Antimicrobial Stewardship Interventions for Staphylococcus aureus Bacteremia: Cost Analysis of Alternative Therapies

Abstract

Background. Staphylococcus aureus bacteremia (SAB) is a significant cost burden to the US Health System. Clinical management of SAB becomes challenging in patients who are not candidates for or fail first line therapies such as vancomycin (V), semisynthetic penicillin's (SSP) or cefazolin (C). Alternative agents for SAB includes ceftaroline (CPT) and daptomycin (DAP), however outcomes data are limited. The purpose of this study was to assess inpatient pharmacy drug costs of alternative antimicrobials for treatment of SAB in patients who cannot tolerate or fail recommended therapies from the hospital perspective. Methods. We conducted a retrospective chart review of all SAB episodes at an academic medical center in Rochester, New York from November 2014 to April 2016. Inclusion criteria were patient's ≥18 years who received alternative antimicrobials for treatment of SAB, defined as agents other than V, SSP, C or other ß-lactam for methicillin-sensitive SAB (MSSAB) or any parenteral agent with MRSA activity other than V for methicillin-resistant SAB (MRSAB). Pharmacy cost of antimicrobial therapy was calculated based on the group purchasing organization (GPO) cost per vial. Cost of therapy was assessed per total milligram administered and total number of vials used. Antimicrobial dosing followed local recommendations and/or institution guidelines. Inferential statistics were used to analyze cost differences between CPT and DAP. Results. Two hundred sixty-four episodes of SAB occurred in 246 unique patients; 53% were MSSAB. Sixteen episodes met inclusion criteria; 14 were MRSAB (88%). The mean duration of inpatient alternative antimicrobial therapy for SAB was 11 days. Cost per episode based on total milligram: CPT-q12: $2197.44; CPT-q8: $3261.28 and DAP: $4144.08. Cost per episode based on number of vials used: CPT-q12: $2220.69; CPTq8: $3243.84 and DAP: $4325.85. There was an overall difference in mean cost per episode based on number of vials used between CPT-q12 and DAP (p = 0.031) but not CPT-q8 and DAP (p = 0.31). Conclusion. Applying GPO costs per vial, use of CPT-q12 resulted in more economical drug costs for inpatient parenteral alternative antimicrobial therapy than DAP. Further studies evaluating efficacy and economic outcomes of CPT and DAP as alternative therapy for SAB are needed.