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.
High blood pressure (BP) is a common, powerful, and independent risk
factor for cardiovascular disease (CVD). Almost 50 million US adults, or approximately
25% of the US adult population, have hypertension, defined as BP of 140/90
mm Hg or higher and/or current use of antihypertensive medication.1 The prevalence of hypertension increases progressively
with age, so that more than half of all individuals aged 60 years or older
in the United States have hypertension.2 The
estimated lifetime risk of developing hypertension is 90%.3
Above-optimal BP that is not in the hypertensive range also confers
excess CVD risk.4 In fact, almost a third of
BP-related deaths from coronary heart disease are estimated to occur in nonhypertensive
individuals with a systolic BP of 120 to 139 mm Hg or diastolic BP of 80 to
89 mm Hg.5 Therefore, reduction of BP to optimal
levels, control of hypertension, and prevention of the age-related increase
in BP remain major public health priorities.
Current national recommendations for the prevention and treatment of
high BP emphasize nonpharmacological therapy, also termed "lifestyle modification."6,7 Lifestyle modifications that effectively
lower BP are weight loss, reduced sodium intake, increased physical activity,
limited alcohol consumption, and the Dietary Approaches to Stop Hypertension
(DASH) diet.6-8 The
DASH diet emphasizes consumption of fruits, vegetables, and low-fat dairy
products; includes whole grains, poultry, fish, and nuts; and is reduced in
fats, red meat, sweets, and sugar-containing beverages. As such, the DASH
diet has reduced levels of total fat, saturated fat, and cholesterol and increased
levels of potassium, calcium, magnesium, fiber, and protein.9
These lifestyle modifications are recommended in nonhypertensive individuals
with above-optimal BP. Lifestyle modification is also recommended as initial
therapy in stage 1 hypertension (for up to 12 months in those without other
risk factors [risk class A] or for up to 6 months in those with other risk
factors [risk class B]).7 For individuals taking
BP medication, lifestyle modification is recommended as adjunctive therapy
to lower BP. Although lifestyle therapies are generally recommended as a group,
no previous trial has evaluated the effects of implementing these recommendations
simultaneously, and no trial has tested the feasibility of implementing the
DASH diet in free-living persons.
The rationale for the PREMIER clinical trial10 has
been published. Participating institutions included the National Heart, Lung,
and Blood Institute Project Office (Bethesda, Md), the coordinating center
(Kaiser Permanente Center for Health Research in Portland, Ore), and 4 clinical
centers (Johns Hopkins University, Baltimore, Md; Pennington Biomedical Research
Center, Baton Rouge, La; Duke University Medical Center, Durham, NC; and Kaiser
Permanente Center for Health Research, Portland, Ore). Institutional review
boards at each center and an external protocol review committee approved the
protocol. Each participant provided written consent.
The target population consisted of generally healthy adults with above
optimal BP including individuals with stage 1 hypertension who met Joint National
Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC-VI)
criteria for at least a 6-month trial of nonpharmacological therapy.7 Persons were eligible if they were not taking antihypertensive
medication and had a systolic BP of 120 to 159 mm Hg and diastolic BP of 80
to 95 mm Hg, based on the mean BP across 3 screening visits. Nonhypertensive
individuals with above optimal BP (120-139 mm Hg systolic and/or 80-89 mm
Hg diastolic) were included because of the potential for preventing hypertension
and the excess CVD risk associated with BP in this range.4 Individuals
with stage 1 hypertension (140-159 mm Hg systolic and/or 90-95 mm Hg diastolic)
were included because of the potential for nonpharmacological control of hypertension.
Other inclusion criteria were 25 years of age or older and body mass
index (BMI) of 18.5 to 45.0 (measured as weight in kilograms divided by the
height in meters squared). Major exclusion criteria were regular use of drugs
that affect BP, JNC-VI risk category C (target organ damage and/or diabetes),
use of weight-loss medications, prior cardiovascular event, congestive heart
failure, angina, cancer diagnosis or treatment in past 2 years, consumption
of more than 21 alcoholic drinks per week, and pregnancy, planned pregnancy,
or lactation. Although individuals with diabetes were excluded, persons with
other cardiovascular risk factors (ie, cigarette smoking and dyslipidemia)
could enroll. Vitamin and mineral supplement use was not an exclusion.
