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Effects of Reduced Sodium Intake on Hypertension Control in Older Individuals
Results From the Trial of Nonpharmacologic Interventions in the Elderly (TONE)
Lawrence J. Appel, MD, MPH;
Mark A. Espeland, PhD;
Linda Easter, MS, RD;
Alan C. Wilson, PhD;
Steven Folmar, PhD;
Clifton R. Lacy, MD
Arch Intern Med. 2001;161:685-693.
ABSTRACT
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Background Few trials have evaluated the effects of reduced sodium intake in older
individuals, and no trial has examined the effects in relevant subgroups such
as African Americans.
Patients and Methods The effects of sodium reduction on blood pressure (BP) and hypertension
control were evaluated in 681 patients with hypertension, aged 60 to 80 years,
randomly assigned to a reduced sodium intervention or control group. Participants
(47% women, 23% African Americans) had systolic BP less than 145 mm Hg and
diastolic BP less than 85 mm Hg while taking 1 antihypertensive medication.
Three months after the start of intervention, medication was withdrawn. The
primary end point was occurrence of an average systolic BP of 150 mm Hg or
more, an average diastolic BP of 90 mm Hg or more, the resumption of medication,
or a cardiovascular event during follow-up (mean, 27.8 months).
Results Compared with control, mean urinary sodium excretion was 40 mmol/d less
in the reduced sodium intervention group (P<.001);
significant reductions in sodium excretion occurred in subgroups defined by
sex, race, age, and obesity. Prior to medication withdrawal, mean reductions
in systolic and diastolic BPs from the reduced sodium intervention, net of
control, were 4.3 mm Hg (P<.001) and 2.0 mm Hg
(P = .001). During follow-up, an end point occurred
in 59% of reduced sodium and 73% of control group participants (relative hazard
ratio = 0.68, P<.001). In African Americans, the
corresponding relative hazard ratio was 0.56 (P =
.005); results were similar in other subgroups. In dose-response analyses,
end points were progressively less frequent with greater sodium reduction
(P for trend = .002).
Conclusion A reduced sodium intake is a broadly effective, nonpharmacologic therapy
that can lower BP and control hypertension in older individuals.
INTRODUCTION
HYPERTENSION and its treatment with medication are extremely common
in the elderly. According to the Third National Health and Nutrition Examination
Survey, conducted between 1988 and 1991, the prevalence of hypertension, defined
as a systolic blood pressure (BP) of 140 mm Hg or more, a diastolic BP of
90 mm Hg or more, or treatment with medication, exceeds 50% in the civilian,
noninstitutionalized population aged 60 years and older.1
In certain subgroups, hypertension is nearly ubiquitous. For example, the
prevalence of hypertension among African American women aged 60 to 69 years
is 78%. Medication use is also highly prevalent in the elderly, ranging from
31% of Mexican American women with hypertension 70 years and older to 70%
of African American women with hypertension 70 years and older.
Sodium reduction is widely advocated as a means to reduce BP and control
hypertension in older persons,2-3
yet empiric evidence is sparse. Little is known about the ability and willingness
of older persons to reduce their sodium intake, the effects of a reduced sodium
intake on BP and hypertension control in this population, dose-response relationships,
and the effects in relevant subgroups, such as African Americans. Applegate
et al4 demonstrated that a multifactorial intervention,
consisting of sodium reduction, weight loss, and increased physical activity,
can reduce BP in older persons. Otherwise, only a few trials, each with small
sample size, have examined the impact of sodium reduction as a means to reduce
BP5-6 and control hypertension7 in older persons. In these trials, few, if any, participants
were African American.
Sodium reduction should be particularly effective in older persons.
First, because arterial compliance decreases with age, any change in intravascular
volume related to sodium intake should result in a greater BP change in older
persons than in younger individuals.8 Second,
because of the decline in kidney function associated with aging, older individuals
may retain sodium to a greater extent than younger persons.9
Third, older individuals may be more willing and able to reduce their sodium
intake than younger individuals who have yet to experience the adverse health
consequences of elevated BP.
