Dietary Reference Intakes for Sodium and Potassium (2019) / Chapter Skim
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10 Sodium: Dietary Reference Intakes Based on Chronic Disease
10 Sodium: Dietary Reference Intakes Based on Chronic Disease
Pages 263-368
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From page 263... ...
The committee characterized and graded the intake–response relationships between sodium intake and the selected indicators, which informed the sodium CDRR values.1 REVIEW AND SELECTION OF CHRONIC DISEASE INDICATORS The Guiding Principles Report recommended: The ideal outcome used to establish chronic disease [DRIs] should be the chronic disease of interest, as defined by accepted diagnostic criteria, 1 The terminology "intake–response" is used for consistency with the DRI organizing framework (see Chapter 1, Box 1-2)
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From page 264... ...
The section that follows describes the committee's approach to using the evidence provided in the TABLE 10-1 Potential Chronic Disease Indicators Reviewed for a Causal Relationship with Sodium Intake, in Order of Presentation AHRQ Committee's 2005 DRI Systematic Supplemental Indicator Report Review Literature Search Cardiovascular disease morbidity X and mortality Hypertension X X Blood pressure X X Cardiovascular disease mortalitya X X Strokea X X Myocardial infarctiona X Left ventricular mass and gross Xb X morbiditya Osteoporosis and related indicatorsa Xc X Kidney diseasea X All-cause mortalitya X NOTE: AHRQ = Agency for Healthcare Research and Quality; DRI = Dietary Reference Intake. aIndicators were reviewed as potentially informing the sodium CDRRs, but were ultimately not selected.
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From page 265... ...
. Therefore, in agreement with the AHRQ Systematic Review, the committee found insufficient evidence for an inverse relationship between low sodium intake levels (below 2,300 mg/d [100 mmol/d]
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From page 266... ...
For example, the only studies on cardiovascular disease outcomes meeting the inclusion criteria of the AHRQ Systematic Review that characterized groups with sodium intakes below 2,300 mg/d (100 mmol/d) and above 4,100 mg/d (178 mmol/d)
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From page 267... ...
. Recognizing this limitation of random-effects meta analyses, the committee also reports results using fixed-effects models for the overall effect of sodium reduction intake on cardiovascular disease incidence, hypertension incidence, systolic blood pressure, and diastolic blood pressure.
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From page 268... ...
. However, whereas the AHRQ Systematic Review used the Knapp-Hartung variance estimate throughout, the committee used the approach detailed in a February 2018 update on recom mended methods for quantitative assessment published by AHRQ (Morton et al., 2018)
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From page 269... ...
and others have noted that asymmetry in the results with seemingly missing small effects in studies with reduced sample size can be attributable to publication bias or possible other reasons, including selective outcome and/or selective analysis reporting; spurious large effects in studies of reduced sample size due to poor methodological quality of such tudies; hetero s geneity leading to an association between the size of the effect with the size of the study; or simple sampling variation. The patterns in the data can be evaluated for publication bias using a number of different approaches, with the funnel plot being the most common.
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From page 270... ...
Contrasts of low versus medium sodium intake levels, and Review of Evidence on Indicators The sections that follow present the body of evidence for a causal relationship between sodium intake and four indicators: cardiovascular disease incidence, hypertension incidence, systolic blood pressure, and diastolic blood pressure. For context, evidence and conclusions presented in the 2005 DRI Report and in the AHRQ Systematic Review are summarized for each of the indicators; the committee, however, relied on its analyses to assess the strength of the evidence.
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From page 271... ...
"combined cardiovascular disease morbidity and mortality." Many of the studies were short term, some lasting only 8 weeks, with very few cardiovascular disease events, some as low as one to three outcomes. The AHRQ Systematic Review included these studies using a continuity correction, leading to very wide confidence intervals (CIs)
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. The AHRQ Systematic Review concluded that there is a low strength of evidence to support an effect of sodium reduction on any cardiovascular disease event or the combination of morbidity and mortality.
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From page 273... ...
