Clinical phenotyping and prognostic factors in inclusion body myositis: Data from The Johns Hopkins Myositis Center

  • Analysis of inclusion body myositis (IBM) subtypes is of great priority to understand underlying pathophysiology, predict disease progression, and develop efficient treatment.
  • Evidence from a cohort of 335 patients showed that 64% of men (average age of disease onset: 58.7 years) had a 5.2-year delay to diagnosis. Endomysial inflammation, mononuclear cell invasion, and rimmed vacuoles were present in 43% of muscle biopsies. Muscle strength (arm abductors, hip flexors, and knee flexors) was weaker among Black than non-Black patients, and females having increased muscle strength than men.   
  • According to the authors, demographical phenotypes play a role in the clinical pathophysiology of IBM. Early subgroup identification may better support treatment for these individuals with distinct phenotypes.