Effects of Comprehensive Lifestyle Modification on Diet, Weight, Physical Fitness, and Blood Pressure Control: 18-Month Results of a Randomized Trial

Context Can adults make sustained changes in unhealthy lifestyle behaviors? Content In this multicenter trial, 810 adult volunteers with prehypertension or stage 1 hypertension were randomly assigned to a multicomponent behavioral intervention group, a group combining the behavioral intervention plus the Dietary Approaches to Stop Hypertension (DASH) diet, or an advice only group. At 18 months, participants in both behavioral intervention groups had less hypertension, more weight loss, and better reduction in sodium and fat intake than those receiving advice only. The participants in the DASH diet group also increased their intake of fruits, vegetables, and fiber. Implications Motivated adults can sustain several lifestyle changes over 18 months, which might reduce their risk for cardiovascular disease. The Editors The public health burden of chronic diseases related to suboptimal diet and physical inactivity is enormous. It has been estimated that these lifestyle factors contribute to approximately 20% of deaths in the United States (1). Incidence of atherosclerotic cardiovascular disease, overweight and obesity, elevated blood pressure and lipid levels, diabetes, osteoporosis, and cancer is increased by unhealthy lifestyles (2-8). Multiple lifestyle factors, such as physical inactivity; excessive intake of calories, sodium, saturated fat, and cholesterol; and inadequate intake of fruits, vegetables, and low-fat dairy products, are etiologically related to the development of these diseases (4, 5, 8-10). To reduce the burden of chronic disease, increased physical activity and changes in diet are needed, yet few intervention studies have attempted to achieve many lifestyle changes simultaneously. The PREMIER randomized trial tested the effects of 2 multicomponent behavioral interventions on blood pressure (11). Both interventions promoted increased physical activity, weight loss, and reduced sodium intake, each of which is recommended by the 2005 Dietary Guidelines Scientific Advisory Committee (12). One intervention also added the Dietary Approaches to Stop Hypertension (DASH) diet (13). This diet, which is high in fruits, vegetables, and low-fat dairy products and low in saturated fat, total fat, and cholesterol, meets each of the major nutrient recommendations that were established by the Institute of Medicine (14-18). We report the effects of the PREMIER interventions on lifestyle changes and blood pressure status at 18 months. The main results of PREMIER, namely change in blood pressure at 6 months, were reported previously (11). Methods The PREMIER study design and rationale (19) and intervention methods (11) have been described previously. The institutional review boards at each clinical center; an external protocol review committee appointed by the National Heart, Lung, and Blood Institute (NHLBI); and the NHLBI reviewed and approved the protocol (available at www.kpchr.org/public/premier/intervention/default.asp). The NHLBI also appointed a data and safety monitoring board to monitor the trial. Each participant provided written informed consent. The trial was conducted from January 2000 through November 2002. Study Participants Participants were generally healthy adults, age 25 years or older, who had prehypertension or stage 1 hypertension and met the Joint National Committee VI (JNC VI) criteria for a 6-month trial of nonpharmacologic therapy (2). Targeted recruitment methods were used to ensure adequate representation of clinically important subgroups, in particular, African-American persons. Specific methods varied from site to site but included direct mailings, radio and newspaper advertisements, and networking within the local African-American communities. Eligibility criteria included not taking antihypertensive medication and having a systolic blood pressure of 120 to 159 mm Hg and a diastolic blood pressure of 80 to 95 mm Hg, based on the average of 3 screening visits. Persons with prehypertension (systolic blood pressure of 120 to 139 mm Hg or diastolic blood pressure of 80 to 89 mm Hg) were included because of the excess risk for cardiovascular disease in those with blood pressure within this range (20). Major exclusion criteria were a body mass index less than 18.5 kg/mg2 or greater than 45.0 kg/m2, use of antihypertensive drugs or other drugs that affect blood pressure, JNC VI risk category C (target organ damage or diabetes), use of prescription weight loss medications, previous cardiovascular event, congestive heart failure, angina, cancer, and consumption of more than 21 alcoholic drinks per week. Trial Conduct Eligible participants were randomly assigned, with equal probability, to 1 of 3 groups: an advice only comparison group (advice only); an intervention group that targeted established, guideline-recommended lifestyle recommendations (established) (2); or an intervention group targeting the established