Recruitment and baseline characteristics of participants in the Dietary Approaches to Stop Hypertension trial

Dietary Approaches to Stop Hypertension (DASH) was a randomized, multicenter feeding study designed to assess the effects of modifying dietary patterns on blood pressure. Among the most challenging aspects of conducting the DASH trial nas the recruitment of participants at the 4 clinical centers. As part of the recruitment drive, 347,500 brochures were mailed, 250,500 coupons were distributed in coupon packs, 114 advertisements were published in newspapers or bulletins, 140 radio and 74 television advertisements were broadcast, and 68 screening events and presentations were conducted. These efforts yielded a total of 459 enrolled participants, ahead of schedule. The most common source of participants was mass mailing of individual brochures (n=194, 42.3%), followed by word-of-mouth (n=82, 17.8%), and then other types of mass mailing (n=44, 9.6%). Recruitment of minority participants followed a similar pattern. Among the 3,192 persons attending the first in-person screening visit, the major reason for nonenrollment was low blood pressure (56%) rather than a diet-related factor. The study population was demographically heterogeneous (49% women, 60% African American, 48% married, and 77% employed full-time). On average, the diet of participants before the DASH feeding study was more similar to the trial control diet than to the combination diet, which reduced blood pressure more effectively. In summary, recruitment of a heterogeneous study population that includes a substantial number of minority participants is a feasible undertaking. However, the effort is considerable and requires a major commitment of resources.