Recruiting Phobic Research Subjects: DISCUSSION

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. However, the range was between 5 and 90%, with about half the investigators reporting less than a 15% enrollment rate from initial contacts. Our recruitment yield (15.9%) is thus similar to other studies recruiting patients with psychiatric conditions.

Bielski and Lydiard also reported that advertising resulted in 87% of all enrollment. The most common method was newspaper advertisement that was usually complemented with TV and radio advertising. cheap cialis canadian pharmacy

Paid print advertising in our study was most successful (63%). Including TV and Internet advertising, the yield through advertisement was approximately 70% of enrolled subjects. The bus advertisements attracted the greatest number of initial contacts and the largest number of enrollees. Second best were posters and third were newspapers. The advantage of bus advertisement and posters is that people see them daily. Frequent reminders seem to be important for anxious people. Posters, which were inexpensive, yielded 29 subjects. From other sources, such as television and radio, information about the study is delivered quickly and thus potential participants do not have the benefit of repeated expo­ sure to the recruitment message. To be effective, these sources must be used frequently, demanding a large advertisement budget. Professional referral was not a very effective method in the present study, producing only 16 enrollees, probably because anxious patients avoid dental care.

In this study, an average of $79 (1996 dollars) was spent to enroll a subject. This rate is much lower than the $535 average advertising investment reported in an article comparing recruitment strategies in 18 therapeutic trials. The main strategy in the cited studies was newspaper advertisement. Our cost per enrolled subject (inflated to current dollars) could be used as a minimal guideline when making a budget for recruitment advertising. Staff time spent during screening and designing advertisements and indirect costs were not included. Also, unsuccessful methods were dropped during the monitoring meetings. Thus, total recruitment costs may be underestimated. prescription drugs from canada