Exploring rheumatoid arthritis associated interstitial lung disease a retrospective study from two Saudi tertiary care centers.

Background: Interstitial lung disease (ILD) is an increasingly recognized complication of rheumatoid arthritis (RA) and is associated with significant morbidity and mortality. Many risk factors for RA-related ILD were reported. The current study aims to explore the features and risk factors of Saudi patients with RA-ILD.

Methods: This is a multicenter, retrospective, observational study of patients with RA-ILD. Clinical and radiological data from patients with RA-ILD were obtained from electronic medical records, including demographics, clinical characteristics, laboratory tests, pulmonary function tests, ECHO, and HRCT images.

Result: Out of 732 patients, 57 had RA-ILD. The mean age at the time of ILD diagnosis was 61.9 (± 12.2) years. RA-ILD diagnosis was significantly less among females (p = 0.008). Patients who ever smoked had significantly more RA-ILD (p < 0.001). Patients with RA-ILD were more likely to present with medical comorbidities, namely diabetes (p < 0.001), hypertension (p < 0.001), ischemic heart disease (p < 0.001), and osteoarthritis (p = 0.030). The multivariate analysis revealed that the age (OR: 1.035, 95% CI: 48.45-52.86, p = 0.0001); gender (OR: 2.581, CI: 1.77-1.86, p = 0.001), DM (OR: 2.498, 95% Cl: 1.65-1.76, P = 0.0001), HTN (OR: 1.975, 95% Cl: 1.61-1.74, P = 0.019), IHD (OR: 6.043, 95% Cl: 1.89-1.93, P = 0.0001) have a significant positive association with RA-ILD. No significant differences were observed between seropositive parameters with or without RA-ILD (p > 0.05). The most common symptoms of RA-ILD were cough (55.6%) and dyspnea (30.2%), and the most common ILD pattern was Non-specific Interstitial Pneumonia (NSIP) (55.6%) followed by Usual Interstitial Pneumonia (UIP) (38.9%). Traction bronchiectasis (75.5%) and glass ground opacities (73.6%) were also observed. The mean FVC and DLCO at baseline were 64.6% and 53.3%, respectively.

Conclusion: In this cohort of patients, Saudi RA-ILD patients had a predominant NSIP pattern conversely to what is seen globally. These findings could be explained by the lower rates of smoking in our patient population. Future prospective national studies are needed to confirm the current findings and better evaluate RA-ILD epidemiology and risk factors.