Eva Obarzanek

Effects on Blood Pressure of Reduced Dietary Sodium and the Dietary Approaches to Stop Hypertension (DASH) Diet

Background The effect of dietary composition on blood pressure is a subject of public health importance. We studied the effect of different levels of dietary sodium, in conjunction with the Dietary Approaches to Stop Hypertension (DASH) diet, which is rich in vegetables, fruits, and low-fat dairy products, in persons with and in those without hypertension. Methods A total of 412 participants were randomly assigned to eat either a control diet typical of intake in the United States or the DASH diet. Within the assigned diet, participants ate foods with high, intermediate, and low levels of sodium for 30 consecutive days each, in random order. Results Reducing the sodium intake from the high to the intermediate level reduced the systolic blood pressure by 2.1 mm Hg (P<0.001) during the control diet and by 1.3 mm Hg (P=0.03) during the DASH diet. Reducing the sodium intake from the intermediate to the low level caused additional reductions of 4.6 mm Hg during the control diet (P<0.001) and 1.7 mm Hg during t...

Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates

BACKGROUND The possible advantage for weight loss of a diet that emphasizes protein, fat, or carbohydrates has not been established, and there are few studies that extend beyond 1 year. METHODS We randomly assigned 811 overweight adults to one of four diets; the targeted percentages of energy derived from fat, protein, and carbohydrates in the four diets were 20, 15, and 65%; 20, 25, and 55%; 40, 15, and 45%; and 40, 25, and 35%. The diets consisted of similar foods and met guidelines for cardiovascular health. The participants were offered group and individual instructional sessions for 2 years. The primary outcome was the change in body weight after 2 years in two-by-two factorial comparisons of low fat versus high fat and average protein versus high protein and in the comparison of highest and lowest carbohydrate content. RESULTS At 6 months, participants assigned to each diet had lost an average of 6 kg, which represented 7% of their initial weight; they began to regain weight after 12 months. By 2 years, weight loss remained similar in those who were assigned to a diet with 15% protein and those assigned to a diet with 25% protein (3.0 and 3.6 kg, respectively); in those assigned to a diet with 20% fat and those assigned to a diet with 40% fat (3.3 kg for both groups); and in those assigned to a diet with 65% carbohydrates and those assigned to a diet with 35% carbohydrates (2.9 and 3.4 kg, respectively) (P>0.20 for all comparisons). Among the 80% of participants who completed the trial, the average weight loss was 4 kg; 14 to 15% of the participants had a reduction of at least 10% of their initial body weight. Satiety, hunger, satisfaction with the diet, and attendance at group sessions were similar for all diets; attendance was strongly associated with weight loss (0.2 kg per session attended). The diets improved lipid-related risk factors and fasting insulin levels. CONCLUSIONS Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize. (ClinicalTrials.gov number, NCT00072995.)

Long term effects of dietary sodium reduction on cardiovascular disease outcomes: observational follow-up of the trials of hypertension prevention (TOHP)

Objective To examine the effects of reduction in dietary sodium intake on cardiovascular events using data from two completed randomised trials, TOHP I and TOHP II. Design Long term follow-up assessed 10-15 years after the original trial. Setting 10 clinic sites in 1987-90 (TOHP I) and nine sites in 1990-5 (TOHP II). Central follow-up conducted by post and phone. Participants Adults aged 30-54 years with prehypertension. Intervention Dietary sodium reduction, including comprehensive education and counselling on reducing intake, for 18 months (TOHP I) or 36-48 months (TOHP II). Main outcome measure Cardiovascular disease (myocardial infarction, stroke, coronary revascularisation, or cardiovascular death). Results 744 participants in TOHP I and 2382 in TOHP II were randomised to a sodium reduction intervention or control. Net sodium reductions in the intervention groups were 44 mmol/24 h and 33 mmol/24 h, respectively. Vital status was obtained for all participants and follow-up information on morbidity was obtained from 2415 (77%), with 200 reporting a cardiovascular event. Risk of a cardiovascular event was 25% lower among those in the intervention group (relative risk 0.75, 95% confidence interval 0.57 to 0.99, P=0.04), adjusted for trial, clinic, age, race, and sex, and 30% lower after further adjustment for baseline sodium excretion and weight (0.70, 0.53 to 0.94), with similar results in each trial. In secondary analyses, 67 participants died (0.80, 0.51 to 1.26, P=0.34). Conclusion Sodium reduction, previously shown to lower blood pressure, may also reduce long term risk of cardiovascular events.

