Discussion
CRC
RECRUITMENT
The CONFIRM study has enrolled 50 126 veterans at average risk for CRC and randomized them to screening with either colonoscopy or annual FIT. In this cross-sectional study, we describe characteristics of the cohort and factors associated with ineligibility for enrollment or declining participation in the study. We specifically analyzed data from individuals who declined because of a stated preference for screening with FIT or colonoscopy and found that preference varied by region of recruitment and increased over the period of recruitment.A major design goal of the CONFIRM study was to recruit a diverse cohort of individuals representative of the US population. While the cohort is largely male, it is diverse with respect to race and ethnicity. Given that recruitment was within the VA health care system, it was not possible to have strong female participation, despite adjunctive efforts to recruit female veterans. As of 2017, it was estimated that approximately 9.6% of VA health system users were female,Accomplishing racial and ethnic diversity within large clinical trials is often challenging. For example, 1 analysis examining racial and ethnic distribution in oncology trials (N = 145) showed that Black individuals comprised only 22% and Hispanic individuals 44% of the expected proportion.While this report describes trial participant data in detail, we also were able to explore reasons for nonparticipation in CONFIRM. In terms of veterans found ineligible for enrollment, the most common reason was that the individual was not due for screening. This finding is not particularly surprising given that approximately 80% of veterans enrolled in primary care within the VA are found to be up to date with CRC screening.We were also interested in studying veterans who were eligible for enrollment but declined participation. The most common reason for declining was that the individual simply preferred one of the screening tests and did not want to be randomly assigned. This observed variation in preference for screening between the 2 most common screening options is, in and of itself, an important research finding. Interestingly, within this VA-based cohort, preference was higher for FIT than colonoscopy in those declining participation. This finding may reflect long-standing patterns of screening test use in the VA. In 2003, estimates using VA data suggested that 90% of CRC screening was done by FOBT.We also observed time trends for increasing FIT preference over the recruitment period and some regional preference for FIT. Specifically, we observed a greater preference for FIT in the western US, and this finding would be consistent with recently reported National Health Interview Survey data that examined screening trends in 2019 and 2012.