Abstract
BACKGROUND
Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND), is a rare neurodegenerative disease. Approximately 5% to 7% of ALS/MND patients report a family history of a similarly affected relative. Superoxide dismutase-1 gene mutations are the cause in about 20% of familial cases. In those with non-familial (sporadic) ALS/MND the cause is unknown. Also unknown is whether patients with familial and sporadic ALS/MND respond differently to treatment.
OBJECTIVES
To systematically review the literature and to answer the specific question: 'Is there a difference in the response to treatment between patients with sporadic and familial forms of ALS?'
SEARCH STRATEGY
In May 2006 we searched the Cochrane Neuromuscular Disease Group Trials Register, MEDLINE (January 1966 to May 2006) and EMBASE (January 1980 to May 2006) for randomized controlled trials (RCTs). Two review authors read the titles and abstracts of all articles and reviewed the full text of all possibly relevant articles. We scanned references of all included trials to identify additional relevant articles. For all trials eligible for inclusion we contacted the authors to request the necessary raw data.
SELECTION CRITERIA
Studies had to meet two criteria: (a) randomized controlled study design, and (b) inclusion of patients with both familial and sporadic ALS/MND.
DATA COLLECTION AND ANALYSIS
We attempted to contact authors of all trials that met inclusion criteria. We obtained data regarding ALS/MND type (sporadic versus familial), treatment assignment (active versus placebo), survival and ALS Functional Rating Scale scores for four large RCTs that included 822 sporadic and 41 familial ALS patients. We could not obtain data from 25 potentially eligible studies (17 trial authors could not be contacted and eight were unwilling to provide data).
MAIN RESULTS
There was no statistical evidence for a different response to treatment in patients with familial ALS/MND compared to those with sporadic ALS/MND. The pooled estimate of the hazard ratio for the interaction term (treatment x familial ALS) suggested a more beneficial response with respect to survival among patients with familial ALS/MND, but the result was not statistically significant. Estimates of the rate of decline on the ALS Functional Rating Scale also suggested a slightly better response to treatment among those with familial ALS/MND, but the result was not statistically significant.
AUTHORS' CONCLUSIONS
Future RCTs should document whether patients with familial ALS/MND are included and the presence or absence of a mutation in the superoxide dismutase-1 gene amongst those with familial ALS/MND.
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