The Diabetes Prevention Program: recruitment methods and results

Abstract

The Diabetes Prevention Program (DPP) is a multicenter randomized controlled trial designed to test whether diet and exercise or medication can prevent or delay the onset of type 2 diabetes in persons with impaired glucose tolerance, who are at increased risk of the disease. This paper describes DPP recruitment methods, strategies, performance, and costs. The DPP developed an organizational structure for comprehensive management and continuous monitoring of recruitment efforts. The DPP utilized a variety of recruitment strategies, alone or in combination, and a stepped informed consent procedure leading to randomization. Studywide and clinic-specific recruitment data were monitored, analyzed, and used to modify recruitment approaches. DPP recruitment was completed slightly ahead of schedule, meeting goals for the proportion of women enrolled and nearly meeting goals for the proportion of racial/ethnic minorities. Clinics varied widely in the recruitment strategies they used, and these strategies also varied by participant age, gender, and race/ethnicity. Staff time devoted to recruitment averaged 86.8 hours per week per clinic, with the majority of effort by staff specifically assigned to recruitment. The number of staff hours required to recruit a participant varied by recruitment strategy. Recruitment cost (excluding staff cost) was about 1075 US dollars per randomized participant. The DPP experience offers lessons for those planning similar efforts: (1) a method for ongoing assessment and revision of recruitment strategies is valuable; (2) a range of recruitment strategies may be useful; (3) the most effective methods for recruiting potential subjects may vary according to the gender, age, and race/ethnicity of those individuals; (4) recruitment strategies vary in the amount of staff time required to randomize a participant; and (5) a stepped screening may make it easier to identify and recruit volunteers who understand the requirements of the study.