Disease progression in sporadic inclusion body myositis: observations in 78 patients.

Functional decline for each decade at symptom onset and need for cane, walker, or wheelchair were assessed in 78 biopsy-proved patients with sporadic inclusion body myositis. Patients with disease onset between 40 and 59 years used a walker after 10.2 +/- 5.8 years, whereas those with disease onset between 60 and 79 years used a walker after 5.7 +/- 5.0 years (p = 0.05). Because patients progress faster to disability when symptoms begin after the age of 60, age at disease onset may define patient subsets for stratification in clinical trials.