Colorectal cancer screening in individuals with multiple sclerosis: A mixed-methods study.

INTRODUCTION: People with multiple sclerosis (pwMS) have a lower reported risk of colorectal cancer, which may reflect reduced access to colorectal cancer screening (CCS). OBJECTIVES: Compare CCS in pwMS and the general population and identify barriers and facilitators using mixed methods. METHODS: In 2022-2024, PwMS aged 50-74 years and matched controls (3:1) were selected. Overall and age-stratified CCS coverage rates were computed. In pwMS, multivariable mixed-effects logistic models identified factors associated with CCS ⩾ 80%. Semi-structured interviews were carried out with 20 pwMS. RESULTS: The cohort included 63,509 pwMS and 190,527 controls (72.0% women, mean age 59.2 years). Annual CCS coverage was 41.2% in pwMS and 42.4% in controls (p < 0.001). In pwMS, CCS was higher in the 50-54 years (+1.5%, p < 0.001) and lower in the ⩾65 years group (-1.6% to -6.2%, p < 0.001). Male sex (odds ratio = 0.90; 95% CI = [0.86-0.93]) and lower ecological socioeconomic status (0.81 [0.76-0.86]) were associated with lower CCS, while disease-modifying therapies (1.12 [1.08-1.16]) and high healthcare use with higher CCS. Qualitative barriers included motor or digestive MS symptoms and feelings of disgust. Facilitators included health system trust and prevention awareness. CONCLUSION: CCS is lower among older pwMS and remains suboptimal in both pwMS and controls.