. China SSS = China Salt Substitute Study; CI = confidence interval; CVD = cardiovascular disease; df = degrees of freedom; I2 = statistic that describes the percent of variation across studies due to heterogeneity; Na = sodium; Q = Q statistic; REML = restricted maximum likelihood; rev = revised as compared to estimate used in the AHRQ Systematic Review; TOHP = Trials of Hypertension Prevention; TONE = Trial of Nonpharmacologic Interventions in the Elderly.
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From page 274... ...
. CI = confidence interval; CVD = cardiovascular disease; df = degrees of freedom; I2 = statistic that describes the percent of variation across studies due to heterogeneity; Na = sodium; Q = Q statistic; REML = restricted maximum likelihood; rev = revised as compared to estimate used in the AHRQ Systematic Review; TOHP = Trials of Hypertension Prevention; TONE = Trial of Nonpharmacologic Interventions in the Elderly; w/o = without.
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From page 275... ...
Updated strength-of-evidence evaluation Using GRADE and the additional analyses described above, the committee reassessed the strength of evidence for the causal relationship between sodium intake reduction and reduction in cardiovascular disease incidence (see Table 10-2)
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" (downgrade two levels) other possibility is that the intervention only occurred during the initial trial, so it is possible that sodium intake changed during the long-term follow-up period.
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" or "(+2) " depending on whether upgrade is one or two levels bThis terminology was used for consistency with the AHRQ Systematic Review.
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BOX 10-4 Summary of Evidence Presented in the 2005 DRI Report and the AHRQ Systematic Review on Hypertension 2005 DRI Report Three trials on the relationship between sodium intake and incidence of hy pertension were explored in the 2005 DRI Report (IOM, 2005) : the Hypertension Prevention Trial (HPTRG, 1990)
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From page 279... ...
Updated strength-of-evidence evaluation Using GRADE and the additional analysis described above, the committee reassessed the strength of evidence for a causal relationship between sodium intake reduction and reduction in hypertension incidence (see Table 10-3)
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Blood Pressure As summarized in Box 10-5, evidence on the relationship between sodium intake and blood pressure was included in both the 2005 DRI Report (IOM, 2005) and the AHRQ Systematic Review (Newberry et al., 2018)
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BOX 10-5 Summary of Evidence Presented in the 2005 DRI Report and the AHRQ Systematic Review on Blood Pressure 2005 DRI Report Based on the number of trials that found a positive relationship between sodium intake and blood pressure and the persuasive data of blood pressure as a biomarker of cardiovascular disease, blood pressure was selected as the indicator of adverse effects from excessive sodium intake in the 2005 DRI Report (IOM, 2005)
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From page 282... ...
Children and Adolescents 1–18 Years of Age Eight parallel trials were included in the AHRQ Systematic Review that assessed the relationship between sodium reduction and systolic blood pres sure and seven trials assessed the relationship between sodium reduction and diastolic blood pressure in children and adolescents. The overall effects were nonsignificant.
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From page 283... ...
. The AHRQ Systematic Review concluded that there was low strength of evidence that so dium reduction may not significantly lower systolic blood pressure in children and adolescents and that there was low strength of evidence that sodium reductions reduce diastolic blood pressure (based only on low- and moderate-risk-of-bias studies)
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From page 284... ...
In addition, the definitions for hypertension have changed over time and so may not be consistent from study to study or with current guidelines. Results from the committee's analyses on systolic blood pressure The metaanalyses results using the revised data were similar to those in the AHRQ Systematic Review.
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From page 285... ...
For studies with multiple contrasts, a description of the comparison represented in the meta-analysis follows the author's name. CI = confidence interval; DASH = Dietary Approaches to Stop Hypertension; HPT = Hypertension Prevention Trial; I2 = statistic that describes the percent of variation across studies due to heterogeneity; K-H = Knapp-Hartung variance estimate; Na = sodium; RE = random-effects; rev = revised as compared to estimate used in the AHRQ Systematic Review; SBP = systolic blood pressure; TOHP = Trials of Hypertension Prevention.
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From page 286... ...
Given the evidence for an intake–response gradient for sodium intake and systolic blood pressure from meta-regression analyses, the committee also evaluated whether effects of sodium reduction on systolic blood pres
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linear meta-regression model with each of these spline regression models were not statistically significant (p = .27) , supporting linearity of the effect on systolic blood pressure over the range of sodium intake levels.
