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Recovery After Stroke: Not So Proportional After All?

Hope, Thomas M.H., Friston, Karl J., Price, Cathy J., Leff, Alex P., Rotshtein, Pia, Bowman, Howard (2019) Recovery After Stroke: Not So Proportional After All? Brain, 142 (1). pp. 15-22. ISSN 0006-8950. E-ISSN 1460-2156. (doi:10.1093/brain/awy302) (Access to this publication is currently restricted. You may be able to access a copy if URLs are provided)

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Abstract

The proportional recovery rule asserts that most stroke survivors recover a fixed proportion of lost function. To the extent that this is true, recovery from stroke can be predicted accurately from baseline measures of acute post-stroke impairment alone. Reports that baseline scores explain more than 80%, and sometimes more than 90%, of the variance in the patients’ recoveries, are rapidly accumulating. Here, we show that these headline effect sizes are likely inflated. The key effects in this literature are typically expressed as, or reducible to, correlation coefficients between baseline scores and recovery (outcome scores minus baseline scores). Using formal analyses and simulations, we show that these correlations will be extreme when outcomes are less variable than baselines, which they often will be in practice regardless of the real relationship between outcomes and baselines. We show that these effect sizes are likely to be over optimistic in every empirical study that we found, which reported enough information for us to make the judgement, and argue that the same is likely to be true in other studies as well. The implication is that recovery after stroke may not be as proportional as recent studies suggest.

Item Type: Article
DOI/Identification number: 10.1093/brain/awy302
Uncontrolled keywords: proportional recovery, stroke, methods, statistics
Divisions: Faculties > Sciences > School of Computing
Depositing User: Howard Bowman
Date Deposited: 22 Oct 2018 14:47 UTC
Last Modified: 29 May 2019 21:20 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/69746 (The current URI for this page, for reference purposes)
Bowman, Howard: https://orcid.org/0000-0003-4736-1869
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