In view of these considerations, the Trial of Nonpharmacologic Interventions
in the Elderly (TONE) was a randomized trial that tested whether reduced sodium
intake and/or weight loss can maintain satisfactory medication-treated hypertension
control in older persons with hypertension. The main results of TONE have
been published.10 In brief, TONE demonstrated
that a reduced sodium intake and weight loss, alone or combined, could effectively
control hypertension. The objectives of this article, which focuses on only
the sodium component of TONE, are to examine the following issues: (1) the
effects of a reduced sodium intake in subgroups defined by sex, ethnicity,
age, and obesity; (2) dose-response relationships; and (3) the effects of
a reduced sodium intake on subtypes of the primary outcome variable, dietary
intake of other nutrients, and the occurrence of adverse events.
SUBJECTS AND METHODS
A detailed description of the design and methods of this trial has been
published.11 The trial protocol was approved
by institutional review boards at each participating center and by an external
protocol review board appointed by the funding agencies: the National Institute
on Aging and the National Heart, Lung, and Blood Institute. Each participant
provided written informed consent.
STUDY POPULATION
The study population consisted of healthy persons (aged 60-80 years)
with systolic BP of less than 145 mm Hg and diastolic BP of less than 85 mm
Hg (mean of 9 measurements, ie, 3 BPs at each of 3 visits) while taking 1
antihypertensive medication, ie, 1 type of medication whether or not multiple
doses were used. Individuals treated with 2 antihypertensive medications were
also eligible, if they were successfully weaned from 1 of these medications
during the screening phase. Major exclusion criteria were use of antihypertensive
medication for conditions other than hypertension (eg, ischemic heart disease),
myocardial infarction or stroke within 6 months, angina pectoris, congestive
heart failure, serum creatinine level of more than 176.8 µmol/L (>2
mg/dL), blood glucose level of more than 14.4 mmol/L (>260 mg/dL), and self-report
of average alcoholic beverage intake of more than 14 drinks per week.
A detailed description of recruitment procedures has been published.12 In brief, each TONE clinical center implemented site-specific
strategies, which included (1) mass mailings of brochures; (2) radio, television,
and newspaper advertisements; (3) BP screenings; and (4) enrollment of participants
from previous studies. Enrollment began in August 1992 and ended in June 1994.
DATA COLLECTION
Individuals provided a medical history, underwent a physical examination,
and had routine laboratory tests to confirm eligibility. TONE data collection
visits included 2 screening visits, a randomization visit, drug withdrawal
visits (beginning 90 days [±14 days] after the start of intervention),
and follow-up visits scheduled every 3 months. For screenees who were taking
2 antihypertensive medications, medication stepdown visits took place after
the second screening visit but prior to the randomization visit. Closeout
visits occurred between July 1995 and December 1995. The median duration of
follow-up was 29 months (maximum of 36 months). During follow-up, safety monitoring
visits took place whenever a participant's mean systolic BP was 150 mm Hg
or more or diastolic BP was 90 mm Hg or more.
All BP measurements were obtained by trained and certified observers
who were masked to intervention assignment. Systolic BP was defined as the
appearance of the first Korotkoff sound, and diastolic BP as the point of
disappearance of the fifth Korotkoff sound. At each visit, 3 BP measurements
were obtained while the participant rested quietly in the seated position.
Random-zero sphygmomanometers were used to minimize observer bias.
Twenty-four-hour urine collections were obtained twice prior to randomization
and once at the 9-, 18-, and 30-month follow-up visits and at closeout, if
this visit did not coincide with 1 of the follow-up visits. Twenty-four-hour
dietary recalls were obtained twice prior to randomization and again at the
9- and 12-month follow-up visits and every 6 months thereafter by trained,
certified technicians who were masked to intervention assignment. Nutrient
calculations were performed using the Minnesota Data System software (food
database version 6A; nutrient database version 21), developed by the Nutrition
Coordinating Center, University of Minnesota, Minneapolis.13
Data from the 24-hour recalls were used to determine macronutrient, micronutrient,
and energy intake in randomized groups at baseline and during follow-up.
