Women and willingness to participate in clinical trials: results from a hypothetical randomized control trial

Purpose The U.S. Congress, the Institute of Medicine, and the National Institutes of Health have all expressed great concern about insufficient representation of women in medical research, particularly within large-scale cohort and clinical safety and efficacy trials. Despite federal mandates requiring adequate representation and enrollment of women in such healthcare research, gender-related participation disparities often persist. We asked whether underrepresentation of women in clinical trials could be due to a lesser willingness to participate (WTP) on the part of women relative to men. Methods We randomly approached patients from 13 Maryland outpatient clinics to self-complete a survey of their WTP in a hypothetical cardiovascular chemoprevention randomized control trial (RCT). After participants rated their WTP on a five-point Likert scale (+WTP = very likely, likely), impact of gender on WTP was analyzed from logistic regressions, adjusted for potential sociodemographic and clinical confounders. Interactions between gender and covariates were also evaluated. Results Of 1132 eligible individuals, 70% responded. By gender, 31% of women were WTP in the hypothetical RCT, compared with 38% of men. In crude analysis, women were marginally less willing to participate in the trial (odds ratio OR = 0.74, 95% confidence interval CI = 0.55–1.00, P = 0.049). In the adjusted model, women indicated a significantly lower WTP than men (OR = 0.61, 95% CI = 0.49–0.77, P < 0.001). Covariates interacting with gender associated with increased female WTP included lower education (<12 years education; P = 0.001), having a sick family member (P = 0.03), being current smoker (P = 0.08), Caucasian race (P = 0.10), having greater income (>$30,000/yr; P = 0.09), and rating religion as being less important in their lives (P = 0.04). Conclusion Women appear less willing to participate in randomized control trials than men. This gender disparity in trial participation may be an obstacle to federal mandates requiring adequate representation of women in cohorts and clinical trials.