Participants were recruited using mass mailings, community-based screening,
and mass-media announcements. Enrollment began in January 2000 and ended in
June 2001. For logistical purposes, participants were enrolled in 3 or 4 cohorts
at each center. Baseline data were collected during 3 screening visits and
a randomization visit, each scheduled at least 7 days apart. Follow-up data
were collected at 1 visit 3 months after randomization and at 3 visits 6 months
after randomization. Participant flow during the trial is shown in Figure 1.
Randomization assignments were made centrally by a computer program.
Clinical center staff then notified participants of their assigned group.
Assignments were stratified by clinic and hypertension status; the randomization
block size was 24. Eligible participants were randomly assigned to 1 of 3
groups: (1) an "advice only" comparison group; (2) a behavioral intervention,
termed "established" that implemented traditional lifestyle recommendations,11 ie, weight loss among those who were overweight,
reduced sodium intake, increased physical activity, and limited alcohol intake
among those who drank alcohol; or (3) a behavioral intervention, termed "established
plus DASH" that implemented the same traditional recommendations plus the
DASH diet.7
An interventionist, typically a registered dietitian, discussed nonpharmacological
factors that affect BP (weight, sodium intake, physical activity, and the
DASH diet) and provided printed educational materials. This advice was provided
in a single 30-minute individual session immediately following randomization.
Counseling on behavior change was not provided. No further contact with the
interventionist occurred until after completion of the data collection visits
at 6 months.
Participant goals for both the established and established plus DASH
interventions were as follows: (1) weight loss of at least 15 lb (6.8 kg)
at 6 months for those with a BMI of at least 25, (2) at least 180 min/wk of
moderate-intensity physical activity, (3) daily intake of no more than 100
mEq of dietary sodium, and (4) daily intake of 1 oz or less of alcohol (2
drinks) for men and ½ oz of alcohol (1 drink) for women.
The established and the established plus DASH interventions differed
from each other with respect to certain dietary goals and the strategies to
achieve weight loss. Only the participants in the established plus DASH intervention
received instruction and counseling on the DASH diet. In this intervention,
participant goals designed to accomplish the DASH diet were increased consumption
of fruits and vegetables (9-12 servings/d) and low-fat dairy products (2-3
servings/d), and reduced intake of saturated fat (≤7% of energy) and total
fat (≤25% of energy). The established intervention did not have goals for
fruit, vegetable, or dairy intake; the goal for saturated fat was 10% of energy
or less, and the goal for total fat was 30% of energy or less. To achieve
weight loss, both interventions emphasized increased physical activity and
reduced total energy intake; in addition to these strategies, the established
plus DASH intervention also emphasized substitution of fruits and vegetables
for high-fat, high-calorie foods.
The format and contact pattern of the established and established plus
DASH interventions were identical. During the initial 6 months, there were
18 face-to-face intervention contacts (14 group meetings and 4 individual
counseling sessions). Participants in both interventions kept food diaries,
recorded physical activity, and monitored calorie and sodium intake. Participants
in the established plus DASH group also monitored intake of fruits, vegetables,
and dairy products and monitored their intake of fat.
Staff who were masked to randomization assignment collected measurements.
Blood pressure measurements were obtained by trained, certified individuals
who used a random zero sphygmomanometer. The BP measurement protocol was similar
to protocols used in prior studies.12,13 After
the participant sat quietly for 5 minutes, the observer measured BP in the
right arm with an appropriately sized cuff. At each visit, 2 BP measurements
separated by at least 30 seconds were obtained. Systolic BP was the appearance
of the first Korotkoff sound, and diastolic BP was the disappearance of Korotkoff
sounds. At each assessment point, BP was the mean of all available measurements
(baseline [8 BP measurements across 4 visits], 3-month assessment [2 BP measurements
at 1 visit], and 6-month assessment [6 BP measurements across 3 visits]).
Weight was measured using a calibrated scale, and height was measured
using a wall-mounted stadiometer. Other data included the Rose Angina questionnaire14; a medication questionnaire; a symptoms/adverse effects
questionnaire; 24-hour urine collections for sodium, potassium, phosphorus,
and urea nitrogen; submaximal treadmill tests; waist circumference; 24-hour
dietary recalls; fasting blood analysis; and 7-day physical activity recalls.