INTERVENTION
Overweight participants were randomly assigned, in a 2 x 2 factorial
design, to 1 of the following 4 groups: (1) combined weight loss and reduced
sodium, (2) reduced sodium alone, (3) weight loss alone, or (4) usual lifestyle
(UL) control group. Nonoverweight participants were randomly assigned to reduced
sodium alone or UL groups. Body mass index values (calculated as weight in
kilograms divided by the square of height in meters) of 27.8 for men and 27.3
for women were used as the thresholds to define overweight.14
This article presents data on participants, both overweight and nonoverweight,
who were assigned to the reduced sodium alone or UL group.
The intervention goal for reduced sodium groups was to achieve and maintain
a 24-hour dietary sodium intake of 80 mmol/L or less of sodium, as measured
by 24-hour urine collections. This level of sodium intake is slightly below
the currently recommended upper limit of 100 mmol/L of sodium per day for
the prevention and treatment of hypertension.3
Participants were expected to modify only those aspects of their diet that
led to a high sodium intake; a comprehensive change in diet was not expected.
To achieve its goal, TONE used intervention techniques derived from experience
in clinical trials that achieved BP control through interventions focusing
on behavioral change.15-17
Social learning theory and behavioral approaches that enhance the understanding
of behavior change and the ways to achieve it were incorporated.
In the reduced sodium group, each person had an introductory individual
session with the interventionist assigned to their group. This session occurred
within 4 weeks of randomization. Intervention groups, typically consisting
of 9 to 12 participants, were then formed in a timely manner so that participants
began the reduced sodium program within 45 days after randomization. Each
of the TONE interventions consisted of a 4-month "intensive" phase with weekly
meetings, a 3-month "extended" phase with biweekly meetings, and a maintenance
phase. The interventionist typically was a registered dietitian. The meetings
were conducted as group sessions with individual sessions held at every fourth
contact.
During the group and individual sessions, interventionists provided
information using both centrally and locally prepared materials, motivated
participants to make and sustain long-term lifestyle changes, and monitored
individual and group progress at frequent intervals. In the process, participants
learned about sources of sodium, particularly those foods with a high salt
content, and about alternative foods, condiments, and spices. They also learned
how to adapt the reduced sodium lifestyle recommendations to their own individual
situations, eg, how to select appropriate foods at restaurants.
To enhance follow-up among participants assigned to UL, meetings were
held on a regular basis with speakers who led discussions on topics unrelated
to BP, cardiovascular disease, or nutrition. To facilitate masking of the
data collectors, intervention visits were conducted at separate times and
places from data collection visits.
WITHDRAWAL OF ANTIHYPERTENSIVE MEDICATION
Drug withdrawal began 90 days (±14 days) after the first group
intervention session. Participants randomized to UL began drug withdrawal
at a comparable time. The drug withdrawal process, which was standardized
across the 4 clinical centers, used drug-specific tapering regimens. As the
medication was tapered, participants were evaluated weekly. After discontinuation
of the drug, participants had 3 additional biweekly visits to confirm that
their systolic BP remained less than 150 mm Hg and diastolic BP less than
90 mm Hg. The rationale for beginning medication withdrawal 90 days after
the start of intervention, as opposed to immediately after randomization,
was to increase the likelihood of successful drug withdrawal.
OUTCOME VARIABLES
In primary analyses, the outcome variable was a composite end point
defined by the need for, or actual resumption of, antihypertensive drug therapy.
Specifically, a TONE participant reached a trial end point when any of the
following occurred:
- High BP, as indicated by (1) elevated BP measured by TONE BP technicians
(at 1 visit, mean diastolic BP
 110 mm Hg or systolic BP 190 mm Hg;
at 2 visits, mean diastolic BP 100 mm Hg or systolic BP 170 mm Hg;
or at 3 visits, mean diastolic BP 90 mm Hg or systolic BP 150 mm Hg),
or (2) resumption of antihypertensive medication initiated either by the participant
or personal physician for elevated BP measured outside a clinical center.
