Quality assurance and monitoring in the Hypertension Prevention Trial. Hypertension Prevention Trial Research Group

Abstract

The Hypertension Prevention Trial (HPT), was a randomized, controlled, multicenter (four clinics, four resource centers) trial designed to test the feasibility of achieving and sustaining dietary changes in the intake of calories, sodium, and potassium and to assess the effect of those changes on blood pressure in a normotensive population. The trial involved 841 men and women (plus a test cohort of 78) who, at the first baseline (BL) examination were in the age range of 25-49 years and had diastolic blood pressure (DBP) greater than or equal to 76 but less than 100 mm Hg (average of two readings), and at the examination prior to randomization (BL 2) had DBP greater than or equal to 78 but less than 90 mm Hg (also averaged). Participants were randomly assigned to a control treatment group (no dietary counseling) or to one of four dietary treatment groups involving counseling designed to reduce calorie intake, reduce sodium intake, reduce sodium and calorie intake, and reduce sodium and increase potassium intake. This chapter describes HPT procedures for training and certifying clinic staff, for data entry checks and data audits of its distributed data entry system, and for inspecting clinical equipment. Replicate analyses were performed regularly by the two arms of the Data Coordinating Center. The Food Coding Center and the Central Laboratory were evaluated by both internal and external monitoring techniques. The performance monitoring report, prepared semiannually for the governing committees of the HPT, reported on the effectiveness of quality assurance procedures and served to alert staff to developing problems.