It is well known that an unhealthy diet and physical inactivity are related to elevated blood pressure; the challenge for physicians is helping patients make and maintain multiple lifestyle changes. The PREMIER randomized trial showed that a comprehensive behavioral intervention program emphasizing changes in diet and physical activity led to a clinically significant reduction in blood pressure after six months. Elmer and colleagues compared how the PREMIER interventions (i.e., two behavioral interventions and an advice-only intervention) affected blood pressure after 18 months.

The study included 810 otherwise healthy adult volunteers 25 years or older who had prehypertension (i.e., systolic blood pressure, 120 to 139 mm Hg; and diastolic blood pressure, 80 to 89 mm Hg) or stage 1 hypertension (i.e., systolic blood pressure, 140 to 159 mm Hg; or diastolic blood pressure, 90 to 95 mm Hg) averaged over three screening visits. Participants were excluded if they were taking antihypertensive or prescription weight loss medications; had a body mass index (BMI) less than 18.5 kg per m² or more than 45 kg per m²; consumed more than 21 alcoholic drinks per week; or had a personal history of cancer, cardiovascular disease, or diabetes. A typical participant was 50 years of age and had a BMI of 33 kg per m². Sixty-two percent of participants were women, and one third were black.

Participants were randomly assigned to one of three intervention groups: advice only, established behavioral intervention, or established behavioral intervention plus the Dietary Approaches to Stop Hypertension (DASH) diet. The advice-only group attended two 30-minute individual sessions with a trained counselor who provided general education and community resource materials based on National High Blood Pressure Education Program lifestyle recommendations for blood pressure control. Participants in the behavioral intervention and behavioral intervention plus DASH groups attended 25 group and seven individual sessions and kept daily logs of food, calorie, and sodium intake and recorded minutes of physical activity. Specific goals included losing 15 lb (6.8 kg) in patients with a BMI of 25 kg per m² or greater; participating in 180 minutes or more of weekly physical activity; consuming a maximum of 2.3 g (100 mmol) per day of dietary sodium; and consuming a maximum of two alcoholic drinks per day for men and one per day for women. Participants in the behavioral intervention plus DASH group received additional counseling on the DASH diet.

Data of interest at six and 18 months included measured blood pressure, 24-hour dietary recall, 24-hour urinary excretion of sodium and potassium, weight gain or loss, and performance on a 10-minute treadmill exercise test. Fourteen percent of participants were prescribed antihypertensive medications by their physicians during the study. To account for this factor, “hypertension status” (i.e., hypertensive blood pressure measurement or antihypertensive medication use at 18 months) was substituted for absolute blood pressure as an outcome measure.

All groups showed similar degrees of improved fitness by the end of the study. Compared with the advice-only group, the behavioral intervention and behavioral intervention plus DASH groups achieved statistically significant decreases in mean weight (4 lb 13 oz [2.2 kg] and 5 lb 15 oz [2.7 kg], respectively), urinary sodium excretion, and total and saturated fat consumption. The behavioral intervention plus DASH group reported a significant increase in fruit, vegetable, and dairy product intake and a decrease in dietary cholesterol intake compared with the two other groups. The prevalence of hypertension (i.e., systolic blood pressure more than 140 mm Hg, diastolic blood pressure more than 90 mm Hg) decreased in all three groups, although the decrease was greater in the behavioral intervention and behavioral intervention plus DASH groups than in the advice-only group. After 18 months, 18 percent of the advice-only group, 24 percent of the behavioral intervention group, and 24 percent of the behavioral intervention plus DASH group had normal blood pressure measurements (i.e., systolic blood pressure less than 120 mm Hg, diastolic blood pressure less than 80 mm Hg).

The authors conclude that behavioral intervention programs emphasizing multiple lifestyle changes successfully maintained lower blood pressures in patients with prehypertension and stage 1 hypertension over 18 months. They also conclude that the maximal clinical effect was achieved by adding the DASH diet to established recommendations.