- Resumption of antihypertensive medication initiated by either
a personal physician or participant for a symptom or condition other than
elevated BP or a cardiovascular clinical event. Participants given medication
for non-BP and noncardiovascular conditions, such as migraine headaches and
benign prostatic hypertrophy, were censored.
- A cardiovascular clinical event (myocardial infarction, angina,
congestive heart failure, hypertensive encephalopathy, stroke, or procedure
[bypass surgery, angioplasty, endarterectomy]). These clinical events were
included as components of the composite end point to reduce the possibility
of informative censoring.
Medical records were retrieved for all end points occurring outside
a TONE visit. An end point committee, masked to intervention assignment, made
final decisions concerning the end point status of each participant.
To determine the impact of the interventions on BP, change in BP was
calculated as the difference between mean BP prior to randomization and BP
at the visit when medication withdrawal was first attempted. At both times,
participants were receiving drug therapy.
ANALYSES
Analyses were conducted on an intention-to-treat basis. In primary analyses,
the distributions of times until first occurrence of an end point were compared
in participants assigned to the reduced sodium and UL groups. Times were measured
from the end of the drug withdrawal process until the occurrence of the end
point. Participants who met an end point criterion prior to, or during, drug
withdrawal were treated as instantaneous failures. Each comparison was performed
using proportional hazards regression. Kaplan-Meier curves were used to portray
the distribution of times until failure for each of the study cohorts. For
continuous outcomes, eg, BP and nutrient intake, differences in change (follow-up
minus baseline levels) between the reduced sodium and UL groups were compared
using unpaired t tests. In all analyses, a 2-sided
significance level of .05 was considered statistically significant.
RESULTS
At baseline, mean (SD) age was 65.8 (4.6) years, and 79% of participants
were between 60 and 69 years of age. Of the participants, 47% were women,
23% African Americans, 34% college graduates, and 43% overweight. Mean (SD)
systolic and diastolic BPs at baseline, while participants were taking medication,
were 128.0 (9.4) and 71.3 (7.3) mm Hg, respectively. On average, participants
had hypertension for 13 years and had been taking antihypertensive medication
for 12 years. At baseline, 32% of participants were taking a diuretic, 27%
a calcium channel blocker, 22% an angiotensin-converting enzyme inhibitor,
11% a ß-blocker, and 8% another antihypertensive agent. Mean (SD) urinary
sodium excretion was 161 (54) mmol/d in men and 126 (47) mmol/d in women.
There was no evidence of a substantial imbalance between the reduced sodium
and UL groups.
FOLLOW-UP
At the 9-month follow-up visit, attendance was 91% and 88% of expected
in the reduced sodium and UL groups, respectively; at the 18-month follow-up
visit, corresponding attendance was 85% and 83%, respectively. At the 9-month
follow-up visit, 24-hour urine collections were provided by 99% of reduced
sodium and 97% of UL participants attending these visits. Among participants
attending the 18-month follow-up visit, 97% of reduced sodium and 99% of UL
participants provided 24-hour urine collections. Closeout visits occurred
from 15 to 36 months after randomization. Attendance at the closeout visits
was 90% and 93% in the reduced sodium and UL groups. Of those attending a
closeout visit, 97% of reduced sodium and 98% of UL participants provided
urine specimens. At the end of follow-up, end point status was known in 98%
of reduced sodium and UL participants.
INTERVENTION RESULTS
The reduced sodium group achieved and maintained a substantial reduction
in sodium levels. At the 9-, 18-, and 30-month follow-up visits, more than
40% of reduced sodium participants had an absolute urinary sodium excretion
of 80 mmol/d or less in contrast to less than 15% of UL participants. Table 1 displays mean (SD) sodium urinary
excretion at baseline, within-group changes, and between-group differences
in sodium excretion. Overall, urinary sodium excretion was reduced by 40 mmol/d
in the reduced sodium group, net of UL (P<.001).
