Stroke prevention trials: How many enrollees can be expected by site?

A major challenge in the planning phase of a clinical trial is the estimation of the number of enrollees that can be expected at individual sites. Often, the initial enthusiasm for a new study leads trial organizers and local investigators to be optimistic and to overestimate the expected number of enrollees by site. As the trial progresses, however, narrow time windows and other restrictive enrollment criteria reduce the available pool of potential enrollees beyond the expectations of investigators.1 Whereas the issue of patient accrual has been reported for oncology trials,2 cardiovascular trials,3,4 an ophthalmology trial,5 and a review of select Veterans Administration (VA) trials,6 relatively little has been written about this problem in stroke prevention trials. Our objective was to review accrual data from major stroke prevention trials and provide comparative and average estimates for monthly enrollment per site. The stroke trials that we selected for study were those that enrolled at least 400 patients and had been published since 1987. They …