Clinical features of acute exacerbation in rheumatoid arthritis-associated interstitial lung disease: Comparison with idiopathic pulmonary fibrosis

Abstract

Background: Several studies have reported that acute exacerbation (AE), which occurs during the clinical course of idiopathic pulmonary fibrosis (IPF), also occurs in rheumatoid arthritis-associated interstitial lung disease (RA-ILD). However, the incidence, clinical features, and risk factors for AE, a major cause of death of RA-ILD patients, and the differences in clinical aspects of AE between RA-ILD and IPF have yet to be fully understood.

Methods: We retrospectively reviewed data on 149 RA-ILD patients and 305 IPF patients. We investigated the frequency of AE and compared the clinical data between RA-ILD with and without AE to clarify the risk factor for AE. We also compared the post-AE prognosis and cause of death between RA-ILD and IPF patients.

Results: Twenty-seven (18.1%) RA-ILD patients and 84 (27.5%) IPF patients developed AE. The median survival time (MST) after AE of RA-ILD and IPF was 277 days and 60 days, respectively (log rank, p = 0.038). In a multivariate analysis, hypoalbuminemia [odds ratio (O.R.) 0.090 (95%CI 0.011-0.733), p = 0.012] and % carbon monoxide diffusion capacity (%DL_CO) [O.R. 0.810 (95%CI 0.814-0.964), p < 0.01] were independent risk factors for AE. AE was the most frequent cause of death of RA-ILD and IPF.

Conclusion: RA-ILD patients could develop AE, and AE was not uncommon in RA-ILD or IPF. %DL_CO and hypoalbuminemia were predictive factors of AE in RA-ILD. The prognosis after AE of RA-ILD was significantly better than that of IPF. The most frequent cause of death in RA-ILD and IPF was AE.

Keywords: Acute exacerbation; Interstitial pneumonia; Rheumatoid arthritis; Risk factor.