The extent of sodium reduction was less in women than in men (27 vs 53 mmol/d; P<.001), in part as a result of baseline differences
in sodium intake. In the 2 age groups (60-69 and 70-80 years), the reductions
in sodium levels were similar. Sodium reduction tended to be greater in overweight
persons than in nonoverweight persons (44 vs 34 mmol/d; P = .24). Because the sex distribution in African Americans differed
from that in non–African Americans, we performed sex-stratified analyses
(Table 2). In these analyses,
sodium reduction was similar in African Americans and non–African Americans;
however, differences by sex persisted. The pattern of findings from 24-hour
dietary recalls was similar to that of the 24-hour urinary excretion (data
not presented). Compared with the UL group, the reduced sodium group lost
an average of 1.1 kg (2.5 lb) during follow-up (P<.001).
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Table 1. Twenty-four-Hour Urinary Sodium Excretion Overall and by Subgroup*
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Table 2. Twenty-four-Hour Urinary Sodium Excretion Stratified by Sex
and Race*
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EFFECTS OF INTERVENTIONS ON BP
The effect of the reduced sodium intervention on BP was assessed by
comparing the change in BP from baseline with BP at the visit prior to medication
withdrawal (mean interval, 3.5 months). In Table 3, the reduced sodium group experienced a mean reduction in
systolic BP of 4.3 mm Hg (P<.001) and in diastolic
BP of 2.0 mm Hg (P = .001), net of BP change in UL.
In all subgroup analyses, the mean reduction in systolic BP in the reduced
sodium group was greater than that of the UL group, achieving statistical
significance in all but 1 stratum (the 70-80 year age group). Likewise, diastolic
BP reductions were consistently greater in the reduced sodium group than in
the UL group; however, a few between-group differences did not achieve statistical
significance.
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Table 3. Systolic and Diastolic Blood Pressure (BP) Overall and by
Subgroup*
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EFFECTS OF INTERVENTIONS ON HYPERTENSION CONTROL
Of the 448 end points, 334 occurred as a result of elevated BP (of which
203 occurred from measurements in the TONE clinic), 22 as a result of a clinic
cardiovascular event, and 92 as a result of participant and personal physician
decisions for symptoms and conditions other than elevated BP. The distributions
of event subtype in the reduced sodium and UL groups were similar (P = .45,  23 test).
Figure 1 displays the distribution
of end point times after completion of medication withdrawal by intervention
group. Beginning with completion of medication withdrawal and continuing throughout
follow-up, the proportion who remained end point free in the reduced sodium
group exceeded that of the UL group. After 30 months of follow-up (after drug
withdrawal), the proportion without an end point was 36% in the reduced sodium
group and 21% in the UL group. The relative hazard ratios associated with
assignment to reduced sodium vs UL were 0.68 (95% confidence interval [CI],
0.56-0.82; P<.001) and 0.69 (95% CI, 0.57-0.84; P<.001, adjusting for weight change). In analyses restricted
to end points defined by elevated BP in any setting (Figure 2), the proportion without elevated BP was 43% in the reduced
sodium group and 27% in the UL group at the end of follow-up. The corresponding
relative hazard ratio was 0.67 (95% CI, 0.54-0.83; P<.001).
In analyses restricted to end points defined by an elevated BP as measured
in a TONE clinic, the relative hazard ratio remained virtually identical,
ie, 0.62 (95% CI, 0.47-0.82; P<.001).
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Figure 1. Proportion of participants who
remained free of a trial end point (elevated blood pressure, resumption of
medication, and cardiovascular events) during follow-up.
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Figure 2. Proportion of participants who
remained free of elevated blood pressure during follow-up. Cardiovascular
events were censored.
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In dose-response analyses that assessed the risk of an end point by
quintiles of change in urinary sodium excretion (Figure 3), the relative hazard ratio decreased with greater reductions
in urinary sodium excretion (P for trend = .002).
The risk of an end point was unrelated to baseline dietary sodium intake or
excretion (data not presented).
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Figure 3. Relative hazard ratio (with 95%
confidence interval) of a trial end point by quintile of change in urinary
sodium excretion (observational analyses, n = 639). The cut points for the
quintiles are as follows: +19, -9, -35, and -70 mmol/d.
