Recruitment index as a measure of patient recruitment activity in clinical trials.

Recruitment of patients for clinical trials is one of the major hurdles on the way to successful completion of any human research study. Direct comparison of recruitment activity in different sites and projects is not easy due to lack of a unified measure of recruitment efficacy. The author introduces a new variable, the Recruitment Index, which represents the number of days required for an average study site in a multicenter study to recruit one analyzable patient. Once established in previous studies, an indication-specific Recruitment Index can be used for a variety of purposes, e.g. evaluation of efficacy of various recruitment strategies, planning duration of recruitment period for a new study, or projecting the number of participating sites required to supply a given number of analyzable patients within a certain period.