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Systematic Review. As presented in Figure 10-9, the committee's overall estimate was a diastolic blood pressure change of −2.16 mm Hg ([95% CI: −2.84, −1.48]
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For studies with multiple contrasts, a description of the comparison represented in the metaanalysis follows the author's name. CI = confidence interval; HPT = Hypertension Prevention Trial; I2 = statistic that describes the percent of variation across studies due to heterogeneity; K-H = Knapp-Hartung variance estimate; Na = sodium; RE = random-effects; rev = revised as compared to estimate used in the AHRQ Systematic Review; SBP = systolic blood pressure; TOHP = Trials of Hypertension Prevention.
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From page 290... ...
There was no apparent effect of baseline sodium level on either measure, suggesting a similar effect of sodium reduction throughout the baseline range of sodium examined. Publication bias was not detected for systolic blood pressure, but it was suggested in diastolic blood pressure.
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From page 291... ...
Therefore, the effect of potential publication bias is not likely to be large enough to affect the overall strength of the evidence. Using GRADE and the committee's analyses, the committee reassessed the strength of evidence that reducing sodium intake reduces systolic blood pressure or diastolic blood pressure (see Tables 10-6 and 10-7, respectively)
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From page 292... ...
FIGURE 10-11 Meta-regression of trials of sodium intake reduction showing the e ffect of the baseline diastolic blood pressure on the diastolic blood pressure effect size. NOTE: CI = confidence interval; DBP = diastolic blood pressure; I2 = statistic that describes the percent of variation across studies due to heterogeneity.
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From page 293... ...
For studies with multiple contrasts, a description of the comparison represented in the meta-analysis follows the author's name. CI = confidence interval; DBP = diastolic blood pressure; HPT = Hypertension Prevention Trial; I2 = statistic that describes the percent of variation across studies due to heterogeneity; K-H = Knapp-Hartung variance estimate; Na = sodium; RE = random-effects; rev = revised as compared to estimate used in the AHRQ Systematic Review; TOHP = Trials of Hypertension Prevention.
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From page 294... ...
Although the overall summary estimate had substantial heterogeneity, with I2 = 76 percent, meta-regression and subgroup analyses showed that most of the heterogeneity is explained by the difference in sodium intake between control and intervention groups and hypertension status and/or baseline systolic blood pressure. The residual I2 = 41 percent is considered "moderate."c Indirectness No (0)
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From page 295... ...
Meta-regression showed that the substantial heterogeneity of the overall summary estimate (I2 = 79 percent) is partially explained by baseline diastolic blood pressure and to a small extent by the difference in sodium intake between control and intervention groups.
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From page 296... ...
Removing these large effect studies reduced heterogeneity to a low to moderate level, and there remained a statistically significant reduction in diastolic blood pressure. Based on the committee's synthesis of the evidence, as well as the Guiding Principles Report recommendation that there should be at least moderate strength of evidence of a causal relationship between intake and chronic disease, the committee selected cardiovascular disease, hypertension, systolic blood pressure, and diastolic blood pressure as the indicators that would inform the sodium CDRRs.
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From page 297... ...
Pursuant to the Guiding Principles Report recommendation on the use of surrogate markers, the committee further considered whether blood pressure could serve as a qualified surrogate marker in context of sodium intake reduction interventions. The evidence and rationale for qualifying systolic blood pressure and diastolic blood pressure as surrogate markers for predicting the effects of changes in sodium intake on changes in the incidence of hypertension and cardiovascular disease is presented in Annex 10-2.
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From page 298... ...
Of these two blood pressure measures, systolic blood pressure is more strongly related to cardiovascular disease risk than is diastolic blood pressure. Although any of these indicators alone may be adequate for supporting an intake–response relationship between sodium and chronic disease risk, the committee considered the evidence to be stronger if there were consistency across these four indicators in accordance with the relationships depicted in the framework for sodium chronic disease outcomes (see Figure 10-13)
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From page 299... ...
. Sodium Intake Levels Studied in Eligible Randomized Controlled Trials The second framing issue is to characterize the range of sodium intakes over which the available studies have examined the selected indicators of cardiovascular disease, hypertension, systolic blood pressure, and diastolic blood pressure.
