Epidemiology of sporadic inclusion body myositis

Abstract

Population-based data indicate that the prevalence of IBM in Europe is higher than expected from previous studies. Diagnostic delay appears to be a persisting problem in IBM; a major challenge with promising new therapies on the horizon.

The Clinical and Pathological Spectrum of Idiopathic Inflammatory Myopathies : Implications for pathogenesis, classification and diagnosis

“…Earlier, the male to female ratio was estimated to 3:1 [3], but in 2 recent population-based studies it was found to be 3:2 [70,71]. A higher prevalence of IBM was further found in Olmstead county, USA, than in Western Australia, the Netherlands and Turkey, which was consistent with the frequency of the HLA-DR3 allele in the respective populations [68].…”

“…Biopsy and EMG findings reminiscent of neurogenic disease and case reports of concomitant axonal neuropathies [104,105] earlier led to a suspicion that the disease affected both nerve and muscle, but this has not found support in later studies [97]. An association with systemic inflammatory diseases has been reported [71,106], but not with malignancy [107]. An autoantibody has recently been detected in patients with IBM (cNIA), see Table 1.…”

Immune and myodegenerative pathomechanisms in inclusion body myositis

“…It develops insidiously, leading to frequent choking episodes and is, alongside pneumonia as a result of immobility, considered to be a potentially fatal complication of IBM. Importantly, dysphagia may be an isolated, initial manifestation and IBM should be considered by the examining physician as differential diagnosis for new onset of dysphagia in the elderly 13, 14, 17, 18, 19, 20, 21. Early in the disease course, tendon reflexes remain unaffected, however, hyporeflexia may occur at later stages of the disease due to significant muscle atrophy 19.…”

“…Prolonged life span and concomitant increase of the fraction of elderly people as well as westernization of dietary habits in Japan might be contributing factors for this observation 33. Although it was suggested that mortality is increased in IBM patients, solid evidence is still insufficient and the matter remains subject to larger studies 17, 34…”

Idiopathic inflammatory myopathies – a guide to subtypes, diagnostic approach and treatment

“…Apart from inclusion body myositis (IBM), all IIM subtypes occur more commonly in women (ratio 2:1); IBM occurs twice as commonly in men as women. 4 …”