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

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). To elucidate the clinical characteristics and poor prognostic factors in Japanese dermatomyositis patients with anti-MDA5 antibody. Clinical features of anti-MDA5 antibody-positive dermatomyositis patients and risk factors, potentially associated with a poor prognosis, were retrospectively analysed. 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 (PaO2) was significantly low at first visit. Among patients with anti-MDA5 antibody with RP-ILD, non-survivors were older and revealed lower PaO2 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. 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.