the participant’s PCP or other provider may still be 
pending. In these instances, the clinician can delay issuing a varenicline prescription for up to 2 
weeks. Undecided participants will be told to inform study staff if they decide to take varenicline. 
If PCP/provider approval is still pending, the study clinician will directly contact the PCP/provider 
to ensure that a direct answer is provided within the 2-week window. Upon meeting with the 
participant, the study clinician may determine based on chart review or clinical assessment that 
the participant has concerning comorbidities, symptoms, or circumstances that were not 
uncovered during screening and enrollment. In these cases, the clinician may determine that 
direct PCP input is necessary before prescribing varenicline and will direct message the 
participant’s PCP to obtain this input before prescribing.  
For participants who are prescribed varenicline at baseline, treatment will continue for 12 
weeks, distributed in 1-month allotments in conjunction with follow-up clinician visits at 3 and 7 
weeks to assess medication adherence and tolerance. Dose adjustments will be made for 
participants who experience non-serious side effects. 
The clinician will electronically send varenicline prescriptions directly to the BHCHP pharmacy 
or to an alternative pharmacy (based on patient request and current supply), where participants 
will be instructed to fill their prescriptions. The majority of participants will have MassHealth 
insurance and can obtain their prescription with a $3.40 copay that can be waived by the 
pharmacy if needed. The BHCHP pharmacy is also a covered entity under the 340B low-cost 
medication program and can therefore dispense varenicline at a very low cost (~$0.55 per 
month) to participants without insurance. Given the low cost of varenicline under 340B pricing 

and the low likelihood of recruiting participants without MassHealth, BHCHP has agreed to 
voucher the medication costs for participants who have no insurance or who have insurance 
that only offers varenicline at a high copay. If a participant requests to use an alternative 
pharmacy, the clinician will electronically send the varenicline prescription to this preferred 
pharmacy instead. 
C. Devices 
Participants who do not have a mobile phone of their own will be given a low-cost mobile device 
(~$30/unit) with a 12-month talk and text plan (~$125/year through Tracfone) to facilitate 
communication and follow-up. If a participant loses or sells their device, the phone will not be 
replaced, and their plan will be deactivated. To incentivize phone retention, participants who still 
have their device at the end of the study will be allowed to keep it. 
D. Procedures 
There will be no procedures or surgical interventions in this study. 
E. Data Collection 
All data will be collected using password-protected, Mass General Brigham-approved laptops or 
tablets with full-disk encryption. We will use the Mass General Brigham-hosted Research 
Electronic Data Capture (REDCap) application for data collection and management. The 
specific data elements collected at each study visit are detailed below in section VI. 
F. Electronic Communication 
The Twilio text messaging feature will be integrated into our REDCap database. This will allow 
study staff to send participants automated text message reminders about their next scheduled 
appointment and the maximum potential payment they can earn at this visit. Text messages will 
not include any identifying information and participants can opt out at any time by texting the 
word “STOP” (see Appendix 1 for sample text messages). Participants must consent to receive 
these text messages. The consent form includes information outlined in the Mass General 
Brigham guidelines for texting research subjects.63 
Study staff may use Mass General Brigham’s HIPAA-compliant video conference platforms, 
Microsoft Teams or Enterprise Zoom, to administer surveys and complete coaching sessions as 
part of the team’s in-person remote COVID-19 safety protocol (see section V.A). Participants 
who prefer this form of engagement will arrive to the BHCHP clinic where on-site study staff will 
set up a Teams or Zoom call on a study tablet for the participant to use. Participants will 
participate in the video call using headphones in a private or semi-private space within the clinic; 
study staff will administer the survey or complete the coaching session via Teams or Zoom 
either on-site (in a separate room) or remotely. This will minimize in-person contact between 
study staff and participants while allowing participants and study staff to engage in potentially 
sensitive conversations during the surveys and coaching sessions. For safety and security, no 
Teams or Zoom links will be shared with participants. Teams or Zoom meetings will require 
passwords and will not be shared with anyone other than study staff. Participants will be 
instructed not to use the chat function during these meetings as the feature is not encrypted. 
Participants will also be advised that photographs and recordings of Teams or Zoom calls are 
not allowed. 

Participants may meet with the study clinician via MGB-hosted Microsoft Teams, MGB 
Enterprise Zoom, or BHCHP’s Epic/OCHIN integrated HIPAA-compliant Zoom platform. The 
third option allows participants to engage with the clinician in the manner currently used to 
provide COVID-safe virtual clinical care at BHCHP.  
Study staff may also engage with participants over the phone. If participants prefer remote 
virtual study visits for COVID-19 precautions, study staff will conduct surveys, coaching visits, 
interviews, and some clinician visits over the phone. Study staff will call participants from study 
cellphones or BHCHP land lines. Participants will provide a contact number during the 
enrollment visit and can update the contact number as necessary.  
Study staff may use Imprivata cortex, a HIPAA-compliant secure communications platform, to 
communicate with the study clinician using designated work iPhones encrypted with iOS 
MobileIron Mobile Device Management (MDM) software. 
G. COVID-19 Contingency Plans:  
The team is engaged in contingency planning and will continue to monitor hospital, state, and 
federal guidance on COVID-19. Should a resurgence of COVID interfere with the ability to 
implement the study protocol as written here, the team will implement contingency plans that will 
be adopted for the circumstances and restrictions present at the time of a future surge.  
Participants and staff will be asked to follow current CDC guidelines regarding isolation and/or 
quarantine in the event of developing COVID-19 symptoms or experiencing a significant 
COVID-19 exposure. The implications of COVID-related absences for incentive arm payments 
are discussed above.  
H. Procedures for Restarting Enrolled Participants 
As described in protocol amendment 11, all study activities were paused on 07/06/21 due to a 
global shortage of varenicline resulting from elevated levels of nitrosamine contaminants 
prompting a recall of all Pfizer-manufactured varenicline on the market. The safety 
considerations related to this are addressed in section VII.B. At the time of study suspension, 11 
participants were enrolled. 
Once the study resumes, the 11 participants who were previously enrolled will be approached 
by phone or in person to be invited to restart the study. Participants interested in restarting the 
study will do so under their original study ID number and randomized group assignment but will 
be asked to redo all other study activities. If participants are interested in restarting the study, 
they will be asked to complete the eligibility screener questions and saliva test (see section 
V.A.1.) to confirm their continued eligibility before completing two study restart appointments as 
described below.    
To ease the response burden, participants will be offered the option to complete the eligibility 
screener questions over the phone. If their responses to the questions suggest that they are still 
eligible to participate, they will be invited to meet with study staff in person at JYP within two 
weeks to confirm their eligibility with a saliva test for cotinine. If the cotinine saliva test is 
consistent with current smoking, participants will immediately proceed with the first study restart 
appointment. Participants who opt to complete all components of the eligibility re-screening in 
person will meet with study staff at JYP and, if still eligible, will be invited to complete the first 
study restart appointment either immediately or within 2 weeks. Participants who are found to no 

