Abstract
BACKGROUND: Despite their potential as tools for improving the efficiency of accrual in clinical research, few analyses have assessed the effectiveness of recruitment registries. We investigated referrals to clinical research studies from the University of California, Irvine Consent-to-Contact registry, a local online recruitment registry in Orange County, CA. Our analyses sought to quantify the total number of referrals and the proportion of referrals leading to subsequent enrollment in a clinical research study. Key secondary objectives were to investigate the relationship with referral outcomes for registrant research attitudes and the participant burden of the contacting study. METHODS: We categorized referral outcomes as: (i) unable to reach, (ii) declined to participate, (iii) phone screened but ineligible, (iv) consented but ineligible, or (v) consented and enrolled. We assessed the overall effectiveness of the registry using the observed distribution of referral outcomes. We investigated the marginal relationship between referral outcome and the participant burden of the contacting study using distributions of referral outcomes conditional on participant burden. We used a binary logistic linear mixed effects model to investigate relationships between registrant characteristics and the odds of a referral leading to participant consent. RESULTS: Overall, the registry made 6,314 resolved referrals of 3,843 unique registrants to 57 unique research studies. 1,642 (26%) of these referrals were successful, leading to enrollment. Among referrals to interview studies, registrant research attitudes as measured by the research attitudes questionnaire were not associated with the odds of successful first referral (odds ratio per 5 points: 1.00, 95% CI: (0.79, 1.28), p = 0.98). Registrant research attitudes were positively associated with the odds of a successful first referral in non-invasive longitudinal studies (odds ratio per 5 points on the research attitudes questionnaire: 1.17, 95% CI: (1.03-1.32), p = 0.02). The observed relationship was stronger, though not significant in invasive and interventional research (odds ratio: 1.22, 95% CI: (0.99-1.49), p = 0.06). CONCLUSIONS: Our results emphasize the potential effectiveness of recruitment registries and of the research attitudes questionnaire to predict referral outcomes to higher burden clinical research.