A Randomized Controlled Trial of Opt-in Versus Opt-Out Colorectal Cancer Screening Outreach


Objectives: Colorectal cancer (CRC) screening uptake is suboptimal, despite national efforts to increase screening rates. Behavioral economic approaches such as changing defaults may increase participation. We compare response rates to opt-in or opt-out messaging in mailed fecal immunochemical test (FIT) outreach.

Methods: This is a two-arm randomized controlled trial among 314 patients aged 50–74 years who had at least two primary care visits in the 2-year pre-enrollment period and were screening-eligible but not up-to-date. Eligible patients received invitation by electronic health record (EHR) portal or mail with randomization to receive mailed FIT: (1) only if they actively opted-in to do so (opt-in) or (2) unless they opted-out of screening (opt-out). The primary outcome was FIT completion rate within 3 months of initial outreach.

Results: Patients randomized to opt-in agreed to participate 23.1% of the time, and only 2.5% of those in opt-out chose not to participate. FIT kits were mailed to 22.4% and 93% of patients in opt-in and opt-out arms, respectively. In intention-to-screen analysis, patients in the opt-out arm had a higher FIT completion rate (29.1%) than in the opt-in arm (9.6%) (absolute difference 19.5%; 95% confidence interval, 10.9–27.9%; P < .001). Results were similar in subgroup analysis of those sent initial messaging through the EHR portal (9.5% opt-in versus 37.5% in opt-out).

Conclusions: Mailed CRC screening outreach providing an option to opt-out had significantly higher participation rates than opt-in messaging. Opt-out messaging approaches can boost participation in population health outreach efforts.