Evaluation of long-term pulmonary functions after COVID-19 infection in children: a longitudinal observational cohort study

Introduction: We aimed to present the changes that may occur in pulmonary functions in children who experienced more severe coronavirus disease 2019 (COVID-19) during long-term follow-up. Methodology: A prospective longitudinal observational cohort study was conducted with 34 pediatric patients (7-18 years) who were hospitalized with COVID-19 infection (moderate n = 25, severe n = 9), and followed up at our Pediatric Infection Outpatient Clinic for approximately two years. Pulmonary function tests (PFTs) were performed using spirometry. Results: Data from the hospitalization period revealed no significant differences between the severity groups in terms of demographic, clinical, laboratory, radiological, treatment, and outcome (p > 0.05). The median time interval between COVID-19 infection and PFTs was 15 months (range 11-29 months), and there was no significant difference between severity groups (p = 0.878). Eight patients (24%) had abnormal pulmonary functions; among them, seven had an obstructive pattern (21%) and one had a restrictive pattern (3%). The severity groups had no statistical difference in pulmonary functions (p = 0.105). While forced expiratory volume in 1 second (FEV1) %, FEV1/forced vital capacity (FVC)%, and forced expiratory flow during the middle half of FVC (FEF25-75%) ratios were lower in the severe patient group, Z-scores were similar. Among the patients continuing polyclinic follow-up, 41% had persistent respiratory symptoms before PFTs. No differences were observed in PFTs when compared based on the presence of symptoms (p > 0.05). Conclusions: We observed no significant long-term differences in pulmonary function between moderate and severe COVID-19 cases in children.