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(Stroke. 2001;32:909.)
© 2001 American Heart Association, Inc.
Original Contributions |
Entry Criteria and Baseline Characteristics Predict Outcome in Acute Stroke Trials
From the Department of Neurology and Statistics, University of Washington, Seattle.
Correspondence to Steven C. Cramer, MD, University of Washington, Department of Neurology, 1959 NE Pacific St, Room RR650, Box 356465, Seattle, WA 98195-6465. E-mail cramers{at}u.washington.edu
Background and Purpose—We sought to study the range of entry criteria and baseline characteristics in acute stroke trials and to understand their effects on patient outcomes.
Methods—Randomized, placebo-controlled therapeutic trials in patients with acute ischemic stroke were identified. Entry criteria, baseline clinical characteristics, and outcome were extracted for the placebo group of each trial. The relationship between key variables was then determined.
Results—Across 90
placebo groups identified, there was great variation in entry
criteria and outcome measures. This was associated with divergent
outcomes; for example, in some studies most placebo group patients
died, while in other studies nearly all had no disability. Entry
criteria were significantly correlated with outcome; for example,
higher age cutoff for study entry correlated with 3-month mortality.
Entry criteria also predicted baseline clinical characteristics; for
example, wider time window for study entry correlated directly with
time to treatment and inversely with stroke severity (initial National
Institutes of Health Stroke Scale score). Baseline characteristics
predicted outcome. Greater stroke severity predicted higher 3-month
mortality rate; despite this, successful thrombolytic
trials have enrolled more severe strokes than most trials. The mean age
of enrollees also predicted 3-month mortality and was inversely related
to percentage of patients with 3-month Barthel Index score 
95. The
strongest predictors of 3-month mortality were obtained with
multivariate models.
Conclusions—Acute stroke studies vary widely in entry criteria and outcome measures. Across multiple studies, differences in entry criteria, and the baseline clinical characteristics they predict, influence patient outcomes along a continuum. In some studies, enrolling a specific subset of patients may have improved the chances of identifying a treatment-related effect, while in others, such chances may have been reduced. These findings may be useful in the design of future stroke therapeutic trials.
Key Words: clinical trials • outcome • stroke, acute
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