Testing Financial Incentive Interventions in Dyadic-Smoker Couples
Phase: NA
Conditions: Nicotine Dependence
Sponsor: University of Georgia

 
Testing Financial Incentive Interventions in Dyadic-Smoker Couples 
NCT04832360 
Document Date: April 13, 2024 
 

METHODS 
Participants and Recruitment 
As participation in the study was conducted virtually (e.g., over video teleconference and 
electronic survey), we utilized a Nationwide recruiting strategy to reach smokers across the 
contiguous United States. We recruited from three primary sources: Facebook/Instagram 
advertisements, Craigslist advertisements, and the ResearchMatch database of individuals 
interested in participating in health research studies. Both Facebook and ResearchMatch 
recruitment allowed for nationwide placement of recruiting messages. On Craiglist, we placed 
134 advertisements in distinct geographic regions, targeting all 48 contiguous states at some 
point during the study. Each advertisement ran for 28 days. 
We enrolled 95 dual-smoker couples (total N=190) from February 2021 to May 2022, 
consistent with recommendations to recruit ~30 participants per treatment arm for quantitative- 
focused feasibility studies27. Prior to data collection, we had identified that an intent-to-treat 
sample of ~95 targets would allow us power of ~82% to compare the control and PIF conditions; 
estimates were power were based on prior research and past research on financial incentive 
treatments for smoking.21,28 Eligibility requirements were a) smoking ≥ 5 cigarettes daily, b) 
18+ years of age, c) romantically partnered and cohabiting with another eligible participant. 
Individuals with psychosis risk, recent hospitalization, or current pregnancy were not eligible. 
Motivation or readiness to quit smoking was not a study prerequisite. Figure 1 shows the 
CONSORT diagram of enrollment; Table 1 shows the characteristics of enrolled participants. 
The first member of the couple to make contact with the research team was labeled the target; the 
other member was labeled the partner. 
Overview of Procedures 

The study consisted of a) a baseline video conference with surveys and biochemical 
verification of smoking, b) ten weeks of brief surveys, c) four weeks of optional online 
psychoeducation, and d) a 3-month follow-up video conference with surveys. 
Baseline 
Prior to the baseline video conference, both members of the couple completed surveys 
assessing smoking history, relationship quality, and smoking variables. Between the completion 
of these surveys and the video conference, randomization via a random number generator 
occurred. During the video conference, each person confirmed consent and used an IcoQuit 
Smokerlyzer to collect expired CO. Next, research staff explained procedures to participants, 
including the administration of experimental conditions. Dyads were randomly assigned via a 
random number generator to either a) No-FIT control, b) PIF-ST, or c) PIF-DT. In PIF 
conditions, either the target (PIF-ST) or both members (PIF-DT) were offered compensation of 
$100 for completing the psychoeducation training and $100 for being quit at follow-up. 
Participants could receive either or both incentives; partners could earn different amounts of 
incentives. Randomization was supplemented with stratification, resulting in slightly different 
sample sizes across condition. We stratified couples based on a) target gender, b) target smoking 
heaviness (<20 cigarettes per day, 20+ cigarettes per day), and 3) same- of different- sex couple 
status. 
Treatment as usual 
All participants received weekly links to a four-module (~ 1 hour weekly) online 
psychoeducation program combining behavioral change coaching with information about 
addiction and quitting. The program began one week after baseline; participants could access 

links at any time during the study. Participants were also offered home delivery of NRT (patch 
and/or gum) calibrated to their quantity of smoking (patches) or time to first cigarette (gum).  
Weekly surveys 
Participants received weekly emails (if necessary, they received a follow-up reminder 
within three days) in which they engaged in a Timeline Follow-back (TLFB; Harris et al., 2009) 
to report if they had smoked cigarettes and/or used NRT in the past eight days (today + each day 
of the prior week). On average, participants completed 8.42 surveys. 
Follow up 
As with baseline, participants completed surveys at follow-up. Participants received 
bonus compensation for attending a video session; all participants who indicated abstinence in 
the survey were required to hold the video session to complete a breath test before receiving 
abstinence incentives. Participants were instructed not to vape within 24 hours of the breath test.  
Measures 
The primary outcomes were: 1) Feasibility, defined as percentage of targets retained at 
follow-up, aiming for >80%; and 2) Tolerability, defined from 8 items assessing the 
accessibility, benefits, and costs of the study scored on a 1(strongly disagree) to 7(strongly agree) 
scale. Participants also completed five open-ended questions on their experiences. The four 
secondary outcomes were: 1) Program completion, defined as completing all four 
psychoeducation modules; 2) Quit attempts (i.e., self-reported duration of greater than 24 hours 
without smoking), assessed via weekly surveys; 3) Point prevalence abstinence, defined as a) 
self-reported abstinence for 7+ days and b) expired CO collected via ICOquit breath sensors (≤5 
ppm30); and 4) Joint abstinence, defined as both couple members being abstinent at follow-up.  
Data Analysis 

The primary outcomes were feasibility and tolerability in targets. The secondary 
outcomes were preliminary intervention effects among targets, with partners' outcomes as further 
descriptive dependent variables. Thus, for each analysis, we report outcomes separately by target 
and partner, with the exception of joint abstinence which was defined at the dyad-level. Results 
presented in Table 2 and Figure 2 thus show results separately for targets and partners. Student t, 
one-way ANOVA, ANOVA contrast tests, and Chi Square tests were used for analyses. For each 
analysis, we provide descriptive information as well as comparisons across conditions. When 
evaluating intervention outcomes, we focused our tests of significance on the PIF conditions 
combined compared to the no-FIT control. We provide descriptive follow-up tests comparing 
PIF-ST and PIF-DT, but note these tests necessarily involve larger confidence intervals and 
should be interpreted cautiously in a pilot trial. Data analysts were not blind to condition; two 
researchers verified the data and results. For retention rate and all preliminary efficacy outcomes, 
we utilized an intent-to-treat sample such that all participants’ data were included in analyses. 
For the tolerability ratings, we report only participants who completed follow-up.