Recruitment Strategies and Consent Rates in a National Prospective Colorectal Cancer Screening Cohort: Results from Year 1 of the Voyage Study

Abstract Background : Adherence to recommended colorectal cancer (CRC) screening among US adults is below the public health target of 80%. The multi-target stool DNA assay (mt-sDNA) is a self-administered CRC screening test that may remove barriers to adherence. To improve understanding of long-term outcomes and the real-world impact of mt-sDNA screening, Mayo Clinic and Exact Sciences Laboratories are collaborating on a prospective cohort study of CRC incidence and mortality outcomes in individuals screened with mt-sDNA. We conducted an embedded experiment to identify the optimal incentive protocol for maximizing participation while managing study costs. Methods : A subset of the opt-in cohort was randomized to receive postage stamps as a pre-consent incentive, or as a post-consent incentive after completion of the consent and questionnaire. Descriptive statistics from year one of recruitment, as well as the incentive experiment, are reported. Results : During year 1 of the Voyage trial, a total of 600,258 individuals with mt-sDNA orders received at Exact Sciences Laboratories were randomly selected and invited to participate. Of those, 26,429 (4.4%) opted in, 14,365 of whom (54.3%) consented. The opt-in and consent samples were similar to the target population with respect to sex but differed by geographic residence and age (p<0.001). For the embedded incentive experiment, 2,333 were randomized to the pre-incentive arm while 2,342 were randomized to the post-incentive arm. Overall consent rate in the incentive trial was 56.4% (60.9% for the pre-consent incentive arm (1421/2333) vs. 52.0% for the post-consent incentive arm (1217/2432), p<0.001). A cost reduction was observed for the pre-consent incentive group. Higher response rates were seen among older vs. younger individuals, reflecting a common pattern in healthcare-related survey research participation. Age adjusted incidence rates for CRC have been shown to vary regionally; thus, adjustment for differential response by region will be important to ensure representativeness. Conclusions : CRC incidence and mortality vary with age; thus, adjusting for differential participation by age will be important in analyses of Voyage data. Pre-consent incentive option was associated with a higher participation rate and lower costs, and will be used for the remainder of the study recruitment. Trial Registration : NCT04124406; October 11 th , 2019