The prognostic factor in patients with myositis-associated interstitial lung disease

Introduction : Anti-aminoacyl-transfer RNA synthetase antibodies (anti-ARS-abs) are most common antibodies in patients with polymyositis (PM) /dermatomyositis (DM). Anti-melanoma differentiation-associated gene 5 antibody (Anti-MDA5-ab) is a marker for rapidly progressive and poor prognostic interstitial lung disease (ILD) with amyopathic DM. Objectives: To evaluate the prognosis markers in patients with ILDs associated to PM/DM. Methods : We reviewed clinical (C-reactive protein, Krebs von den Lungen-6, anti-ARS-abs, anti-MDA5-ab, lymphocytes in bronchial lavage, amyopatic DM) and radiological data of the 51 consecutive patients with ILDs related to PM/DM, retrospectively. Anti-ARS-abs and anti-MDA5-ab were screened out by immunoprecipitation techniques in Department of Dermatology, Kanazawa University and ELISA method in Department of Dermatology, Nagoya University. Results : Median age was 61 years old and male gender was 25%. 23 patients had anti-ARS-abs and 9 patients had anti-MDA5 ab. 19 patients had neither of them. 6 patients (26%) with anti-ARS-abs, 5 (56%) with anti-MDA5-ab and 5 (26%) with double negative died in follow up period (45 months, median). C-reactive protein (CRP) g 1.0 (p=0.031, OR 1.91) was the only significant factor between overall survivors and non-survivors. On the other hand, anti-ARS-abs positive (p=0.031, OR 0.54) and anti-MDA5-ab positive (p=0.005, OR 2.04) were significant factors between 1 year survivors and non-survivors. Amyopathic DM was not risk factor on both long and short-term survivals. Conclusion: Anti-MDA5-ab was a risk factor on short-term survivals and CRP value was related to long-term prognosis in this cohort.