Each of these measurements was obtained at baseline and 6 months after randomization.
Intake of nutrients and food groups was assessed from unannounced 24-hour
dietary recalls conducted by telephone interviewers.15 Two
recalls (one obtained on a weekday and the other on a weekend day) were obtained
at baseline and 6 months by the Diet Assessment Center of Pennsylvania State
University. Nutrient and food group intakes were then calculated using the
Nutrition Data System Version NDS-R 1998 (University of Minnesota). Biomarkers
of dietary intake were 24-hour urinary excretion of sodium, potassium (reflecting
fruit and vegetable intake), phosphorus (reflecting dairy intake), and urea
nitrogen (reflecting protein intake). Alcohol intake was obtained from questionnaire.
Cardiorespiratory fitness was assessed using a submaximal treadmill
exercise test developed for the PREMIER trial. This 2-stage, 10-minute protocol
was designed to achieve an age- and sex-specific effort of moderate intensity.16 The first stage achieved a light-intensity effort
(approximately 40% estimated maximal metabolic equivalents [METs]), followed
by a second stage of moderate intensity (approximately 60% estimated maximal
METs). The main fitness outcome was heart rate at the end of stage 2 or the
last available heart rate from stage 1 for participants who did not complete
stage 2. A 7-day physical activity recall was used to assess physical activity.17 Participants who reported 35 kcal/kg or less daily
of physical activity were classified as sedentary.18
Specific Aims and Outcomes
The specific aims of the trial were to test the effects of the established
intervention compared with the advice only intervention; the effects of the
established plus DASH intervention compared with the advice only intervention;
and the effects of the established plus DASH intervention compared with the
established intervention. The primary outcome was change in systolic BP from
baseline to 6 months. Hypertension status and change in diastolic BP at 6
months were secondary outcomes. Blood pressure measurements were censored
if the participant reported taking any antihypertensive medication or other
medications known to have major BP effects (eg, oral steroids). Hypertension
was defined as a mean BP of 140/90 mm Hg or higher or use of antihypertensive
medication.
Although the intervention programs lasted 18 months, the protocol-specified,
primary outcome assessment occurred at 6 months because national guidelines
recommend that individuals with persistent BP of 140/90 mm Hg or higher after
a period of lifestyle modification be referred for medication treatment.7 During the design of the trial, we anticipated that
approximately 30% of participants would have stage 1 hypertension at baseline.10 Hence, we expected that a large number of individuals
would need to be referred for medication treatment at 6 months, requiring
censoring of their BP data, and that medication treatment would occur differentially
across the 3 randomized groups. Defining the primary outcome at 6 months reduced
the risk of bias and ensured that we would have a maximum number of BP measurements
for analysis.
Blood pressure data were analyzed using a linear regression model in
which change in BP (mean 6-month value − mean baseline) was regressed
on indicators of the 2 behavioral interventions, indicators of clinical center
and cohort, and baseline BP. In prespecified subgroup analyses (hypertensive
and nonhypertensive), the models also included a main effect for the subgroup
indicator and interactions between this indicator and the 2 treatment group
indicators. The effects of the interventions did not differ by clinical center
(P = .62 for center × treatment interaction
for systolic BP and P = .54 for diastolic BP).
Primary analyses of BP change are based on intention to treat. For individuals
without BP at the 6-month assessment and for those who had been taking antihypertensive
medication, 3-month BP measurements were carried forward; if a 3-month BP
measurement was unavailable, values were imputed using a "hot deck" procedure
that drew values from participants in the advice only group.19 We
also conducted post-hoc "on treatment" analyses limited to those participants
in the established and established plus DASH groups who attended at least
15 intervention sessions.
For all other variables, including hypertension status, we used available
data and did not impute values for missing data. To analyze continuous indicators
of intervention effects, such as change in body weight, we used a similar
analytic model. We used the Mantel-Haenszel χ2 test for 2 ×
2 tables to compare the proportion of individuals meeting intervention targets
at 6 months.20 Because the focus of these analyses
was the proportion actually meeting target at 6 months in each group and not
necessarily the change from baseline status, these analyses did not condition
on initial status.
