Diagnostic Architecture of Healthcare-Associated Infection Surveillance Definitions: A Comparative Methodological Analysis of International Surveillance Frameworks.

BACKGROUND: Healthcare-associated infection (HAI) surveillance relies on standardized case definitions, yet variation in diagnostic criteria across surveillance frameworks may affect interpretation and comparability of infection indicators. METHODS: Official surveillance manuals and guidance documents from 13 international, regional, and national HAI surveillance frameworks were reviewed. Seven systems with sufficiently detailed diagnostic criteria were included in a structured comparative analysis. Four infection categories (CLABSI, CAUTI, pneumonia, and surgical site infection) were evaluated across four diagnostic domains: clinical criteria, microbiological evidence, device/procedure association, and temporal thresholds. RESULTS: Seven surveillance systems yielded 52 surveillance definitions and 208 coded diagnostic elements. Comparative analysis identified variation in how surveillance frameworks operationalized clinical criteria, microbiological evidence, device/procedure association, and temporal thresholds. Device/procedure association and temporal thresholds were consistently specified, whereas microbiological requirements varied across infection types and surveillance contexts. Pneumonia definitions demonstrated the greatest heterogeneity in diagnostic specification across surveillance frameworks. DISCUSSION: Structural differences in surveillance definitions may influence how infections are identified and reported within surveillance systems, potentially affecting interpretation of benchmarking data and cross-system comparisons. CONCLUSIONS: Structural variation in HAI surveillance definitions should be considered when comparing infection indicators, implementing automated surveillance systems, or adapting surveillance frameworks across healthcare settings.