Azithromycin combination therapy for community-acquired pneumonia: propensity score analysis

Whether macrolide combination therapy reduces the mortality of patients with severe community-acquired pneumonia (CAP) hospitalized in the non-intensive care unit (ICU) remains unclear. Therefore, we investigated the efficacy of adding azithromycin to β-lactam antibiotics for such patients. This prospective cohort study enrolled consecutive patients with CAP hospitalized in the non-ICU between October 2010 and November 2016. The 30-day mortality between β-lactam and azithromycin combination therapy and β-lactam monotherapy was compared in patients classified as mild to moderate and severe according to the CURB-65, Pneumonia Severity Index (PSI), and Infectious Diseases Society of America (IDSA)/American Thoracic Society (ATS) criteria. Inverse probability of treatment weighting (IPTW) analysis was used to reduce biases. Based on the CURB-65 and PSI, combination therapy did not significantly reduce the 30-day mortality in either group (179 patients in the combination group, 952 in the monotherapy group). However, based on the IDSA/ATS criteria, combination therapy significantly reduced the 30-day mortality in patients with severe (odds ratio [OR] 0.12, 95% confidence interval [CI] 0.007–0.57), but not non-severe pneumonia (OR 1.85, 95% CI 0.51–5.40); these results were similar after IPTW analysis. Azithromycin combination therapy significantly reduced the mortality of patients with severe CAP who met the IDSA/ATS criteria.