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

Abstract

BackgroundSeveral 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. MethodsWe 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. ResultsTwenty-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 (%DLCO) [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. ConclusionRA-ILD patients could develop AE, and AE was not uncommon in RA-ILD or IPF. %DLCO 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.