Sodium Reduction and Weight Loss in the Treatment of Hypertension in Older Persons: A Randomized Controlled Trial of Nonpharmacologic Interventions in the Elderly - TONE

Description:

TONE was a multicenter, randomized, controlled trial designed to determine whether weight loss or reduced sodium intake is effective in the treatment of older persons with hypertension.

Hypothesis:

The TONE trial was designed to test the following hypotheses: 1) Prescribing a sodium reduction program for obese and nonobese older patients with hypertension reduces the rate of primary endpoints following the withdrawal of blood pressure-lowering medications. 2) Prescribing a weight loss program for obese individuals reduces the rate of primary endpoints following the withdrawal of blood pressure-lowering medications.

Study Design

Study Design:

Patient Populations:

Age 60-80 years with an average systolic BP <145 mm Hg and diastolic BP <85 mm Hg (mean of nine measurements, three at each of three visits) while taking a single antihypertensive medication or a single combination regimen consisting of a diuretic agent and a nondiuretic agent. If individuals were taking two antihypertensive medications, they were enrolled if they could be successfully weaned to one antihypertensive medication during the screening phase.

Exclusions:

History of a heart attack or stroke within the preceding six months, current angina pectoris, congestive heart failure, insulin-dependent diabetes mellitus, serious mental or physical illness, unexplained or involuntary weight loss of ≥4.5 kg during the previous year, a body mass index <21 kg/m squared in men or women or >33 kg/m squared in men or >37 kg/m squared in women, presumed inability to comply with the protocol, hypercreatinemia, hyperkalemia, hyperglycemia, and anemia

Primary Endpoints:

High blood pressure at one or more visit following attempted withdrawal of antihypertensive medication, treatment with an antihypertensive medication, or occurrence of a clinical cardiovascular disease complication during follow-up (myocardial infarction, angina, congestive heart failure, stroke, coronary artery bypass surgery, or coronary artery angioplasty)

Secondary Endpoints:

Drug/Procedures Used:

A total of 585 overweight patients were randomized to weight loss (n=147), sodium reduction (n=144), combined intervention (n=147), or usual care (n=147). A total of 390 not overweight patients were randomized to sodium reduction (n=196) or usual care (n=194). Withdrawal of antihypertensive medication was attempted after three months of intervention.

The goal for sodium reduction, both alone and combined with weight loss, was achieving and maintaining a 24-hour dietary sodium intake of 1800 mg or less (as measured by 24-hour urine collection). The goal for weight loss was achieving and maintaining a weight loss of 4.5 kg or greater. The usual care groups received no study-related counseling in lifestyle change techniques. Nutritionists and exercise counselors advised participants on ways to change eating patterns and increase physical activity.

Each active intervention consisted of three phases (intensive, extended, and maintenance). The primary goal during the initial four-month intensive phase was to provide participants with the core knowledge and behavior skills necessary to achieve and maintain their desired reductions in sodium intake and body weight. During the next four months (extended phase), participants focused on problem solving and prevention of relapse. Thereafter (maintenance phase), continued attempts were made to maintain participant interest in the intervention program and to reengage those who were less active in practicing behavior change techniques. Visits were initially weekly and then monthly.

Principal Findings:

Baseline characteristics were similar in each group. At the nine-month follow-up visit, 36% of the 443 participants assigned to sodium reduction versus 11% of the 424 participants not assigned to sodium reduction had a urinary sodium excretion level that met the intervention goal of ≤80 mmol/day. At the nine-month follow-up visit, 47% of the 275 participants assigned to weight loss compared with 13% of the 260 participants not assigned to weight loss achieved the intervention goal of weight loss of ≥4.5 kg. Antihypertensive drug therapy was stopped in 86.8% of those assigned to usual care, in 92.6% assigned to sodium reduction alone, in 93.2% assigned to weight loss alone, and in 93.2% assigned to weight loss and sodium reduction combined.

Among obese participants, the hazard ratio for endpoints was 0.70 (95% confidence interval [CI] 0.57-0.87) for weight loss compared with those not assigned to weight loss (p=0.001), with 39% of those randomized to weight loss compared with 26% of those not randomized to weight loss remaining free of trial endpoints 30 months after attempted withdrawal of antihypertensive drug therapy (p=0.001). Freedom from cardiovascular events and high blood pressure and those who did not have an antihypertensive agent prescribed during follow-up was 37.8% in the reduced sodium intake intervention group and 24.4% in those not assigned to the reduced sodium intake intervention group (p<0.001).

In an analysis limited to the 886 participants in whom medication was successfully tapered, the hazard ratio for experiencing a trial endpoint, relative to usual care, was 0.68 (95% CI 0.54-0.82) for those assigned to sodium reduction, 0.75 (95% CI 0.57-0.93) for those assigned to weight loss, and 0.55 (95% CI 0.41-0.69) for those assigned to sodium reduction and weight loss combined. Among the 328 participants who were still off antihypertensive medication at the final study visit, average systolic and diastolic blood pressures were 131 and 74 mm Hg, respectively, for the sodium reduction group, 133 and 75 mm Hg for the weight loss group, 130 and 73 mm Hg for the sodium reduction and weight loss combined group, and 134 and 75 mm Hg for the control group. There were no significant differences in the rates of cardiovascular events among groups.

Interpretation:

Among older patients with hypertension, treatment with a dietary lifestyle intervention was associated with improvements in high blood pressure control and decreased need for antihypertensive medication.

References:

Whelton PK, Appel LJ, Espeland MA, et al. Sodium reduction and weight loss in the treatment of hypertension in older persons: a randomized controlled trial of nonpharmacologic interventions in the elderly (TONE). TONE Collaborative Research Group. JAMA 1998;279:839-46.

Clinical Topics: Prevention, Diet, Hypertension

Keywords: Life Style, Behavior Therapy, Follow-Up Studies, Diuretics, Counseling, Urine Specimen Collection, Problem Solving, Sodium, Dietary, Weight Reduction Programs, Motor Activity, Obesity, Diet, Nutritionists, Confidence Intervals, Hypertension


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