Comparing the use of intravenous antibiotics under the medical benefit with the use of oral antibiotics under the pharmacy benefit in treating skin and soft tissue infections.

PURPOSE To assess differences in the simultaneous management of pharmacy and medical benefits by analyzing the health care utilization and costs associated with managed care patients who received oral linezolid as a pharmacy benefit or intravenous (IV) daptomycin or IV vancomycin as medical benefits for skin and soft tissue infections (SSTIs). METHODOLOGY The first medical or pharmacy claim from 03/01/2007 to 03/01/2010 was defined as the index date. Patients 18-64 years of age, with an inpatient SSTI diagnosis and > or = 1 target antibiotic claim(s), were included. Follow-up was 45 days; hospitalizations, emergency room (ER) visits, outpatient medical services, prescription fills, and total health care costs were compared for the treatments using univariate generalized linear modeling (GLM) analyses. Total health care costs were compared with GLM multivariate analyses adjusting for baseline covariate values. RESULTS Of the 8,905 patients included, 2,123 received linezolid, 5,503 vancomycin, and 1,279 daptomycin therapy; 14.4% of linezolid, 37.7% of vancomycin, and 22.8% of daptomycin patients were re-hospitalized (p < 0.001). A smaller proportion of linezolid patients (8.6%) required emergency services, versus 11.6% of vancomycin and 10.8% of daptomycin patients (p < 0.001). Multivariate analyses showed vancomycin costs to be significantly lower than daptomycin costs, -$5,425 (95% CI, -$1,535 to -$9,315), and a significantly higher mean cost difference for vancomycin, $11,182 (95% CI, $6,255 to $16,108), and daptomycin, $16,607 (95% CI, $9,426 to $23,788), versus linezolid. CONCLUSION Patients treated with oral linezolid had fewer re-hospitalizations and emergency room visits and lower total costs compared with patients who received vancomycin or daptomycin therapy, suggesting that oral linezolid, which is covered under members' pharmacy benefits, may be more cost-effective than the two intravenous treatments for SSTIs.