Beyond Average Hand Hygiene Compliance: Performance Instability and Critical Low-Compliance Days Are Associated With Healthcare-Associated Infection Incidence in Intensive Care Units

Background Previous studies have demonstrated heterogeneous associations between average hand hygiene (HH) compliance and healthcare-associated infection (HAI) incidence, suggesting that mean compliance alone may not adequately capture clinically relevant performance failures. We aimed to explore whether alternative analytical approaches applied to the same HH dataset provide more informative insights into the relationship between HH performance and HAI incidence. Methods We conducted a prospective observational study using hand hygiene data collected on audit days across three hospital units with distinct workforce stability profiles. Monthly HAI incidence data were obtained from a parallel prospective surveillance study performed by the same infection prevention team. Hand hygiene performance was characterized using multiple predefined metrics, including mean compliance, variability (coefficient of variation), extreme-low-performance days (10th percentile), and the number of critical HH days, defined as daily compliance below 40%. Associations with HAI incidence were evaluated using correlation analyses with an emphasis on effect size and consistency. Results Mean HH compliance showed little to no association with monthly HAI incidence. Measures reflecting overall variability demonstrated moderate associations, while metrics capturing extreme or threshold-based performance failures were more strongly and consistently associated with HAI incidence. The number of critical HH days (< 40% compliance) exhibited the strongest association with HAI incidence (r = 0.48), outperforming average and variability-based measures across units with differing workforce characteristics. Conclusions Analytical approaches that focus on days with critically low hand hygiene performance appear more informative than average compliance metrics for assessing infection risk. These findings suggest that monitoring and targeting performance instability may offer a more actionable framework for infection prevention and workforce-focused management strategies.