Spatial inequalities in cardiovascular health: a cross-sectional study with small-area health insurance claims and individual-level primary care data in Belgium

Atherosclerotic cardiovascular disease (ASCVD) continues to pose a growing burden driven by aging, comorbidities, and socioeconomic vulnerability. Yet, the regional distribution of these disparities remains poorly characterized, partly because no single dataset provides comprehensive ASCVD surveillance data. To address this gap, we combined insights from small-area health insurance claims and individual-level primary care data to assess how socioeconomic vulnerability relates to ASCVD indicators across regional contexts in Belgium. We conducted a cross-sectional study using two complementary data sources: (i) small-area ASCVD indicators from a nationwide health insurance organization and (ii) individual-level clinical diagnoses from a general practice (GP) registry in Flanders. A multidimensional small-area socioeconomic vulnerability index was constructed using established methodology. Associations were examined using Spearman correlation, Mann-Whitney U tests, bootstrapping, and hierarchical logistic regression models. Both small-area health insurance claims data and small-area predictions derived from individual-level GP registry data revealed regional disparities in ASCVD prevalence that overlapped with patterns of socioeconomic vulnerability. Socioeconomic vulnerability was positively correlated with ASCVD prevalence at both small-area and individual levels. In the claims dataset, the median ASCVD prevalence was 1.57 times higher (95% CI: 1.46–1.65) in high-vulnerability areas compared with low-vulnerability areas. In the GP registry, overall ASCVD prevalence was 6.46%, with marked disparities by age, sex, socioeconomic status, and lipid-lowering medication. Increased compensation, a proxy for individual-level socioeconomic vulnerability, was associated with higher ASCVD prevalence, particularly among individuals not receiving lipid-lowering therapy. Small-area risk estimates of increased compensation derived from the GP registry showed moderate agreement with the multidimensional vulnerability index. An accompanying geoportal visualizes small-area data, enabling stakeholders to identify high-vulnerability areas and support targeted public health interventions. Combining small-area health insurance claims with individual-level primary care data provides a more comprehensive framework for cardiovascular health surveillance, revealing socioeconomic disparities that are not fully captured by either dataset alone. The agreement between the findings from these data sources strengthens confidence in the observed spatial patterns and highlights regional inequalities in indicators of ASCVD prevalence across Belgium, underscoring the value of integrated data approaches for public health monitoring and the need for localized public health interventions addressing both area-level and individual-level social determinants of health.