High prevalence of acute exacerbation of interstitial lung disease in Japanese patients with systemic sclerosis

Systemic sclerosis (SSc) is a systemic autoimmune disease characterized by extensive fibrosis and autoantibodies. Its clinical manifestations are diverse and include Raynaud’s phenomenon, gastrointestinal dysmotility, interstitial lung disease (ILD), pulmonary hypertension, and renal crisis. Among these, ILD is the primary cause of SSc-related death. It has been considered that acute exacerbation of ILD (AE-ILD) is not common in patients with SSc; however, little is known about the prevalence of AE-ILD in Japanese patients with SSc. In this study, we aimed to clarify the prevalence, clinical characteristics, and prognosis of patients with SSc who developed AE-ILD and to identify predictive factors for AE-ILD in our Japanese cohorts. Clinical data of patients who visited our department from 1990 to 2014 and fulfilled the 2013 classification criteria for SSc were retrospectively reviewed. A total of 139 patients were enrolled. The mean age of onset was 49.1 years, and 113 (81.3%) patients were female; 116 (83.5%) had limited cutaneous involvement, and the overall 10-year survival rate was 92.0%. Among 66 (47.5%) patients with ILD, 13 (9.4%) developed AE-ILD. Patients with AE-ILD had a significantly higher incidence of overlap with polymyositis (PM) or dermatomyositis (DM) and lower prevalence of anticentromere antibodies with higher mortality rate compared with those without AE-ILD. Multivariate Cox regression analysis identified that an overlap with PM or DM was the most significant predictive factor for AE-ILD. Our study results suggest that Japanese patients with SSc, particularly patients overlapped with PM or DM, have a high risk of AE-ILD.