Research article

Practical considerations for estimating clinical trial accrual periods: application to a multi-center effectiveness study

Rickey E Carter¹ , Susan C Sonne² and Kathleen T Brady²

¹  Department of Biostatistics, Bioinformatics and Epidemiology, Medical University of South Carolina, Charleston, SC, USA

²  Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA

author email corresponding author email

BMC Medical Research Methodology 2005, 5:11doi:10.1186/1471-2288-5-11

Published:	30 March 2005

Abstract

Background

Adequate participant recruitment is vital to the conduct of a clinical trial. Projected recruitment rates are often over-estimated, and the time to recruit the target population (accrual period) is often under-estimated.

Methods

This report illustrates three approaches to estimating the accrual period and applies the methods to a multi-center, randomized, placebo controlled trial undergoing development.

Results

Incorporating known sources of accrual variation can yield a more justified estimate of the accrual period. Simulation studies can be incorporated into a clinical trial's planning phase to provide estimates for key accrual summaries including the mean and standard deviation of the accrual period.

Conclusion

The accrual period of a clinical trial should be carefully considered, and the allocation of sufficient time for participant recruitment is a fundamental aspect of planning a clinical trial.