recommendations and adding the DASH dietary pattern (established plus DASH) (13). Computer-generated treatment assignments were stratified by clinic and hypertension status and were assigned in blocks of varying sizes to provide balance over time. The actual assignments were administered by using a password-protected, Web-based application developed by the coordinating center and accessible only by authorized individuals. All clinic measurement staff were blinded to treatment assignment, and all intervention staff were blinded to clinic measurements. Hypertension was defined by using the JNC VI criteria for hypertension treatment: an average systolic blood pressure of 140 mm Hg, a diastolic blood pressure greater than 90 mm Hg, or use of antihypertensive medication. Normal blood pressure was defined as systolic blood pressure less than 120 mm Hg, diastolic blood pressure less than 80 mm Hg, and no use of antihypertensive medication (21) (Figure). Intervention was provided by master's degreelevel counselors (dietitians and health educators trained in behavioral methods). The counselors were centrally trained before the start of the study, attended annual 3-day training sessions, and participated in monthly conference calls. Figure. Flow diagram of enrollment, measurements, and visit completion. Advice Only Group Participants in the advice group received advice to follow the National High Blood Pressure Education Program lifestyle recommendations for blood pressure control (2). Lifestyle recommendations included reducing weight (if overweight), following a reduced-sodium diet, engaging in regular moderate-intensity physical activity, and eating a heart-healthy diet, including the DASH diet. This advice was provided in two 30-minute individual sessions, 1 immediately after random assignment and 1 after the 6-month data collection visit. A PREMIER counselor reviewed the guidelines with the participant and provided printed educational materials and information about community resources. This intervention did not include advice to keep a food or exercise diary. Behavioral Interventions in the Established and Established plus DASH Groups Participant goals for the established and established plus DASH groups included weight loss of at least 6.8 kg (15 lb) for those with a body mass index of 25 kg/m2 or greater, at least 180 minutes per week of moderate-intensity physical activity, no more than 100 mmol per day of dietary sodium, and alcohol consumption of no more than 30 mL (1 oz) per day (2 drinks) for men and 15 mL (0.5) oz per day (1 drink) for women. Participants assigned to the established plus DASH group (but not those in the established group) also received counseling on the DASH diet, with goals for increased consumption of fruits and vegetables (9 to 12 servings/d) and low-fat dairy products (2 to 3 servings/d) and reduced consumption of saturated fat ( 7% of energy) and total fat ( 25% of energy). The intervention format, contact pattern, and behavior change strategies for the established and established plus DASH groups were identical. During the first 6 months, participants in both behavioral intervention groups attended 14 group sessions and 4 individual sessions; during months 7 to 18, they attended monthly group sessions supplemented with 3 individual counseling sessions. Throughout the trial, participants in the established and established plus DASH groups (but not those in the advice group) kept food diaries, monitored dietary calorie and sodium intakes, and recorded minutes of physical activity. Self-monitoring was used to provide individualized feedback, reinforcement, problem solving, and support. Social support for initial behavior changes and maintenance of change was provided during the group sessions. More detailed descriptions of the behavorial intervention methods are available (22). Measurements Blood pressure was assessed twice at each measurement, and systolic and diastolic blood pressures were calculated by using the mean of all available measurements (4 sets before random assignment, 3 sets at 6 and 18 months, and 1 set at 3 and 12 months). For 4 participants who were started on antihypertensive drug therapy between the 12- and 18-month visits, we obtained an official set of blood pressure measurements before initiation of therapy and used these as our 18-month blood pressure values for analysis. A similar procedure was used to obtain the 6-month blood pressure value for the 1 participant who began taking antihypertensive drugs between the 3- and 6-month visits. Two 24-hour dietary recalls, 1 obtained on a weekday and the other obtained on a weekend, were collected at baseline and at 6 and 18 months by telephone interview (23). Intakes of nutrients and food groups were calculated by using the Nutrition Data System for Research, version NDS-R 1998 (University of Minnesota, Minneapolis, Minnesota). Urinary excretion of sodium (reflecting salt intake) and potassium (reflecting fruit and vegetable intake) was obtained from 24-hour urinary collections at baseline a