Clinical characteristics and risk factors associated with objective flares in patients with dermatomyositis

Flares in dermatomyositis (DM) are associated with increased disability, health care utilization, and reduced quality of life. We aim to determine the characteristics and risk factors of flares in patients with DM.

Patients were included if seen at The Johns Hopkins Myositis Center and fulfilled the 2017 EULAR/ACR Classification Criteria for DM. Two authors reviewed all notes and recorded patient symptoms, exams, labs, imaging findings, and medication changes. Objective flare was defined as active disease on exam or ancillary testing that resulted in an increase in immunosuppressive therapy. Characteristics of patients and flares were summarized using descriptive statistics. We assessed the association between patient characteristics and time to first flare using Cox proportional hazards models.

In this study with 637 patients with DM, rash was the most common finding of flare (75.7%), followed by muscle weakness (58.4%), new/worsening findings on lung function tests and/or imaging (19.0%) and arthritis (12.4%). Over 85% of the patients who reported rash, weakness, dyspnea, joint swelling, dysphagia or fever met the definition of objective flare. Black race and shorter time to diagnosis were associated with increased flare risk. Among patients with DM who experienced an objective flare, only 2-5% had a cancer diagnosis within 6-24-months of flare. In a subset of newly diagnosed patients, 26% had ≥1 flare during follow-up. The incidence rate of flares was 5.1 per 100 person-years. The average time between diagnosis and the first flare was 2.9 years (SD 2.3) ranging between 6.2 months and 10.8 years.

In this tertiary care center cohort of DM patients, patient-reported symptoms of increased disease activity were often indicative of objective flare. We identified Black race and shorter time to diagnosis as risk factors for flare. Understanding these factors can inform clinicians about monitoring strategies and improved patient outcomes.