Abstract
Purpose: Estimating recruitment for clinical trials is vital to ensuring the feasibility of larger multi-centre trials. We compared estimates of potential recruitment from a prospective eight-week screening study and a retrospective chart review across sites participating in three fracture management trials.
Method: During the planning phase of two multi-centre, randomized controlled trials regarding the operative treatment of hip (two studies) and tibial shaft (one study) fractures, 74 clinical sites provided estimates of the annual recruitment rate both retrospectively (based on chart reviews) and prospectively. The prospective estimate was generated by screening all incoming patients for eligibility in the concerning trial, without actually enrolling any patient, for eight weeks. These prospective and retrospective estimates were correlated with each other (for 74 sites) and with actual one-year recruitment rates in the definitive trial (for nine sites).
Results: On average, a centre’s prospective estimate was only slightly lower than its retrospective estimate (3.1 patient-difference, p=0.64). Both predictions were substantial overestimations of recruitment in the definitive trial; only 31% (95% confidence interval: 28%–35%) of retrospectively estimated patients and 34% (95% confidence interval: 30%–37%) of prospectively estimated patients were recruited in the definitive trials (p< 0.001 and p=0.001 for both overestimations, respectively). The overall costs of conducting retrospective chart reviews and prospective screening studies in 65 sites were $68,107 ($CAN) and $153,725 ($CAN), respectively.
Conclusion: Compared to relatively simple and inexpensive chart reviews, prospectively screening for eligible patients at clinical sites did not result in more accurate predictions of accrual in large randomized controlled trials.
Correspondence should be addressed to: COA, 4150 Ste. Catherine St. West Suite 360, Westmount, QC H3Z 2Y5, Canada. Email: meetings@canorth.org
