Table 3.

Effective Retention Strategies

Reference	Sample	Study design	Effective retention strategies
Langer et al. (2018)	107 cancer survivor/ partner dyads	Smartphone-based ecological momentary assessment (twice-daily assessments for 14 days)	Piloted smartphone application to assess usability and acceptability; altered design and timing based on feedback Met face-to-face with participants to support download of smartphone app required to complete twice-daily assessments, extremely helpful for older and less tech-savvy participants; fully explained process. Sent couples home with user-friendly guide with clear visuals Remotely monitored data completion; contacted non-responders to help troubleshoot. Incentivized data completion per assessment plus extra if completed > 85% of assessments
Joseph et al. (2019)	60 insufficiently physical active African American women with obesity	Pilot RCT	Consent process included manualized orientation session (structured PowerPoint presentation outlining study purpose and procedures, expectations of study participants, and what participants could expect from research team) Contacted participants bi-weekly to inquire about any issues/ problems encountered with study smartphone app Compensated participants for parking and other transportation-related costs incurred (i.e., bus or light rail fare) for attending assessment sessions Scheduled follow-up assessments on days/times convenient for participants, including early morning and weekends Delivered cash incentives at the time of assessment Sent text and email reminders for scheduled study assessments
Kim et al. (in preparation)	96 hematopoietic cell transplant recipient/ primary caregiver dyads	RCT	Maintained strong rapport with participants at baseline and provided clear explanations of follow-up plans Administered assessments remotely via REDCap, easing participant burden Sent weekly emails and phone calls for reminders and to maintain current contact information Provided in-person orientation to facilitate use of web-based intervention Incentivized data completion per assessment
Lee, Reese-Smith et al. (2017)	310 African American and Hispanic or Latina overweight/obese, sedentary women	RCT	2-week run-in phase that included the completion of a packet of questionnaires, health behavior monitoring logs, and attendance at a pre-randomization session to determine commitment At pre-randomization orientation, asked participants to consider importance of the study and possible reasons for dropout Asked to withdraw before randomization if not willing to be randomized
Lee et al. (2017)	89 children or their parents attending early care and education centers in neighborhoods with high proportions of individuals who identify as Hispanic	Cluster RCT	Sent weekly infographic-style newsletters to parents describing their child’s activities in school and family-friendly home and community activities that could enrich in-school learning
Menon/ Larkey et al. (2020)	419 unscreened or due for colorectal cancer screening	RCT	Contacted both intervention and control group participants (nearly) weekly by phone to set goals or investigate barriers to continuing through steps of the study to obtain colorectal cancer screening Adjustments were made to address individual participants’ insurance and clinic status (e.g., if no medical home, recommended nearby federally qualified health center) Addressed changes in medical reimbursement and immigration policies (e.g., new laws affecting racial-ethnic profiling) by building relationships, remaining transparent, asking no questions regarding social security ID, continuing to provide services
Reifsnider et al. (2018)	175 Mexican American mother/infant dyads	RCT	Maintained contact with participants through texts and phone calls Conducted all study visits in the home, negating participant travel Contacted participants one day before home visit to remind and confirm time Trained promatoras conducted all study visits in participant’s preferred language Promotoras created friendships with families, often invited to family celebrations Provided cash incentive at each visit Provided non-cash incentive (book, toy, etc.) to intervention group participants Mailed birthday cards to children Entered active participants in a $50 gift card raffle every 6 months (those remaining in 3-year study) Hosted fiesta at end of study (food and fellowship) Honored completers with “graduation” certificates
Soltero et al. (2018)	160 Latino adolescents with obesity	RCT	Maintained regular contact by phone, email, or text based on participant preference Sent automated text messages for birthdays and holidays Allowed family household members to attend intervention sessions Provided childcare during intervention Sent automated appointment reminders 1 week, 3 days, and the evening prior to scheduled appointments; included images for visit instructions and parking directions Offered tiered incentive program that included intervention participation and completion of all study-related visits and procedures Provided updated information on incentives as intervention goals were met
Youngstedt et al. (2021)	71 veterans with PTSD	RCT	Weekly assessments allowed for frequent interaction Compensated participants at multiple time points Connected regularly with participants via telephone, provided encouragement When possible, the same research team member communicated with a given participant throughout the study

Note. PTSD = post-traumatic stress disorder; RCT = randomized controlled trial. Terms used to describe samples with regard to race and ethnicity differ across studies due to variations in usage and preference, and to denote specificity when possible, e.g., Mexican American.