Long-Term Weight Loss and Changes in Blood Pressure: Results of the Trials of Hypertension Prevention, Phase II

Approximately one fourth of the U.S. adult populationnearly 50 million peoplehas hypertension (1, 2). Taking a broader perspective, more than half of the adult population has higher than optimal blood pressure (1), defined as systolic blood pressure greater than 120 mm Hg and diastolic blood pressure greater than 80 mm Hg (2). These persons are at significantly increased risk for cardiovascular disease and stroke (3). Although pharmacologic treatment for hypertension significantly reduces morbidity and mortality from cardiovascular diseases (4, 5), long-term pharmacologic therapy can have undesirable side effects and requires the expense of continuing medical supervision. Furthermore, pharmacologic therapy is not usually initiated when blood pressure is higher than optimal yet below diagnostic thresholds for hypertension. Thus, lifestyle interventions for primary prevention and initial treatment of high blood pressure remain a vital strategy for controlling this highly prevalent condition (2). Weight loss has been shown to reduce blood pressure in overweight hypertensive patients (6-9) and in overweight persons with high-normal blood pressure (10-12). Two reviews of randomized trials of weight reduction to reduce blood pressure examined the results of nine studies (13, 14). Most of these trials were small, only one had more than 500 participants (11), and most had short-term follow-up (1 year or less). Only three studies had follow-up of 3 to 5 years (8, 10, 11). Compared with controls, weight loss averaged nearly 7 kg in the short-term trials and approximately 3 kg in the three longer-term trials. In almost all trials, systolic blood pressure and diastolic blood pressure were reduced in the intervention groups. Since these reviews were published, the Trials of Hypertension Prevention (TOHP) Phase I reported mean weight reduction of 3.9 kg at 18 months in 564 overweight participants with high-normal blood pressure, resulting in significant decreases in systolic blood pressure and diastolic blood pressure compared with a usual care control group (12, 15). To investigate whether nonpharmacologic interventions can prevent hypertension over the long term, TOHP II was initiated. This was a randomized, controlled trial examining the effects of weight loss and dietary sodium reduction, alone and in combination, in reducing blood pressure in overweight adults with high-normal diastolic blood pressure (16). This target population is at high risk for hypertension as they age. The primary outcome paper from this trial (17) provided only a brief overview of the effects of weight loss on blood pressure. Here, we provide more detailed analysis of weight loss and blood pressure in TOHP II. Of special interest are the long-term effects of weight loss on blood pressure, the magnitude of the doseresponse relationship at 36 months, the effect of patterns of weight loss on blood pressure, and the predictors of weight loss and blood pressure response. Methods Participants Participants in TOHP II were overweight adults with nonmedicated diastolic blood pressure of 83 to 89 mm Hg and systolic blood pressure less than 140 mm Hg. Other eligibility criteria included age 30 to 54 years and a body mass index of 26.1 to 37.4 kg/m2 for men and 24.4 to 37.4 kg/m2 for women, approximately 110% to 165% of ideal weight (18). Principal exclusion criteria were current treatment with medications that might affect blood pressure, clinical or laboratory evidence of cardiovascular disease, diabetes mellitus, renal insufficiency (serum creatinine concentration 150 mol/L [ 1.7 mg/dL] for men and 132 mol/L [ 1.5 mg/dL] for women), and current or planned pregnancy. Detailed descriptions of recruitment and participant characteristics have been published elsewhere (19, 20). The study was reviewed and approved by the institutional review boards at all nine TOHP centers and the coordinating center, and all participants signed informed consent forms. Design Eligible participants were randomly assigned with equal probability to one of four groups: weight loss only, sodium reduction only, combined weight loss and sodium reduction, or usual care (controls). Measurements Age, sex, ethnicity, and years of education were obtained by questionnaire. Baseline blood pressure measurements were taken at three screening visits, each separated by 7 to 45 days. At each visit, three readings of systolic blood pressure and diastolic blood pressure were obtained and averaged. Certified staff obtained measurements in seated participants by using a Hawksley random-zero sphygmomanometer (21). Body weight was measured to the nearest 0.2 kg (0.5 lb) by using a calibrated balance-beam scale; participants wore indoor clothing (without shoes). Blood pressure and weight were measured every 6 months after randomization to the end of follow-up at 36, 42, or 48 months, depending on randomization date. Clinic staff who were blinded