Hypertension status at 6 months was assessed separately for those who
were and were not hypertensive at baseline, reflecting persistent and incident
hypertension, respectively. We also compared the prevalence of hypertension
in all participants. Pairwise differences in the incidence, persistence, and
overall prevalence of hypertension between treatment groups were also assessed
using the Mantel-Haenszel test.20
Based on a planned sample size of 800 (267 per group), the study had
90% power to detect pairwise between-group differences in systolic BP of 1.6
to 1.8 mm Hg in the whole sample, 3.2 to 3.6 mm Hg among hypertensive participants
(assuming that 30% of the individuals in the sample were hypertensive), and
1.7 to 1.9 mm Hg among nonhypertensive participants.
All analyses were performed using SAS version 8 (SAS Institute Inc,
Cary, NC). Nominal P values are presented. For a
given outcome, we only considered the pairwise contrasts vs the advice only
intervention to be significantly different if at least one of them achieved
a P value of <.025; in that case, the other contrast
with advice only and the contrast between the established and established
plus DASH interventions were evaluated at the .05 level.21
A total of 810 participants were enrolled in the trial (Figure 1). Baseline characteristics were similar in the randomized
groups (Table 1). The mean (SD)
age was 50.0 (8.9) years, 62% were women, and 34% were African Americans.
Of the 279 African Americans, 74% were women. The participants were generally
overweight and sedentary. Mean (SD) systolic and diastolic BP were 134.9 (9.6)
and 84.8 (4.2) mm Hg. Among the 38% of participants with hypertension, mean
(SD) systolic and diastolic BP were 143.9 (7.6) and 87.5 (4.3) mm Hg; corresponding
BP measurements in the nonhypertensive participants were 129.5 (5.8) and 83.2
(3.1) mm Hg. Six months after randomization, 94% of participants had their
BP measured at 1 or more visits; 87% attended all 3 visits.
Intervention Attendance and Effects
Of the 18 intervention sessions offered during the intial 6 months,
70% of participants in the established group attended at least 15 sessions;
just 8% attended 5 sessions or less. In the established plus DASH group, corresponding
data were 78% and 7%. Mean (SD) attendance was 14.5 (4.5) and 15.4 (4.4) sessions,
respectively.
Differences in weight, physical fitness, and diet among the randomized
groups were achieved. Table 2 displays
intervention outcomes, and Table 3 lists
the number of individuals who reached the intervention goals. Weight loss
occurred in each group, including the advice only group. While changes in
physical activity did not differ among the groups, fitness significantly improved
in both behavioral interventions. Alcohol intake was low and did not change
in any group.
Mean reductions in urinary sodium excretion occurred in both behavioral
interventions, but only the reduction in the established group differed significantly
from that of advice only group. However, in both behavioral intervention groups,
the percentage of individuals who achieved the trial goal of less than 100
mEq/d differed significantly from the advice only group (Table 3). Also, based on 24-hour dietary recall data, both behavioral
interventions significantly reduced sodium intake in comparison with the advice
only group (data not shown).
In the established plus DASH group, fruit and vegetable intake increased
significantly compared with the other 2 groups; parallel changes in urinary
potassium excretion occurred. One third of participants in the established
plus DASH group, but only 6% of participants in the other 2 groups, consumed
the goal of 9 or more servings of fruits and vegetables per day at 6 months.
Compared with the advice only and established groups, consumption of dairy
products increased significantly in the established plus DASH group as did
dietary calcium intake and net urinary phosphorus excretion. The percentage
of established plus DASH participants who consumed 2 or more dairy servings
was 59%. Saturated and total fat consumption significantly decreased in both
intervention groups.
Blood pressure declined progressively over time in each group (Figure 2). From baseline to 6 months, mean
(SD) reductions in systolic BP were 6.6 (9.2) mm Hg in the advice only group,
10.5 (10.1) mm Hg in the established group, and 11.1 (9.9) mm Hg in the established
plus DASH diet group. Corresponding diastolic BP reductions were 3.8 (6.3),
5.5 (6.7), and 6.4 (6.8) mm Hg, respectively. In hypertensive participants,
mean (SD) reductions in systolic BP were 7.8 (10.3), 12.5 (11.5), and 14.2
(10.1) mm Hg, and mean (SD) reductions in diastolic BP were 3.8 (7.1), 5.8
(7.0), and 7.4 (7.1) mm Hg, respectively. In nonhypertensive participants,
mean (SD) reductions in systolic BP were 5.8 (8.4), 9.4 (9.1), and 9.2 (9.3)
mm Hg, and mean (SD) reductions in diastolic BP were 3.8 (5.8), 5.3 (6.5),
and 5.8 (6.6) mm Hg, respectively.
