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Contemp Clin Trials Commun. 2017 Jun;6:140-146. doi: 10.1016/j.conctc.2017.04.002. Epub 2017 Apr 10.

Comparison of recruitment and retention among demographic subgroups in a large diverse population study of diet.

Author information

Henry Ford Health System, Department of Public Health Sciences, 1 Ford Place, Detroit, MI 48202, USA.
Health Studies Section, Westat, 1600 Research Boulevard, Rockville, MD, USA.
Kaiser-Permanente, Division of Research, 2000 Broadway, Oakland, CA, USA.
Marshfield Clinic Research Foundation, Epidemiology Research Center, 1000 North Oak Avenue, Marshfield, WI, USA.
National Cancer Institute, Division of Cancer Control and Population Sciences, 9609 Medical Center Drive, Rockville, MD, USA.



We examined the feasibility of conducting a longitudinal study of diet among diverse populations by comparing rates of response throughout recruitment and retention phases by demographic and other characteristics.


Using quota sampling, participants were recruited from 3 geographically and demographically diverse integrated health systems in the United States. Overall, 12,860 adults, ages 20-70, were invited to participate via mail. Participation first required accessing the study's website and later meeting eligibility criteria via telephone interview. Enrollees were asked to provide two 24-hour dietary recalls, either interviewer-administered or self-administered on the web, over 6 weeks. Stepped monetary incentives were provided.


Rates for accessing the study website ranged from 6% to 23% (9% overall) across sites. Site differences may reflect differences in recruitment strategy or target samples. Of those accessing the website, enrollment was high (≥ 87%). Of the 1185 enrollees, 42% were non-Hispanic white, 34% were non-Hispanic black, and 24% were Hispanic. Men and minorities had lower enrollment rates than women and non-Hispanic whites, partially due to less successful telephone contact for eligibility screening. Once enrolled, 90% provided 1 recall and 80% provided both. Women had higher retention rates than men, as did older compared to younger participants. Retention rates were similar across race/ethnicity groups.


While study recruitment remains challenging, once recruited most participants, regardless of race/ethnicity, completed two 24-hour dietary recalls, both interviewer-administered and self-administered on the web. This study demonstrates the feasibility of collecting multiple 24-hour recalls including less expensive automated self-administered recalls among diverse populations.


automated nutritional assessment; diet survey; experimental design; population; recruitment; retention

Conflict of interest statement

Conflicts of interest: No conflict of interest was declared by the authors of this paper.

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