Association of Peak Expiratory Flow with Pulmonary Fungal Infection in Hospitalized Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Single-Center Retrospective Study.

Objective: Pulmonary fungal infections are increasingly recognized as important complications of acute exacerbations of chronic obstructive pulmonary disease (AECOPD), but early identification remains challenging. This study investigated the independent association between peak expiratory flow (PEF) and pulmonary fungal infection in hospitalized patients with AECOPD. Methods: This retrospective study enrolled 729 adult inpatients with AECOPD admitted to a tertiary hospital in Chongqing from January to December 2023. PEF was measured after admission and before treatment initiation. Pulmonary fungal infection was diagnosed based on host risk factors, microbiological evidence, clinical findings, and histopathology. Multivariable logistic regression assessed the association between PEF and pulmonary fungal infection. Subgroup and mediation analyses were also performed. Results: The mean age was 71.7 years, and 68.4% were male. Patients with pulmonary fungal infection were older and had lower PEF values than those without infection (2.1 ± 0.9 vs 2.4 ± 1.3, respectively), and showed higher ESR, CRP, and IL-6 levels. After covariate adjustment, higher PEF was independently associated with a lower risk of pulmonary fungal infection (OR = 0.81, 95% CI: 0.66-0.98, P = 0.034). This association remained consistent across age, sex, and smoking subgroups, without significant interactions. Age partially mediated this association, accounting for 15.68% of the total effect. Conclusion: Lower PEF was independently associated with increased pulmonary fungal infection risk in hospitalized patients with AECOPD. PEF may serve as a simple bedside indicator for early risk stratification and targeted clinical evaluation.