Mechanic’s hands are associated with interstitial lung disease in myositis patients regardless of the presence of antisynthetase antibodies

Dear Editor, Idiopathic inflammatory myopathies (IIM) are a group of rare multisystemic disorders. Autoantibody expression significantly impacts clinical features and prognosis. Antisynthetase antibodies (ASAb) are positive in 11–39% of IIM patients and are usually associated with antisynthetase syndrome (ASSD), characterized by myositis, arthritis and interstitial lung disease (ILD). However, ASSD presentation and severity vary greatly. This work aimed to define the clinical characteristics of ASAb-positive IIM patients and identify clinically useful markers of typical ASSD manifestations. We conducted a multicentre cohort study based on a retrospective analysis of prospectively collected data, including IIM patients registered in the Rheumatic Diseases Portuguese Register (Reuma.pt) from April 2019 until January 2022. Patients were screened with indirect immunofluorescence assay on HEp-2 cells and EUROLINE IIM 16Ag (IgG) immunoblot. Univariate analysis was performed using χ2, Fisher’s exact, Mann–Whitney or t test. Predictors of different manifestations were identified through binomial logistic regression modelling and confirmed using sensitivity analysis. The study was approved by the Ethics Committee of Centro Académico de Medicina de Lisboa (195/21). Included patients signed the Reuma.pt informed consent. Reuma.pt is approved by the national data protection board (Comissão Nacional de Proteção de Dados) and by the Ethics Committee of all participating centres.