DASH effects for weight

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Hi All, The PDF is available for the below. apater@...

I noted that " it is worth focusing on weight, the risk factor most likely

contributing most to the patient's level of risk. Weight loss has many

benefits for obese and overweight individuals other than lowering blood

pressure. For normal-weight individuals with hypertension, the DASH diet

also may be beneficial.13 "

Cheers, Al. email:

Effects of Comprehensive Lifestyle Modification on Blood Pressure Control:

Main Results of the PREMIER Clinical Trial

Writing Group of the PREMIER Collaborative Research Group

JAMA 2003;289 2083-2093

ABSTRACT

Context Weight loss, sodium reduction, increased physical activity, and

limited alcohol

intake are established recommendations that reduce blood pressure (BP). The

Dietary

Approaches to Stop Hypertension (DASH) diet also lowers BP. To date, no

trial has

evaluated the effects of simultaneously implementing these lifestyle

recommendations.

Objective To determine the effect on BP of 2 multicomponent, behavioral

interventions.

Design, Setting, and Participants Randomized trial with enrollment at 4

clinical centers

(January 2000-June 2001) among 810 adults (mean [sD] age, 50 [8.9] years;

62% women;

34% African American) with above-optimal BP, including stage 1 hypertension

(120-159 mm

Hg systolic and 80-95 mm Hg diastolic), and who were not taking

antihypertensive

medications.

Intervention Participants were randomized to one of 3 intervention groups:

(1) " established, " a behavioral

intervention that implemented established recommendations (n = 268); (2)

" established plus DASH, " which also

implemented the DASH diet (n = 269); and (3) an " advice only " comparison

group (n = 273).

Main Outcome Measures Blood pressure measurement and hypertension status at

6 months.

Results Both behavioral interventions significantly reduced weight,

improved fitness, and lowered sodium

intake. The established plus DASH intervention also increased fruit,

vegetable, and dairy intake. Across the

groups, gradients in BP and hypertensive status were evident. After

subtracting change in advice only, the

mean net reduction in systolic BP was 3.7 mm Hg (P<.001) in the established

group and 4.3 mm Hg (P<.001) in

the established plus DASH group; the systolic BP difference between the

established and established plus DASH

groups was 0.6 mm Hg (P = .43). Compared with the baseline hypertension

prevalence of 38%, the prevalence

at 6 months was 26% in the advice only group, 17% in the established group

(P = .01 compared with the advice

only group), and 12% in the established plus DASH group (P<.001 compared

with the advice only group; P = .12

compared with the established group). The prevalence of optimal BP (<120 mm

Hg systolic and <80 mm Hg

diastolic) was 19% in the advice only group, 30% in the established group (P

= .005 compared with the advice

only group), and 35% in the established plus DASH group (P<.001 compared

with the advice only group; P = .24

compared with the established group).

Conclusion Individuals with above-optimal BP, including stage 1

hypertension, can make multiple lifestyle

changes that lower BP and reduce their cardiovascular disease risk.

]Weight decreased 1.1% in usual advice, 4.9 with Dash + usual advice and 5.8

with both.]

Vol. 289 No. 16, April 23, 2003

Editorial

Lifestyle Modification and Blood Pressure Control

Is the Glass Half Full or Half Empty?

G. Pickering, MD, DPhil

JAMA. 2003;289:2131-2132.

The idea that lifestyle modifications can ameliorate mild hypertension has

been popular for

many years and was given a huge boost by the publications of results

obtained with the

Dietary Approaches to Stop Hypertension (DASH) diet.1-2 At last, there was

convincing

evidence that a nondrug form of treatment could reduce blood pressure

(averaging

decreases of 11.4/5.5 mm Hg in hypertensive patients and 5.5/3.0 mm Hg in

those with

borderline blood pressure) as much as some drugs.1 A second study (DASH

Sodium)

combined the DASH diet with sodium restriction and reported a blood pressure

reduction of

5.9/2.9 mm Hg with the DASH diet in patients with borderline hypertension

and 8.9/4.5 mm

Hg with a combination of the DASH diet and sodium restriction.2 In a

subsequent study, the Diet, Exercise, and

Weight Loss-Intervention Trial (DEW-IT),3 overweight hypertensive

individuals who had been treated with drugs

reported a net change of 9.5/5.3 mm Hg in ambulatory pressure and 7.4/5.7 mm

Hg in clinic pressure using a

low-calorie version of the DASH diet in combination with weight loss.

Now, a fourth study (PREMIER), reported in this issue of THE JOURNAL by the

Writing Group of the PREMIER

Collaborative Research Group,4 has investigated the effects of combining the

DASH diet with " established "

recommendations, comprising weight loss, exercise, and restriction of sodium

and alcohol. Since all these

interventions have been shown to lower blood pressure individually, it might

be anticipated that the effects of

combined interventions on blood pressure would be additive. In actuality,

the net changes (blood pressure

change from baseline to 6 months in each treatment group minus that in the

advice only group) were smaller

than expected. In the group assigned to lifestyle modification only, the

established group, the mean net

reduction in blood pressure was 3.7/1.7 mm Hg, whereas for the group that

followed the established

recommendations together with the DASH diet, the net mean blood pressure was

reduced by 4.3/2.6 mm Hg.

Thus, the addition of the DASH diet in the PREMIER trial produced an

incremental decrease of blood pressure of

only 0.6/0.9 mm Hg (1.7/1.6 mm Hg in the individuals with hypertension).

What happened?

Several explanations need to be considered. Patients in the PREMIER study

were not following the DASH diet as

closely as in the 3 earlier DASH studies, in which the participants were

provided with prepared meals. PREMIER is

the first study to intentionally investigate the effects of the DASH diet

when patients actually purchased their

own food. Thus, in the original DASH study, patients were provided with an

average of 9.6 daily servings of

fruits and vegetables, whereas in PREMIER, the intake increased from 4.8

servings at baseline to 7.8 servings.