longer be eligible during any component of the eligibility re-screening process will be given the 
option to either screen again at a later date (if the reason for ineligibility is a time-limited issue 
such as connectedness to care) or to unenroll from the study.  
At the first study restart appointment, participants will follow procedures similar to the enrollment 
appointment discussed in section V.A.2. Study staff will review an updated version of the 
consent form with participants, and participants will be required to sign this updated version of 
the consent form to continue study participation. Study staff will then confirm participants’ 
current demographic and contact information and repeat the full baseline survey. Participants 
will receive $25 for completing this first appointment. Following this first appointment, all PCPs 
will be messaged using the same procedures described in sections V.A.4 and V.B. PCPs will 
need to give permission for the study clinician to prescribe varenicline for participants who 
report various health concerns during their most recently-completed eligibility screener and 
baseline survey. 
The second study restart appointment must be completed within 4 weeks of the first study 
restart appointment. Participants will follow the same procedures described in sections V.A.3 
and V.A.4, with the exception that participants who were previously randomized will retain their 
original treatment group assignment. Participants who do not have their own phone will be 
offered a study phone and will be paid $10 for completing this study visit. 
Participants who complete both the first and second appointments will restart the study at week 
0, which corresponds with the quit date and first tobacco coaching session, approximately 1 
week after their second study restart appointment. 
All data collected during the original study launch prior to the pause will be exported from 
REDCap and archived in the secure Lab Archives system to allow for a clear audit trail of any 
changes to the data. In REDCap, new instances of forms will be created for any repeatable 
forms, and new data will overwrite old data as needed for non-repeatable forms. Study staff will 
log all instances of updates to existing non-repeatable forms within REDCap. The most recent 
data will be used for analyses and earlier data will be disregarded.  
 
VI. BIOSTATISTICAL ANALYSIS 
A. Specific data variables 
The specific data elements collected at each visit are as follows: 
1) Screening visit data elements: This visit will focus on assessing variables related to the 
inclusion and exclusion criteria. Variables collected during this visit will include: 
- 
First and last name 
- 
Date of birth 
- 
Native language and self-reported comfort communicating in English among non-native 
speakers 
- 
Ever smoked ≥100 cigarettes 
- 
Current cigarettes per day 
- 
Saliva cotinine level ≥30 ng/mL, based on point-of-care testing 
- 
Prior serious allergic reactions to varenicline  

- 
Currently pregnant, planning to become pregnant, or breastfeeding 
- 
Readiness to try quitting smoking within the next 3 months 
- 
Prior experience with homelessness 
- 
Presence of BHCHP electronic health record 
- 
Name of BHCHP PCP (and if PCP has been seen within the past year) 
- 
History of psychiatric hospitalization within the past 3 months 
- 
Suicidal ideation and behavior, based on the C-SSRS48 
- 
Among individuals who are eligible and wish to schedule an enrollment visit or who are 
ineligible but would be interested in attempting screening again in the future, we will 
collect their current phone number (if any) to facilitate communication about the 
enrollment visit 
2) Enrollment visit data elements: When individuals present for enrollment, we will confirm 
that they have previously screened eligible for the study. For those who wish to enroll in the 
study, we will collect additional demographic and contact information: 
- 
Gender 
- 
Pronouns 
- 
Social security number 
- 
Current residence or place where sleeping at night 
- 
Current phone number (if any); confirm/update number if previously collected at 
screening visit 
- 
Emergency contact information 
- 
BHCHP medical record number 
- 
Insurance coverage listed within BHCHP electronic health record 
We will also conduct a baseline survey assessing the following variables at the time of 
enrollment: Italicized measures will be collected during follow-up surveys at weeks 12 and 24:  
Domains 
Measures 
Sociodemographic 
Race/ethnicity; education; health insurance (all based on items from the 
2003 HCH User Survey23, 64 and our prior survey work45, 65, 66) 
Homelessness 
Homelessness  episodes and duration67; living situation; past-month 
subsistence difficulties53  
Mental/physical 
health 
General health status (SF-1)68, 69; single item measurement of cigarette 
craving70; chronic medical conditions; Domains related to COVID-19, 
including diagnosis and symptom history71, 72, change in quitting 
motivation 73, 74, and receipt of the COVID-19 vaccine; AUDIT 76-78; 
DAST-10 78,79; past 3-month drug use inventory80,81 ; PHQ-9 82,83; GAD-
784; MDQ85, 88, 89; PSQ92, 95, 96  
Tobacco use 
Age of initiation; past quit attempts (>24 hours); use of cessation aids; 
use of e-cigarettes or vape products; cigarettes/day; Fagerstrom Test 
for Nicotine Dependence88; 10-point importance and confidence 
scales2, 16, 18; stage of change91, 92; Contemplation Ladder91; social 
support for quitting18, past month use of alternative tobacco products 66 
 
3) On-treatment monitoring visit data elements: The following variables will be collected at 
the timepoints specified in parentheses. If participants miss their week 12 monitoring visit, the 
underlined elements will be asked during the follow-up survey visit up to 2 weeks later. 

- 
Point-of-care saliva cotinine level (every monitoring visit, per Figure 3) 
- 
Date and time last smoked all or most of a cigarette (every monitoring visit) 
- 
Date and time of last puff of cigarette (every monitoring visit) 
- 
Number of smoking days in the past 7 days (every monitoring visit) 
- 
Average number of cigarettes per day (every monitoring visit) 
- 
Use of vape or e-cigarette in past 7 days (every monitoring visit) 
- 
Use of other tobacco products in past 7 days (every monitoring visit) 
- 
Single item measurement on cigarette craving (every monitoring visit)70 
- 
Past week use of varenicline prescribed by study clinician (every monitoring visit) 
- 
Average number of varenicline pills taken per day (if applicable, based on whether the 
participant is prescribed varenicline by the study clinician; every monitoring visit) 
- 
Use of other quit smoking aids (every monitoring visit) 
- 
Side effects to varenicline, including abnormal dreams, aggressive/erratic behavior, 
headaches, nausea, sleep disturbance/insomnia, vomiting, and other (if applicable; 
every monitoring visit) 
- 
Suicidal thoughts, intention, and behaviors since last study visit, as measured by a 
modified version of the C-SSRS (if applicable; every monitoring visit).48 
- 
Other adverse events not related to varenicline if reported by participant (every 
monitoring visit) 
- 
All items italicized in the baseline survey table above at 12 weeks, or within 2 weeks 
post 
- 
Saliva cotinine level from results of laboratory cotinine testing at 12 weeks, or within 2 
weeks post 
4) Post-treatment outcome assessment visit data elements: The following variables will be 
collected at 24 weeks, or within 2 weeks post, unless otherwise specified in parenthesis.  
- 
Point-of-care saliva cotinine level (incentive participants only)  
- 
Date and time last smoked all or most of a cigarette 
- 
Date and time of last puff of a cigarette  
- 
Number of smoking days in the past 7 days 
- 
Number of quit attempts in the past 3 months  
- 
Use of cessation aids 
- 
Use of vape or e-cigarette in the past 7 days 
- 
Use of other tobacco products in the past 7 days 
- 
All items italicized in the baseline survey table above 
- 
Laboratory saliva cotinine level 
5) Coaching session data elements: Baseline, 2, 4, 8, and 12 weeks (or within 1 week) 
- 
Confidence to quit smoking (or to stay quit) 
- 
Importance of quitting smoking (or staying quit) 
- 
Past-month quit attempts 
- 
Summary of coaching session, including experiences delivering the intervention 
including the ease of delivery (including the length, scheduled time); the apparent 
acceptability and relevance; comprehension of the material by the participants; and 
factors that impeded or assisted in the delivery, and any issues related to safety or 
potential harms that emerge.  

