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The efficacy of daptomycin versus vancomycin for methicillin-resistant Staphylococcus aureus bloodstream infection in
Adam Weston1, Yoav Golan, Christina Holcroft
1Division of Geographic Medicine and Infectious Diseases, Tufts Medical Center and Tufts University School of Medicine.
Background:
Concerns 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.
Methods:
We 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.
Results:
One 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).
Conclusions:
In 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.
Insights
Daptomycin is effective for methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections, regardless of kidney function. This study found daptomycin efficacy similar to vancomycin in patients with varying GFR levels.
Area of Science:
- Infectious Diseases
- Pharmacology
- Nephrology
Background:
- Recent FDA concerns suggest reduced daptomycin efficacy for MRSA bloodstream infections in patients with impaired renal function.
- This concern is based on a small subgroup analysis, necessitating further investigation into the true association.
Purpose of the Study:
- To evaluate the efficacy of daptomycin compared to vancomycin for MRSA bacteremia in patients with varying renal function.
- To assess the impact of estimated glomerular filtration rate (GFR) on treatment failure rates for daptomycin and vancomycin.
Main Methods:
- Retrospective cohort study of 150 patients with MRSA bacteremia treated with vancomycin or daptomycin (2001-2011).
- Propensity score and multivariable logistic regression used to analyze treatment failure.
- Blinded adjudication assessed outcomes, with analysis stratified by GFR levels (<50 mL/min/1.73 m² and >50 mL/min/1.73 m²).
Main Results:
- Daptomycin treatment was not significantly associated with treatment failure compared to vancomycin in patients with GFR >50 mL/min/1.73 m² (OR, 0.45; 95% CI, .11 -1.79).
- Similarly, daptomycin efficacy was not affected by renal impairment, with no significant difference in treatment failure rates for patients with GFR <50 mL/min/1.73 m² (OR, 0.46; 95% CI, .11 -1.94).
- No significant interaction was observed between daptomycin use and GFR level (P = .54).
Conclusions:
- Daptomycin efficacy for MRSA bacteremia is not influenced by GFR and is comparable to vancomycin.
- While the study sample size was limited, it was larger than the FDA's subgroup analysis.
- Larger studies may be needed to detect smaller, potentially significant differences in efficacy.
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