Table 4 displays pairwise
differences in BP. In all participants, nonhypertensive participants, and
hypertensive participants, the established and established plus DASH interventions
significantly reduced systolic and diastolic BP in comparison with the advice
only group. Although BP change in the established plus DASH group was consistently
greater than corresponding BP change in the established group, none of the
pairwise differences was statistically significant.
The pattern of results was similar in the "on treatment" analyses, which
included those individuals in the established and established plus DASH groups
(70% and 78% of participants, respectively) who attended more than 15 intervention
sessions. For contrasts with the advice only group, BP reductions in the on
treatment analyses were approximately 20% to 40% greater than corresponding
reductions in the intention to treat analyses.
Figure 3 displays the percentage
of nonhypertensive participants who became hypertensive, the percentage of
hypertensive participants who remained hypertensive, and the percentage of
all participants who were hypertensive at 6 months. In each instance, there
was a gradient in hypertensive status across the 3 groups. The lowest prevalence
of hypertension (12%) occurred in the established plus DASH group; this prevalence
corresponds to a 53% risk reduction (ie, 1 – relative risk) compared
with the advice only group. By 6 months, antihypertensive medication had been
started in 19 participants in the advice only group, 2 participants in the
established group, and 5 participants in the established plus DASH group.
The established and established plus DASH groups significantly increased the
percentage of individuals who achieved an optimal BP (<120 mm Hg systolic
and <80 mm Hg diastolic; Figure 4).
A serious musculoskeletal injury occurred in 20 participants in the
advice only group, 17 in the established group, and 16 in the established
plus DASH group. One stroke, 1 transient ischemic attack, and 1 myocardial
infarction occurred in the advice only group. No cardiovascular event occurred
in the established group, and 1 myocardial infarction occurred in the established
plus DASH group.
The PREMIER trial documented that individuals with above-optimal BP,
including stage 1 hypertension, can make multiple lifestyle changes that lower
BP and control hypertension. Both of the PREMIER behavioral interventions
accomplished substantial weight loss, reduced sodium intake, and increased
physical fitness. Individuals assigned to the established plus DASH intervention
also made dietary changes consistent with the DASH diet, ie, increased their
intake of fruits, vegetables, and dairy products. In aggregate, these lifestyle
changes should substantially lower the risk of CVD as well as the risk of
other chronic diseases, including diabetes, osteoporosis, and perhaps cancer.
Trial participants were demographically heterogeneous. More than 50%
were women, and more than 30% were African American. The distributions of
educational attainment and household income were broad, but slightly skewed
toward persons with higher education and income. The BP inclusion criteria
of PREMIER would include approximately 50% of US adults. These aspects of
the study suggest that trial results should be applicable to a large portion
of the US population.
Markers of adherence, including several objective measurements, confirmed
that participants in the behavioral interventions made lifestyle changes.
Each behavioral intervention led to substantial weight loss as well as increased
fitness. The reduced heart rate on the treadmill test, an objective measure
of improved fitness, suggests that participants increased their physical activity,
even though self-reported physical activity as measured by 7-day physical
activity recalls did not change significantly. Both behavioral interventions
significantly reduced sodium intake, although not to the same extent as behavioral
interventions that focused exclusively on this factor.12,13,22 The
established plus DASH intervention also increased consumption of fruits, vegetables,
and dairy products; analyses of urinary potassium and phosphorus were consistent
with data from the 24-hour dietary recalls.
Across the 3 groups, gradients in BP and hypertensive status were evident.
The smallest BP reduction occurred in the advice only group, while the greatest
BP reduction occurred in the established plus DASH group. Hypertension control
was most successful in the established plus DASH group, in which 77% of individuals
with stage 1 hypertension at baseline had a systolic BP of less than 140 mm
Hg and a diastolic BP of less than 90 mm Hg at 6 months. In the established
group, the corresponding figure was 66%. These rates compare favorably with
survey data2 and trial data,23 in
which drug therapy controls BP in approximately half of hypertensive individuals.
