Statistical analysis of the primary outcome in acute stroke trials

Bath, P.M.W., Lees, K.R., Schellinger, P.D., Altman, H., Bland, M., Hogg, C., Howard, G. and Saver, J.L. (2012) Statistical analysis of the primary outcome in acute stroke trials. Stroke, 43(4), pp. 1171-1178. (doi: 10.1161/STROKEAHA.111.641456)

Abstract

Common outcome scales in acute stroke trials are ordered categorical or pseudocontinuous in structure but most have been analyzed as binary measures. The use of fixed dichotomous analysis of ordered categorical outcomes after stroke (such as the modified Rankin Scale) is rarely the most statistically efficient approach and usually requires a larger sample size to demonstrate efficacy than other approaches. Preferred statistical approaches include sliding dichotomous, ordinal, or continuous analyses. Because there is no best approach that will work for all acute stroke trials, it is vital that studies are designed with a full understanding of the type of patients to be enrolled (in particular their case mix, which will be critically dependent on their age and severity), the potential mechanism by which the intervention works (ie, will it tend to move all patients somewhat, or some patients a lot, and is a common hazard present), a realistic assessment of the likely effect size, and therefore the necessary sample size, and an understanding of what the intervention will cost if implemented in clinical practice. If these approaches are followed, then the risk of missing useful treatment effects for acute stroke will diminish.

• Item Type: Articles
• Additional Information: Embargo expires 16 September 2012
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Lees, Professor Kennedy
• Authors: Bath, P.M.W., Lees, K.R., Schellinger, P.D., Altman, H., Bland, M., Hogg, C., Howard, G., and Saver, J.L.
• College/School: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
• Journal Name: Stroke
• Publisher: American Heart Association
• ISSN: 0039-2499
• ISSN (Online): 1524-4628
• Published Online: 15 March 2012
• Copyright Holders: Copyright © 2012 American Heart Association, Inc.
• First Published: First published in Stroke 2012 43 (4):1171-1178
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher