• Adam Weston, Yoav Golan, Christina Holcroft, and David R Snydman.
• Division of Geographic Medicine and Infectious Diseases, Tufts Medical Center and Tufts University School of Medicine.
• Clin. Infect. Dis. 2014 Jun 1;58(11):1533-9.

BackgroundConcerns regarding the efficacy of daptomycin for methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections in patients with impaired renal function are reflected in a recent package insert change by the Food and Drug Administration (FDA). However, this decision was based on a small subgroup analysis and it is unclear if this is a true association.MethodsWe conducted a retrospective cohort study of patients with MRSA bacteremia treated at a tertiary hospital from 2001 to 2011 and who received either vancomycin or daptomycin. We used propensity score and multivariable logistic regression to assess the outcome of treatment failure, via blinded adjudication, in daptomycin- vs vancomycin-treated subjects and the interaction with renal function.ResultsOne hundred fifty patients were analyzed, 100 in the vancomycin arm and 50 in the daptomycin arm. The average age was 61 years, and 60% were men. Of patients treated with daptomycin or vancomycin, 29 (58%) and 51 (51%), respectively, had an estimated glomerular filtration rate (GFR) <50 mL/minute/1.73 m(2). Compared with vancomycin, the usage of daptomycin in patients was not significantly associated with treatment failure in patients with a GFR >50 mL/minute/1.73 m(2) (odds ratio [OR], 0.45; 95% confidence interval [CI], .11 -1.79), nor in patients with a GFR of <50 mL/minute/1.73 m(2) (OR, 0.46; 95% CI, .11 -1.94). There was no significant interaction between them (P = .54).ConclusionsIn patients with MRSA bacteremia, daptomycin efficacy was not affected by GFR level and was similar to vancomycin's efficacy. Although our sample size was small, it was larger than than the one used by the FDA. However, smaller differences may be significant with a larger sample size.

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