Background: To assess the prevalence and clinical relevance of anti-Jo-1 autoantibodies in a representative sample of patients with definite dermatomyositis (DM).
Methods: This retrospective cohort study took place from 2005 to 2020 and assessed 118 adult patients from a tertiary center who were diagnosed with definite DM. A commercial kit was used to detect anti-Jo-1 autoantibodies.
Results: The presence of anti-Jo-1 autoantibodies was observed in 10 out of 118 (8.5%) patients with definite DM. The following variables were comparable between individuals with and without anti-Jo-1 autoantibodies: age at diagnosis, sex, ethnicity, disease duration, follow-up period, recurrence rate, complete clinical response, death rate, and cancer incidence. There was no difference in clinical features between groups, except for an increased prevalence of "mechanic's hands," joint involvement, and lung disease, as well as a reduced occurrence of skin findings in patients positive for anti-Jo-1 autoantibodies. No anti-Jo-1-positive patients went into remission; they required greater use of glucocorticoids and immunosuppressive drugs.
Conclusions: Anti-Jo-1 positivity was found in 8.5% of patients with definite DM. This autoantibody was associated with an antisynthetase syndrome phenotype and might predict clinical outcomes in patients with definite DM.
Keywords: Autoantibodies; Dermatomyositis; Inflammatory myopathies; Myositis.