to study group assignment made these assessments. Blood pressure measurements were obtained during a single visit at all follow-up points except for 18 and 36 months, when measurements were taken at a series of three visits approximately 1 week apart. Multiple measurements were taken at 18 and 36 months to provide a more precise assessment of average blood pressures at these primary outcome points. Dietary intake was assessed by 24-hour recall, and physical activity was assessed by questionnaire. Intervention Participants assigned to the weight loss intervention group sought to lose at least 4.5 kg (10 lb) during the first 6 months of the intervention and to maintain their weight loss for the remainder of the trial. A brief description of the intervention methods is presented here; a more detailed description has been published elsewhere (22). The intervention started with an individual counseling session, followed by 14 weekly group meetings led by dietitians or health educators. After this 14-week intensive phase, participants attended six biweekly group meetings and then monthly group meetings. Beginning in the 18th month, participants were offered a variety of options to keep them involved in the intervention, including individual counseling sessions and special group sessions focused on selected weight loss topics. The intervention focused on self-directed behavior change (behavioral self-management), nutrition education, information on physical activity, and social support for making and maintaining behavior changes. Specific behavior change techniques included self-monitoring (food diaries and graphs of minutes of physical activity per day), setting explicit short-term goals and developing specific action plans to achieve those objectives, and developing alternative strategies for situations that trigger problem eating. The dietary intervention focused on reducing caloric intake by decreasing consumption of excess fat, sugar, and alcohol. Keeping daily food diaries was emphasized for monitoring intake and assessing progress. With experience, the participants determined the caloric intake that produced moderate weight loss for them. It was suggested that men not consume less than 1500 kcal/d and women not less than 1200 kcal/d. Weight loss of more than 0.9 kg (2 lb) per week was discouraged. The physical activity goal was to gradually increase activity to 30 to 45 minutes per day, four to five days per week. Exercise intensity was moderate, approximately 40% to 55% of heart rate reserve, and consisted primarily of brisk walking. Statistical Analysis Baseline characteristics of the weight loss and usual care groups were compared overall and by sex by using t-tests for means and chi-square tests for proportions. Although weight and blood pressure data were collected every 6 months, special efforts were made to achieve high follow-up rates at 18 and 36 months; at each of these two time points, nine blood pressure readings were collected over three visits and were averaged. For participants prescribed antihypertensive medication, follow-up blood pressure for all subsequent visits was taken to be the last study blood pressure before therapy was started. Participants receiving medications that affect blood pressure for reasons other than hypertension or who became pregnant were treated as missing at that visit. We used two-sample t-tests to compare changes in weight and blood pressure from baseline in the weight loss intervention and usual care groups overall, by sex, by ethnicity, and by sex and ethnicity. The effects of the intervention in terms of changes in weight and blood pressure were examined overall and in subgroups defined by sex, ethnicity, and sex and ethnicity. Subgroup differences were tested by using terms for the interaction of treatment group with sex and with ethnicity in multiple linear regression models. Regression analyses were also used to analyze the doseresponse relationship between change in weight and change in blood pressure, overall and within sex and ethnicity subgroups. Differences in dose response were tested by using interaction terms in linear regression models. All regressions were adjusted for age and baseline weight. We also adjusted for baseline blood pressure in the blood pressure regression models. Change in blood pressure was also examined in relation to quintile of weight loss. Quintiles were computed by using the distribution of weight change in the weight loss intervention group. Additional multiple regression analyses were performed in which weight loss participants were categorized according to patterns of weight loss at 6 and 36 months. The PROC MIXED function of SAS software (SAS Institute, Inc., Cary, North Carolina) was used to perform repeated-measures analyses that tested differences over time by pattern of weight loss. Cox proportional-hazards models were used for survival analyses, with onset of hypertension as the outcome. Results Baseline Findings The baseline characteristics of participants assigned to th

