The Cost-Time Index: a new method for measuring the efficiencies of recruitment-resources in clinical trials.

Paid media are important resources used to recruit subjects in clinical trials. An index for evaluating which advertising resource has minimal cost and time requirement for patient accrual, for a given study design, has not been previously introduced. In this communication the authors present a new index, the Cost-Time Index, which represents a measure of the average amount of money and time spent, simultaneously, on a given advertising resource to recruit one analyzable subject. This index can be calculated using retrospective data and may be a useful tool for comparing recruitment efficiencies among various resources. The authors demonstrate the utility of the Cost-Time Index and recommend its use as an additional variable in future studies regarding recruitment strategies in clinical trials.