Is accreditation linked to hospital infection rates? A 4-year, data linkage study of Staphylococcus aureus rates and accreditation scores in 77 Australian acute hospitals

Objectives: To test our hypothesis that hospitals with higher accreditation scores, specifically in infection control, would be associated with lower Staphylococcus aureus bacteraemia (SAB) rates. Design: A retrospective cohort study. Setting and Participants: Acute public hospitals (n = 77) in New SouthWales, Australia, with reported SAB rates, results from two accreditation surveys and results from at least four hand hygiene audits. Methods: We linked three separate data sets comprising SAB rates, accreditation scores and hand hygiene rates. SAB rates were regressed against accreditation scores, hand hygiene audit rates and hospital demographics using a generalized linear model to account for the non-linear nature of our outcome variable. Results: Significant (P < 0.05) findings included the following: SAB rates across all hospitals fell from 1.34 per 10 000 bed days in 2009 to 0.77 per 10 000 bed days in 2012; mean SAB rates in small hospitals (0.62/10 000 bed days) over the study period were lower than those for principal referral hospitals (1.52/10 000 bed days); smaller hospitals with higher accreditation scores had lower SAB rates, but larger hospitals with higher overall accreditation scores had higher SAB rates, although the effect size was small (<2%). Conclusions: There is a strong evidence base for using SAB rates to measure the impact of infection control programs that are assessed during accreditation. However, there is less evidence to support whether accreditation scores accurately reflect implementation of the infection control accreditation standards. This impacts identification of indicators to measure patient safety and quality of care, especially in ensuring these are appropriate across a range of hospital size and activities.