Comparative clinical response, safety, and institutional drug use efficiency of intravenous azithromycin versus erythromycin in pediatric Mycoplasma pneumoniae pneumonia: a real-world evidence study

Objective This study aims to compare real-world clinical response, safety, and institutional medication efficiency of intravenous (IV) azithromycin (AZI) versus erythromycin lactobionate (ERY) in hospitalized children with Mycoplasma pneumoniae pneumonia (MPP). Methods A retrospective cohort of 1,049 children with PCR- or serology-confirmed MPP was assembled (AZI: n = 672; ERY: n = 377). Propensity scores were estimated using prespecified baseline confounders (sex, age, severity phenotype, concomitant antibacterial agents, antiviral co-treatment). A 1:1 nearest-neighbor propensity score matching (PSM) without replacement cohort was built (364 matched pairs per arm). The primary endpoint was a three-level composite ordinal outcome (cure, improvement, ineffective) hierarchically assigned at 72 ± 12 h after IV macrolide initiation, without assuming that missing domains imply success. Two sensitivity cohorts tested missingness assumptions. Secondary endpoints included LOS, macrolide duration, and corticosteroid escalation, interpreted as adaptive process nodes. Sparse safety used bias-reduced likelihood inference. Institutional drug efficiency was evaluated by decomposing macrolide costs into dispensed, consumed, and wastage-related avoidable cost signals. Results Before matching, ordinal response distributions differed modestly ( P = 0.040). After PSM, composite ordinal outcomes were similar (paired ordinal P = 0.599), with comparable cure rates (33.8% vs. 32.7%). A treatment × age interaction signal was observed ( P _interaction=0.008). In smaller strata (