Clinical features and poor prognostic factors of anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis with rapid progressive interstitial lung disease

Background Anti-melanoma differentiation-associated gene 5 (MDA5) antibody has been recognized to be significantly associated with a subset of dermatomyositis patients with rapidly progressive interstitial lung disease (RP-ILD). Objectives To elucidate the clinical characteristics and poor prognostic factors in Japanese dermatomyositis patients with anti-MDA5 antibody. Materials and methods Clinical features of anti-MDA5 antibody-positive dermatomyositis patients and risk factors, potentially associated with a poor prognosis, were retrospectively analysed. Results A total of 37.3% (28/75) dermatomyositis patients were positive for anti-MDA5 antibody. The frequency of Gottron’s papules, palmar violaceous macules, antihelix/helix violaceous macules, and clinically amyopathic dermatomyositis (CADM) was significantly higher in patients with anti-MDA5 antibody. Of anti-MDA5 antibody-positive dermatomyositis patients, 57.1% developed RP-ILD, and in those with RP-ILD, serum ferritin level was markedly high and partial pressure of arterial oxygen (PaO 2 ) was significantly low at first visit. Among patients with anti-MDA5 antibody with RP-ILD, non-survivors were older and revealed lower PaO 2 at first visit relative to survivors. Furthermore, patients who did not take triple therapy (prednisolone, calcineurin inhibitor and cyclophosphamide) as initial treatment resulted in poor outcome. Conclusion Anti-MDA5 antibody may be associated with CADM, the progression to RP-ILD, high serum ferritin level, and characteristic skin manifestations. High serum ferritin level in patients with anti-MDA5 antibody may be associated with the development of RP-ILD and poor prognosis. Early treatment with triple therapy, including intravenous cyclophosphamide, may improve the prognosis of RP-ILD.