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 masters 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

Joint Effects of Sodium and Potassium Intake on Subsequent Cardiovascular Disease: The Trials of Hypertension Prevention Follow-up Study

BACKGROUND Previous studies of dose-response effects of usual sodium and potassium intake on subsequent cardiovascular disease (CVD) have largely relied on suboptimal measures of intake. METHODS Two trials of sodium reduction and other interventions collected 24-hour urinary excretions intermittently during 18 months from September 17, 1987, to January 12, 1990 (Trials of Hypertension Prevention [TOHP] I), and during 36 months from December 18, 1990, to April 7, 1995 (TOHP II), among adults with prehypertension aged 30 to 54 years. Among adults not assigned to an active sodium reduction intervention, we assessed the relationship of a mean of 3 to 7 twenty-four-hour urinary excretions of sodium and potassium and their ratio with subsequent CVD (stroke, myocardial infarction, coronary revascularization, or CVD mortality) through 10 to 15 years of posttrial follow-up. RESULTS Among 2974 participants, follow-up information was obtained on 2275 participants (76.5%), with 193 CVD events. After adjustment for baseline variables and lifestyle changes, there was a nonsignificant trend in CVD risk across sex-specific quartiles of urinary sodium excretion (rate ratio [RR] from lowest to highest, 1.00, 0.99, 1.16, and 1.20; P = .38 for trend) and potassium excretion (RR, 1.00, 0.94, 0.91, and 0.64; P = .08 for trend) but a significant trend across quartiles of the sodium to potassium excretion ratio (RR, 1.00, 0.84, 1.18, and 1.50; P = .04 for trend). In models containing both measures simultaneously, linear effects were as follows: RR, 1.42; 95% confidence interval (CI), 0.99 to 2.04 per 100 mmol/24 h of urinary sodium excretion (P = .05); and 0.67; 0.41 to 1.10 per 50 mmol/24 h of urinary potassium excretion (P = .12). A model containing the sodium to potassium excretion ratio (RR, 1.24; 95% CI, 1.05-1.46; P = .01) had the lowest Bayes information criterion (best fit). CONCLUSION A higher sodium to potassium excretion ratio is associated with increased risk of subsequent CVD, with an effect stronger than that of sodium or potassium alone.

Descriptive Characteristics of the Dietary Patterns Used in the Dietary Approaches to Stop Hypertension Trial

The Dietary Approaches to Stop Hypertension trial was a randomized, multicenter, controlled feeding study to compare the effect on blood pressure of 3 dietary patterns: control, fruits and vegetables, and combination diets. The patterns differed in selected nutrients hypothesized to alter blood pressure. This article examines the food-group structure and nutrient composition of the study diets and reports participant nutrient consumption during intervention. Participants consumed the control dietary pattern during a 3-week run-in period. They were then randomized either to continue on the control diet or to change to the fruits and vegetables or the combination diet for 8 weeks. Sodium intake and body weight were constant during the entire feeding period. Analysis of variance models compared the nutrient content of the 3 diets. Targeting a few nutrients thought to influence blood pressure resulted in diets that were profoundly different in their food-group and nutrient composition. The control and fruits and vegetables diets contained more oils, table fats, salad dressings, and red meats and were higher in saturated fat, total fat, and cholesterol than was the combination diet. The fruits and vegetables and combination diets contained relatively more servings of fruits, juices, vegetables, and nuts/seeds, and were higher in magnesium, potassium, and fiber than was the control diet. Both the fruits and vegetables and combination diets were low in sweets and sugar-containing drinks. The combination diet contained a greater variety of fruits, and its high calcium content was obtained by increasing low-fat dairy products. In addition, the distinct food grouping pattern across the 3 diets resulted in substantial differences in the levels of vitamins A, C, E, folate, B-6, and zinc.

Weight-loss experience of black and white participants in NHLBI-sponsored clinical trials.

