RCT of a tailored reminder to improve mammography participation among non-responders

Abstract With over 2 million cases annually, breast cancer (BC) remains a major cause of cancer mortality. In Flanders, Belgium, the BC screening program (BCSP) reduces BC-specific mortality by 51%. Yet, participation remains low among previous non-responders, an issue that particularly affects underserved groups such as low-income individuals and minorities. A participatory approach was used to develop a tailored reminder letter, specifically addressing participation barriers faced by underserved groups. The co-creation process included 33 underserved women - mostly non-native Dutch speakers - and refined with stakeholder input. Compared to the official invitation letter, the reminder incorporated culturally tailored, simplified text and visuals and a QR code with 12-language translations. A randomized controlled trial (RCT) assessed the effectiveness of the reminder from April to June 2024. Participants were non-responders who previously received invitations but never participated. In total, 7922 individuals were randomized 1:1 to receive either the standard invitation alone (control) or with the tailored reminder (intervention). Participation rates were compared using the χ² test. Overall, 643 (12.1%) attended screening within 40 days. Intention-to-treat analysis showed a 6.5% absolute increase in participation in the intervention group (16.2% vs. 9.7%; OR 1.81 [95%CI 1.58-2.07], p < 0.001). The intervention improved participation across all age groups, provinces, and radiologic units. The largest gains occurred among participants aged 51-54 (+9.7%), residents of Limburg (+10.3%), and appointments at private radiologists (+8.7%). Preliminary cost-effectiveness data is promising and will inform decisions regarding implementation. The intervention significantly increased BC screening participation among previous non-responders, indicating potential to reduce disparities in screening access. Ongoing discussions with health authorities aim to assess its integration into the BCSP. Key messages • A simplified reminder letter tailored for a low-literate audience significantly increased mammography screening among previous non-responders. • Co-created health communications tailored to underserved groups are effective and a scalable public health strategy to reduce disparities in access to breast cancer screening.