Ward-Level Factors Associated with Methicillin-Resistant Staphylococcus aureus Acquisition − an Electronic Medical Records study in Singapore

Abstract

Background Methicillin-Resistant Staphylococcus aureus (MRSA) is endemic in hospitals worldwide. When patients are transferred between wards within a hospital, their risk of acquiring MRSA may change. In this study, we investigated how ward characteristics and connectivity are associated with MRSA acquisition. Methods We analysed electronic medical records on patient transfers and MRSA screening of in-patients at an acute-care tertiary hospital in Singapore to investigate whether ward characteristics and connectivity within the hospital network were associated with MRSA acquisition rates over a period of four years. Results Most patient transfers concentrated in a stable core network of wards. Factors associated with increased rate of MRSA acquisition were ward MRSA admission prevalence (rate ratio (RR): 1.50, 95% CI: 1.28, 1.71, per one percentage point increase), admission to a critical care ward (RR: 1.86, 95% CI: 1.14, 3.06) and average number of patients in the ward on a typical day (RR: 1.31, 95% CI: 1.02, 1.68, for every 10 patients quarterly). Admission to an oncology ward (RR: 0.61, 95% CI: 0.40, 0.93) (compared to medical ward), and median length of stay (RR: 0.71, 95% CI: 0.54, 0.93) were associated with lower acquisition rates. We did not find evidence that network measures of ward connectivity, including in-degree, weighted in-degree, influenced MRSA acquisition rate after adjusting for other ward characteristics. Conclusion Ward MRSA admission prevalence, critical care ward, ward patient capacity, ward specialty, and median length of stay, rather than relative connectivity of the ward in the hospital network were associated with MRSA acquisition.