Cross-national variations and demographic disparities in health surveillance system performance: a comparative analysis of OECD member countries.

This study examines cross-country variation in public health surveillance performance across 30 OECD member states, drawing on Institutional Capacity Theory and governance dynamics. The analysis uses the Organization for Economic Cooperation and Development (OECD) Health Statistics Body Weight Surveillance Dataset (2018-2022). A composite index was developed to evaluate infrastructure capacity, data quality, coverage equity and temporal consistency on the basis of 847 000 surveillance observations across seven age groups and two genders, in order to assess how institutional structures and governance arrangements shape surveillance effectiveness. Substantial heterogeneity in performance was observed, with composite scores ranging from 3.2 to 9.2 on a 10-point scale. Cluster analysis showed that the five Nordic countries consistently grouped in the highest-performing cluster, each scoring above 8.6, while Eastern European countries displayed systematically lower performance, averaging 4.8. Overall, six distinct performance clusters emerged, reflecting shared healthcare system characteristics and institutional development trajectories. Multivariable regression results indicated that infrastructure investment, primary care density and digital health integration explained 68% of the variance in surveillance performance, while governance quality contributed an additional 14% beyond economic factors. Gender-based disparity analysis revealed significant coverage gaps in low-capacity systems, with differences of 9.1 percentage points between males and females, compared with narrower gaps of 5.6 points in high-capacity systems. While coverage rates for working-age populations exceeded 93%, participation among younger and older age groups was notably lower. Intersectional findings further indicated that stronger institutional capacity was associated with higher levels of age- and gender-based coverage equity. Overall, the findings suggest that surveillance effectiveness depends more on institutional coherence, governance coordination and adaptive capacity than on financial investment alone. Countries with robust institutional frameworks and collaborative governance arrangements demonstrate superior performance in both effectiveness and demographic inclusion. These results underscore the need for institutional reform to better integrate technological advancements and strengthen inclusive public health intelligence systems.