6) Qualitative interview data elements: 12 and 24 weeks (or within 2 weeks post) 
    We will create 2 interview guides for incentive arm participants selected for qualitative 
interviews: one guide to address part A of this aim at 12 weeks, and a second guide to address 
part B of this aim at 24 weeks. Both will be structured around exploring the cognitive (‘why?’), 
procedural (‘how?’), and contextual (‘under what circumstances?’) dimensions of participants’ 
response (or lack of) to the financial incentives intervention during and after treatment. 
    ▪ Cognitive: Questions in this domain will explore why participants abstain (or not) from 
smoking in response to financial incentives. A) At 12 weeks, interviewers will probe: the 
perceived impact of incentives on smoking cognitions, such as readiness, motivation, and 
confidence to quit or importance of quitting; the extent to which the extrinsic motivation of 
incentives was internalized by participants; the importance of incentive dollar amounts, 
frequency, and format on the perceived potency of incentives; the perceived fairness and 
understandability of the incentives scheme; and the overall utility of financial incentives in 
promoting cessation, particularly in relation to other treatments tried by participants. B) At 24 
weeks, interviewers will probe: how participants coped with transitioning off incentives; how 
smoking cognitions, such as readiness, motivation, and confidence to quit or importance of 
quitting, changed following the removal of incentives; and the extent to which participants were 
successful (or not) in shifting from extrinsic to intrinsic motivational pathways. 
    ▪ Procedural: Questions in this domain will explore how participants abstain (or not) from 
smoking in response to financial incentives. A) At 12 weeks, interviewers will probe: 
participants’ use of varenicline and other pharmacotherapies, coaching or other counseling 
services, or other mainstream or alternative strategies for quitting; how these supplemental 
strategies facilitated or impeded their response to the incentives intervention; and whether the 
intervention had spillover effects in promoting related healthy behaviors that reinforced 
abstinence, such as increasing physical activity or reducing concurrent substance use. B) At 24 
weeks, the above areas will be explored again, but with a focus on assessing whether these 
behavioral strategies for sustaining abstinence increased, waned, or remained stable after 
incentives were removed. 
    ▪ Contextual: Questions in this domain will explore the individual and social circumstances 
under which participants abstain (or not) from smoking in response to financial incentives. At 
both 12 and 24 weeks, interviewers will probe the ways in which individual material 
circumstances, such as housing status, food security, personal safety, and other basic survival 
needs; individual comorbidities, such as physical ailments, psychiatric symptoms, and 
concurrent substance use disorders; and social milieu characteristics, such as friends who 
smoke, second-hand smoke exposure, social support for quitting, and access to smoke-free 
settings, collectively influence A) on-treatment abstinence initiation and B) post-treatment 
abstinence maintenance in response to the financial incentives intervention. We will also probe 
whether and how this relatively ‘high-touch’ intervention strategy fits within the broader social 
context of participants’ lives in order to optimize the approach for subsequent studies aiming to 
disseminate and implement this treatment modality. 
    A third interview guide will be developed for control arm participants that will generically 
explore their experiences with quitting smoking in the context of homelessness or unstable 
housing. 
B. Study Endpoints 

1)  Primary outcome: The Aim 1A outcome is saliva cotinine-verified 7-day smoking abstinence 
at 12 weeks. Participants who report not smoking in the past 7 days and have a saliva cotinine 
level of <10 ng/mL at the week 12 timepoint will be considered abstinent.  
2)  Secondary outcome: The Aim 1B outcome is 7-day smoking abstinence at 24 weeks, 
based on self-report and verified by a salivary cotinine level of <10 ng/mL. 
3)  Other outcomes: Other outcomes include 7-day smoking abstinence at weeks 1-11 
(defined as no smoking the past 7 days and having a point-of-care saliva cotinine level <30 
ng/ml), use of varenicline or other smoking cessation medications (assessed by self-report and 
BHCHP chart review), use of other tobacco treatment resources, changes in past-month drug 
and alcohol use and psychiatric symptoms (assessed with the AUDIT 76-78, DAST-10 78,79,drug 
use inventory, PHQ-9, 82,83 GAD-7,84  at 12 and 24 weeks).  
C. Statistical Methods 
Quantitative analysis: Quantitative analysis will be based on the intention-to-treat principle. 
We will use Chi-squared tests to assess the difference between arms on attainment of the 
primary and secondary outcomes. Cochran-Mantel-Haenszel tests will determine whether the 
intervention effect is homogenous across study sites. We will use logistic regression to assess 
the intervention effect while adjusting for site. In primary analysis, participants who do not 
provide a saliva sample or are lost to follow-up will be assumed non-abstinent. A sensitivity 
analysis will use multiple imputation to impute missing outcomes data based on non-missing 
variables.94, 95 In addition to cross-sectional analyses of the primary and secondary outcomes, 
we will conduct a repeated measures analysis of smoking status at 12 and 24 weeks to assess 
the overall impact of financial incentives on smoking abstinence. This analysis, which provides 
greater statistical power than cross-sectional analyses, will use generalized estimating 
equations (GEE) to account for the correlated data structure. We will also use GEE to analyze 
the other outcomes of changes in cigarette consumption, WHO ASSIST drug and alcohol 
scores, and mental health scores, each measured at baseline and 12 and 24 weeks. 
Qualitative analysis: All interviews will be transcribed verbatim by a professional service and 
analyzed using NVivo 11 software. Data analysis will be based on a grounded theory 
approach94 and will occur concurrently with data collection to ascertain when thematic saturation 
is reached for each sampling stratum. Two trained study staff members, working in parallel 
under the direction of Drs. Baggett, Park, and Kruse, will begin by open-coding the raw 
transcript data to form initial categories using a principally inductive approach.95 During weekly 
team meetings, the method of constant comparison96,97 will be used to iteratively refine these 
categories, to resolve discrepancies through discussion and reference to raw data until high 
inter-rater reliability (K≥0.80) is achieved, and to organize emergent major and minor themes 
into a hierarchical framework. Analyses will compare findings across treatment response 
profiles to generate insights about the reasons for response variability. Consistent with the 
embedded-experiment mixed methods design,44 the qualitative data will be used to answer the 
basic question: “To what extent do the qualitative process findings enhance the understanding 
of the experimental outcomes?”98 Toward that end, the qualitative findings will be included in the 
main paper reporting the RCT results to provide a more nuanced picture of why and how the 
intervention produced the outcomes it did. Subsequent papers will make further use of the 
qualitative data to examine why certain subgroups fare better with financial incentives, to 
introduce a conceptual framework for incentive-based health interventions for homeless 

individuals, to share lessons learned about the practicalities of designing and deploying an 
incentives intervention for this population, and to inform future modifications of the intervention. 
D. Power Analysis 
Our power calculation is based on the Aim 1A outcome of cotinine-verified smoking abstinence 
at 12 weeks. With a sample arm of 90 per arm, we will have >80% power to detect a difference 
in abstinence at 12 weeks of 4% in the control arm and 17.5% in the incentives arm at a two-
tailed p of 0.05.  
 
