Recruitment of young adults into a randomized controlled trial of weight gain prevention: message development, methods, and cost

Abstract

Background: Young adulthood (age 18 to 35) is a high-risk period for unhealthy weight gain. Few studies have recruited for prevention of weight gain, particularly in young adults. This paper describes the recruitment protocol used in the Study of Novel Approaches to Prevention (SNAP).

Methods: We conducted extensive formative work to inform recruitment methods and message development. We worked with a professional marketing firm to synthesize major themes and subsequently develop age-appropriate messages for recruitment. A variety of approaches and channels were used across two clinical centers to recruit young adults who were normal or overweight (body mass index (BMI) 21 to 30 kg/m2) for a 3-year intervention designed to prevent weight gain. We tracked recruitment methods, yields, and costs by method. Logistic regression was used to identify recruitment methods that had the highest relative yield for subgroups of interest with covariate adjustments for clinic.

Results: The final sample of 599 participants (27% minority, 22% male) was recruited over a 19-month period of sustained efforts. About 10% of those who initially expressed interest via a screening website were randomized. The most common reason for ineligibility was already being obese (BMI >30 kg/m2). The top two methods for recruitment were mass mailing followed by email; together they were cited by 62% of those recruited. Television, radio, paid print advertising, flyers and community events each yielded fewer than 10% of study participants. Email was the most cost-effective method per study participant recruited.

Conclusions: These findings can guide future efforts to recruit young adults and for trials targeting weight gain prevention.

Trial registration: ClinicalTrials.gov NCT01183689 (registered 13 August 2010).

Figures

Figure 1

Major recruitment events May 2010 to March 2012. C, community events; E, emails or mailed letters to individuals or smaller groups; I, internet ad or website posting; ME, mass email to listserv or purchased email list; MM, mass mailing; N, newspaper ad; R, radio ad; TV, television ad. (* denotes multiple runs during period). Not shown: flyers posted or “word of mouth”. Events shown in blue were in Providence and those in black were done in North Carolina. Symbols indicate when a cohort was randomized at each location: # in North Carolina; @ in Providence.

Figure 2

Recruitment materials.

Figure 3

CONSORT diagram.

Figure 4

Recruitment of subgroups by mass mailing and email. Note: percent recruited with mass mailing and email within subgroups will not add to 100% as those recruited with other methods are not displayed.