Hence, these behavioral interventions should be viable treatment options,
at least among those hypertensive individuals who are motivated to make lifestyle
changes.
The established and established plus DASH interventions also reduced
BP in nonhypertensive individuals with above-optimal BP. Specifically, an
optimal BP level (<120 mm Hg systolic and <80 mm Hg diastolic) was achieved
in 40% and 48% of participants assigned to these 2 interventions, respectively.
Overall, this pattern of findings suggests that even in the context of other
effective lifestyle modifications, adoption of the DASH diet further improves
BP control.
Still, the BP effects attributed to the DASH diet, specifically the
BP differences between the established plus DASH and the established interventions,
were less than previously found in the DASH feeding studies,8,24 and
none of the contrasts in hypertension status was statistically significant.
One potential reason is that participants received an inadequate "dose" of
the DASH diet. For instance, even though mean fruit and vegetable intake increased
from 4.8 to 7.8 servings per day in the established plus DASH intervention,
the latter is below what was provided in the DASH feeding studies, namely,
9.6 servings per day.
Another plausible reason is subadditivity of intervention effects. Specifically,
the net BP effect of the DASH diet in the PREMIER trial likely underestimates
the BP effects of the DASH diet if it were implemented alone.8,25 It
has been well documented that the combined effect of an intervention that
implements 2 or more BP-reducing components is less than the sum of BP reductions
from interventions that implement each component alone. Subadditivity can
occur from reduced adherence13 because of the
effort and complexity of making more than 1 lifestyle change. For example,
participants in the established plus DASH intervention were advised to increase
their intake of dairy products while reducing total caloric intake. Still,
even in the setting of high adherence, such as feeding studies, subadditivity
occurs.24
The advice only comparison group in the PREMIER trial likely accomplished
some lifestyle modifications. Such behavior changes might have resulted from
recruitment of motivated participants; secular trends (eg, growing awareness
of the obesity epidemic); the 30-minute intervention session postrandomization;
and the multiple, regular data collection visits and contacts (4 visits and
2 dietary recalls at baseline; 1 visit at 3 months and 3 visits at 6 months,
along with telephone calls and reminders). Although before-after changes must
be interpreted cautiously, the weight loss of 1.1 kg at 6 months in this group
exceeded what has occurred in other trials, which have often reported weight
gain in the control group.13 Also, the 20-mEq
reduction in sodium excretion may reflect efforts to lower salt intake. Such
modest changes in behavior might have reduced BP in this group, thereby attenuating
the pairwise differences in BP between the advice only group and the 2 behavioral
interventions. In fact, the within-group BP reductions observed in the advice
only group (systolic BP reduction of 6.6 mm Hg and diastolic BP reduction
of 3.8 mm Hg) greatly exceed what was observed in the control groups of other
studies.8,12,13,22
In the PREMIER trial, the primary outcome variables were collected at
6 months postrandomization. The inclusion of hypertensive individuals in the
PREMIER trial precluded use of BP measured at a later follow-up visit as the
primary outcome because national guidelines recommend initiation of drug therapy
for individuals with Class B hypertension who remain hypertensive after a
6-month period of nondrug therapy.7 Still,
evidence from clinical trials suggests that as long as adherence is sustained,
BP effects persist.26,27 Also,
in longitudinal observational studies, healthy dietary patterns indicative
of long-term habits are associated with reduced CVD28,29 and
mortality.30
In addition to hypertension, high-normal BP is also associated with
excess CVD risk.4 Of the general population,
about 34% have BP in the nonhypertensive yet above optimal BP range and another
14% have stage 1 hypertension.2 Furthermore,
the majority of BP-related events occur in the range of BP studied in the
PREMIER trial.5 In this setting, it is reasonable
to speculate that widespread implementation of the PREMIER behavioral interventions,
particularly the established plus DASH intervention, should decrease CVD risk
through reduced BP in nonhypertensive individuals and increased BP control
in hypertensive individuals.
