Recruitment of Study Participants

Abstract

Often the most difficult task in a clinical trial involves obtaining sufficient study participants within a reasonable time. Time is a critical factor for both scientific and logistical reasons. From a scientific viewpoint, there is an optimal window of time within which a clinical trial can and should be completed. Changes in medical practice, including introduction of new treatment options, may make the trial outdated before it is completed. Other investigators may answer the questions sooner. In terms of logistics, the longer recruitment extends beyond the initially allotted recruitment periods, the greater the pressure becomes to meet the goal. Lagging recruitment will also reduce the statistical power of the trial. Selective recruitment of a lower proportion of eligible participants may increase the non-representative nature of the sample. Costs increase, frustration and discouragement often follow. The primary reasons for recruitment failure include overly optimistic expectations, failure to start on time, inadequate planning, and insufficient effort.