Pain Phenotypes in Patients With Inflammatory Myopathies: A Latent Class Analysis
Authors' conclusion
In this large international cohort of patients with self-reported IIM and pain, we identified four different pain phenotypes. These phenotypes range from a localized, disease-related nociceptive pattern to a widespread, fibromyalgia-like nociplastic pattern.
Study context
- Population
- Patients with self-reported idiopathic inflammatory myopathies (IIM) and pain attributable to myositis
- Participants
- 426 patients
- Exposure
- Class 1 vs Class 2 vs Class 3 vs Class 4
- Outcome
- Pain phenotypes identified by LCA (distribution, pattern, pain during flare vs now, disease duration)
Methodological detailsanonymous electronic survey, latent class analysis, international
- Anonymous electronic survey
- Latent class analysis
- International
Main finding
As reported in the abstract
Pain phenotypes (LCA classes)
- Latent class analysis (LCA) identified four classes: class 1 proximal arm- and leg-predominant pain, lowest persistent pain; class 2 diffuse axial and proximal limb-predominant pain; class 3 diffuse axial and distal leg-predominant pain; class 4 widespread axial and extremity pain, highest persistent pain
Observational data: associations, not effects.
Further findings
Class characteristics (post hoc analyses)
- Class 1: mainly earlier IIM and lower rate of FM
- Classes 2 and 3: intermediate FM symptom burden
- Class 4: highest pain intensity and FM
- Post hoc analyses
Original publication
Pain Phenotypes in Patients With Inflammatory Myopathies: A Latent Class Analysis. Arthritis Care Res (Hoboken). Published 15 September 2026. doi:10.
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