A 12-year Follow-up in Sporadic Inclusion Body Myositis

An End Stage With Major Disabilities

Fieke M. Cox; Maarten J. Titulaer; Jacob K. Sont; Axel R. Wintzen; Jan J. G. M. Verschuuren; Umesh A. Badrising

Disclosures

Brain. 2011;134(11):3167-3175. 

In This Article

Abstract and Introduction

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.

Introduction

Sporadic inclusion body myositis (IBM) is rare, but nevertheless thought to be the most frequently occurring, acquired, progressive myopathy affecting patients over 50 years of age (Needham and Mastaglia, 2007). It is considered to be a slowly but steadily progressive disease, which does not interfere with life expectancy (Badrising et al., 2000; Dalakas, 2006).

Data on the clinical course of sporadic IBM are limited. Although two retrospective studies (Lindberg et al., 1994; Felice and North, 2001) and two prospective studies (Rose et al., 2001; Dalakas et al., 2009) have been published, these investigated small cohorts with a short follow-up period. The rate of decline of muscle strength reported in these studies showed a large variation. Small studies do not allow the identification of prognostic factors, although one did find a possible association between being positive for human leucocyte antigen (HLA) DR3 and a faster decline in quadriceps strength in six patients (Needham et al., 2008).

A larger natural history study in sporadic IBM with long-term follow-up provides important data for multiple reasons. Firstly, patients can be better informed about the expected course of their disease. Secondly, possible influencing factors, such as HLA, might provide more insight into disease pathology. Thirdly, when planning future trials, these data might help in the selection of appropriate outcome measures and enable power calculations.

We conducted a follow-up study of 64 patients with sporadic IBM over a period of 10–13 years, focusing on decline in muscle strength, functional status and life expectancy.

Comments

3090D553-9492-4563-8681-AD288FA52ACE

processing....