Programme-level determinants of participation in colorectal cancer screening in Italy: a national cross-sectional study

BACKGROUND: Participation in organised colorectal cancer (CRC) screening is influenced by multiple organisational factors; however, existing evidence has mainly focused on isolated interventions, with limited understanding of how these components jointly influence participation within real-world screening settings. This study aimed to identify the organisational determinants of participation in population-based CRC screening in Italy and to quantify their relative contribution within a real-world, decentralised healthcare system, hypothesising that participation is determined by the effect of multiple organisational domains rather than by isolated interventions. METHODS: We conducted a national cross-sectional survey of Italian CRC screening programmes using a validated web-based questionnaire. Fifty-eight programmes from 17 regions were included. The outcome was the adjusted participation rate in 2022. Associations between organisational characteristics and participation were assessed using multiple fractional logistic regression models. RESULTS: The participating services covered a target population of 5.9 million individuals. Participation varied substantially across settings (range 6.5%-67.1%). In multivariable analysis, higher participation was independently associated with Northern geographic area (OR 2.03; 95% CI 1.73-2.38; p < 0.001), programme duration > = 16 years (OR 1.87; 95% CI 1.28-2.73; p < 0.01), the presence of a unified regional management system (OR 1.45; 95% CI 1.08-1.94; p = 0.01), coordinated communication of positive faecal immunochemical test (FIT) results (OR 1.44; 95% CI 1.13-1.84; p = 0.003), communication by general practitioners (OR 1.35; 95% CI 1.06-1.72; p = 0.014), and structured invitation procedures including educational materials and reminders. These findings suggest that participation is shaped by the effect of multiple organisational components rather than by isolated interventions. CONCLUSIONS: This study provides a system-level evaluation of organisational determinants of CRC screening participation and quantifies their relative contribution within real-world programmes. The proposed framework may support screening services in identifying priority organisational domains for intervention and in designing integrated strategies tailored to their operational context.