Document Detail

The distribution of new enhancing lesion counts in multiple sclerosis: further explorations.
MedLine Citation:
PMID:  18845655     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: A statistical distribution describing the number of new enhancing lesions seen on MRI in patients with MS is of great importance for improving the statistical methodology of clinical trials using new enhancing lesions as outcome measure. We examined whether there are superior alternatives for the currently proposed negative binomial (NB) distribution. OBJECTIVE: To determine the optimal statistical distribution describing new enhancing lesion counts from a selection of six conceivable models, and to assess the effect on the distribution of a treatment effect, varying follow-up duration and selection for activity at baseline. METHODS: The statistical NB, Poisson-Inverse Gaussian (P-IG), Poisson- Lognormal (P-LN), Neyman type A (NtA), P?lya-Aeppli (PA) and Zero Inflated Poisson (ZIP) distribution were fitted on new enhancing lesion data derived from one treated and two untreated cohorts of RRMS and relapsing SPMS patients and on subgroups of varying follow-up duration and selection for baseline activity. Measure of comparison was Akaike's information criterion (AIC). RESULTS: Both the subgroup analyses as well as a treatment had a noticeable effect on the distributional characteristics of new enhancing lesion counts. The NB distribution generally provided the most optimal fit, closely followed by the P-IG distribution and the P-LN distribution. Fits of the PA and NtA distribution were suboptimal, while the ZIP distribution was the least adequate for modelling new enhancing lesion counts. CONCLUSION: The NB distribution is the optimal distribution for modelling new enhancing lesion counts, irrespective of the effect of treatment, follow-up duration or a baseline activity selection criterion.
Ij van den Elskamp; Dl Knol; Bmj Uitdehaag; F Barkhof
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-10-09
Journal Detail:
Title:  Multiple sclerosis (Houndmills, Basingstoke, England)     Volume:  15     ISSN:  1352-4585     ISO Abbreviation:  Mult. Scler.     Publication Date:  2009 Jan 
Date Detail:
Created Date:  2008-12-23     Completed Date:  2009-03-23     Revised Date:  2010-03-23    
Medline Journal Info:
Nlm Unique ID:  9509185     Medline TA:  Mult Scler     Country:  England    
Other Details:
Languages:  eng     Pagination:  42-9     Citation Subset:  IM    
Department of Radiology, VU University Medical Center, Amsterdam, The Netherlands.
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MeSH Terms
Brain / pathology*
Databases, Factual
Follow-Up Studies
Gadolinium / diagnostic use
Magnetic Resonance Imaging / methods*
Middle Aged
Multiple Sclerosis / pathology*
Poisson Distribution
Young Adult
Reg. No./Substance:

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