Assessing the Impact of myHealth Rewards Program-related Email Communications on Enrollment
Conditions: Health Promotion, Wellness Programs
Sponsor: Geisinger Clinic

 
1 
Assessing the Impact of myHealth Rewards Enrollment Emails (NCT03965754) 
 
Study Protocol with Statistical Analysis Plan 
 
August 27, 2020 
 

 
2 
 
Study Protocol 
 
Purpose 
 
The purpose of the study was to evaluate, prospectively, the potential impact of 
different email message conditions (no email, standard promotional email, social norms, and 
loss frame) on enrollment in a wellness program (myHealth Rewards) by Geisinger Health Plan 
(GHP) members. The current study was developed to test whether different versions of emails 
were more effective than a standard reminder email or no-email condition in increasing 
myHealth Rewards login and enrollment rates.  It was hypothesized that, on average, each of 
the emails would increase enrollment compared with no email. 
 
Methods 
 
Sample 
 
The population consisted of adult (age 18 and older) Geisinger employees who were 
eligible for the myHealth Rewards program. This group also included people who were 
employees but not GHP members. As long as the employee was eligible for GHP and the mHR 
program benefit, they can sign up for the program. The goal of the mHR program is to reach all 
employees who can or potentially can benefit from the program. With this inclusion criteria, if 
employees who are not GHP members later decide to get a GHP plan, they will be able to 
benefit from any rewards gained from participating in the program. We excluded non-
employee spouses and domestic partners (as they could not benefit from the program), 
employees who had already registered for mHR in 2019, up through May 6, 2019, and new 
Geisinger employees hired between December 1, 2018 and May 6, 2019.  
 
We also excluded existing Geisinger employees who transitioned from non-subscribers 
in 2018 to subscribers in 2019; i.e., these employees could not be included clearly with those 
who “never enrolled” (because they did not have an opportunity to enroll in 2018 for a 
monetary incentive), nor could they be included with those who “previously enrolled,” even 
though they were likely similar to this latter group in terms of willingness. 
 
After exclusions, there were 5,697 GHP members eligible for the study, with 2,967 
having been enrolled previously and 2,730 never having been previously enrolled.  In each of 
these subgroups, employees were randomly assigned to one of the four email conditions. See 
Table 1 for sample sizes for all three studies and their conditions. 
 
Control and experimental conditions 
 
No Email. From the start of the study, employees in the no-email group did not receive 
any communication related to mHR for at least seven days. This group served as the passive 
control group. 

 
3 
 
Standard Email. The standard email had the subject line “Are you still planning to join 
myHealth Rewards?” It mentioned the average premium savings, the speed and ease of starting 
the enrollment process, and the deadline for registering and having health measures on file.  
The standard email also provided two button links for registering and finding free health 
screenings where health measures could be collected and registered at one convenient time 
and location. This group served as the active control group. 
 
The other emails contained and built upon all of the same information included in the standard 
email. 
 
Social norms email. The social norms email had the subject line “Don't miss your chance 
to join in!” It noted that a majority of employees' colleagues had enrolled previously, provided 
a testimonial from a Geisinger medical director, and emphasized the simplicity and ease of 
taking the first step toward enrollment. 
 
This intervention introduced recipients to descriptive social norms specifying that a 
majority of their colleagues (78%) had enrolled in the same program in 2018, which set a 
normative standard against which recipients were expected to compare themselves and to 
change their behavior accordingly (i.e., when they realized that their behaviors were discrepant 
from those of relevant others).  The personal endorsement from a medical director at 
Geisinger's Commonwealth School of Medicine—stating the ways in which the mHR program 
helped that doctor personally—presented an exemplar that was intended to further enhance 
the effect of the social norms with an implicit indication that the behavior was desirable and 
feasible. 
 
Loss frame email. The loss frame email had the subject line “Why are you throwing 
away $2,113?” It suggested that employees were currently "throwing away" a precise dollar 
amount by not participating and that they could therefore avoid missing out on substantial 
gains (i.e., savings) by taking action. 
 
This intervention framed the status quo as a state from which recipients, via inaction, 
were slated to forfeit a sizable and precise monetary amount ($2,113; i.e., the total annual 
premium savings realized by successful enrollees in the family plan) to which they should 
otherwise feel entitled (via loss aversion and the endowment effect).  People tend to be risk-
seeking in the domain of losses; therefore, this intervention was hypothesized to increase 
enrollment via employees’ hopes of achieving zero loss by meeting program goals, as opposed 
to a sure loss via inaction. 
 
Outcome measures 
 
The outcome measures were (1) enrollment in the mHR program and (2) clicking on the 
link to the mHR program website portal. Both measures were binary and measured within 7 full 

 
4 
days of the beginning of the intervention (i.e., when the emails were first sent). The study 
period was from the morning of May 7 through the end of May 13, 2019. 
 
Enrollment was the ultimate outcome of interest, since it reflected the terminal 
behavior that could lead to savings and health outcomes improvements. However, clicks were 
also of interest, in that they represented a more proximal measure of the impact of the 
experimental conditions on behavior. 
 
 
 
 

 
5 
Statistical Analysis Plan 
 
We conducted separate, parallel analyses for those who previously participated and 
never participated in the program. Binary logistic generalized linear models (GLMs) were used 
to analyze (1) enrollment and (2) click rates as a function of experimental condition, with the 
standard email group as a reference group for both outcomes and the no-email group as an 
additional reference group for enrollment.  We could not compare clicks to the no-email group, 
as employees need to receive an email to click on the link. Odds ratios (ORs) were calculated, 
along with 95% confidence intervals (CIs); two-tailed p-values < 0.05 were used to determine 
statistical significance.  To represent effect size, the standardized statistic, Cohen’s d, was 
estimated using the formula 𝐿𝑜𝑔𝑂𝑑𝑑𝑠𝑅𝑎𝑡𝑖𝑜 × √3 𝜋
⁄  (Hasselblad & Hedges, 1995). Raw 
percentages with 95% CIs were also presented in graphs. All analyses were conducted in R.