ABSTRACT NUMBER: ESOC2026A1772 WHY POPULATION-BASED REGISTRIES ARE ESSENTIAL FOR COMPREHENSIVE STROKE CASE ASCERTAINMENT

Abstract Background and aims Stroke is a major public health concern and population-based stroke registries are essential for monitoring, its incidence and outcomes. To ensure comprehensive case ascertainment, the World Health Organization recommends the use of Multiple Overlapping Sources. The objective of this study was to assess the contribution of multiple data sources to stroke case ascertainment in a population-based registry. Methods Stroke events in residents of Lille are recorded by the Lille Stroke Registry through exhaustive ascertainment from local sources: the Lille University Hospital Center, private clinics, private hospitals, emergency medical services, public and private rehabilitation centers, nursing homes, death certificates, the Regional Health Agency and local town halls. Results Between 2015 and 2023, 2928 cases were recorded. More than one source was identified in 96.0% of cases, with a mean of 3.6 sources per case. More specifically, 11% had 2 sources, 34.5% had 3 sources, 29.1% had 4 sources, and 21.4% had 5 or more sources. The main sources were the Hospital Discharge Database (89.5%), hospital discharge summaries (89.0%), and neuroradiology reports (68.5%). If any of primary hospital-based sources were not available, non-hospital (including clinics) sources have made possible to identify of 4.3% of all cases, mainly from death certificates and nursing homes. Conclusions Although hospital-based sources captured the majority of stroke cases, reliance on a single hospital data source would have resulted in incomplete case ascertainment. The use of multiple complementary sources improves the completeness and robustness of population-based stroke registry, thereby supporting more comprehensive and representative estimates of stroke incidence and recurrence. Conflict of interest No author has anything to disclose