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

*Corresponding author: Stylianos Tomaras* and Jörn Kekow

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original research

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.

Keywords

Myositis; Idiopathic inflammatory myopathy; Dermatomyositis; Antisynthetase syndrome; Overlap myositis; Rituximab.

Abbreviations

CCP: Cyclic Citrullinated Peptide; CK: Creatine kinase; CYC: Cyclophosphamide; IIM: Idiopathic Inflammatory Myopathy; ILD: Interstitial lung disease; IMACS: International Myositis Assessment and Clinical Studies Group; MDI: Myositis Damage Index; MMT8: Manual muscle test 8; MTX: Methotrexate; MYOACT: MYOsitis disease ACTivity; RTX: Rituximab; TIF-1γ: Transcriptional factor-1γ.