RESUMEN
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.