Yet most health care insurers do not cover behavioral interventions
for the prevention and treatment of hypertension.31 Given
the substantial health benefits of these programs in improving BP control,
preventing diabetes,32,33 and
controlling dyslipidemia,34 it is time to consider
how such programs might be implemented, particularly for those patients at
elevated CVD risk. The costs of such programs should be balanced against the
benefits of preventing hypertension, diabetes, heart disease, and other conditions,
thereby preventing the need for medical treatments that may be costly.
In summary, our trial results demonstrate the feasibility of comprehensive
behavioral interventions and their beneficial effects on BP and hypertension
control. Benefits extend to both nonhypertensive individuals at risk for developing
hypertension and hypertensive individuals who are not receiving medication
therapy. Although we did not study individuals receiving drug therapy, available
data indicate that nonpharmacological interventions also reduce BP in these
individuals.35,36 Ultimately,
population-wide adoption of healthy lifestyles as promoted in the PREMIER
interventions should substantially reduce the societal burden of CVD and other
chronic diseases.
1.Muntner P, He J, Roccella EJ, Whelton PW. The impact of JNC-VI guidelines on treatment recommendations in the
US population.
Hypertension.2002;39:897-902.Google Scholar 2.Burt VL, Whelton P, Roccella EJ.
et al. Prevalence of hypertension in the US adult population: results from
the Third National Health and Nutrition Examination Survey, 1988-1991.
Hypertension.1995;25:305-313.Google Scholar 3.Vasan RS, Beiser A, Seshadri S, Larson MG, Kannel WB, D'Agostino RB, Levy D. Residual life-time risk for developing hypertension in middle-aged
women and men: the Framingham Heart Study.
JAMA.2002;287:1003-1010.Google Scholar 4.Vasan RS, Larson MG, Leip EP.
et al. Impact of high-normal blood pressure on the risk of cardiovascular
disease.
N Engl J Med.2001;345:1291-1297.Google Scholar 5.Stamler J, Stamler R, Neaton JD. Blood pressure, systolic and diastolic, and cardiovascular risks: US
population data.
Arch Intern Med.1993;153:598-615.Google Scholar 6.Whelton PK, He J, Appel LJ.
et al. Primary prevention of hypertension: clinical and public health advisory
from the National High Blood Pressure Education Program.
JAMA.2002;288:1882-1888.Google Scholar 7.Joint National Committee on Prevention, Detection, Evaluation, and
Treatment of High Blood Pressure. The Sixth Report of the Joint National Committee on the Prevention,
Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI).
Arch Intern Med.1997;157:2413-2446.Google Scholar 8.Appel LJ, Moore TJ, Obarzanek E.
et al. A clinical trial of the effects of dietary patterns on blood pressure.
N Engl J Med.1997;336:1117-1124.Google Scholar 9.Karanja NM, Obarzanek E, Lin PH.
et al. Descriptive characteristics of the dietary patterns used in the Dietary
Approaches to Stop Hypertension trial.
J Am Diet Assoc.1999;99(suppl):S19-S27.Google Scholar 11.Joint National Committee on Detection, Evaluation, and Treatment of
High Blood Pressure. The Fifth Report of the Joint National Committee on the Detection,
Evaluation, and Treatment of High Blood Pressure (JNC V).
Arch Intern Med.1993;153:154-183.Google Scholar 12.The Trials of Hypertension Prevention Collaborative Research Group. The effects of nonpharmacologic interventions on blood pressure of
persons with high normal levels.
JAMA.1992;267:1213-1220.Google Scholar 13.The Trials of Hypertension Prevention Collaborative Research Group. Effects of weight loss and sodium reduction intervention on blood pressure
and hypertension incidence in overweight people with high-normal blood pressure:
the trials of hypertension prevention, phase II.
Arch Intern Med.1997;157:657-667.Google Scholar 14.Rose G, McCartney P, Reid DD. Self-administration of a questionnaire on chest pain and intermittent
claudication.
Br J Prev Soc Med.1977;31:42-48.Google Scholar 15.Fox TA, Heimendinger J, Block G. Telephone surveys as a method for obtaining dietary information: a
review.
J Am Diet Assoc.1992;92:729-732.Google Scholar 16.American College of Sports Medicine. ACM's Guidelines for Exercise Testing and Prescription. 5th ed. Media, Pa: Williams & Wilkins; 1995.
17.Blair SN, Haskell WL, Po H.
et al. Assessment of habitual physical activity methodology by a seven-day
recall in a community survey and controlled experiments.