VII. RISKS AND DISCOMFORTS 
The potential risks and discomforts associated with this study are detailed below. The methods 
for mitigating these risks and monitoring the safety of participants are described in section IX.B. 
A. Complications of surgical/non-surgical procedures 
Not applicable. 
B. Drug side effects and toxicities 
Participants will be offered a prescription for varenicline. Common side effects of varenicline are 
nausea, sleep problems, constipation, gas, and vomiting. Other possible, but less common, side 
effects include cardiovascular (chest pain, hypertension, tachycardia), sleep walking, allergic 
reactions, or serious skin reactions. Participants who are taking varenicline prescribed by the 
study clinician will be assessed for varenicline side effects and suicidality at each on-treatment 
monitoring visit. Procedures for addressing participants with significant side effects and 
suicidality are described below (section IX. D.). 
In June 2021, Pfizer announced a halt in global distribution of varenicline (brand name: Chantix) 
and a voluntary recall of selected lots after finding heightened levels of N-nitroso-varenicline (a 
nitrosamine compound) in some pills. Although the risk posed by N-nitroso-varenicline is 
uncertain, nitrosamine compounds in general are considered carcinogenic when exposure 
occurs in sufficient doses over prolonged periods of time. The nitrosamine levels found in 
Pfizer’s varenicline product exceeded the FDA’s acceptable intake limit of 37 ng per day. In 
September 2021, Pfizer extended its recall to all lots of varenicline. 
The FDA has since approved two generic versions of varenicline: one manufactured by Apotex 
and one manufactured by Par Pharmaceuticals. The FDA also announced that they would not 
object to manufacturers distributing varenicline tablets above the FDA’s original acceptable 
intake limit of 37 ng per day but below an interim acceptable intake limit of 185 ng per day. Both 
of the above generic versions of varenicline distributed by Apotex and Par have levels of N-
nitroso-varenicline that are within the FDA’s interim acceptable intake limit.99  
Study staff are working closely with the BHCHP pharmacy to ensure participants receive a 
varenicline product that falls within these interim safe limits. During informed consent, staff will 
inform participants of the risk of contamination of varenicline products while also clarifying that 
the versions they will receive have been deemed safe by the FDA. 
C. Device complications 

Not applicable.  
D. Psychosocial (non-medical) risks 
i) Psychological and/or physical discomfort: Quitting smoking can be psychologically stressful 
and, at times, physically uncomfortable because of cravings and nicotine withdrawal symptoms, 
such as irritability, depressed mood, sleep difficulty, and concentration difficulty. Participants will 
be asked to what extent they have craved cigarettes at each on-treatment monitoring visit.  
ii) Risk to privacy: We will collect and record identifying information (e.g. name, date of birth, 
and social security number) and ask participants about potentially sensitive topics. There is a 
risk to privacy if this data is compromised. 
E. Radiation risks 
Not applicable. 
G. Potential loss of study mobile phone  
Participants may be at minimal risk of a breach of privacy if someone else gains access to their 
phone during the study. Therefore, we will inform participants of this risk during recruitment and 
encourage participants to mitigate this risk by 1) not sharing their phone with others, 2) 
password protecting their mobile device, and 3) in the event of loss, notifying research staff to 
terminate service to the device. Automated appointment reminder text messages will be sent to 
participants. These text messages are designed to convey relevant information to participants 
while having a protective level of ambiguity. 
 
VIII. POTENTIAL BENEFITS 
A. Potential benefits to participating individuals 
Potential benefits for participants include the opportunity to receive assistance with smoking 
cessation, which may reduce their risk of tobacco-related health complications in addition to 
reducing the amount of money they direct toward purchasing cigarettes. The scope and 
magnitude of these potential benefits outweigh the risks to human subjects. 
B. Potential benefits to society 
As in the general population, cigarette smoking is a major contributor to morbidity and mortality 
among homeless people.14, 15 Strategies to reduce smoking among homeless people may 
reduce the personal and financial costs of smoking-related health complications in this 
population. Knowledge gained from this study could contribute to this effort by improving the 
treatment of homeless smokers in other settings. 
 
IX. MONITORING AND QUALITY ASSURANCE 
We judge the proposed study to represent a low-risk phase III behavioral intervention trial. In 
view of the vulnerable nature of the study population, we will create a Data and Safety 
Monitoring Board (DSMB), consisting of researchers not involved in the study who have 
expertise in clinical trials and/or vulnerable populations, to oversee the integrity of the data and 

the safety of participants. The objectives and procedures of the DSMB are explained further 
below (section IX.I.). The following data and safety monitoring procedures (sections IX.A.-IX.G.) 
will be implemented throughout the study.  
A. Data acquisition and monitoring 
All data will be collected using password-protected, Mass General Brigham-approved laptops or 
tablets with full-disk encryption. We will use the Mass General Brigham-hosted Research 
Electronic Data Capture (REDCap) application for data collection and management. REDCap is 
a secure, HIPAA-compliant web-based application hosted by Mass General Brigham 
HealthCare Research Computing Enterprise Research Infrastructure & Services (ERIS). 
Because a Mass General Brigham username is required for logging in to REDCap, all activity on 
study documents is electronically logged and therefore traceable. To help guard against errant 
data entries, REDCap has built-in functions providing real-time data entry validation to help 
ensure accuracy and completeness. Data will be collected according to a standardized protocol 
that will detail which data elements should be collected at each study visit and the methods for 
doing so. We will operationalize this protocol by using the calendar function in REDCap to 
specify which data collection forms to administer on which dates for each participant. Each data 
collection form will have instructions or prompts for collecting the required data elements, and 
the response fields for each item will have appropriate ranges and formats to ensure that the 
data is entered in a valid way. 
Data collected in REDCap is saved by default to a secure, HIPAA-compliant server. To help 
ensure the safety and integrity of the study data, the data will be periodically exported from 
REDCap and backed up to a HIPAA-secure shared file area (SFA) accessible only to authorized 
study staff after logging on to the Mass General Brigham network. Data saved to the study SFA 
can be accessed only via the Mass General Brigham-approved computing device, which by 
default includes antivirus software and, if the device is portable, full-disk encryption. The SFA is 
backed up nightly by the Mass General Brigham Information Systems department to guard 
against data loss or corruption. Access to the study SFA will be overseen by the PI and can be 
changed only by a designated key-giver (who is independent of the study) under the explicit 
direction of the PI. In addition to the SFA, selected data elements may also be stored on a 
project-dedicated Mass General Brigham Microsoft SharePoint site. Data saved on the project-
dedicated SharePoint site will be accessible only to study staff. 
The qualitative interviews conducted at 12 and 24 weeks will be recorded by a microphone 
connected directly to a password-protected, Mass General Brigham-approved laptop or tablet 
with full-disk encryption. Audio files will be backed up to the PI’s SFA described above and then 
deleted from the portal device. 
The study data will be examined on a weekly basis by the REDCap database programmer, 
working in conjunction with the PI, to identify patterns of missing data or non-response, to 
ensure that critical variables are being captured and recorded as intended, and to generate 
recruitment and enrollment reports for review by the PI in conjunction with the co-investigators. 
Free-text notes recorded by data collectors will be examined to identify potentially problematic 
items that may require additional clarification. The database programmer will prepare cleaned, 
de-identified analytic datafiles for use by the biostatistician to conduct the data analyses 
described in the Research Strategy. Analyses will occur periodically throughout the study and 