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In subgroups defined by sex, ethnicity, age group, and weight (Table 4), results were similar to overall
findings. For instance, in African Americans, the relative hazard ratio associated
with assignment to reduced sodium vs UL was 0.56 (95% CI, 0.37-0.84; P = .005). The relative hazard ratio by class of withdrawn
medication was 0.62 (95% CI, 0.42-0.92; P = .02)
for diuretic users, 0.61 (95% CI, 0.42-0.92; P =
.02) for calcium channel blocker users, 0.50 (95% CI, 0.40-0.94; P = .02) for angiotensin-converting enzyme inhibitor users, 1.66 (95%
CI, 0.79-3.50; P = .18) for ß-blocker users,
and 1.53 (95% CI, 0.62-3.80; P = .36) for users of
other antihypertensive medications (all adjusted for sex, ethnicity, age,
weight, and change in urine sodium excretion).
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Table 4. Relative Hazard Ratio for End Points Associated With Assignment
to Reduced Sodium Intervention vs Usual Lifestyle Control Group
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OTHER EFFECTS OF THE INTERVENTIONS
Except for a tendency toward less angina in the reduced sodium group
compared with the UL group (9 vs 17 individuals, P
= .16), the occurrence of cardiovascular events was similar in the 2 groups
(Table 5). Headache occurred less
frequently in the reduced sodium group compared with the UL group (35 vs 54
individuals, P = .04); otherwise, the occurrence
of adverse symptoms was similar in the 2 groups. Compared with the UL group,
intake of total energy, dietary fat, saturated fat, monounsaturated fat, iron,
calcium, thiamin, and riboflavin declined in the reduced sodium group, while
intake of potassium and magnesium increased (each P<.05; Table 6).
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Table 5. Number of Individuals Reporting Cardiovascular and Other Adverse
Events (and Total Number of Events) During Follow-up by Randomized Group*
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Table 6. Daily Nutrient Intake*
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COMMENT
This large randomized controlled trial demonstrated that free-living,
older people with hypertension can reduce their sodium intake and that a reduced
sodium intake can lower BP and the need for antihypertensive drug therapy.
The effects were consistent in subgroups defined by sex, ethnicity, and weight
status. However, the effects of the intervention on BP and end points in the
age group 70 to 80 years did not achieve statistical significance, perhaps
as a result of small sample size. In dose-response analyses, progressively
greater reductions in sodium intake were associated with a reduced risk of
a trial end point. In aggregate, these data indicate that a modest reduction
in sodium intake is a feasible and broadly effective nonpharmacologic therapy
in older persons.
The reduction in sodium intake observed in this trial had a substantial
impact on BP, despite the fact that mean baseline BP, while participants were
taking medication, was within the nonhypertensive range. Specifically, from
a mean baseline BP of 128/71 mm Hg, a reduced sodium intake lowered systolic
and diastolic BPs by 4.3 and 2.0 mm Hg, respectively. The extent of sodium
reduction at 3 months after randomization (before drug withdrawal) is not
known, because the first 24-hour urine collection was obtained 9 months after
randomization (about 6 months after drug withdrawal). Nonetheless, if the
average 40-mmol/d reduction in sodium intake occurred by 3 months, then the
BP reduction observed in TONE is similar to that expected, ie, approximately
half of the estimated 10– and 4–mm Hg declines in systolic and
diastolic BPs from a 100-mmol/d sodium reduction in persons 60 to 69 years
of age.18 TONE did not assess the impact of
sodium reduction in persons with high BP. However, it is likely that the extent
of BP reduction would be greater than that observed in this trial.
In the design, analysis, and presentation of main trial results, the
primary outcome variable included clinical, potentially BP-related events
(eg, stroke and myocardial infarction) as well as resumption of medication
initiated by either the participant or personal physician for reasons other
than elevated BP. The rationale for this decision was to minimize the potential
for informative censoring that otherwise might occur in this trial of older
persons had the end point been restricted to only elevated BP. This decision
tends to inflate the number of end points and might obscure differences between
groups. It is illustrative that in subsidiary analyses, restricted to the
334 events that were related only to elevated BP, the main trial findings
persist.
