Effect of lifestyle modifications on blood pressure by race, sex, hypertension status, and age

Recommendations for control of high blood pressure (BP) emphasize lifestyle modification, including weight loss, reduced sodium intake, increased physical activity, and limited alcohol consumption. The Dietary Approaches to Stop Hypertension (DASH) dietary pattern also lowers BP. The PREMIER randomized trial tested multicomponent lifestyle interventions on BP in demographic and clinical subgroups. Participants with above-optimal BP through stage 1 hypertension were randomized to an Advice Only group or one of two behavioural interventions that implement established recommendations (Est) or established recommendations plus DASH diet (Est plus DASH). The primary outcome was change in systolic BP at 6 months. The study population was 810 individuals with an average age of 50 years, 62% women, 34% African American (AA), 95% overweight/obese, and 38% hypertensive. Participants in all the three groups made lifestyle changes. Mean net reductions in systolic (S) BP in the Est intervention were 1.2 mmHg in AA women, 6.0 in AA men, 4.5 in non-AA women, and 4.2 in non-AA men. The mean effects of the Est Plus DASH intervention were 2.1, 4.6, 4.2, and 5.7 mmHg in the four race-sex subgroups, respectively. BP changes were consistently greater in hypertensives than in nonhypertensives, although interaction tests were nonsignificant. The Est intervention caused statistically significant BP reductions in individuals over and under age 50. The Est Plus DASH intervention lowered BP in both age groups, and significantly more so in older individuals. In conclusion, diverse groups of people can adopt multiple lifestyle changes that can lead to improved BP control and reduced CVD risk.

Comparing office-based and ambulatory blood pressure monitoring in clinical trials

Ambulatory blood pressure monitoring (ABPM) is commonly used in clinical trials. Yet, its ability to detect blood pressure (BP) change in comparison to multiple office-based measurements has received limited attention. We recorded ambulatory and five daily pairs of random zero (RZ) BPs pre- and post-intervention on 321 adult participants in the multicentre Dietary Approaches to Stop Hypertension trial. Treatment effect estimates measured by ambulatory monitoring were similar to those measured by RZ and did not differ significantly for waking vs 24-h ambulatory measurements. For systolic BP, the standard deviations of change in mean 24-h ambulatory BP (8.0 mmHg among hypertensives and 6.0 mmHg among nonhypertensives) were comparable to or lower than the corresponding standard deviations of change in RZ-BP based on five daily readings (8.9 and 5.9 mmHg). The standard deviations of change for mean waking ambulatory BP (8.7 and 6.7 mmHg) were comparable to those obtained using three to four daily RZ readings. Results for diastolic BP were qualitatively similar. Ambulatory monitoring was more efficient (ie, a smaller sample size could detect a given BP change) than three to four sets of daily RZ readings and required fewer clinic visits. The average of 33 ambulatory BP readings during the waking hours had an efficiency comparable to that from the mean of four daily pairs of RZ-BPs. Participants readily accepted the ABPM devices, and their use requires less staff training. ABPM provides a useful alternative to RZ-BP measurements in clinical trials.

Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. DASH-Sodium Collaborative Research Group

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 the DASH diet (P<0.01). The effects of sodium were observed in participants with and in those without hypertension, blacks and those of other races, and women and men. The DASH diet was associated with a significantly lower systolic blood pressure at each sodium level; and the difference was greater with high sodium levels than with low ones. As compared with the control diet with a high sodium level, the DASH diet with a low sodium level led to a mean systolic blood pressure that was 7.1 mm Hg lower in participants without hypertension, and 11.5 mm Hg lower in participants with hypertension.

CONCLUSIONS

The reduction of sodium intake to levels below the current recommendation of 100 mmol per day and the DASH diet both lower blood pressure substantially, with greater effects in combination than singly. Long-term health benefits will depend on the ability of people to make long-lasting dietary changes and the increased availability of lower-sodium foods.

The treadmill test--where to stop and what does it mean?

The prognostic utility of an exercise ECG test depends upon having an adequate workload to stress the cardiac system. A negative stress test, in which there are no adverse clinical or ECG findings, and in which an adequate workload is achieved, stratifies patients into a low-risk group. The 1997 American Heart Association guidelines imply that any index of workload--heart rate, rate-pressure product, or exercise duration in multiples of resting O2 consumption (METS)--could be used to indicate that adequate stress was achieved. However, while there is considerable evidence supporting the use of METS as a strong independent prognostic variable, there is less support for the use of rate-pressure product or heart rate. Indeed, there is evidence that a high heart rate at a low workload carries an adverse prognosis. Further research is needed to identify the number of METS achieved that would define an adequate workload. In the meantime, a review of the literature suggests that 7 to 10 METS is a reasonable ballpark figure of the minimum workload in patients with a negative stress test that would imply a favorable outcome.

Recruitment and retention of minority participants in the DASH controlled feeding trial. DASH Collaborative Research Group. Dietary Approaches to Stop Hypertension

The Dietary Approaches to Stop Hypertension (DASH) study was a National Heart, Lung, and Blood Institute multicenter trial that compared the impact of three dietary patterns on blood pressure (BP) among adults with high normal blood pressure or mild (Stage I) hypertension. DASH's high minority representation (two-thirds of the 459 randomized participants came from minority populations, and 60% of the cohort were African American) offered a valuable opportunity to assess factors affecting minority enrollment and retention in clinical trials of lifestyle modification. Recruitment strategies included targeted mailings to specific groups, mass mailings, community and worksite screenings, and mass media advertising; the four DASH clinical centers also reimbursed participants from $150 to $160. The most productive recruitment strategies tended to be mass mailings directed at a broad audience that was weighted toward, but not limited to, minority participants. DASH's African-American participants overwhelmingly (89%) cited health and dietary factors, such as learning more about blood pressure and healthy eating habits, as their primary reason for participating, while only six percent listed the financial incentives as their primary reason for participating. Eighty-eight percent of African-American respondents reported they would participate again in a similar study. The insights from DASH should help inform future efforts to recruit minority participants.

Inheritance and the pigmentary dispersion syndrome

The authors studied 33 patients in five families and have found that 14 of these patients fulfill criteria for the pigmentary dispersion syndrome. Affected patients had characteristics associated with the pigmentary dispersion syndrome, which are: peripheral slit-like iris transillumination defects, increased trabecular meshwork pigmentation, Krukenberg spindle, myopia, and elevated intraocular pressure. The authors observed this syndrome to be transmitted in a direct linear manner from parent to sibling in three of the four families. The transmission of this syndrome was found to be independent of refractive error, iris color, and sexual predilection, all of which are presented.

Inheritance and the pigmentary dispersion syndrome

We studied 23 patients in four families and have found that ten of these patients fulfill criteria for the pigmentary dispersion syndrome. Affected patients had characteristics associated with the pigmentary dispersion syndrome, which are: peripheral slit-like iris transillumination defects, increased trabecular meshwork pigmentation, Krukenberg spindle, myopia, and elevated intraocular pressure. We observed this syndrome to be transmitted in a direct linear manner from parent to sibling in three of the four families. The transmission of this syndrome was found to be independent of refractive error, iris color, and sexual predilection; all of which will be presented.