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


CONCLUSIONS
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.
Carter
Rickey E
RE
Department of Biostatistics, Bioinformatics and Epidemiology, Medical University of South Carolina, Charleston, SC, USA. carterre@musc.edu
Sonne
Susan C
SC
Brady
Kathleen T
KT
D006801:Humans; D015337:Multicenter Studies as Topic / Q000379:methods*; D018579:Patient Selection; D016012:Poisson Distribution; D016032:Randomized Controlled Trials as Topic / Q000379:methods* / Q000706:statistics & numerical data; D012107:Research Design; D013269:Stochastic Processes; D013997:Time Factors