Hypertension Treated by Salt Restriction

Morgan, Trefor; Adam, W. R.; Gillies, Alastair J.; Wilson, M. G. A.; Morgan, G. W.; Carney, Shane

doi:10.1016/s0140-6736(78)90479-8

Cited by 320 publications

(101 citation statements)

References 11 publications

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“…17 Among the 28 trials included in our meta-analysis, 14,18-41 10 had to have variance imputed. 18,19,23,24,27,31,32,38,39 Mean effect sizes were calculated by weighting each trial by the inverse of the variance. 16 Weighted linear regression was used to examine the dose response relationship between the change in urinary sodium and the change in blood pressure.…”

Section: Statistical Analysesmentioning

confidence: 99%

“…14,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] The median age was 50 years (ranging from 24 to 73 years). Of the 17 trials, 11 employed crossover design 14,18,20,21,24,[27][28][29][31][32][33] and six used paralleled comparisons.…”

Section: Effect On Blood Pressurementioning

confidence: 99%

“…Of the 17 trials, 11 employed crossover design 14,18,20,21,24,[27][28][29][31][32][33] and six used paralleled comparisons. 19,22,23,25,26,30 Nine out of the 17 trials were double-blind, 20,21,27-33 seven were blood pressure observer-blind, 14,19,[22][23][24][25][26] and one did not report any blinding procedure. 18 The study Figure 1 Summary of studies assessed and excluded through the stages of the meta-analysis.…”

Section: Effect On Blood Pressurementioning

confidence: 99%

“…18,19,[22][23][24][25][26] The number of trials using intention-to-treat analysis was small (seven out of 28 trials). 14,26,29,30,36,37 However, the percentage of subjects who were lost to follow-up after randomisation was small (6% on average).…”

Section: Study Qualitymentioning

confidence: 99%

“…In relation to salt, this can only be done by the use of salt tablets (Slow Sodium and placebo). Among the 28 trials included in our metaanalysis, 16 were double-blind, 20,21,[27][28][29][30][31][32][33][34][35][36][38][39][40] 11 were blood pressure observer-blind, 14,19,[22][23][24][25][26]37,41 and only one small trial in hypertensives was non-blind. 18 Reanalysing the data by excluding the non-blind study 18 showed that the results were unchanged.…”

Section: Study Qualitymentioning

confidence: 99%

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

2002

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Two recent meta-analyses of randomised salt reduction trials have concluded that there is little purpose in reducing salt intake in the general population. However, the authors, as with other previous meta-analyses, included trials of very short duration (eg 1 week or less) and trials of acute salt loading followed by abrupt reductions to very low salt intake (eg from 20 to less than 1 g of salt/day). These acute salt loading and salt depletion experiments are known to increase sympathetic tone, and with salt depletion cause a rise in renin release and, thereby, plasma angiotensin II. These trials are not appropriate, therefore, for helping to inform public health policy, which is for a more modest reduction in salt intake, ie, from a usual intake of E10 to E5 g of salt per day over a more prolonged period of time. We carried out a meta-analysis to assess the effect of a modest salt reduction on blood pressure. Our data sources were MEDLINE, EMBASE, Cochrane library, CINAHL, and the reference lists of original and review articles. We included randomised trials with a modest reduction in salt intake and a duration of 4 or more weeks. Meta-analysis, meta-regression, and funnel plots were performed. A total of 17 trials in hypertensives (n ¼ 734) and 11 trials in normotensives (n ¼ 2220) were included in our study. The median reduction in 24-h urinary sodium excretion was 78 mmol (equivalent to 4.6 g of salt/day) in hypertensives and 74 mmol in normotensives. The pooled estimates of blood pressure fall were 4.96/2.73 7 0.40/0.24 mmHg in hypertensives (Po0.001 for both systolic and diastolic) and 2.03/ 0.97 7 0.27/0.21 mmHg in normotensives (Po0.001 for both systolic and diastolic). Weighted linear regression analyses showed a dose response between the change in urinary sodium and blood pressure. A reduction of 100 mmol/day (6 g of salt) in salt intake predicted a fall in blood pressure of 7.11/3.88 mmHg (Po0.001 for both systolic and diastolic) in hypertensives and 3.57/ 1.66 mmHg in normotensive individuals (systolic: Po0.001; diastolic: Po0.05). Our results demonstrate that a modest reduction in salt intake for a duration of 4 or more weeks does have a significant and, from a population viewpoint, important effect on blood pressure in both hypertensive and normotensive individuals. This meta-analysis strongly supports other evidence for a modest and long-term reduction in population salt intake, and would be predicted to reduce stroke deaths immediately by E14% and coronary deaths by E9% in hypertensives, and reduce stroke and coronary deaths by E6 and E4%, in normotensives, respectively.

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