the findings will be reported in annual progress reports to the NIH and in continuing review 
reports for the Mass General Brigham IRB. 
B. Quality assurance 
The tobacco coach will complete a checklist indicating topics covered during the counseling 
sessions and will record process notes after each session. He/she will record experiences 
delivering the intervention including the ease of delivery (including the length, scheduled time); 
the apparent acceptability and relevance; comprehension of the material by the participants; 
and factors that impeded or assisted in the delivery, and any issues related to safety or potential 
harms that emerge. 
Using a random selection process, the tobacco coach will identify a sub-sample of 15% of 
sessions to audio record. A clinical psychologist will periodically review the recordings and 
provide direct feedback to the tobacco coach using a standard coaching evaluation form rating 
adherence to the protocol, adherence to motivational interviewing principles, use of motivational 
interviewing tools/techniques, and participant engagement. The coach will obtain verbal consent 
from participants before starting the recording. Sessions will be recorded by a microphone 
connected directly to a password-protected, Mass General Brigham-approved laptop or tablet 
with full-disk encryption. Audio files will be backed up to the PI’s SFA described above and 
deleted from the portable device. Audio files will also be destroyed immediately after review. 
The coaching evaluation forms will not contain any identifying information and will be securely 
stored on Microsoft Sharepoint. 
 
C. Safety Monitoring 
The eligibility criteria for the study are designed to identify individuals who would most likely 
benefit from the proposed intervention. These criteria represent an expansion of the criteria 
used in our pilot RCT,27 enabling the proposed intervention to reach a broader target population. 
Although all current smokers should be advised to stop smoking and offered assistance in 
quitting, we believe that the proposed financial incentives approach is best targeted to 
individuals who are least contemplative about quitting (i.e. planning to quit in the next 3 months). 
Whether financial incentives might motivate interest in smoking cessation among pre-
contemplative smokers is a separate scientific question that merits separate investigation. 
During eligibility screening, participants will be asked about potential contraindications to 
varenicline, including questions about suicidality via the primary care screening version of the C-
SSRS (see Appendix 3).48 Individuals at low risk of suicide will be allowed to participate while 
being made aware of available behavioral health care resources, including 24-hour crisis line 
numbers and on-site mental health services at BHCHP. Individuals at moderate risk of suicide 
only due to history of suicidal behavior >12 months prior (and not due to current suicidal 
thoughts) will be allowed to participate if all other criteria are met, and will be made aware of 
available behavioral health care resources. Individuals at moderate risk of suicide due to history 
of suicidal behavior in the past 3-12 months (and not due to current suicidal thoughts) will be 
excluded and made aware of available behavioral health care resources. Individuals at 
moderate risk of suicide due to suicidal thoughts with methods but without intent will be 
excluded from the study, provided 24-hour crisis line numbers, and encouraged to make an 
appointment with a behavioral health clinician (at BHCHP or elsewhere) within 3 business days. 

Individuals at high risk of suicide due to past 3-month suicidal behavior (with no current suicidal 
intent) will also be excluded from the study and encouraged to make an appointment with a 
behavioral health clinician within 3 business days. Individuals at high risk of suicide due to 
current suicidal intent based on the C-SSRS will be excluded from the study and referred 
immediately for an urgent on-site same-day mental health evaluation by BHCHP clinical staff. 
To ensure that eligible participants have an adequate understanding of the potential risks 
associated with study participation, all participants will be informed of these risks in plain 
language on a written informed consent document that will be read aloud to each participant, 
making no assumption of literacy. Participants will be informed of the option of not participating 
in the study and that their decision regarding study participation will in no way impact their ability 
to receive future services at BHCHP. Following a practice we established in our prior survey 
work involving homeless smokers45, 66, 101 and further refined in our pilot RCT for homeless 
smokers,27 we will confirm individuals’ understanding of the consent materials with basic 
knowledge questions about the consent document content to ensure that they have the capacity 
to provide informed consent. Individuals who can correctly answer these questions will be asked 
to sign the paper consent form if they wish to enroll in the trial. A signed copy will be retained by 
study staff and a second signed copy of the consent form will be given to participants for their 
own records. 
During the trial, participants will be asked proactively about side effects at regular intervals 
during monitoring visits and encouraged to report side effects to varenicline at any time. 
Adverse reactions will be tracked and addressed according to the adverse event procedures 
outlined below. Participants will be asked to rate the severity of their side effects as none, mild, 
moderate, or severe. Mild reactions will be recorded and monitored, and participants will be 
encouraged to let study staff know if they worsen or persist. If a participant rates a side effect as 
moderate, study staff will ask if the participant wants to speak with a clinician. If so, the clinician 
will phone participants within 48 hours to assess their symptom(s) and formulate a plan, which 
could include continuing as is, modifying the dose of varenicline, or stopping varenicline. If a 
participant experiences severe side effects, study staff will advise the participant to immediately 
stop taking varenicline. The study clinician and PI will be notified and will follow-up with the 
participant within 24 hours to decide with the participant about whether to remain off varenicline 
or resume the medication at a lower dose. Severe, potentially life-threatening reactions (e.g., 
cardiac complications) will prompt immediate on-site medical assessment by a health care 
provider at BHCHP headquarters or at a nearby hospital. The study clinician and PI will be 
notified and will follow-up with the participant within 24 hours.  
Study staff will also proactively assess suicidality at every on-treatment monitoring visit using a 
modified version of the C-SSRS (see Appendix 3).48 Participants at low risk for suicide based on 
the C-SSRS will be made aware of available behavioral health care resources, including crisis 
line numbers and on-site mental health services at BHCHP. Participants at moderate risk for 
suicide based on the C-SSRS will be given 24-hour crisis line numbers and encouraged to 
schedule a visit with their PCP or an on-site behavioral health provider within 2 business days, 
with assistance from study staff. The study clinician or PI will call these participants within 24 
hours to discuss their suicidality and reinforce the above evaluation plan. Participants at high 
risk for suicide based on the C-SSRS will be escorted immediately to the on-site BHCHP clinic 
for an urgent mental health evaluation by BHCHP clinical staff. Study staff will advise these 
participants to stop varenicline. The study clinician and PI will be notified and will follow-up with 

