Characteristics and Predictors of Progression Interstitial Lung Disease in Rheumatoid Arthritis Compared with Other Autoimmune Disease: A Retrospective Cohort Study

Objectives: To describe the characteristics and progression of interstitial lung disease in patients with associated systemic autoimmune disease (ILD-SAI) and to identify factors associated with progression and mortality. Patients and methods: We performed a multicenter, retrospective, observational study of patients with ILD-SAI followed between 2015 and 2020. We collected clinical data and performed pulmonary function testing and high-resolution computed tomography at diagnosis and at the final visit. The main outcome measure at the end of follow-up was forced vital capacity (FVC) > 10% or diffusing capacity of the lungs for carbon monoxide > 15% and radiological progression or death. Cox regression analysis was performed to identify factors associated with worsening of ILD. Results: We included 204 patients with ILD-SAI: 123 (60.3%) had rheumatoid arthritis (RA), 58 had (28.4%) systemic sclerosis, and 23 (11.3%) had inflammatory myopathy. After a median (IQR) period of 56 (29.8-93.3) months, lung disease had stabilized in 98 patients (48%), improved in 33 (16.1%), and worsened in 44 (21.5%). A total of 29 patients (14.2%) died. Progression and hospitalization were more frequent in patients with RA (p = 0.010). The multivariate analysis showed the independent predictors for worsening of ILD-SAI to be RA (HR, 1.9 [95% CI, 1.3-2.7]), usual interstitial pneumonia pattern (HR, 1.7 [95% CI, 1.0-2.9]), FVC (%) (HR, 2.3 [95% CI, 1.4-3.9]), and smoking (HR, 2.7 [95%CI, 1.6-4.7]). Conclusion: Disease stabilizes or improves after a median of 5 years in more than half of patients with ILD-SAI, although more than one-third die. Data on subgroups and risk factors could help us to predict poorer outcomes.

Automated summary

The study found that about half of patients with interstitial lung disease associated with systemic autoimmune disease stabilize or improve after a median of 5 years, but over one-third of patients die. Rheumatoid arthritis is associated with higher rates of disease progression and hospitalization in ILD, while usual interstitial pneumonia pattern, FVC%, and smoking are independent predictors for worsening of ILD-SAI.