Clinical characteristics and associated factors of post-infectious bronchiolitis obliterans in children with severe pneumonia and respiratory failure: a retrospective cohort study

BACKGROUND: Post-infectious bronchiolitis obliterans (PIBO) is a severe sequela of severe pneumonia in children. Data on its occurrence in those with concurrent respiratory failure remain limited. This study aimed to investigate the clinical characteristics and factors associated with PIBO development in this high-risk population, including an age-stratified analysis (< 2 years vs. ≥2 years). METHODS: A retrospective analysis was conducted on the clinical data of 108 children diagnosed with severe pneumonia and respiratory failure between January 2015 and June 2025. Patients were divided into a PIBO group (n = 52) and a non-PIBO group (n = 56) based on the diagnosis of PIBO at 6 months after discharge. Clinical characteristics, etiological profiles, imaging findings, and treatment modalities were compared between the two groups, and further stratified by age (< 2 years and ≥ 2 years). RESULTS: The prevalence of PIBO in this cohort was 48.1% (52/108). Compared to the non-PIBO group, the PIBO group had a significantly longer duration of fever during the acute phase [median 17 (IQR 12-25) days vs. 7 (3-10) days, P < 0.001], a higher prevalence of wheezing (86.5% vs. 58.9%, P = 0.001), and a significantly higher detection rate of adenovirus (ADV) (65.6% vs. 21.2%, P < 0.001). In age-stratified analysis, prolonged fever duration and invasive mechanical ventilation remained significantly associated with PIBO in both children aged < 2 years and ≥ 2 years (all P < 0.05). The PIBO group exhibited significantly higher rates of invasive mechanical ventilation (61.5% vs. 19.6%, P < 0.001) and longer ICU stays [median 14 (7-22) days vs. 6 (2-8) days, P < 0.001], and longer hospitalization [median 28 (21-51) days vs. 15 (8-21) days, P < 0.001]. No significant difference was observed between the two groups regarding a history of atopic diseases (P > 0.05). Conversely, the non-PIBO group had significantly higher incidences of liver function impairment (37.0% vs. 14.3%, P = 0.032), pulmonary consolidation on chest CT (66.1% vs. 34.6%, P = 0.001), and patchy exudation (62.5% vs. 30.8%, P = 0.001). CONCLUSIONS: In children with severe pneumonia and respiratory failure, prolonged fever during the acute phase, ADV infection, and indicators of critical illness such as prolonged invasive ventilation and ICU support are significantly associated with the subsequent development of PIBO, and these associations were consistent across age groups. Enhanced long-term follow-up and early assessment are recommended for children presenting with these features.