Risk Factors for 30-Day Mortality in Patients with Methicillin-Resistant Staphylococcus aureus Bloodstream Infections

Abstract

Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) blood stream infections (BSI) are a major health care problem accounting for a large percentage of nosocomial infections. The aim of this study was to identify risk factors associated with 30-day mortality in patients with MRSA BSI.

Methods: This was a retrospective study performed in Southeast Michigan. Over a 9- year period, a total of 1,168 patients were identified with MRSA BSI. Patient demographics and clinical data were retrieved and evaluated using electronic medical health records.

Results: 30-day mortality during the 9-year study period was 16%. Significant risk factors for 30-day mortality were age, cancer, heart disease, neurologic disease, nursing home residence and Charlson score >3 with Odds Ratio (OR) of 1.03 (CI 1.02-1.04), 2.29 (CI 1.40-3.75), 1.78 (CI 1.20-2.63), 1.65 (CI 1.08-2.25), 1.66 (CI 1.02 - 2.70) and 1.86 (CI 1.18 - 2.95) correspondingly. Diabetes mellitus, peripheral vascular disease (PVD), and readmission were protective factors for 30-day mortality with OR of 0.53 (CI 0.36-0.78), 0.46 (CI 0.26-0.84) and 0.13 (CI0.05 - 0.32) respectively.

Conclusions: Our study identified significant risk factors for 30-day mortality in patients with MRSA BSI. Interestingly, diabetes mellitus, PVD and readmission were protective effects on 30-day mortality. There was no statistically significant variability in 30-day mortality over the 9-year study period.

Keywords: 30-day mortality; Methicillin-resistant Staphylococcus aureus; blood stream infection; risk factors.