Clinical manifestations, outcomes, and antibody profile of Brazilian adult patients with dermatomyositis: a single-center longitudinal study.

BACKGROUND: Currently, only a few retrospective cohort or cross-sectional studies have described the general characteristics of Brazilian patients with classical dermatomyositis (DM). In contrast, we aimed to longitudinally assess a large sample of these patients, and several myositis autoantibodies. METHODS: This single-center longitudinal study included 91 Brazilian adults with defined DM (EULAR/ACR 2017) who underwent follow-up appointments in our tertiary center from 2012 to 2021. Myositis autoantibody analysis was performed using a commercial kit. RESULTS: The mean age of the patients was 47.3 ± 15.4 years, with a predominance of female (67.0%) and White (81.3%) patients. As an initial treatment, 76.9% of the patients received methylprednisolone pulse therapy, 59.3% received intravenous immunoglobulin, and 54.9% received both drugs. The median follow-up duration was 44 months (interquartile 17-67) months. There were 92 severe episodes of infection, and neoplasms were identified in 20 patients (22.0%). Hypertension was identified in 46.2% of patients, whereas diabetes mellitus and myocardial infarction occurred in 19.8% and 4.4%, respectively. Nine patients died during the follow-up. At the last visit, one-third of the patients had disease activity, half had a complete clinical response, and one-fifth were in disease remission. In a univariate logistic regression, anti-aminoacyl-tRNA synthetase antibodies (n = 13) were associated with interstitial lung disease, "mechanic's hands", and anti-Ro-52, and had an inverse association with "V"-neck and "shawl" signs. Anti-MDA-5 (n = 10) were associated with male gender, digital ulcers, vasculitis, arthritis, anti-Ro-52, and active disease. Anti-Ro-52 (n = 26) were associated with "mechanics' hands", arthritis, interstitial lung disease, anti-tRNA synthetases, and anti-MDA-5. No association was found for anti-Mi-2 (n = 10). CONCLUSIONS: This study shows the general profile of a significant sample of Brazilian patients with DM as well as the association of some antibodies with clinical and laboratory manifestations of this myositis.