Short-term and long-term outcomes of patients with anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis.

Objectives: Anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive dermatomyositis (MDA5-DM) is a subtype of dermatomyositis characterized by frequent interstitial lung disease and reduced muscle involvement. This study aimed to determine the short-term and long-term outcomes of patients with MDA5-DM.

Methods: Information on baseline characteristics, treatments and short-term and long-term outcomes of patients with MDA5-DM including survival, relapse and the titre of anti-MDA5 antibody, was retrospectively collected. Descriptive statistics regarding clinical outcomes were calculated, and a comparison of clinical parameters between patients with and without relapse was performed. The short-term survival according to the use of Janus kinase inhibitors (JAKi) was also assessed.

Results: A total of 154 patients with MDA5-DM were included in the study. Forty patients (26.0%) died during the remission induction phase, with respiratory failure being the most common cause of mortality. Among the 114 patients who survived the remission induction phase, the 5-year cumulative survival and relapse-free survival rates were 96.8% and 77.4%, respectively, and 7.9% of patients achieved complete drug-free remission. Fifty-four patients achieved normalization of anti-MDA5 antibody titres and only two of them relapsed after normalization. In the severe patients, the 6-month survival rate became significantly higher after the emergence of the JAKi treatment compared with before its existence (P = 0.03).

Conclusion: Although relapse often occurs, the long-term survival of MDA5-DM patients who survived the remission induction phase is generally favourable. The status of the anti-MDA5 antibody is associated with relapse. JAKi may improve the survival of refractory patients with severe MDA5-DM.