An overview of randomized trials of sodium reduction and blood pressure.

Abstract

To test for effects on systolic and diastolic blood pressure and to provide precise estimates of their magnitude, we conducted an overview of randomized clinical trials that aimed to reduce the intake of sodium in human subjects. We excluded from pooled analyses trials with confounded designs, those that compared intake levels beyond the usual range in the population, and those without published reports. Two reviewers abstracted information in duplicate and differences were reconciled. Twenty-three trials with outcome data from an aggregate of 1,536 subjects were included. Data were pooled both separately for hypertensive and nonnotensive subjects and for all trials combined. With the use of sample size weighting, blood pressure reductions (net of controls) were 4.9±13/2.6±0.8 mm Hg (systolic and diastolic, respectively, with 95% confidence limits) in hypertensive subjects and 1.7 ±1.0/1.0 ±0.7 mm Hg in nonnotensive subjects. The combined blood pressure reductions were 2.9±0.8/1.6±0.5 mm Hg. These changes were associated with mean reduction of urinary sodium excretion ranging from 16 to 171 mmol/24 hr for individual trials. A dose-response relation across trials was found, both in nonnotensive and in hypertensive subjects. These results indicate that sodium reduction lowers mean blood pressure in both hypertensive and nonnotensive individuals for periods of at least several months. The findings are highly consistent with results of observational epidemiological studies and have implications for preventive strategies of blood pressure control. {Hypertension 1991;17[suppl I]:I-27-I-33) R andomized intervention trials, properly conducted, provide the best test of an effect of prophylactic or therapeutic treatments. 1 Although the blood pressure effects of reducing dietary sodium have been studied since early in the century, 2 randomized trials have been reported only within the past 17 years, 3 largely the past 10 years. Trials have both increased in frequency and become more varied and complex in design. These changes reflect the importance of the question for public health and biology but also pose a challenge for summarizing and interpreting results. Several reviews have been published in recent years, 4 -5 but they did not present pooled analyses of all relevant trials to the time of the reviews, and several trials have since been completed. We favor pooling as part of a review because it formalizes the objective of including all relevant trials and an explicit method of combining their results. It also furnishes a quantitative estimate of the effect, which

Blood pressure response to changes in sodium and potassium intake: a metaregression analysis of randomised trials

“…[4][5][6][7][8][9][10][11][12][13][14][15][16] An additional MEDLINE search for publications of sodium and potassium trials between January 1995 and March 2001 was performed. Eligibility criteria were (1) randomised design, (2) adult study population (mean age of 18 years or above), and (3) publication date after 1966.…”

“…2,3 Meta-analyses of randomised trials found blood pressure falls of 3-5 mmHg systolic and 1-2 mmHg diastolic for sodium reduction in hypertensives, and reductions half this size in normotensives. [4][5][6][7][8][9][10][11][12] For potassium supplementation, blood pressure reductions of more than 3 mmHg systolic and 2 mmHg diastolic have been reported. [13][14][15][16] Blood pressure response to sodium (and possibly also potassium) could be related to initial blood pressure level, age, gender, race, and genetic factors.…”

Effect of modest salt reduction on blood pressure: a meta-analysis of randomized trials. Implications for public health

“…Several meta-analyses of these salt reduction trials have been performed. [6][7][8][9][10] In two meta-analyses 8,10 including the most recent one, 10 it was claimed that the results showed that salt reduction had no or very little effect on blood pressure in normotensive individuals. The authors concluded that a reduction in population salt intake is not warranted.…”

Trends in the prevalence of isolated systolic hypertension in the middle-aged population in 1972–1992

“…15 Especially in men, the disproportionate decrease in DBP (8 mm Hg) over SBP (4 mm Hg) in the present study may have resulted in a shift towards to a higher prevalence of ISH among untreated hypertensive subjects. In an overview of randomised trials, Cutler et al 32 showed a statistically significant effect of the reduction of sodium intake on SBP in hypertensive and normotensive subjects. 32 The more active application of these strategies to subjects with ISH had possibly produced a fall in the prevalence of ISH among untreated hypertensive subjects.…”

“…In an overview of randomised trials, Cutler et al 32 showed a statistically significant effect of the reduction of sodium intake on SBP in hypertensive and normotensive subjects. 32 The more active application of these strategies to subjects with ISH had possibly produced a fall in the prevalence of ISH among untreated hypertensive subjects.…”