In TONE, there was no evidence of an adverse impact of the reduced sodium
intervention on the occurrence of cardiovascular events. In fact, there was
a tendency toward fewer cardiovascular events in the reduced sodium intervention
group compared with the UL group, primarily as a result of fewer instances
of angina. In terms of adverse symptoms reported by participants, there were
significantly fewer reports of headaches in the reduced sodium intervention
group. No other adverse symptom achieved statistical significance. The reduced
sodium intervention did have an impact on several aspects of diet. For most
nutrients, eg, total energy, fat, and potassium, the changes were favorable.
In a few instances, such as a reduced intake of calcium, the changes were
potentially deleterious. Whether this reduction in calcium intake is clinically
relevant is unclear, because a reduced intake of sodium has opposite effects
on bone demineralization.19 Hence, the net
impact on bone mineral density is uncertain. Overall, TONE results reaffirm
the safety of moderate dietary sodium reduction.20
Findings from this trial have important public health and clinical implications.
Because hypertension is common in the elderly and because sodium reduction
can substantially reduce BP, population-based and individualized efforts to
reduce sodium intake are appropriate. The elderly often live and/or dine in
common settings (eg, community centers, senior centers, or nursing homes).
As such, institutional changes in food preparation can provide an efficient
means to reduce BP in broad populations. While TONE participants were able
to achieve modest reductions in sodium intake through careful selection of
food products, the availability of low-sodium foods was limited. To facilitate
easy access to such items, food manufacturers should minimize the addition
of sodium and should use alternative seasonings for flavor.
Successful sodium reduction will require individualized counseling as
a routine component of hypertension management. Unfortunately, Medicare, the
primary insurer of older persons in the United States, does not cover nutrition
therapy for most outpatient conditions such as hypertension. The TONE trial
provides convincing evidence that individualized counseling can reduce BP
and control hypertension. Such evidence supports current efforts to expand
Medicare coverage of nutrition services.21
From a clinical perspective, TONE results indicate that sodium reduction
can control hypertension in a sizeable proportion of medication-controlled
patients with hypertension. Before clinicians attempt medication withdrawal,
candidate patients must be committed to reducing their sodium intake, ideally
in the setting of a supervised counseling program. Furthermore, regular BP
monitoring is warranted because many individuals will require resumption of
drug therapy. In another article from the TONE study, patients with recently
diagnosed and well-controlled hypertension were most likely to be successful
at medication withdrawal.22 Still, physicians
may decide to promote sodium reduction without medication withdrawal; in this
setting, a reduced sodium intake can substantially lower BP and presumably
decrease the risk of atherosclerotic cardiovascular events.
In summary, a reduced sodium intake is a broadly effective, nonpharmacologic
therapy that lowers BP and controls hypertension in older individuals. Our
results, in combination with the high prevalence of hypertension and its treatment
with medication in the elderly, argue for substantial efforts to reduce sodium
intake in older persons.
AUTHOR INFORMATION
Accepted for publication October 3, 2000.
This work was supported by grants HL02642, HL43641, HL48642, and HL60197
from the National Heart, Lung, and Blood Institute; AG09799, AG09771, and
AG09773 from the National Institute on Aging; and RR00722 from the National
Center for Research Resources of the National Institutes of Health.
We thank the trial participants and the entire TONE Collaborative Research
Group.
Corresponding author and reprints: Lawrence J. Appel, MD, MPH, Johns
Hopkins University, 2024 E Monument St, Suite 2-645, Baltimore, MD 21205-2223
(e-mail: lappel{at}jhmi.edu).
From the Welch Center for Prevention, Epidemiology, and Clinical Research,
Johns Hopkins Medical Institutions, Baltimore, Md (Dr Appel); Departments
of Public Health Sciences (Dr Espeland), General Clinical Research Center
(Ms Easter), and Anthropology (Dr Folmar), Wake Forest University, Winston-Salem,
NC; and Division of Cardiovascular Diseases and Hypertension, University of
Medicine and Dentistry of New Jersey–Robert Wood Johnson Medical School,
New Brunswick (Drs Wilson and Lacy).
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