Lung involvement in children with newly diagnosed rheumatic diseases: characteristics and associations

Background Pulmonary complications of rheumatic diseases may cause functional impairment and increase mortality. However, reports regarding detection of lung involvement in children with treatment-naive, newly diagnosed rheumatic diseases are scarce. Herein, we aimed to describe the characteristics of such patients and explore the association between lung involvement and rheumatic disease. Methods From January 2019 to June 2021, 48 pediatric patients with treatment-naive, newly diagnosed rheumatic diseases at Department of Rheumatology and Immunology, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University were included with pulmonary function tests (PFTs) and high-resolution computed tomography (HRCT) findings, and 51 age-matched healthy controls were examined based on PFTs. Univariate and multivariable logistic regression analyses were used to investigate the clinical characters and laboratory parameters associated with lung involvement in these patients. Results Asymptomatic patients had a faster respiratory rate and a higher ratio of forced expiratory volume in 1 s/forced vital capacity than the controls (P < 0.05). More patients than controls were observed to have a decreased DL.sub.CO below the lower limit of normal (18 of 45 [40.0%] vs. 6 of 36, respectively; P = 0.041). Among the 48 patients, 8 (16.7%) had abnormal HRCT findings and 27 (56.3%) had abnormal PFT results. Thirty-one (64.6%) patients had lung involvement. Logistic regression revealed that increases in the erythrocyte sedimentation rate (ESR) and CD4/CD8 ratio were associated with increased odds ratio of lung involvement (1.037, 95% CI: 1.003-1.072; 9.875, 95% CI: 1.296-75.243, respectively). Conclusions Pediatric patients with treatment-naive, newly diagnosed rheumatic diseases are prone to pulmonary involvement. Increased ESR and CD4/CD8 are associated with elevated odds of lung involvement in patients. We recommend routine pulmonary evaluation in such patients, especially in high-risk patients, even in the absence of respiratory symptoms, once they are diagnosed with rheumatic disease. Keywords: Lung involvement, Rheumatic disease, Pulmonary function test