the participant within 24 hours to discuss the plan for moving forward. In instances in which 
participants show moderate or high risk of suicide based on the C-SSRS, study staff will 
communicate with participants’ PCPs via secure Epic messaging regarding the outcome of this 
assessment within 2 business days (if moderate risk) or within 24 hours (if high risk). Although 
suicidality will not be proactively assessed during tobacco coaching sessions, if participants 
spontaneously bring up suicidal thoughts, the tobacco coach will follow similar procedures to the 
monitoring visits and assess suicidality risk using the modified C-SSRS and react accordingly 
based on level of risk.  
If a participant misses their monitoring visit, this will trigger an automated text message to their 
study phone or personal phone advising them to call study staff if they are experiencing any 
side effects or other concerns related to their participation in the study (see Appendix 1). 
If a participant calls study staff with concerns, study staff will make a note of any reported side 
effects and their severity in a manner similar to that which would occur during an in-person 
monitoring visit. However, to improve the efficiency of phone encounters, reduce the use of 
participants’ cell phone minutes and allow the participant to direct the conversation in a more 
fluid way, a complete checklist of side effects and the C-SSRS scale will not be administered by 
default during these phone calls unless dictated by participants’ reported symptoms. If a 
participant reports mental health concerns, this will prompt administration of the (C-SSRS) over 
the phone, with triage according to the algorithm outlined for in-person monitoring visits.  
Psychological status (including depression and anxiety symptoms) will be formally assessed at 
baseline, and at 12 and 24 weeks, providing additional opportunities to identify and address any 
psychological discomforts that participants may be experiencing. If any participant screens 
positive for any mental health disorders listed, study staff will ask participants whether they are 
currently receiving behavioral health care and assist them with connecting or reconnecting with 
such care, either at BHCHP or at an outside facility (if preferred by the participant). 
Study staff will be trained to recognize the signs of an intoxicated participant and to activate a 
response plan appropriate to the level of symptoms or impairment. Participants demonstrating 
evidence of mild substance intoxication will be informed of on-site behavioral health services to 
address substance use. Participants with more profound levels of intoxication causing 
substantial impairment in functioning and well-being will be referred for immediate on-site 
medical evaluation. The clinic at BHCHP headquarters has walk-in medical and behavioral 
health appointments available every weekday to support the on-site referrals describe above. 
D. Confidentiality safeguards: 
All participants will receive an identification number that will be used for all forms, interviews, 
transcripts, and intervention materials. Forms and databases with identifying information include 
the demographics form and the paper consent form. The demographics form will be completed 
in REDCap. Consent forms will be scanned into REDCap as part of each participant’s individual 
study record. The physical consent form will be stored in a locked filing cabinet at BHCHP that 
only study staff can access. Study staff will periodically hand-carry the consent forms in a locked 
box from the BHCHP site to the main MGH office where the files will be permanently stored in a 
locked filing cabinet. 

Identifiable information from participants who are approached and screened but not enrolled will 
be saved with participant permission until recruitment ends. Once recruitment ends, we will 
remove any identifying information from all non-enrolled participants from our REDCap 
database as well as from any log sheets for tracking recruitment efforts. Identifiers in the 
REDCap database will be erased by using the REDCap data import tool to overwrite all 
identifying information. Identifiers within any additional log sheets for tracking recruitment will be 
manually erased. Identifiable data will be replaced with non-identifiable placeholder data.   
All staff who come into contact with Human Subjects and/or data collected from Human 
Subjects will have received prior training about confidentiality during the course of their IRB-
required Human Subjects training, which is conducted using the Collaborative IRB Training 
Initiative (CITI) system. 
E. Outcomes Monitoring 
Outcome monitoring will occur on a rolling basis each time a participant provides a saliva 
cotinine sample. Because of the low-risk nature of the study, we will not conduct a formal interim 
analysis of the data or define rules for early stopping of the trial.  
F. Adverse Events 
1) Assessing Events: As described in section VI.A., we will assess for adverse events at every 
study visit. For participants who are prescribed varenicline through the study clinician, this will 
include queries about potential side effects to varenicline using a standardized checklist in 
addition to the C-SSRS for suicide risk assessment weekly through week 8 and every other 
week through week 12. 
Participants will also be reminded to report problems, whether related or potentially related to 
study participation or not, to study personnel between scheduled intervention visits and 
assessments. They will be instructed on how to contact study personnel should problems occur 
during intervals between visits. Adverse events will be documented, carefully assessed to 
determine expectedness, relatedness, and potential for harm, and steps will be taken to prevent 
future similar events from occurring. Violations of participant privacy/confidentiality will be 
treated as an unanticipated problem related to the study and will be considered reportable.   
2) Reporting of reportable events to the IRB: We will adhere to the Mass General Brigham 
policy statement on “Reporting Unanticipated Problems including Adverse Events.” Consistent 
with this policy, an adverse event will be defined as “any untoward or unfavorable medical 
occurrence in a human subject, including any abnormal sign, symptom, or disease, temporally 
associated with the subject’s participation in the research, whether or not considered related to 
the subject’s participation in the research.” A serious adverse event will be defined as an 
adverse event that results in death, is life-threatening, requires hospitalization, causes 
persistent or significant disability, or requires medical or surgical intervention. The PI and his 
designated study staff will be responsible for the monitoring of adverse events in study 
participants. 
Adverse events reported to the PI or other study staff will be documented in an adverse event 
report containing a description of the event, the date and time of onset, the date and time of 
resolution, the expectedness of the event, the relationship to the study, the seriousness of the 
event, and the action taken in response to the event. An adverse event will be deemed 

