Clinical profile of pulmonary involvement in rheumatological disorders: a cross-sectional study in a rheumatology-associated lung disease clinic.

Rheumatological diseases (RDs) are characterized by autoimmune-mediated organ damage, with the lungs being an important target organ. Almost all compartments of the pulmonary system may be involved, with considerable heterogeneity in the frequency, severity, and spectrum of pulmonary manifestations. This heterogeneity may result in delayed diagnosis and treatment, leading to adverse outcomes. The objective of this study was to characterize the clinical, demographic, serological, and radiological features of pulmonary manifestations across a spectrum of rheumatic diseases. This cross-sectional study was conducted between 2016 and 2023 at a tertiary care center in New Delhi, India. Patients aged ≥18 years with a diagnosed or suspected RD and pulmonary manifestations were included. Patients who did not fulfill the American College of Rheumatology/European League against Rheumatism classification criteria for RD or the American Thoracic Society/European respiratory Society criteria for interstitial pneumonia with autoimmune features (IPAF), as well as those with chronic hypersensitivity pneumonitis or sequelae of previous pulmonary infections, were excluded. Of the 783 patients screened, 170 were diagnosed with rheumatology-associated lung disease (RALD) or IPAF. The mean age was 44.3 years, with a marked female predominance (85%). Rheumatoid arthritis (RA) and systemic sclerosis (SSc) accounted for 70% of cases, followed by IPAF, overlap syndromes, Sjögren syndrome (SjS), systemic lupus erythematosus (SLE), and idiopathic inflammatory myositis. Twenty-six patients with idiopathic interstitial pneumonia were reclassified as having IPAF, one of whom subsequently progressed to RA. Pulmonary symptoms preceded the diagnosis of RD in 13.6% of patients, occurred concurrently with the diagnosis in 17%, and developed during the course of RD in 69.4%. Antinuclear antibodies and rheumatoid factor were the most commonly detected autoantibodies, while anti-aminoacyl-tRNA synthetase antibodies were identified in 11 patients. RA demonstrated the broadest spectrum of pulmonary manifestations. Interstitial lung disease was the predominant pulmonary manifestation across all RDs except SLE. Non-specific interstitial pneumonia and usual interstitial pneumonia patterns accounted for 87% of cases. Other pulmonary manifestations included infections in RA and SLE; vascular and pleural involvement in RA, SSc, and SLE; and airway involvement in RA and SjS. Pulmonary manifestations may precede, coincide with, or develop after the onset of systemic features in RDs. Comprehensive pulmonary evaluation and collaborative care involving rheumatologists and pulmonologists may facilitate earlier diagnosis and optimize the management of RALDs.