Clinical Characteristics of Rheumatoid Arthritis Patients with Interstitial Lung Disease: Baseline Data of a Single-Centre Prospective Cohort

Abstract Objectives: To establish a prospective cohort for rheumatoid arthritis (RA) patients with interstitial lung disease (ILD) and to identify their clinical features compared to those without ILD. Methods: With a multidisciplinary collaborative approach, a single-centre cohort for RA patients with ILD (RA-ILD) was established in May 2017, and enrolment data from May 2017 to March 2021 was used to compare the clinical features of RA patients without ILD (RA-non ILD). Multivariable logistic regression analysis was used to identify factors associated with ILD in RA patients. Results: Among 148 RA-ILD patients and 410 RA-non ILD patients, the RA-ILD group were older (65.8 ± 9.9 vs. 58.0 ± 10.4 years, P < 0.001) and included more males (35.8% vs. 14.6%, P < 0.001) than the RA-non ILD group. The RA-ILD group had a higher proportion of late-onset RA patients (age ≥ 60 years) than in comparators (43.9% vs. 14.2%, P < 0.001). Multivariable logistic regression analysis showed that higher age at RA onset (OR 1.056, 95% CI 1.021-1.091), higher body mass index (BMI) (OR 1.65, 95% CI 1.036-2.629), smoking history (OR 2.484, 95% CI 1.071-5.764), and oral glucocorticoid use (OR 3.562, 95% CI 2.160-5.874) were associated with ILD in RA patients, whereas methotrexate use was less likely to coexist with ILD (OR 0.253, 95% CI 0.155-0.412). Conclusions: Higher RA onset age, smoking history, and higher BMI were associated with presence of ILD among RA patients. Oral glucocorticoids were more frequently used whereas methotrexate was less likely to be used in RA-ILD patients.