Spilker and Cramer examined recruitment data from a number of medical trials and found the screening yield depends on the type of trial and subject population sought, ranging from 1 to 6% in prevention trials to 20 to 27% in therapeutic trials. Similar results have been reported in the psychology literature for psychotropic drug trials. [...]

Recruitment Outcomes
A total of 911 people contacted the study coordinator. From these initial contacts, 186 (20.4%) were not interested in a study, 165 (18.1%) were rejected (78 during the telephone interview and 87 later), and 530 (58.2%) expressed interest in the study and appeared qualified. Thirty individuals (3.3%) called because they wanted to refer someone [...]

Sample
The recruitment goal was 180 subjects with specific phobia of dental injections according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). The initial expectations were not met. After 3 years, 108 subjects were enrolled and the goal revised downward to 144. Exclusion criteria were (1) obesity, (2) too young/old, (3) [...]

The importance of evidence-based practice has resulted in increasing reliance on clinical trials. A critical aspect of clinical trials is subject recruitment. The tendency to be avoidant makes the anxious population particularly difficult to recruit for studies and increases their time and budget. We were in the situation of having to recruit for a randomized [...]