Background Interstitial lung disease (ILD) is the most common cause of mortality in patients with dermatomyositis (DM). Cyclosporine has been reported to improve clinical outcome in some patients with DM-associated ILD.
Objectives To investigate the benefit of early introduction of cyclosporine on the survival of patients with DM-associated ILD.
Methods All the patients with DM-associated ILD, who were treated with cyclosporine at Seoul National University Hospital (SNUH) and Seoul National University Bundang Hospital (SNUBH) between 1990 and 2013, were enrolled. Enrolled patients were diagnosed with DM according to Bohan-Peter's classification criteria (n=28) or with clinically amyopathic dermatomyositis (CADM) according to Sontheimer's classification criteria (n=19). ILD was diagnosed based on the typical findings on computed tomography (CT) and relevant respiratory symptoms or signs. Kaplan-Meier survival analysis was applied to compare overall mortality rates between patients who took cyclosporine as the initial treatment and those as the delayed treatment. Cox regression analysis was used to estimate the benefit of early treatment with cyclosporine after adjusting confounding characteristics.
Results Among the 47 patients who were diagnosed with DM-associated ILD, 16 patients (34.04%) received cyclosprorine initially after diagnosis and 31 patients (65.96%) received cyclosporine after the trial of other immunosuppressants such as corticosteroids, cyclophosphamide or azathioprine. The mean time of follow-up was 43.57 person-years in initial treatment group and 76.23 person-years in delayed treatment group. The mortality rate was significantly lower in the initial treatment group than the delayed treatment group (0.02 person-years vs 0.18 person-years, p=0.0092 by log-rank test). The two groups did not differ in regard to age, sex, duration of disease, presence of autoantibodies, degree of dyspnea at initial visit, initial requirement of oxygen supplement, functional vital capacity (FVC) and diffusion capacity (DLCO) on pulmonary function test (PFT) and the presence of malignancy. Only the proportion of patients with CADM was higher in the initial treatment group than in the delayed treatment group (62.53% vs 29.03%, p=0.027). Survival benefit in the initial cyclosporine treatment remained significant even after adjusting for the CADM status (HR 0.075, 95% CI 0.009 - 0.603, p=0.015 by Cox-regression analysis).
Conclusions This study showed significant survival benefit of initial cyclosporine treatment in patients with DM-associated ILD. A randomized controlled study is warranted to clearly demonstrate the therapeutic benefit of early use of cyclosporine in this potentially fatal disease.
Disclosure of Interest None declared
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