We examined race-specific weight-loss results from two randomized, multicenter trials; the Hypertension Prevention Trial (HPT) and the Trials of Hypertension Prevention (TOHP). Mean weight change from baseline averaged 2.2 kg less in black women than in white women during 18 mo of follow-up in TOHP and 2.7 kg less during 36 mo of follow-up in HPT. Mean weight loss averaged 2.0 kg less in black than in white men in TOHP and 1.4 kg less in HPT. Because of greater weight gain in black control subjects, a comparison of net weight loss (change in intervention minus change in control participants, within-race) showed a less marked difference than did black-white differences in weight loss within the actively treated group. Thus, relative to weight that would have been gained without the intervention, the experience of blacks and whites was more similar. Racial differences in weight loss may result from a combination of behavioral, sociocultural, biological, and programmatic factors.

Individual Blood Pressure Responses to Changes in Salt Intake Results From the DASH-Sodium Trial

Abstract—Although group characteristics are known to influence average blood pressure response to changes in salt intake, predictability of individual responses is less clear. We examined variability and consistency of individual systolic blood pressure responses to changes in salt intake in 188 participants who ate the same diet at higher, medium, and lower (140, 104, 62 mmol/d) sodium levels for 30 days each, in random order, after 2 weeks of run-in at the higher sodium level. Regarding variability in systolic blood pressure changes over time, changes from run-in to higher sodium (no sodium level change) ranged from −24 to +25 mm Hg; 8.0% of participants decreased ≥10 mm Hg. Regarding variability in systolic blood pressure response to change in sodium intake, with higher versus lower sodium levels (78-mmol sodium difference), the range of systolic blood pressure change was −32 to +17 mm Hg; 33.5% decreased ≥10 mm Hg. Regarding consistency of response, systolic blood pressure change with run-in versus lower sodium was modestly correlated with systolic blood pressure change with higher versus medium sodium; systolic blood pressure change with higher versus lower sodium was similarly correlated with run-in versus medium sodium (combined Spearman r =0.27, P =0.002). These results show low-order consistency of response and confirm that identifying individuals as sodium responders is difficult. They support current recommendations for lower salt intake directed at the general public rather than “susceptible” individuals as one of several strategies to prevent and control adverse blood pressures widely prevalent in the adult population.

Validity and reliability of activity measures in African-American girls for GEMS.

PURPOSE To determine the reliability and validity of physical activity monitors and self-report instruments suitable for young African-American girls. METHODS A validation study was conducted by the Girls health Enrichment Multi-site Studies (GEMS) research team to compare an accelerometer with a pedometer and two self-report instruments for assessing physical activity in African-American girls, age 8-9 yr. Girls (N= 68) attended two clinic visits spaced 4 d apart. Each girl wore a MTI/CSA accelerometer (used as the criterion standard for validity) and a pedometer simultaneously for four consecutive days. Girls completed on two occasions a 24-h physical activity checklist of yesterday and usual activities, including sedentary activities (GEMS Activity Questionnaire, GAQ), and a 3-d computerized self-report instrument (Activitygram). RESULTS Girls were (mean +/- SD) 9.0 +/- 0.6 yr old and had a body mass index of 19.4 kg x m. Reliability measured by intraclass correlations (ICC) and Pearson correlation coefficients (r) were calculated for the MTI/CSA (ICC = 0.37, P< 0.0001), pedometer (ICC = 0.08, = 0.094), Activitygram (ICC = 0.24) (P = 0.005), and GAQ for physical (r = 0.80, P< 0.0001) and sedentary (r = 0.3-0.5, P< 0.005) activities. Significant Pearson correlations between the MTI/CSA and the other instruments, as a measure of validity, were observed for the 4-d average pedometer score (r = 0.47, P< 0.0001), 3-d average Activitygram score (r = 0.37, P= 0.002), and the average of the two yesterday and two usual GAQ activity scores for a subset of 18 physical activities questions (r = 0.27, = 0.03; and r = 0.29,P = 0.02, respectively). The MTI/CSA was uncorrelated with single day scores from the three other instruments. CONCLUSION The reliability of the instruments tested was acceptable, except the pedometer. Validity correlations were significant when more than one day was used. Self-report instruments need further development for improved reliability and validity.