Disease relapse in idiopathic inflammatory myopathies: A 10-year registry-based follow-up multicentre study in Colombia

Abstract

Introduction

Disease relapses of idiopathic inflammatory myopathies (IIM) play a significant role in the burden of disease. However, Colombian studies with long-term follow-ups are scarce.

Objective

To estimate the ten-year relapse-free survival in patients with idiopathic inflammatory myopathy treated at a specialized medical center for autoimmune diseases with presence in different cities in Colombia.

Method

This is a retrospective follow-up study based on medical records. All patients diagnosed with idiopathic inflammatory myopathy treated between January 2012 and June 2022 were included. The time to relapse was defined as the outcome variable. Additionally, demographic, clinical, laboratory, and treatment variables were characterized. Analyses were performed using Weibull survival regression for interval-censored data.

Results

A total of 278 patients followed for a mean of 6.60 years were included. Of these, 70.9% were women, with a median age of 57 (IQR 40–66) years. Dermatomyositis (60.1%) and polymyositis (28.1%) were the most frequent phenotypes. Relapse-free survival at one year was 86.3%, and at five years, 68.3%, with a median relapse-free time of 13.8 years. By phenotype, the lowest median relapse-free survival rates were observed for antisynthetase syndrome at 3 years, immune-mediated necrotizing myopathy at 6 years, and juvenile dermatomyositis at 7.3 years.

Conclusion

Relapse-free survival is highly heterogeneous according to the clinical phenotype of idiopathic inflammatory myopathy, being lowest in patients with antisynthetase syndrome.