A 12-year follow-up in sporadic inclusion body myositis: an end stage with major disabilities

Abstract

Sporadic inclusion body myositis is considered to be a slowly progressive myopathy. Long-term follow-up data are, however, not yet available. Follow-up data are important with a view to informing patients about their prognosis and selecting appropriate outcome measures for clinical trials. We performed a follow-up study of 64 patients with sporadic inclusion body myositis who participated in a national epidemiological study in the Netherlands. Case histories were recorded, and manual and quantitative muscle tests as well as laboratory tests were performed at baseline and 12 years (median) after the first out-patient visit. Date and cause of death were recorded for all deceased patients. Forty-six patients died during the follow-up period, two patients chose not to participate and one patient was lost to follow-up. The remaining 15 surviving patients had a mean disease duration of 20 years and were clinically evaluated at the second time point. The mean decline in strength was 3.5 and 5.4% per year according to the manual muscle testing and quantitative muscle testing, respectively. This decline was most pronounced in the lower legs, which were also the weakest extremities. Life expectancy was normal at 81 years, but activities of daily life were clearly restricted. At follow-up, all patients were found to be using a wheelchair, seven of them (47%) being completely wheelchair-bound. Disorders of the respiratory system were the most common cause of death. In three patients, euthanasia was requested and in another three, continuous deep sedation was applied. The fact that end-of-life care interventions were used in six patients (13%) reflects the severe disability and loss of quality of life at the end stage of this disease. Sporadic inclusion body myositis is a chronic progressive disorder, leading to major disabilities at the end stage of the disease due to extensive muscle weakness.

Sporadic inclusion body myositis: A review of recent clinical advances and current approaches to diagnosis and treatment

“…In the Dutch study, aspiration pneumonia and cachexia were the most frequent causes of death, while cancer was found to be less common than in the general population (Benveniste et al, 2011, Cox et al, 2011.…”

“…A Dutch study of 61 patients who were re-examined after a mean of 12 years estimated an annual rate of decline in muscle strength of 3.5% based on manual muscle testing (MMT) and 5.4% with quantitative muscle testing (QMT) (Cox et al, 2011). A more rapid rate of deterioration (9.5% per annum) was found in a Swedish study of 66 patients assessed with hand-held myometry over a mean follow-up period of 5 years (Lindberg and Oldfors 2012).…”

“…MRI is particularly helpful in patients who lack some of the cardinal muscle biopsy features (Cox et al, 2011), or in whom a muscle biopsy is not possible. T1-weighted and proton-density muscle images demonstrate atrophy and hyperintensity in keeping with fatty infiltration in the affected muscles (Sekul et al, 1997, Phillips et al, 2001, while changes in signal intensity in short tau inversion recovery (STIR) sequences are regarded as an indicator of muscle inflammation and oedema (Cox et al, 2011, Tasca et al, 2015. A number of studies have demonstrated the characteristic pattern of forearm and lower limb muscle involvement which has been shown to have a high specificity for the diagnosis of IBM and allows it to be differentiated from other chronic myopathies (Tasca et al, 2015).…”

Immune and myodegenerative pathomechanisms in inclusion body myositis

“…The clinical presentation is heterogenous and at times difficult to distinguish from other inflammatory myopathies (muscle weakness and atrophy), motor‐neuron disease (asymmetry), and muscular dystrophies (slowly progressive disease) 3. In two large observational studies, the mean age of onset has been reported to be 59 ± 9 and 61 years, respectively 9, 11. The cardinal symptom of this highly debilitating disease is the late‐onset steady acquisition of muscular weakness and atrophy over a long period of time whilst sensory function is completely preserved.…”

“…The cardinal symptom of this highly debilitating disease is the late‐onset steady acquisition of muscular weakness and atrophy over a long period of time whilst sensory function is completely preserved. The decline of muscle strength ranges between 3.5 and 5.5% per annum 9, 11. Unlike other myopathies, during which proximal muscles are initially affected, IBM shows early involvement of distal muscles.…”