Predictors and Features of Interstitial Lung Disease in Patients with Rheumatoid Arthritis

Background: Rheumatoid arthritis is a rare autoimmune disorder. The study aimed to assess the predictors and features of interstitial lung disease in patients with rheumatoid arthritis. Methods: A retrospective study was conducted in the Pulmonology Department of Ibn-e- Siena Hospital, Multan, from August 2024 to August 2025. 200 patients diagnosed with rheumatoid arthritis who underwent pulmonary high-resolution computed tomography scan were included in the study by non-probability consecutive sampling. Based on the results of lung CT, patients were categorized according to the presence or absence of ILD. Data analysis was done by SPSS version 23. ANOVA, t-test and rank sum test were performed to assess quantitative variables, which were compared by x2 test. Statistical significance was set at a probability value of less than 0.05. Results: A total of 86 patients (43%) with RA had interstitial lung disease. The most frequent manifestation in patients with ILD was non-specific interstitial pneumonia pattern in 50 patients (58.2%). The biochemical parameters, including globulin (p=0.005), gamma glutamyl transpeptidase (p=0.031), erythrocyte sedimentation rate (p=0.004), lactate dehydrogenase (p<0.001), CRP (p=0.022) and rheumatoid factor positive (p=0.026) were significantly elevated in ILD positive patients. Multivariate analysis showed age (OR: 1.601, 95% CI: 1.21-2.11), smoking (OR: 2.122, 95% CI: 1.35-3.76), rheumatoid factor (OR:1.689, 95% CI: 1.03-2.78), RA onset duration (OR: 0.373) and lactate dehydrogenase levels (OR: 7.374, 95% CI: 3.24-16.75) as independent risk factors of RA-ILD. Conclusion: The incidence of interstitial lung disease in rheumatoid arthritis patients was 43% with advanced age, smoking, duration of RA onset and positive rheumatoid factor as independent predictor of incidence of ILD. Given the significant association with elevated inflammatory markers and high mortality risk, early HRCT screening is essential for timely diagnosis and improved management.