Defining post-stroke recovery: implications for design and interpretation of drug trials

Measurement of stroke recovery is complex because definition of successful recovery is highly variable across measures and cutoff points for defining successful outcomes vary. The purpose of this paper is to describe patterns of recovery in stroke patients of varying severity when different measures are used and when different cut-off points are selected. 459 individuals e nrolled in a prospective cohort study were assessed within 14 days post str oke and re-evaluated at 1, 3, and 6 months. Recovery was assessed using the NIH Stroke Scale, the Fugl-Meyer Assessment of Motor Recovery, the Barthel Index of Activities of Daily Living, the Physical Function Index of the SF -36, and the Modified Rankin Outcome Scale. Subjects also defined their pre ference (utility) for their current health state with a time-trade off ques tion. We compared patterns of recovery using the different measures and var ying the cut-off points for defining successful recovery. The percentage of patients who are believed to have recovered depends on how recovery is def ined. If recovery is defined at the disability level (Barthel>90), the majo rity 57.3% of stroke survivors experience a full recovery. Fewer individual s are considered to be fully recovered if impairments are measured (NIH les s than or equal to 1, 44.9% and Fugl-Meyer>90, 36.8%. Less than 25% of stro ke survivors are considered recovered if recovery is defined relative to re ported prior function in higher levels of physical activity. Shifting the d efinition of recovery on the modified Rankin scale from less than or equal to 1 to less than or equal to 2 shifts the percentage of those deemed recov ered from less than or equal to 25% to 53.8%. In designing drug trials the methods for defining stroke recovery should be carefully considered. If rec overy is defined in terms of disability, a higher proportion of the placebo group will achieve the outcome than if impairments are used to define reco very. The benchmarks for recovery in minor strokes must include measures of higher functioning (e.g. the SF-36 physical functioning index or a Rankin 0 (no symptoms). (C) 2000 Published by Elsevier Science Ltd. All rights res erved.