Factors associated with male recruitment in a multi-site randomized behavioral clinical trial targeting the metabolic syndrome: analysis of screening and recruitment data from the ELM trial

Background: Males are underrepresented in behavioral clinical trials of lifestyle. The aim of this exploratory study was to investigate factors associated with trial interest in males at different stages of recruitment and overall, into a multi-site behavioral trial targeting lifestyle change and remission of the metabolic syndrome. Similar analyses were performed for female participation to investigate the uniqueness or consistency with the findings for males.

Methods: Data collected at various stages of recruitment in an ongoing multi-site behavioral clinical trial were used. A series of logistic regressions compared respondents who moved forward to the next step of the screening process versus those who did not. These analyses were stratified by sex. A chi-squared test was used to directly compare proportions of men and women who chose to advance to the next step.

Results: Males who showed interest in the trial were more likely to be self-aware of their current health risk. Comparison of males and females showed that men tended to lose interest earlier in the recruitment process (58.3% of men vs. 66.5% of women attended an in-person information session, p < 0.001), but the proportion that moved forward among those who demonstrated initial interest was similar in men and women.

Conclusion: Efforts to increase male enrollment in behavioral clinical trials will benefit from a focus on early stages of recruitment, aiming to increase potential participants' initial levels of interest and awareness of their health risk. As men and women differ in the reasons they choose to participate in a behavioral trial, recruitment should be tailored to sex to maximize trial participation.

Trial registration: ClinicalTrials.gov NCT04036006. Registered on July 29, 2019. https://clinicaltrials.gov/study/NCT04036006.