Prospectively screening for eligible patients was inaccurate in predicting patient recruitment of orthopedic randomized trials Bauke W. Kooistra a, * , Bernadette G. Dijkman a , Gordon H. Guyatt b , Sheila Sprague a,b , Paul Tornetta III c , Mohit Bhandari a,b a Division of Orthopaedic Surgery, Department of Surgery, McMaster University, Hamilton, Ontario L8L 2X2, Canada b Department of Clinical Epidemiology & Biostatistics, McMaster University, Ontario L8L 2X2, Canada c Department of Orthopaedic Surgery, Boston University, Boston, MA, USA Accepted 14 May 2010 Abstract Objective: To compare the accuracy of estimates of potential recruitment from a prospective 8-week screening study compared with a retrospective chart review across sites participating in two fracture management trials. Study Design and Setting: During the planning phase of two large, multicenter, randomized controlled fracture management trials, 74 clinical sites provided estimates of the annual recruitment rate both retrospectively (based on chart reviews) and prospectively. The pro- spective estimate was generated by screening, for 8 weeks, all incoming patients for eligibility in the concerning trial, without actually enrolling any patient. We compared these prospective and retrospective estimates with one another (for 74 sites in the two trials) and with actual 1-year recruitment rates in the definitive trial (for nine sites in one trial). Results: There was a median difference of four patients (interquartile range: 14 to 18 patients; P 5 0.89) between a center’s prospec- tive estimate and its retrospective estimate. Both predictions were overestimations of recruitment in the definitive trial; only 31% (95% confidence interval [CI]: 28, 35) of retrospectively estimated patients, and 31% (95% CI: 27, 35) of prospectively estimated patients were recruited in the definitive trials. Conclusion: Compared with relatively simple chart reviews, prospectively screening for eligible patients at clinical sites, which is associated with substantial costs, did not result in more accurate predictions of accrual in large, multicenter, randomized controlled trials. Ó 2011 Elsevier Inc. All rights reserved. Keywords: Patient recruitment; Randomized controlled trials; Prospective screening; Chart review; Prediction; Accuracy 1. Introduction Lower than expected recruitment in surgical randomized trials risks underpowered studies with inconclusive results [1,2]. The success of both efficient and adequate patient en- rollment in surgical trials is largely based on estimates from participating investigators. Although researchers can com- pensate for lower than expected recruitment by increasing the number of participating centers after the trial has begun, this strategy delays the study completion and increases costs. These considerations suggest the advisability of prelim- inary screening studies before the study start. Two options to estimate recruitment across sites include retrospective and prospective screening studies. Investigators planning multicenter randomized trials must weigh the additional time and costs of a prospective screening study against its potentially greater accuracy. The added time and costs of conducting a prospective screening for study eligibility across sites are warranted only if these estimates better pre- dict actual recruitment. Using estimates for centers participating in two fracture management trials, we aimed to investigate whether a pro- spective 8-week screening study would result in significantly different estimates of recruitment potential than a retrospec- tive chart review. We also examined which approach more accurately predicted the actual recruitment rate of one sub- sequent trial. 2. Methods We collected both retrospective and prospective esti- mates of patient recruitment potential across 65 sites in * Corresponding author. Division of Orthopaedic Surgery, Department of Surgery, McMaster University, 293 Wellington Street North, Suite 110, Hamilton, Ontario L8L 2X2, Canada. Tel.: 905-527-4322 ext. 44490; fax: 905-527-523-8781. E-mail address: baukekooistra@hotmail.com (B.W. Kooistra). 0895-4356/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved. doi: 10.1016/j.jclinepi.2010.05.002 Journal of Clinical Epidemiology 64 (2011) 537e542