Document Detail

Clinical trials of multiple sclerosis monitored with enhanced MRI: new sample size calculations based on large data sets.
MedLine Citation:
PMID:  11254773     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: A new parametric simulation procedure based on the negative binomial (NB) model was used to evaluate the sample sizes needed to achieve optimal statistical powers for parallel groups (with (PGB) and without (PG) a baseline correction scan). It was also used for baseline versus treatment (BVT) design clinical trials in relapsing-remitting (RR) and secondary progressive (SP) multiple sclerosis (MS), when using the number of new enhancing lesions seen on monthly MRI of the brain as the measure of outcome.
METHODS: MRI data obtained from 120 untreated patients with RRMS selected for the presence of MRI activity at baseline, 66 untreated and unselected patients with RRMS, and 81 untreated and unselected patients with SPMS were fitted using an NB distribution. All these patients were scanned monthly for at least 6 months and were all from the placebo arms of three large scale clinical trials and one natural history study. The statistical powers were calculated for durations of follow up of 3 and 6 months.
RESULTS: The frequency of new enhancing lesions in patients with SPMS was lower, but not significantly different, from that seen in unselected patients with RRMS. As expected, enhancement was more frequent in patients with RRMS selected for MRI activity at baseline than in the other two patient groups. As a consequence, the estimated sample sizes needed to detect treatment efficacy in selected patients with RRMS were smaller than those of unselected patients with RRMS and those with SPMS. Baseline correction was also seen to reduce the sample sizes of PG design trials. An increased number of scans reduced the sample sizes needed to perform BVT trials, whereas the gain in power was less evident in PG and PGB trials.
CONCLUSION: This study provides reliable estimates of the sample sizes needed to perform MRI monitored clinical trials in the major MS clinical phenotypes, which should be useful for planning future studies.
M P Sormani; D H Miller; G Comi; F Barkhof; M Rovaris; P Bruzzi; M Filippi
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of neurology, neurosurgery, and psychiatry     Volume:  70     ISSN:  0022-3050     ISO Abbreviation:  J. Neurol. Neurosurg. Psychiatr.     Publication Date:  2001 Apr 
Date Detail:
Created Date:  2001-03-20     Completed Date:  2001-05-24     Revised Date:  2011-11-03    
Medline Journal Info:
Nlm Unique ID:  2985191R     Medline TA:  J Neurol Neurosurg Psychiatry     Country:  England    
Other Details:
Languages:  eng     Pagination:  494-9     Citation Subset:  IM    
Neuroimaging Research Unit, Department of Neuroscience, Scientific Institute Ospedale San Raffaele, University of Milan, Via Olgettina 60, 20132 Milan, Italy.
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MeSH Terms
Clinical Trials as Topic* / statistics & numerical data*
Magnetic Resonance Imaging / methods*
Monitoring, Physiologic
Multiple Sclerosis / pathology*,  physiopathology
Sample Size*
Grant Support
491//Multiple Sclerosis Society

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