Evaluation of the frequency and risk factors of spontaneous intramuscular hemorrhage associated with dermatomyositis.

Dermatomyositis (DM) is an idiopathic inflammatory myositis (IIM) characterized by skin manifestations and muscle involvement. Spontaneous intramuscular hemorrhage (SIH) is a fatal complication that is very rare in the course of DM, but not well known to rheumatologists. Our aim was to determine the frequency and possible risk factors of DM-related SIH. A retrospective analysis was conducted on a cohort of DM patients who were observed in the rheumatology department of the university hospital between 1998 and January 2024. The clinical, laboratory, radiological data of the patients and the treatments they received during the follow-up were analyzed. To determine possible risk factors for the development of SIH in the course of DM, our patients with DM were analyzed together with other rare SIH cases in the literature. The study included 42 of our DM patients. 32 of the patients (76.2%) were female. The median age of the patients was 53 (24-82) years, the median age of DM diagnosis of the patients was 47 (18-75) years, and the median duration of DM of the patients was 36 (2-276) months. 7.1% of patients had dysphagia, and 16.7% had intertitial lung disease (ILD). 5 (11.9%) patients were diagnosed with malignancy. The incidence rate of SIH development in our DM cohort was 0.238/100 patient years (95% CI 0.006-1.256). We tried to identify independent risk factors for SIH development by comparing our 41 DM patients without SIH with the data of patients with 23 DM-related SIH collected from the literature by adding our 1 patient (24 pts). Male sex (OR 4.97, 95% CI 1.66-14.92, p = 0.003), ILD presence (OR 9.71, 95% CI 2.99-31.47, p < 0.001), anti-MDA5 positivity (OR 16.0, 95% CI 1.60-159.3, p = 0.006), anti-Ro52 positivity (OR 11.6, 95% CI 2.93-46.34, p < 0.001), heparin use (OR 4.42, 95% CI 2.68-7.24, p < 0.001), intravenous immunoglobulin (IVIG) use (OR 11.7, 95% CI 2.26-60.54, p < 0.001), and steroid dose (OR 1.03, 95% CI 1.00-1.05, p = 0.005) were identified as risk factors for the development of SIH in the univariate analysis. The death rate due to hemorrhage was 50%. No single risk factor was found to be associated with death. As a result, SIH may occasionally arise in patients with DM. Rheumatologists should be aware that patients with dysphagia and/or ILD, who are on heparin, getting high doses of steroids, and test positive for anti-MDA5 and/or anti-Ro52 antibodies may develop SIH in the early stages of DM.