Outcomes Associated with Initial versus Later Vancomycin Use in Patients with Complicated Skin and Skin-Structure Infections

Background: Delayed coverage of pathogens including meticillin-resistant Staphylococcus aureus (MRSA) in pneumonia and bacteraemia has been associated with increased mortality and length of hospital stay (LOS). However, less is known about the impact of delayed appropriate coverage in complicated skin and skin-structure infections (cSSSIs). Objective: To evaluate the clinical and economic outcomes associated with early versus late use of vancomycin in the management of patients hospitalized for cSSSIs. Methods: Retrospective analysis was performed using an inpatient claims database of >500 US hospitals in 2005. Using prescription claims, patients with primary or secondary cSSSI admissions were classified into three groups: 1=early vancomycin monotherapy; 2=early vancomycin combination therapy; 3=late vancomycin therapy. Outcomes studied included LOS and inpatient hospital costs. One-way analysis of variance was used for unadjusted analysis and multivariate regression methods were used to control for co-variates. Results: A total of 34942 patients (27.78% of all patients with cSSSIs) were treated with vancomycin. Mean age was 54.7 years and 54.3% of the patients were males. Mean unadjusted total LOS was 8.46, 9.44 and 13.2 days, and hospital costs in 2005 values were $US10211.94, $US12361.94 and $US 18 344.00 for groups 1, 2 and 3, respectively. In-hospital mortality rate was highest in group 3 (4.18%) and lowest in group 1 (.75%). Generalized linear models used to control for potential confounding variables between early versus late vancomycin use suggest that among cSSSI patients late vancomycin use is an independent predictor of higher LOS and costs. Conclusion: In this large inpatient database, later vancomycin use in patients with cSSSIs appears to be significantly associated with higher LOS and total costs.