In the original DASH study, urine potassium increased by 105% with the

change of diet, whereas in the

combined group in the PREMIER study, it increased by only 28%. The same

explanation could account for the

results of the DASH Sodium study, in which the effects of sodium restriction

(a reduction of blood pressure of

6.7/3.5 mm Hg) greatly exceeded the changes observed in almost all other

studies in which participants

prepared their own low-salt meals.

Another possibility is that the beneficial effects of the interventions were

masked by parallel reductions of blood

pressure in the control group. In the PREMIER study, the control group was

given advice on diet and lifestyle

changes in a single 30-minute session, but they showed a fairly large

absolute decrease in blood pressure

(absolute change from baseline to 6 months of 6.6/3.8 mm Hg, compared with

absolute changes of 10.5/5.5 mm

Hg in the established group and 11.1/6.4 mm Hg in the established plus DASH

group). In the original DASH

study, patients consuming the control diet showed no significant change of

blood pressure.1 Likewise, in the

DEW-IT study, the control group showed no change of ambulatory blood

pressure.3 However, potential

similarities in diet and lifestyle would not explain the lack of effect of

adding the DASH diet.

Yet another potential explanation is what the authors term " subadditivity of

intervention effects, " ie, the

combination of 2 or more interventions has a smaller effect on blood

pressure than the sum of the effects of the

individual interventions. In the DEW-IT study, in which obese hypertensive

patients were given a hypocaloric

DASH diet, the net reduction of clinic blood pressure was 7.4/5.7 mm Hg,

comparable to the effects of the

DASH diet alone. However, these patients lost 5.5 kg of body weight, which

might have been expected to result

in a further blood pressure decrease of around 6/5.5 mm Hg (the decrease

reported in the Trials of Hypertension

II [TOHP II] study, in which the weight loss was 4.4 kg).5 In the TOHP II

study, the effect of adding sodium

restriction to weight loss produced no further decrease of blood pressure,

even though sodium restriction alone

produced a modest but significant decrease. Similarly, in the DASH Sodium

study, the combined effects of the

DASH diet and sodium restriction were less than the effects of either

intervention on its own.2 So far,

therefore, no study has demonstrated any additive effect of combining

lifestyle interventions on blood pressure.

Why should this be so? Two possibilities must be considered. First, it may

be that most individuals are not

capable of changing more than 1 lifestyle factor at a time. This explanation

does not hold up, however. The

TOHP II study had 3 groups: weight loss, sodium restriction, and both in

combination. The decreases of body

weight and sodium excretion were only marginally less in the combined group

than in the 2 individual

intervention groups, but the reduction of blood pressure was no greater than

with weight loss alone.6 Since the

DASH Sodium trial was a feeding study it seems unlikely that the

participants were not consuming the diets they

were prescribed, an observation verified by measuring urinary excretion of

key minerals.

A second possibility is that the different lifestyle interventions may act

through the same physiological

mechanism, and that as with antihypertensive drugs, the dose-response

relationship is nonlinear. For most

drugs, doubling the dose produces only a small further decrement of blood

pressure.7 In contrast, combining 2

different drugs often has an additive effect,8 unless the 2 drugs have a

similar mechanism of action. Thus,

adding a diuretic to the treatment of patients whose blood pressure is not

controlled with a combination of

amlodipine and lisinopril is more effective than adding a -blocker.9

Unfortunately, relatively little is known about

the mechanisms by which lifestyle factors such as obesity increase blood

pressure.10-11

Perhaps the most important issue is how these new findings should be

interpreted and put into practice. While it

is often stated that nondrug treatment is less expensive and has fewer

adverse effects than drug treatment,

this is not necessarily the case. Interventions such as those studied in the

PREMIER trial require numerous

counseling sessions to achieve their results and are not feasible in

everyday practice. Nevertheless, for

whatever reason, the advice only group in the PREMIER trial did have a

substantial decrease in blood pressure.

Physicians should certainly continue to counsel patients using the type of

advice provided to the advice only

group of the PREMIER study and advocated in the sixth report of the Joint

National Committee on Detection,

Evaluation, and Treatment of High Blood Pressure (JNC VI).12 Beyond this, it

is worth focusing on weight, the

risk factor most likely contributing most to the patient's level of risk.

Weight loss has many benefits for obese

and overweight individuals other than lowering blood pressure. For

normal-weight individuals with hypertension,

the DASH diet also may be beneficial.13

Based on studies such as DASH, DEW-IT, and now PREMIER, clinicians should

consider that the glass (or

perhaps the plate) is indeed " half-full " when it comes to the potential

benefit of promoting lifestyle changes for

patients with hypertension.

REFERENCES

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2. Sacks FM, Svetkey LP, Vollmer WM, et al, for the DASH-Sodium

Collaborative Research Group. Effects on

blood pressure of reduced dietary sodium and the Dietary Approaches to Stop

Hypertension (DASH) diet. N Engl

J Med. 2001;344:3-10. ABSTRACT/FULL TEXT

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comprehensive lifestyle modification

on blood pressure control: main results of the PREMIER clinical trial. JAMA.

2003;289:2083-2093.

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Med. 1997;157:657-667. ABSTRACT

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lisinopril. Hypertension.

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Detection, Evaluation, and Treatment of

High Blood Pressure. Arch Intern Med. 1997;157:2413-2446. ABSTRACT

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Hypertension: Lower Your Blood

Pressure in 14 Days—Without Drugs. New York, NY: Free Press; 2001.