Prognostic Implications of Myositis‐Specific Autoantibodies on Mortality, Relapse, and Remission in Dermatomyositis Patients

Objectives To explore the clinicopathological features and treatment prognosis including death, relapse and remission of dermatomyositis (DM) based on myositis‐specific autoantibody (MSAs) stratification. Methods Patients with DM come from a provincial neuromuscular center in northern China. Patients who underwent biopsy from 2010 to 2023 were collected, and the follow‐up time was all more than 6 months. Clinical characteristics, serum samples, and muscle biopsies were collected. Kaplan–Meier analysis, Cox regression, and competing risk model were used for analysis. Results Our study included 140 patients with DM. Among the 25 juvenile patients, 9 (36%) were anti‐NXP2 antibody positive. About 80.95% of the patients with anti‐TIF1‐γ antibodies had neck flexion weakness. Patients with anti‐Mi‐2 antibodies showed a predominance of severe muscle fiber necrosis/regeneration (76.19%) rather than perifascicular atrophy (14.29%). Compared to the seronegative subgroup, the short‐ and long‐term risks of death were higher in anti‐TIF1‐γ‐positive patients, and the 3‐year risk of death was higher in anti‐MDA5 patients. The short‐ and long‐term dangers of relapse were consistently higher in anti‐Mi‐2‐positive patients, with a higher 3‐year relapse risk in the anti‐NXP2 subgroup. In the case of death as a competing risk of relapse, patients with anti‐Mi‐2 and patients with anti‐NXP2 had higher short‐ and long‐term risks of relapse. No difference was found in the clinical remission rate based on the DM‐MSA stratification. Conclusion Evaluating the characteristics and prognosis of DM subgroups based on serum MSA stratification is helpful for patient management and treatment strategies.