Evaluation of Postcard Mailers Enhanced With Behavioral Nudges to Promote Mammogram Screening
Phase: NA
Conditions: Breast Cancer
Sponsor: Geisinger Clinic

Evaluation of Mailers Promoting Mammogram Screening 
(NCT04555902) 
 
Study Protocol with Statistical Analysis Plan 
 
June 11, 2021 
 
 

Study Protocol 
 
Purpose 
 
The purpose of this study is to evaluate, prospectively, the potential impact of different mailer 
conditions (standard content including a free gift, content designed with behavior science, 
content designed with behavior science including a free gift) on mammogram screening. 
 
Introduction 
 
Mammogram screening for women, starting at age 50, can significantly reduce the risk of 
complications due to breast cancer. As part of an existing outreach campaign, the health system 
mails a postcard and small gift (pink socks) to women on the month of their 50th and 64th 
birthdays to promote annual mammogram screening. 
 
The researchers are evaluating two new versions of the mailers against a standard mailer to see 
which version leads to greater uptake in mammograms. The new mailers had content that applied 
behavioral nudge theory - specifically, loss frames and fear appeals - to encourage taking action. 
One of the two new versions did not include the small gift, to test whether its inclusion or 
exclusion has any effect on mammogram screening. 
 
Methods 
 
Sample 
 
Female Geisinger Health Plan members turning age 50 and 64 in that month were included in the 
study. Although the intervention began in October, women with birthdays as early as June 2020 
were included. These additional participants were included because the mailer program was 
paused from June to October 2020 due to the COVID-19 pandemic; the October mailing was 
meant to contact all the eligible women who were not contacted since June. 
 
Experimental conditions 
 
All participants received a two-sided, 9x6 postcard that had a picture and attention-grabbing 
slogan in the front. The back of the postcard included a brief, persuasive message, with a toll-
free number that could be used for scheduling a mammogram. Participants were randomly 
assigned to receive one of the three versions of mailers detailed below. 
 
Standard Version with Socks (V1): The picture in front showed a woman posing against a pink 
background. The slogan in front said, “It’s time to think pink” and the back of the postcard 
mentioned that staying healthy benefited the recipient and their loved ones. It encouraged 
recipients to get their annual mammogram and show they are “part of the fight against breast 
cancer” by putting on some cute pink socks. This postcard and a pair of pink socks were sent 
together in a larger envelope. 
 

Enhanced Version without Socks (V2): The picture in front showed two women with pink- and 
grey-colored clothing jogging together. The slogan in front said, “To do: Lower my risk of breast 
cancer.” The back of the postcard framed an annual mammogram as the best way to find and 
beat breast cancer, with late detection leading to more costs, less effective treatments, and lower 
chances of recovery. Like the standard version, it mentioned that staying healthy benefited the 
recipient and their loved ones. This version was not accompanied by socks and was not sent in an 
envelope. 
 
Enhanced Version with Socks (V3): This postcard was identical to V2, with the exception of an 
additional message at end, which asked recipients to accept the socks as a small gift and 
reminder to take care of their health. This postcard and a pair of pink socks were sent together in 
a larger envelope. 
 
Outcome measures 
 
The primary outcome measure was mammogram completion (yes/no) 6 months from the 
intervention date. 
 
The secondary outcome measures were mammogram completion at 12 months (yes/no), primary 
care provider (PCP) visits (count) at 6 and 12 months, Obstetrician-Gynecologist (OB-GYN) 
visits (count) at 6 and 12 months, breast cancer diagnosis (lab notes) at 6 and 12 months, and 
emergency department visits (count) at 6 and 12 months. 
 
Exploratory outcome measures were mammogram completion, primary care provider visits, 
breast cancer diagnosis, and emergency department visits in 2019. 
 
The preregistered plan was to randomly assign participants to different groups through April 
2021 (6 months from the start of the intervention; April mailers were sent on April 6, 2021). 
However, data have not yet been viewed or analyzed as of the uploading of this document. 
Therefore, random assignment continued past April 2021 and will continue until results inform a 
decision regarding which version should be sent to all participants. Data until April 2021 will be 
pulled and examined for the primary analysis. Data past April 2021 may be examined in 
exploratory analyses. 
 
Statistical Analysis Plan 
 
As of the writing of this plan, all mailers have been sent and the data have not yet been 
examined. 
 
Primary Research Question: Which mailer version leads to more mammograms? 
 
H1a: Compared to V1, V2 will lead to more mammograms at 6 months. 
H1b: Compared to V1, V3 will lead to more mammograms at 6 months. 
 