unexpected if the nature, severity, or frequency of the event is not consistent with a known or 
foreseeable risk given the research procedures, the characteristics of the subject population, or 
with an expected progression of an underlying condition. The following attribution scale will be 
used to describe the relationship of the adverse event to the study protocol: unrelated, possibly 
related, or related to the protocol. 
Unexpected adverse events that are at least possibly related to the research and suggest the 
research puts participants at increased harm will be reported to the Mass General Brigham IRB 
and Data and Safety Monitoring Board (DSMB; see section H below) within 5 working days or 7 
calendar days. Serious adverse events that are unexpected and at least possibly related to the 
research will be assumed to suggest that the research puts participants at increased risk of 
harm and will be reported to the Mass General Brigham IRB and DSMB within the same time 
frame. Any action resulting in a temporary or permanent suspension of this study will be 
reported to the NIH funding agency’s program official. A summary safety report detailing all 
adverse events and their handling will be included in annual study progress reports to the Mass 
General Brigham IRB (if requested) and the NIH funding agency. Adverse event reports and 
annual safety summaries will be documented by study ID number; personal identifiers will not 
be included in these reports. 
3) Reporting mechanisms to NCI and DSMB: The PI will report reportable events to the NCI 
Project Officer by phone or email within 5 working days and follow-up with a written report (by 
fax or email) within 10 calendar days, detailing any additional information and whether or not the 
event is related to participation in the study or may affect future participation in the study.  
The PI will make a report to the Chairperson of the DSMB within 5 working days of learning of 
the event. The DSMB will review the event (usually on the phone or via email) and make a 
report via email to the PI, who will forward the report to the IRB and NCI Project Officer. 
G. Protocol Adherence 
1) Research staff: The study coordinators will be trained on the data collection protocols 
described above. Their understanding of these protocols will be assessed by asking them to 
demonstrate competency in using the REDCap data collection forms and in collecting the saliva 
samples for both point-of-care and laboratory cotinine testing.  
2) Tobacco coach: The tobacco coach will receive online and in-person training to prepare for 
the role. S/he will first complete the online 9-module course on “Basic Skills for Working with 
Smokers” sponsored by the University of Massachusetts Center for Tobacco Treatment 
Research & Training (UMass TTRT).101 The tobacco coach will then attend a Tobacco 
Treatment Specialist Core Certificate training (UMass TTRT).102 Prior to the start of the study, 
the tobacco coach will be required to demonstrate competency in fulfilling the duties of the role. 
The tobacco coach will not be a certified Tobacco Treatment Specialist (TTS) because this is a 
lengthy and intensive process that would reduce the generalizability of the intervention to more 
resource-limited homeless health care settings that do not currently have a TTS and count not 
afford to hire or train one. This approach is consistent with the concept of “task-shifting” 
endorsed by the World Health Organization for delivering needed care in resource-limited 
settings.103 
H. Data and Safety Monitoring Board (DSMB) 

The DSMB will provide independent oversight of the safety monitoring of study participants. The 
DSMB will review the study protocol and recommend changes that may improve the protocol, as 
needed. Throughout the duration of the study, the DSMB will revisit the protocol to identify any 
emerging issues and recommend improvements and will monitor the safety of study participants 
by assessing social impact and adverse event reports. The DSMB may recommend 
modifications to the protocol, or early termination of the study, should overwhelmingly significant 
benefits or risks become apparent, or if the DSMB deems that the trial cannot be completed 
successfully.  
The main objectives of the DSMB include:  
i. Protocol review: The DSMB will review the study protocol and data and safety monitoring 
plan before data collection begins. The DSMB will recommend modifications to the study 
protocol and safety monitoring plan as needed. The members will also review subsequent 
protocol changes proposed by the investigators and will recommend a timeframe for 
implementing protocol changes. The NCI Program Officer will be informed of any protocol 
changes recommended by the DSMB.  
ii. Participant safety: The DSMB will review unanticipated problems, adverse events, and 
other reportable events and formulate recommendations to continue, amend, or terminate 
the study based on established safety criteria.  
iii. Study progress: The DSMB will review screening, recruitment, and retention data to 
ensure that the study can be completed in a reasonable timeframe to be of significant 
clinical relevance. 
1) Frequency of DSMB meetings: The DSMB will review and provide input on study 
procedures prior to the start of enrollment. Following the start of enrollment, the DSMB will 
convene at designated intervals to provide oversight of study progress and safety. The first 
oversight meeting will occur 6 months following the start of enrollment. Subsequent oversight 
meetings will occur annually, or more frequently if deemed necessary by the DSMB Chair or the 
study PI. Potential formats for DSMB oversight and review of study procedures could include 
phone conferences, video conferences, or carefully documented email exchanges at the 
discretion of the DSMB chair, DSMB members, and the PI Dr. Travis Baggett.  
 
2) DSMB reports: The DSMB Chair will prepare a draft report of the DSMB review. The report 
will outline and summarize all discussions during the meeting and will clearly note 
recommendations and action items from the Board. The report will be reviewed by all members 
of the DSMB and the Principal Investigator prior to finalizing the report. The DSMB Report will 
be forwarded to the Project Officer. Clerical support will be provided by the MGH site as 
requested by the Chair of the DSMB. Following each DSMB review, the Chair shall prepare a 
written report to be finalized within 14 working days following the formal meeting and be sent to 
the PI. The report will review the 2 main aspects of the trial for which the DSMB is responsible 
as noted in section 2 above (see sections I.I & I.II). In addition, following each study review, the 
DSMB will recommend one of the following: 
i. 
Continuation of the trial using the current protocol and statistical plan. 
ii. 
Continuation of the project with modifications as outlined by the Board. 
iii. 
Immediate suspension of the trial for safety reasons for all participants, with a 
recommended plan of follow-up to minimize subject harm (requires unanimous vote). 
iv. 
Suspension of enrollment but continuation of assigned treatments for already-enrolled 
participants. Enrollment may resume once clarifications requested by the Board have been 
addressed and resolved (requires unanimous vote). 

3) Discussion of confidential material: No communications, either written or oral, of the 
deliberations or recommendations of the DSMB will be made outside of the DSMB except as 
provided by written policy. Study data are strictly confidential and must not be divulged to any 
nonmember of the Board except as indicated by policy. 
4) Disclosure of any conflict of interest: DSMB members will have no financial and/or 
scientific ties to the outcome of the study. Each DSMB member will be asked to provide 
financial disclosure documentation prior to the start of the member's term. Each DSMB member 
will also be asked to sign a confidentiality statement promising not to disclose any data.  
 
X. PARTICIPANT REMUNERATION  
The remuneration of homeless individuals for participating in research studies requires special 
consideration of both practical and ethical issues. This section contains a discussion of these 
issues. 
A. Summary of remuneration plan 
All participants will receive $25 for completing a baseline survey at the enrollment visit, $10 for 
the randomization and clinician visit, and $15 for every tobacco coaching session they attend. 
Additionally, all participants will receive $30 for completing follow-up data collection visits 
(survey and laboratory saliva cotinine test) at 12 and 24 weeks. Up to 80 selected participants 
(50 from the incentives arm, 30 from the control arm) will each receive $30 for completing a 
qualitative interview. Participants will also be offered token items (e.g fidget toys, tote bags, 
single serve snacks or drinks) at study visits to help pass time while completing the saliva 
assessments. Prior focus group data revealed that such items are greatly appreciated in this 
population and may enhance study visit adherence. 
Participants in the incentive arm will get escalating payments for negative cotinine levels based 
on the point-of-care saliva test. Participants will receive payments starting at $25 and increasing 
by $5 for each successive cotinine-negative measurement, up to a maximum of $70. Non-
negative measurements, or failure to provide a saliva sample for cotinine testing, will result in no 
payment and will reset the subsequent payment back to the starting value of $25 (exceptions to 
this procedure are described above in section V.A). The maximum cotinine-based reward 
payout will be $475. Thus, the maximum total amount that participants in the incentives arm can 
earn over the course of the study will be $675: $25 for the baseline survey, $10 for the 
randomization visit, $75 if they attend all tobacco coaching sessions, $60 if they attend both 
follow-up data collection visits, $475 for cotinine-based abstinence at all visits, and $30 if they 
complete a qualitative interview. However, our pilot RCT experience suggests that actual 
remuneration will average out to about 41% of the maximum, or about $277 per incentive arm 
participant. 
Participants in the control arm will get fixed $10 payments for attending on-treatment monitoring 
visits regardless of their cotinine levels on the point-of-care saliva test. The maximum total 
amount that participants in the control arm can earn over the course of the study will be $300: 
$25 for the baseline survey, $10 for the randomization visit, $75 if they attend all tobacco 
coaching sessions, $100 if they attend all on-treatment monitoring visits, $60 for completing 
both follow-up data collection visits, and $30 if they complete a qualitative interview. 

