Factors influencing recruitment and retention of participants in clinical studies conducted at a tertiary referral center: A five-year audit

INTRODUCTION: A key determinant of the success of any study is the recruitment and subsequent retention of participants. Screen failure and dropouts impact both the scientific validity and financial viability of any study. We carried out this audit with the objective of evaluating the recruitment and retention of participants in clinical studies conducted over the last five years at our center. METHODS: Studies completed between 2014 and 2018 at our center were included. Screening ledgers and study trackers were hand searched for screen failures and dropouts. Four pre-identified predictors were evaluated – risk as per the classification of Indian Council of Medical Research 2017 Ethical Guideline, nature of funding, study design, and nature of participants. Association of the predictors with screen failures and dropouts was determined using crude odds ratios along with 95% confidence intervals. All analyses were done at 5% significance using Microsoft Excel 2016. RESULTS: A total of n = 19 completed studies had n = 2567 screened and n = 2442 enrolled participants with a screen failure and dropout rate of 5% and 4%, respectively. We found 59% screen failures due to abnormal laboratory values. The main reasons for dropouts were lost to follow-up 86 (88%). High-risk and interventional studies were the predictors for both screen failures and dropouts, but pharmaceutical industry-funded studies and healthy participants were predictors for only screen failures. CONCLUSION: Risk, funding, study design, and nature of participants are important to be considered while planning studies to minimize screen failures and dropouts.