Published Online
on December 1, 2005

A more recent version of this article appeared on January 1, 2006

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Submitted on July 14, 2005
Accepted on August 3, 2005

Recruiting Subjects for Acute Stroke Trials. A Meta-Analysis

Jacob S. Elkins MD; Talayeh Khatabi BA; Lawrence Fung MD; John Rootenberg MD; and S. Claiborne Johnston MD, PhD^*

From the University of California, San Francisco (J.S.E., T.K., J.R., S.C.J.); Kaiser Permanente San Francisco, California (L.F.).

^* To whom correspondence should be addressed. E-mail: Clay.Johnston{at}ucsfmedctr.org.

Background and Purpose--Recruitment rate is a major determinant of the duration, cost, and feasibility of acute stroke trials.

Methods--We performed a meta-analysis of all randomized, controlled trials of 300 subjects that were designed to evaluate the efficacy of a medical intervention for the treatment of acute ischemic stroke. Data about trial recruitment, organization, and inclusion/exclusion criteria were abstracted independently by 2 reviewers who applied predefined criteria. Recruitment efficiency was defined as the number of subjects enrolled per study center per month of recruitment.

Results--Of 32 trials meeting inclusion criteria, the average recruitment efficiency was 0.79 subjects per center per month (range 0.08 to 3.7). Recruitment efficiency did not vary by geographic region (P=0.36), but trials conducted in 1 country had more efficient recruitment than international studies (P=0.03), and recruitment efficiency declined with each percentage increase in the total number of study centers (P=0.002). The primary study entry criteria that predicted reduced recruitment efficiency were the maximum allowable time from stroke to study enrollment (P=0.002) and the exclusion of mild strokes (P=0.009). Trials with a treatment window >6 hours had approximately double the recruitment rates of trials that used treatment windows 6 hours (1.03 versus 0.52 patients per center per month).

Conclusion--Recruitment rates for acute stroke trials are influenced by organizational structure and study entry criteria. Characterizing predictors of recruitment may help optimize future trial design.

Key words: randomized controlled trials • stroke, acute

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