All payments will be issued to participants via reloadable Visa debit cards through a secure 
payment portal hosted by CT Payer. CT Payer is a secure web-based platform that facilitates 
HIPAA-compliant clinical trial and study-related payments onto reloadable Visa cards. Unlike 
payment systems offered by banks and third-party payment providers, CT Payer does not 
collect any protected health information from research participants. Study staff members add 
funds onto cards through an online payment portal, reimbursing participants accordingly 
following study visits. Funds are available to the study participant immediately and may be used 
with the same convenience as a debit card. Every card is shipped with a “Card Kit” containing 
the number of CT Payer’s 24/7 customer service line, which can be called for card balance 
inquiries or to report a lost/stolen card. All payments are tracked in real-time and may be 
organized by date, participant ID, or card number. On-demand reporting features provide a 
convenient way to determine the total amount a participant received in reimbursements for tax 
or other purposes. Participants will sign a form acknowledging receipt when they receive a new 
CT Payer Visa debit card. As demonstrated in the email communication attached to this 
application, the Mass General Brigham Research Controller, Rhonda Lowe, has reviewed 
and approved our proposed use of CT Payer for this study. 
If the CT Payer platform is temporarily unable to load payments onto existing debit cards or 
issue new cards, we will provide participants with single-use, non-reloadable gift cards in 
denominations of $10, $15, $25, and $30 to correspond to the payment amount they are entitled 
to receive for each visit completed. Participants will sign a form acknowledging receipt when 
they receive a non-reloadable gift card. Participants who complete visits over the phone may 
choose to pick up their non-reloadable gift card in person or have it mailed to them. This 
alternative payment system was also reviewed by Rhonda Lowe who agreed that this 
was in accordance with MGB policy.   
B. Potential for misuse 
It is possible that some participants will choose to use their debit card or gift cards to purchase 
cigarettes, alcohol, or other items that are potentially harmful to their health. This possibility is 
not unique to homeless people and does not justify violating the ethical principle of 
remunerating homeless participants in a fashion that is equitable with non-homeless people. 
Furthermore, the use of debit cards or gift cards (rather than cash) for study payments markedly 
limits their ability to be used for the purchase of illicit drugs. Another safeguard is that 
participants in the incentives arm receive payments only for biochemically-verified smoking 
abstinence. If a participant chooses to apply this payment toward alcohol, drugs, or tobacco, 
then it is highly likely that the participant will relapse with smoking and/or miss the following 
study visit, resulting in no payment at that visit and resetting the subsequent reward payment to 
the starting value. In this fashion, the contingency management framework provides a negative 
feedback loop for curtailing payments if a participant’s substance use worsens. In support of this 
notion, we observed no worsening of alcohol or drug use severity, measured serially using the 
Addiction Severity Index,105-108 among participants in our pilot RCT. Indeed, in qualitative exit 
interviews, many participants reported using their debit cards to purchase food, clothing, and 
personal care items they otherwise would not have been able to afford. 
C. Consideration of undue influence 
Undue influence occurs when the monetary value of remuneration for research participation is 
so great in relation to the context of an individual’s life circumstances that his/her decision about 

whether to participate is inappropriately overwhelmed in favor of participating because of the 
financial reward for doing so.108 Below we consider the use of undue influence by study arm, 
since the participant payment scheme differs for each arm. Importantly, we note that the 
concept of “coercion” does not apply to either study arm, because there is no threat of negative 
consequences for non-participation in the study or for not quitting smoking while in the study.108 
As per the informed consent procedures outlined below, participants will be informed in plain 
language that their decision about whether to participate in the study will have no adverse 
impact on their ability to receive care at any BHCHP site. 
Control arm: The compensation provided to individuals in the control arm is consistent with that 
provided to homeless participants in other clinical trials110 and appropriate to the level of effort 
being asked of participants in this arm; therefore, payments made to control arm participants do 
not constitute undue influence. 
Incentives arm: Compared with control arm participants, participants in the incentives arm 
have the potential to earn greater total compensation, raising the issue of whether this higher 
dollar amount may represent undue influence. However, we do not believe that the proposed 
payments for incentive arm participants constitute undue influence for several reasons. First, the 
incentives are not designed to encourage trial participation per se and are not guaranteed by 
simply agreeing to participate. Rather, they are tied specifically to biochemically-verified 
smoking abstinence, a health behavior for which there is substantial evidence of benefit,110,111 
unanimous professional consensus,113-116 and minimal risk of harm. Second, the financial 
rewards for smoking abstinence do not require participants to accept a level of risk they would 
not ordinarily accept in the absence of incentive payments. Indeed, we are targeting individuals 
who report a goal of quitting smoking within the next 3 months, and the incentives are designed 
to help facilitate that goal. Third, the incentive payments proposed in this study are comparable 
to those used in our pilot RCT in Boston, in a pilot study of contingent financial rewards for 
homeless smokers in Dallas,29 and in a financial incentive study involving smokers with 
schizophrenia,116 while being less than those used in a financial incentive trial for low-income 
smokers in Switzerland.118, 119 For these reasons, we deem the financial rewards for smoking 
abstinence offered to participants in the incentives arm to be scientifically and ethically 
appropriate and consistent with the evidence base in this area. 
D. Participant safety 
In the setting of homelessness, carrying or possessing items with a high dollar value potentially 
poses a risk that the person carrying such an item could be targeted for theft. During 2 focus 
groups with homeless smokers that we conducted in planning for our pilot RCT, participants 
reported satisfaction with the proposed debit card format and stated that they would not feel 
unsafe carrying them. This sentiment was subsequently echoed by participants in our pilot RCT. 
This is due in large part to the fact that the monetary balance on a given debit card is not readily 
apparent, diminishing its street value and improving the sense of safety that participants have 
when carrying it on themselves. 
E. Exemption from Mass General Brigham remuneration policy 
As noted above, the Mass General Brigham Research Controller has granted an exemption 
from the Mass General Brigham policies on “Payments to Human Subjects for Participation in 
Research” and “Cash Control and Accountability for Payments to Human Subjects for 
Participation in Research” and has approved our proposed use of CT Payer to manage 

participant remuneration via reloadable Visa debit cards in the manner described above (see 
attached email communication). 
 
 

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