An In-Depth Analysis of Our Myositis Cohort Following the Example of the EuroMyositis Registry

Abstract

Background To describe our myositis cohort in-depth. Methods From January 2006 to December 2018, all newly diagnosed myositis patients were retrospectively enrolled in the study. We performed a subtype reclassification using the 2017 EULAR/ACR criteria, following the example of the EuroMyositis registry. Disease activity and damage were measured by the newest standardized assessment-tools for clinical studies. Comparisons between myositis subgroups were conducted using Fisher’s exact test. Results We enrolled 32 patients (25 were female): six patients with dermatomyositis, six with polymyositis, eleven with overlap myositis, six with antisynthetase syndrome, one with autoimmune necrotizing myopathy, one with juvenile antisynthetase syndrome and one with juvenile dermatomyositis. The overall median follow-up period was 23-months (9-44.75). Interstitial lung disease (ILD) was most frequently seen in patients with antisynthetase syndrome. Patients with overlap myositis were more likely to have polyarthritis mimicking rheumatoid arthritis, reduced capillary density in the nail fold capillaroscopy and Raynaud syndrome. Ovarian cancer during the follow-up period occurred in two patients (one with polymyositis and one with dermatomyositis). Myositis-related death was reported in two patients: acute respiratory failure in autoimmune necrotizing myopathy and dysphagia-related complications in polymyositis. Cyclophosphamide, methotrexate and rituximab demonstrated a significant steroid-sparing effect. In 22 of 32 patients, the myositis subgroup classifications made on the basis of our opinion and the new EULAR/ACR classification criteria were different, showing strong disagreement, especially in the subtype polymyositis. Conclusion Our analysis highlights the heterogeneity in myositis subgroups and shows the steroid-sparing effect of cyclophosphamide, methotrexate and rituximab.