A: We were all part of the recruitment and retention workgroup within the Behavior Change Consortium (BCC), a group of 15 NIH-funded projects targeting disease prevention through behavior change. As part of that group, our mission was to provide a forum to discuss and disseminate recruitment and retention strategies among all the involved sites, which covered a variety of health behaviors and diverse populations. Recruitment and retention are both important to be able to generalize an intervention's results, but retention has received less attention and systematic study than recruitment. We wanted to describe and evaluate the retention strategies used by our sites to provide concise retention methods for future investigations.

A: When we brought together representatives from each site, they mentioned several barriers that may cause a participant to drop out of a study such as loss of interest, financial difficulties, and conflicts with staff. They also collectively shared 61 retention strategies that we divided into 8 thematic categories based on the principles of social cognitive theory. The following is a list of those categories with example retention strategies:

• Emphasize benefits of participation.
  • Talk about the importance of study participation for the individual and/or the individual's family.
  • Listen to the participants and work together to understand the reasons for missing visits and to develop new strategies.


• Minimize respondent burden and give control to participants.
  • Give participants a "break" from contact/calls.
  • Modify the number of contacts if it's perceived as too much of a burden by participants.


• Provide incentives or small tokens of appreciation.
  • Mail study-specific items such as magnets or key chains with study logos to participants.
  • Give participants money or gift certificates for interviews and visits.
  • Give each participant a framed Polaroid picture of the participant with peers and/or staff, or if involved in a parenting or family intervention, give participants framed family photos.


• Give instrumental or tangible support.
  • Offer a home visits to house-bound participants.
  • Suggest or help arrange carpools and babysitting.


• Be patient yet persistent.
  • Reschedule visits multiple times if needed.
  • Make multiple calls on different days and at different times, including weekends.


• Be flexible.
  • Structure visits so that "primary" measures are given first and then collect other data as tolerated by the participant.
  • Extend the intervention's hours and consider early morning, evening, and weekend options.


• Enlist support from others and provide social support.
  • Call the participant's physician, health clinic, or recovery center and ask other health care providers to encourage participant to come to the intervention.
  • If the participant is ill, send cards and call to check on his or her status.


• Maintain a good tracking system.
  • Be alert and responsive to potential signs of drop out.
  • Use scheduling and calendar software that's available to all members of the research staff and include prompts to guide reports so that all relevant information is captured.

A: In one of the surveys given to each project site, we asked them to rank the 8 retention categories according to their perceived effectiveness on 7-point scale ranging from 1 (not successful at all) to 7 (extremely successful). These projects involved diverse populations with a variety of health statuses and from different geographic locations, and while our findings suggest that overall a combination of strategies may be needed, we found that effective strategies differed depending on the population under study. For example, provision of incentives was highly rated by study sites involved with children and adolescents, and incentives along with flexibility were highly rated by sites working with low-income populations. These incentives weren't always monetary, and simple things like refreshments and a fun atmosphere were considered to be attractive for study participation.

Among sites working with adults with chronic health conditions or older adults, provision of instrumental or tangible types of support were ranked as effective strategies but not ranked at all by sites working with healthy adults. These problem solving approaches include things like providing childcare or transportation, which highlights a researcher's need to be aware of the circumstances of participants. Similarly, flexible interview schedules and locations such as making home visits and allowing surveys to be given over the phone were considered effective retention strategies when working with older populations. So it's important to tailor your retention strategies to the participant group; be aware of what's valuable to them, and be flexible and attentive to their needs.