Assessment of Pulmonary Function in Children with Juvenile Idiopathic Arthritis: A Cross-Sectional Study

Background/Objectives: Juvenile idiopathic arthritis (JIA) is a chronic autoimmune disorder characterized by joint inflammation, potentially leading to pulmonary involvement. This study aimed to assess pulmonary function in children with JIA compared to controls and identify potential respiratory abnormalities associated with the disease. Methods: This was a prospective cross-sectional study conducted at the Pediatric Rheumatology, Başakşehir Çam and Sakura City Hospital, İstanbul, Türkiye, between July and October 2024. The study included 70 children with JIA and 60 healthy controls aged 6 to 17. Pulmonary function test parameters, such as forced vital capacity (FVC), forced expiratory volume in the 1st second (FEV1), peak expiratory flow (PEF), and FEV1/FVC ratio, were measured using spirometry. Oxygen saturation (SpO₂) was also measured. Results: There were no significant differences in demographic and clinical characteristics between the JIA and control groups (p > 0.05). FVC and FEV1 values were lower in the JIA group, though not significantly (p = 0.831 and p = 0.711). However, PEF was significantly lower in the JIA group than controls (p = 0.005). Children with moderate or high disease activity had significantly lower FVC, FEV1, and FEF 25–75 than those with low disease activity (p < 0.001). Enthesitis-related arthritis patients had higher FVC and FEV1 than other JIA subtypes (p < 0.05). FVC and FEV1 were positively correlated with BMI (p < 0.001). Conclusions: Although PEF values were significantly lower in children with JIA, overall pulmonary function was comparable between the groups. Regular pulmonary monitoring in JIA patients is recommended for early detection and management of respiratory complications.