Comparative antibiotic failure rates in the treatment of community-acquired pneumonia: Results from a claims analysis

INTRODUCTION|: Antibiotic treatment failure contributes to the economic and humanistic burdens of community-acquired pneumonia (CAP) by increasing morbidity, mortality, and healthcare costs. This study compared treatment failure rates of levofloxacin with those of other antibiotics in a large US sample. METHODS|: Medical and pharmacy claims in the nationally representative SDI database were used to identify adults with a new outpatient diagnosis of CAP receiving a study antibiotic (levofloxacin, amoxicillin/clavulanate, azithromycin, moxifloxacin) between September 1, 2005 and March 31, 2008. Treatment failure was defined as ≥1 of the following events ≤30 days after index date: a refill for the index antibiotic after completed days of therapy, a different antibiotic dispensed >1 day after the index prescription, or hospitalization with a pneumonia diagnosis or emergency department visit >3 days postindex. Cohorts were propensity score matched for demographic and clinical characteristics. Treatment failure rates were compared between pairs of cohorts for the full sample and for high-risk patients (age ≥65 and/or on Medicaid). RESULTS|: Among the 3994 study patients, the numbers of dispensed index prescriptions were 268 for amoxicillin/clavulanate, 1609 for azithromycin, 1460 for levofloxacin, and 657 for moxifloxacin. Unadjusted treatment failure rates for the sample were 20.8% for levofloxacin, 23.9% for amoxicillin/clavulanate, 23.9% for azithromycin, and 19.9% for moxifloxacin. For high-risk patients, unadjusted treatment failure rates were 19.1% for levofloxacin, 26.1% for amoxicillin/clavulanate, 26.3% for azithromycin, and 24.3% for moxifloxacin. Propensity score-matched treatment failure rates were significantly lower with levofloxacin than azithromycin (19.8% vs. 24.5%, odds ratio [OR] comparator vs. levofloxacin 1.38; 95% CI: 1.14, 1.67), a difference amplified in high-risk patients (19.0% vs. 26.4%, OR 1.61; 95% CI: 1.22, 2.13). No significant differences were observed for other paired comparisons. CONCLUSION|: In a large US sample, treatment failure in CAP appeared to be less likely with quinolones (such as levofloxacin) than azithromycin, an effect particularly marked in high-risk patients (age ≥65 and/or on Medicaid).