Multiple Sclerosis, 1 June 2003, vol. 9, no. 3, pp. 289-292(4)
Scott T.F.[1]; Schramke C.J.[1]; Cutter G.[2]
[1] Drexel University College of Medicine, Department of Neurology,
Allegheny General Hospital, Pittsburgh, Pennsylvania, USA [2] Center for
Research Design and Statistical Methods, University of Nevada School of
Medicine, Reno, Nevada, USA
Background:
Risk factors for short-term progression in early relapsing–remitting MS have been identified recently.
Previously we determined potential risk factors for rapid progression of early relapsing–remitting MS and identified three groups of high-risk patients.
These non-mutually exclusive groups of patients were drawn from a consecutively studied sample of 98 patients with newly diagnosed MS.
High-risk patients had a history of either poor recovery from initial attacks, more than two attacks in the first two years of disease, or a combination of at least four other risk factors.
Objective:
To determine differences in sample sizes required to show a meaningful treatment effect when using a high-risk sample versus a random sample of patients.
Methods:
Power analyses were used to calculate the different sample sizes needed for hypothetical treatment trials.
Results:
We found that substantially smaller numbers of patients should be needed to show a significant treatment effect by employing these high-risk groups of patients as compared to a random population of MS patients (e.g., 58% reduction in sample size in one model).
Conclusion:
The use of patients at higher risk of progression to perform drug treatment trials can be considered as a means to reduce the number of patients needed to show a significant treatment effect for patients with very early MS.