Am J Epidemiol.1985;122:794-804.Google Scholar 18.Writing Group for the Activity Counseling Trial (ACT) Research Group. Effects of physical activity counseling in primary care: the Activity
Counseling Trial: a randomized controlled trial.
JAMA.2001;286:677-687.Google Scholar 19.Schafer JL. Multiple imputation: a primer.
Stat Methods Med Res.1999;8:3-15.Google Scholar 20.Agresti A. An Introduction to Categorical Data Analysis. New York, NY: John Wiley & Sons Inc; 1996.
21.Aickin M, Gensler H. Adjusting for multiple testing when reporting research results: Bonferroni
vs Holm methods.
Am J Public Health.1996;86:726-728.Google Scholar 22.Whelton PK, Appel LJ, Espeland MA.
et al. for the TONE Collaborative Research Group. Efficacy of sodium reduction and weight loss in the treatment of hypertension
in older persons: main results of the randomized, controlled trial of nonpharmacologic
interventions in the elderly (TONE).
JAMA.1998;279:839-846.Google Scholar 23.Cushman WC, Ford CE, Cutler JA.
et al. Success and predictors of blood pressure control in diverse North American
settings: the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart
Attack Trial (ALLHAT).
J Clin Hypertens.2002;4:393-405.Google Scholar 24.Sacks FM, Svetkey LP, Vollmer WM.
et al. for the DASH-Sodium Collaborative Research Group. A clinical trial of the effects on blood pressure of reduced dietary
sodium and the DASH dietary pattern (the DASH-Sodium Trial).
N Engl J Med.2001;344:3-10.Google Scholar 25.John JH, Ziebland S, Yudkin P, Roe LS, Neil HA. Effects of fruit and vegetable consumption on plasma anti-oxidant concentrations
and blood pressure: a randomised controlled trial.
Lancet.2002;359:1969-1974.Google Scholar 26.Kumanyika SK, Hebert PR, Cutler JA.
et al. Feasibility and efficacy of sodium reduction in the Trials of Hypertension
Prevention, phase I.
Hypertension.1993;22:502-512.Google Scholar 27.Stevens VJ, Obarzanek E, Cook NR.
et al. Long-term weight loss and changes in blood pressure: results of the
Trials of Hypertension Prevention, phase II.
Ann Intern Med.2001;134:1-11.Google Scholar 28.McCullough ML, Feskanich D, Rimm EB.
et al. Adherence to the Dietary Guidelines for Americans and risk of major
chronic disease in men.
Am J Clin Nutr.2000;72:1223-1231.Google Scholar 29.Fung TT, Willett WC, Stampfer MJ, Manson JE, Hu FB. Dietary patterns and risk of coronary heart disease in women.
Arch Intern Med.2001;161:1857-1862.Google Scholar 30.Kant AK, Schatzkin A, Graubard BI, Schairer C. A prospective study of diet quality and mortality in women.
JAMA.2000;283:2109-2115.Google Scholar 31. The Role of Nutrition in Maintaining Health in the Nation's Elderly:
Evaluating Coverage of Nutrition Services for the Medicare Population. Washington, DC: Institute of Medicine, National Academy of Sciences;
2000.
32.Tuomilehto J, Lindstrom J, Eriksson JG.
et al. Prevention of type 2 diabetes mellitus by changes in lifestyle among
subjects with impaired glucose tolerance.
N Engl J Med.2001;344:1343-1350.Google Scholar 33.Knowler WC, Barrett-Connor E, Fowler SE.
et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention
or metformin.
N Engl J Med.2002;346:393-403.Google Scholar 34.Dattilo AM, Kris-Etherton PM. Effects of weight reduction on blood lipids and lipoproteins: a meta-analysis.
Am J Clin Nutr.1992;56:320-328.Google Scholar 35.Langford HG, Davis BR, Blaufox D.
et al. for the TAIM Research Group. Effect of drug and diet treatment of mild hypertension on diastolic
blood pressure.
Hypertension.1991;17:210-217.Google Scholar 36.Miller ER, Erlinger EP, Young DR.
et al. Results of the Diet, Exercise and Weight-loss Intervention Trial (DEW-IT).
Hypertension.2002;40:612-618.Google Scholar