Pulmonary involvement in rheumatoid arthritis: a clinico-radiological cross-sectional study

Background Pulmonary involvement is a significant yet often underrecognized extra-articular manifestation of rheumatoid arthritis (RA). Even in the absence of smoking, interstitial lung disease (ILD) and other respiratory complications may develop subclinically. In this study we evaluated the clinical, functional, and radiological manifestations of lung involvement in non-smoking RA patients and assess correlations with age, disease duration, and disease activity. Methods A cross-sectional study was conducted involving 76 non-smoking patients diagnosed with RA presenting to a tertiary Respiratory Medicine department. Clinical evaluation included assessment of respiratory symptoms and disease activity using the Clinical Disease Activity Index (CDAI). Pulmonary function testing (PFT) and high-resolution computed tomography (HRCT) scans were performed in all patients. Histopathological examination through transbronchial lung biopsy (TBLB) was conducted where indicated. Correlation analyses were performed using appropriate statistical methods. Results The mean age was 56.7 ± 13.5 years, with females constituting 76.3% of the cohort. Respiratory symptoms were prevalent, with cough (82.9%) and dyspnea (64.5%) being most common. Abnormal spirometry findings were observed in 63.2% of patients, primarily restrictive in nature (85.4%). HRCT abnormalities were found in 86.8% of patients, with reticular patterns, ground-glass opacities, and honeycombing being the most frequent. Notably, transbronchial lung biopsy (TBLB) was performed in a clinically indicated subset of 33 patients (43.4%), among whom NSIP and UIP were the predominant histological findings. Increasing age and disease duration were positively associated with dyspnea, restrictive defects, and radiologic abnormalities. CDAI scores showed weak, non-significant associations with pulmonary findings. Conclusion Lung involvement in RA is highly prevalent even in non-smoking cohorts, frequently presenting as subclinical restrictive defects and interstitial abnormalities (predominantly reticular and ground-glass opacities). The progressive nature of these findings, evidenced by their strong positive correlation with advancing age and prolonged disease duration, identifies disease chronicity as a critical predictor of pulmonary complications. This underscores the necessity for targeted, early respiratory screening in older patients with longstanding RA to identify fibrotic patterns—such as NSIP and UIP—before significant structural lung damage occurs.