High Antimicrobial Consumption, Low Reported Infection Rates: An Ecological Analysis of HAI Surveillance Discordance...

Background/Objectives: Healthcare-associated infections (HAI) affect an estimated 4.3 million patients annually in EU/EEA hospitals; yet, reported prevalence rates vary nearly fivefold across member states, a degree of variation inconsistent with clinical or epidemiological differences alone. Romania exemplifies this paradox: it records one of the lowest reported HAI prevalence rates in Europe while sustaining one of the highest antimicrobial consumption levels on the continent. This study examines whether antimicrobial consumption data can serve as a cross-check on reported HAI prevalence across EU/EEA countries and discusses implications for European funding mechanisms. Methods: A cross-sectional ecological analysis was conducted using data from 26 EU/EEA countries. HAI prevalence was extracted from the ECDC Point Prevalence Survey 2022-2023; antimicrobial consumption indicators from the ESAC-Net Annual Epidemiological Report 2023. Pearson and Spearman correlations, multiple linear regression with Cook's distance diagnostics, bootstrap resampling, and k-means cluster analysis were performed. Variance inflation factors were computed to assess multicollinearity; community sector AMC was excluded from the final regression model due to near-perfect collinearity with total AMC. Results: No antimicrobial consumption indicator was significantly associated with reported HAI prevalence (total AMC: r = 0.274, p = 0.175; broad-spectrum hospital proportion: r = 0.082, p = 0.692); bootstrap confidence intervals confirmed the instability of all estimates. Romania and Bulgaria were identified as influential outliers whose consumption profiles are substantially inconsistent with their reported infection rates, with model-based estimates of 7.3% and 7.0% respectively against reported values of 3.1% and 3.7%. Cluster analysis placed both countries in an isolated group with the highest antimicrobial consumption and broad-spectrum hospital antibiotic use in the sample alongside the lowest reported HAI prevalence, a configuration not replicated elsewhere in the EU/EEA. Conclusions: The absence of a significant aggregate association between antimicrobial consumption and reported HAI prevalence, combined with the systematic identification of Romania and Bulgaria as influential observations whose consumption profiles are inconsistent with their reported infection rates, raises the hypothesis of surveillance underreporting as a plausible explanation, though the ecological design does not permit causal inference and alternative explanations, including differences in antimicrobial stewardship maturity and prescribing culture, cannot be excluded. Antimicrobial consumption indicators, particularly the proportion of broad-spectrum antibiotics in hospital use, may serve as a proxy for HAI burden where direct surveillance is incomplete, and their integration into European surveillance frameworks is warranted. These findings have direct policy relevance for the allocation of resources under EU4Health, EU-JAMRAI 2, and national recovery and resilience programmes, and support investment in surveillance reform as a precondition for effective infection prevention programmes.