Shift analysis versus dichotomization of the modified Rankin scale outcome scores in the NINDS and ECASS-II trials
Department of Neurology
Activities of Daily Living; Aged; *Clinical Trials as Topic; Data Interpretation, Statistical; Databases, Factual; *Disability Evaluation; Female; Humans; Male; Middle Aged; National Institutes of Health (U.S.); Odds Ratio; Outcome Assessment (Health Care); Quality Assurance, Health Care; Quality of Life; Self-Evaluation Programs; Stroke; Tissue Plasminogen Activator; United States
Nervous System Diseases | Neurology
BACKGROUND AND PURPOSE: The SAINT I trial that showed a significant benefit of the neuroprotectant NXY-059 used a novel outcome for acute ischemic stroke trials: a shift toward good functional outcome on the 7-category modified Rankin scale (mRS).
METHODS: We used the Cochran-Mantel-Haenszel shift test to analyze the distribution of the 90-day mRS outcomes in the NINDS and ECASS-II databases and compared the results with a dichotomized mRS outcome by logistic regression (0 to 2 vs 3 to 6, or 0 to 1 vs 2 to 6). We also stratified each dataset based on National Institutes of Health Stroke Scale baseline severity.
RESULTS: Each dataset showed a statistically significant shift in the 90-day mRS distributions favoring tissue plasminogen activator (odds ratio, 1.6 for NINDS, 1.3 for ECASS-II). For ECASS-II, larger shift effects appeared in National Institutes of Health Stroke Scale 0 to 6 and 16 to 40 strata. Similarly, the mRS 0 to 2 analysis but not mRS 0 to 1 found similar treatment effects in both datasets (odds ratio, 1.6 for NINDS, 1.5 for ECASS-II) and similar variations in the low and high strata in the ECASS-II trial. NINDS found no significant treatment effects across the strata. After removing the strata at the fringes, the shift test lost significance in both datasets.
CONCLUSIONS: Tissue plasminogen activator causes a beneficial shift toward wellness on the mRS in both the NINDS and ECASS-II trials, and ECASS-II would have been a positive trial according to the shift approach. However, the shift effect is not global for all treated patients and does not outperform the dichotomized 0 to 2 outcome. Patients with mild and severe deficits also shifted favorably on the mRS in the ECASS-II trial.
Rights and Permissions
Citation: Stroke. 2007 Dec;38(12):3205-12. Epub 2007 Nov 1. Link to article on publisher's site