Importance: Optimal strategies for population-based outreach for breast cancer screening remain unknown.
Objective: To evaluate the effect on breast cancer screening of an opt-out automatic mammography referral strategy compared with an opt-in automated telephone message strategy.
Design, setting, and participants: This pragmatic randomized clinical trial was conducted from April 2022 to January 2023 at a single Veterans Affairs (VA) medical center. Participants were female veterans aged 45 to 75 years who were eligible for breast cancer screening and enrolled in VA primary care.
Intervention: Veterans were randomized 1:1 to receive either an automatic mammography referral (opt-out arm) or an automated telephone call with an option for mammography referral (opt-in arm).
Main outcomes and measures: The primary outcome was completed mammography 100 days after outreach. Secondary outcomes were scheduled or completed mammography by 100 days after outreach and referrals canceled if mammography was not scheduled within 90 days. Both intention-to-treat analyses and a restricted analysis were conducted. The restricted analysis excluded veterans who were unable to be reached by telephone (eg, a nonworking number) or who were found to be ineligible after randomization (eg, medical record documentation of recent mammography).
Results: Of 883 veterans due for mammography (mean [SD] age, 59.13 [8.24] years; 656 [74.3%] had received prior mammography), 442 were randomized to the opt-in group and 441 to the opt-out group. In the intention-to-treat analysis, there was no significant difference in the primary outcome of completed mammography at 100 days between the opt-out and opt-in groups (67 [15.2%] vs 66 [14.9%]; P = .90) or the secondary outcome of completed or scheduled mammography (84 [19%] vs 106 [24.0%]; P = .07). A higher number of referrals were canceled in the opt-out group compared with the opt-in group (104 [23.6%] vs 24 [5.4%]; P < .001). The restricted analysis demonstrated similar results except more veterans completed or scheduled mammography within 100 days in the opt-out group compared with the opt-in group (102 of 388 [26.3%] vs 80 of 415 [19.3%]; P = .02).
Conclusions and relevance: In this randomized clinical trial, an opt-out population-based breast cancer screening outreach approach compared with an opt-in approach did not result in a significant difference in mammography completion but did lead to substantially more canceled mammography referrals, increasing staff burden.
Trial registration: ClinicalTrials.gov Identifier: NCT05313737.