Population Health Colorectal Cancer Screening Strategies in Adults Aged 45 to 49 Years

Importance: Colorectal cancer screening is now recommended at age 45 years for average-risk individuals; however, optimal outreach strategies to screen younger adults are unknown. Objective: To determine the most effective population health outreach strategy to promote colorectal cancer screening in adults aged 45 to 49 years. Design, Setting, and Participants: Randomized clinical trial with 20 509 participants conducted in a large health system (UCLA Health). Primary care patients aged 45 to 49 years at average risk for colorectal cancer were randomized 1:1:1:1 to 1 of 4 outreach strategies. The trial ran May 2, 2022, to May 13, 2022, with follow-up through November 13, 2022. Interventions: Colorectal cancer screening via 1 of 4 strategies: (1) fecal immunochemical test (FIT)-only active choice; (2) colonoscopy-only active choice; (3) dual-modality (FIT or colonoscopy) active choice; and (4) usual care default mailed FIT outreach. Main Outcome and Measures: Primary outcome was participation in screening (FIT or colonoscopy) at 6 months. Secondary outcome was screening modality completed. Results: Among 20 509 participants (53.9% female, 4.2% Black and 50.8% non-Hispanic White; mean [SD] age, 47.4 [1.5] years), 3816 (18.6%) underwent screening. Participation was significantly lower in each of the 3 active choice groups (FIT only, 841 of 5131 [16.4%; rate difference, -9.8%; 95% CI, -11.3% to -8.2%]; colonoscopy only, 743 of 5127 [14.5%; rate difference, -11.7%; 95% CI, -13.2% to -10.1%]; dual-modality FIT or colonoscopy, 890 of 5125 [17.4%; rate difference, -8.9%; 95% CI, -10.5% to -7.4%]) than in the usual care default mailed FIT group (1342 of 5126 [26.2%]; all P < .001). Participants offered dual-modality active choice more likely completed any screening than those offered a single active choice modality (17.4% [dual-modality FIT or colonoscopy] vs 15.4% [FIT only and colonoscopy only combined]; rate difference, -1.8%; 95% CI, -3.0% to -0.1%; P = .004]). Among 5125 participants offered a choice between 2 modalities (dual-modality active choice FIT or colonoscopy), colonoscopy was more common than FIT (616 [12.0%] vs 288 [5.6%]; rate difference, -6.4%; 95% CI, -7.5% to -5.3%; P < .001). There was notable crossover in the FIT-only groups to colonoscopy (502 of 5131 [9.8%; FIT-only active choice] and 501 of 5126 [9.8%; usual care default mailed FIT]). Crossover from colonoscopy to FIT was modest (137 of 5127 [2.7%; colonoscopy-only active choice]). Conclusions and Relevance: In this randomized clinical trial, 3 different active choice interventions had lower colorectal cancer screening completion rates among individuals aged 45 to 49 years compared with usual care. Trial Registration: ClinicalTrials.gov Identifier: NCT05275530.