Study groups
The cohort was stratified depending on the antibiotic administered during the first 48 h of admission: macrolide-based and non-macrolide-based treatment. Patients who received an antibiotic accepted by international guidelines plus a macrolide (e.g., azithromycin or clarithromycin) were included in the macrolide-based treatment group. In contrast, those who received other antibiotics recommended by the IDSA/ATS guidelines but not a macrolide were included in the non-macrolide-based treatment group [