The researchers do not have a hypothesis on whether sending enhanced versions with or without 
socks (V2 and V3) would lead to more mammograms. 

 
For these analyses, a logistic regression will be used, using the following model: Outcome ~ 
Condition.  In the model, V2 and V3 will be entered as predictors with V1 as the reference 
group. For all tests, two-tailed p-values < 0.05 were used to determine statistical significance. 
 
Secondary Research Question 1: Which mailer version leads to greater improvements in 
health-related outcomes? 
 
H2a: Compared to V1, V2 will lead to more PCP visits, OB-GYN visits (both as proxies for 
engagement with the health system), and less emergency department visits (less acute issues) at 6 
months. 
H2b: Compared to V1, V3 will lead to more PCP visits, OB-GYN visits (both as proxies for 
engagement with the health system), and less emergency department visits (less acute issues) at 6 
months. 
 
The researchers do not have a hypothesis on whether sending enhanced versions with or without 
socks (V2 and V3) would lead to better health-related outcomes. 
 
For these outcomes, regression models with a log-link function and negative binomial 
distribution will be used (accounting for positively skewed count or count-related data). If the 
negative binomial models fail to converge or fit appropriately, a Poisson distribution or another 
model appropriate for the outcome data will be used instead. 
 
The following basic model will be used for the above analyses: Outcome ~ Condition.  For each 
outcome, V2 and V3 will be entered as predictors with V1 as the reference group. For all tests, 
two-tailed p-values < 0.05 were used to determine statistical significance. 
 
Secondary Research Question 2: Which mailer version leads to more mammograms and 
greater improvements in health-related outcomes in the long term (12 months)? 
 
H3a: Compared to V1, V2 will lead to more mammograms, PCP visits, OB-GYN visits (both as 
proxies for engagement with the health system), and less emergency department visits (less acute 
issues) at 12 months. 
H3b: Compared to V1, V3 will lead to more mammograms, PCP visits, OB-GYN visits (both as 
proxies for engagement with the health system), and less emergency department visits (less acute 
issues) at 12 months. 
 
The researchers do not have a hypothesis on whether sending enhanced versions with or without 
socks (V2 and V3) would lead to better health-related outcomes. 
 
For the mammograms, a logistic regression will be used. For the PCP visits, OB-GYN visits, and 
emergency department visits, regression models with a log-link function and negative binomial 
distribution will be used (accounting for positively skewed count or count-related data). If the 
negative binomial models fail to converge or fit appropriately, a Poisson distribution or another 
model appropriate for the outcome data will be used instead. 
 

The following basic model will be used for the above analyses: Outcome ~ Condition.  For each 
outcome, V2 and V3 will be entered as predictors with V1 as the reference group. For all tests, 
two-tailed p-values < 0.05 were used to determine statistical significance. 
 
Exploratory Research Question: Which mailer version leads to greater improvements in 
health-related outcomes over time? 
 
H4a: Compared to V1, V2 will lead to a greater increase over time of PCP visits, OB-GYN visits 
(both as proxies for engagement with the health system), and decrease over time emergency 
department visits (less acute issues) in the 12 months after the intervention date compared to 12 
months before the intervention date. 
H4b: Compared to V1, V3 will lead to a greater increase over time of  PCP visits, OB-GYN 
visits (both as proxies for engagement with the health system), and decrease over time 
emergency department visits (less acute issues) in the 12 months after the intervention date 
compared to 12 months before the intervention date. 
 
The researchers do not have a hypothesis on whether sending enhanced versions with or without 
socks (V2 and V3) would lead to better health-related outcomes. 
 
While the number of mammograms 12 months before the intervention was included as an 
outcome in the Clinical Trials record, this will no longer be analyzed, as having mammograms in 
this time period was part of the exclusion criteria. The preregistration of this outcome at this 
particular time period was done in error. 
 
For the PCP visits, OB-GYN visits, and emergency department visits, mixed-effects regression 
models with a log-link function and negative binomial distribution will be used (accounting for 
positively skewed count or count-related data). If the negative binomial models fail to converge 
or fit appropriately, a Poisson distribution or another model appropriate for the outcome data will 
be used instead. 
 
The following random intercepts model will be used for the above analyses: Outcome ~ 
Condition + (1| Participant). For each outcome, V2 and V3 will be entered as predictors with V1 
as the reference group. For all tests, two-tailed p-values < 0.05 will be used to determine 
statistical significance. 
 
Examination of Additional Outcomes 
 
Only descriptive statistics will be reported for breast cancer diagnoses at 6 and 12 months. These 
will be used to illustrate how many people detected breast cancer due to the program and to 
estimate the costs to the hospital system.