Clinical outcomes of patients receiving daptomycin for the treatment of Staphylococcus aureus infections and assessment of clinical factors for daptomycin failure: A retrospective cohort study utilizing the Cubicin® Outcomes Registry and Experience

Abstract Background: Daptomycin is most commonly used as a second-line treatment. Previous studies have not differentiated the effect of prior antibiotic therapy on daptomycin clinical outcomes. Objectives: The primary objective of this study was to compare clinical outcomes of patients treated with daptomycin as first-line therapy versus after prior antibiotic therapy (specifically, vancomycin). A secondary objective was to identify other factors associated with the clinical failure of daptomycin therapy. Methods: This was a retrospective cohort study using data from a postlabeling registry database. The effects of relevant patient characteristics on the clinical outcome of individuals treated for Staphylococcus aureus infections with daptomycin were examined in an unblinded approach using univariate and multivariate analyses. Only patients with an evaluable clinical outcome (ie, cure, improvement, failure) and culture-confirmed S aureus infection were included in the analysis cohort. Results: Of 1227 clinically evaluable patients, 250 (20%) received daptomycin as first-line therapy and 977 (80%) received daptomycin after other prior antibiotic therapy. Overall, 53% of patients were male; 64% were aged 31 to 65 years and 26% were aged ≥66 years. Race information was collected beginning in 2007; of the patients studied, 71% were white and 18% were black. The initial daptomycin dose (mean [SD]) overall was 5.1 (1.1) mg/kg and was highest for patients with endocarditis (5.9 [1.2] mg/kg) and lowest for those with uncomplicated skin and skin structure infections (4.4 [0.9] mg/kg). Clinical success , defined as an outcome of cured or improved at the end of daptomycin therapy, was reported for 1140 (93%) of the 1227 evaluable patients. The clinical success rates for first-line therapy with daptomycin and after prior antibiotics were both 93%. Using univariate analysis, 8 variables were associated with clinical failure (receipt of daptomycin in an intensive care unit setting, severe renal dysfunction [creatinine clearance