Prevalence of sporadic inclusion body myositis in Western Australia

A 10-year retrospective review was conducted to ascertain the prevalence of inclusion body myositis (IBM) in Western Australia. Seventeen patients with sporadic IBM aged 45–90 years were identified and the prevalence of IBM was calculated to be 9.3 × 10−6. The prevalence was higher in men (10.9 × 10−6) than in women (7.7 × 10−6). The mean age of onset of IBM was 56.6 years, and the mean delay between onset of symptoms and diagnosis was 4.4 years. The age-adjusted prevalence over the age of 50 years was 35.3 × 10−6. The results suggest a higher prevalence of IBM than has previously been reported