Empiric Weight-Based Vancomycin in Intensive Care Unit Patients With Methicillin-Resistant Staphylococcus aureus Bacteremia

Abstract

Background We have conducted previous studies in all hospitalized patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia to determine safety and effectiveness of guideline-recommended, weight-based dosing of vancomycin. In these studies, we observed that severely ill patients (Pitt bacteremia score ≥ 4 or ICU patients) were at an increased risk of mortality and/or nephrotoxicity. Therefore, we conducted a subanalysis of the effect of guideline-recommended vancomycin dosing on in-hospital mortality and nephrotoxicity in intensive care unit (ICU) patients with MRSA bacteremia. Methods This multicenter, retrospective, cohort study was conducted in a subset of ICU patients from a previous MRSA bacteremia study. Patients were ≥18 years old and received ≥48 hours of empiric vancomycin from 07/01/2002 to 06/30/2008. We compared the incidence of nephrotoxicity and in-hospital mortality in patients that received guideline-recommended dosing (at least 15 mg/kg/dose) to patients that received non-guideline-recommended dosing of vancomycin. Multivariable generalized linear mixed-effects models were constructed to determine independent risk factors for in-hospital mortality and nephrotoxicity. Results Guideline-recommended dosing was received by 34% of patients (n=137). Nephrotoxicity occurred in 35% of patients receiving guideline-recommended dosing and 39% receiving non-guideline-recommended dosing (p=0.67). In-hospital mortality rate was 24% among patients who received guideline-recommended dosing compared with 31% for non-guideline-recommended dosing (p=0.40). Guideline-recommended dosing was not associated with nephrotoxicity (OR 1.10; 95% CI 0.43–2.79) or in-hospital mortality (OR 0.54; 95% CI 0.22–1.36) in the multivariable analysis. Conclusions Guideline-recommended dosing of vancomycin in ICU patients with MRSA bacteremia is not significantly associated with nephrotoxicity or in-hospital mortality. However, the 7% absolute difference for in-hospital mortality suggests larger studies are needed.