Key predictors and burden of meticillin-resistant Staphylococcus aureus in comparison with meticillin-susceptible S. aureus infections in an Australian hospital setting.

Abstract

Staphylococcus aureus is associated with significant mortality and increased burden on the healthcare system. Relatively few reliable estimates are available regarding the impact of meticillin-resistant Staphylococcus aureus (MRSA) compared to meticillin-susceptible Staphylococcus aureus (MSSA) infections. To compare patients with MRSA and MSSA infection to identify differences in inpatient mortality, length of stay and cost of hospital services, and identify predictors of MRSA as a cause of Staphylococcus aureus infection. An analytical, retrospective, longitudinal study using non-identifiable linked data on adults admitted to hospitals of a health district in Australia with a diagnosis of Staphylococcus aureus infection over a 10-year period. The main outcome measure was 30-day inpatient mortality. Secondary endpoints included total overnight stays, all-cause inpatient mortality, and hospitalisation cost within 1 year of index admission. Inpatient mortality at 30, 100, and 365 days was estimated to be significantly greater for patients with MRSA infections. The mean additional cost of MRSA infections when controlling for additional factors was $5,988 and 4 nights' additional hospital stay per patient within 1 year of index admission. Key predictors of MRSA infection were: date of index admission, higher comorbidity score, greater socio-economic disadvantage, admission to hospital other than via the emergency department, older age, and prior admission to hospital within 28-days of index admission. MRSA infections are associated with increased inpatient mortality, cost and hospital length of stay, compared to those caused by MSSA. Efforts are required to alleviate the additional burden of MRSA infections on patients and healthcare systems.