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.