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by dividing by the difference in sodium intake between study arms. Therefore, for each indicator (cardiovascular disease incidence, hypertension incidence, systolic blood pres sure, and diastolic blood pressure)
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Specifically, for each intake range considered, the key question was the strength of evidence of a positive slope -- that is, reductions in sodium intake reduce chronic disease risk. Rating Evidence for Chronic Disease Intake–Response The committee rated the evidence for chronic disease intake–response separately for the three different sodium intake ranges (2,300–4,100, > 4,100, and < 2,300 mg/d [100–178, > 178, and < 100 mmol/d, respectively]
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From page 302... ...
BP = blood pressure; CVD = cardio ascular v disease; DASH = Dietary Approaches to Stop Hypertension; HPT = Hypertension Prevention Trial; HTN = hypertension; mg/d = milligrams per day; Na = sodium; rev = revised as compared to estimate used in the AHRQ Systematic Review; TOHP = Trials of Hypertension Prevention; TONE = Trial of Nonpharmacologic Interventions in the Elderly.
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. The systolic blood pressure slope in all subgroup analyses remained sta 9 Cardiovascular disease events collected in the individual studies included myocardial infarction, angina, congestive heart failure, coronary revascularization, stroke, transient ischemic attack, arrhythmia, or other.
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Each sodium level was consumed for 4 weeks. All participants were normotensive with systolic blood pres sure ≤ 130 mm Hg and diastolic blood pressure ≤ 85 mm Hg and were not on antihypertensive therapy.
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(2012) reported no changes in blood pressure between groups with different sodium intakes.
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To convert to mmol, divide the milligram value by 23.0. DASH = Dietary Approaches to Stop Hypertension; DBP = diastolic blood pressure; HPT = Hypertension Prevention Trial; mg/d = milligrams per day; Na = sodium; rev = revised as compared to estimate used in the AHRQ Systematic Review; SBP = systolic blood pressure; TOHP = Trials of Hypertension Prevention; TONE = Trial of Nonpharmacologic Interventions in the Elderly.
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From page 307... ...
account the multiple indicators, does not combine effect sizes for different endpoints. Instead, the effect estimates are calculated separately for each outcome (cardiovascular disease incidence, hypertension incidence, systolic blood pressure, and diastolic blood pressure)
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From page 308... ...
In that manner, using GRADE and trials results from 3 comparisons on cardiovascular disease risk, 3 comparisons on risk of hypertension, and 21 comparisons on systolic and diastolic blood pressure, the committee assessed the strength of evidence that reducing sodium intake reduces chronic disease risk in the intake range 2,300– 4,100 mg/d (100–178 mmol/d)
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From page 309... ...
To convert to mmol, divide the milligram value by 23.0. CI = confidence interval; DASH = Dietary Approaches to Stop Hypertension; g/d = gram per day; HPT = Hypertension Prevention Trial; I2 = statistic that describes the percent of variation across studies due to heterogeneity; mg/d = milligrams per day; Na = sodium; rev = revised as compared to estimate used in the AHRQ Systematic Review; SBP = systolic blood pressure; TOHP = Trials of Hypertension Prevention.
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From page 310... ...
To convert to mmol, divide the milligram value by 23.0. CI = confidence interval; DASH = Dietary Approaches to Stop Hypertension; DBP = diastolic blood pressure; g/d = gram per day; HPT = Hypertension Prevention Trial; I2 = statistic that describes the percent of variation across studies due to heterogeneity; mg/d = milligrams per day; Na = sodium; rev = revised as compared to estimate used in the AHRQ Systematic Review; TOHP = Trials of Hypertension Prevention.
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From page 311... ...
per 1,000 mg/d (43 mmol/d) sodium intake reduction.
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From page 312... ...
sodium intake reduction, as indicated by cardiovascular disease, hypertension, systolic blood pressure, and diastolic blood pressure, in the intake range 2,300–4,100 mg/d (100–178 mmol/d)
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From page 313... ...
All studies used control and intervention intake levels within the specified intake range. Cardiovascular disease and hypertension are direct measures of chronic disease risk; systolic blood pressure and diastolic blood pressure are indirect but serve as qualified surrogate markers.
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From page 314... ...
To convert to mmol, divide the milligram value by 23.0. DBP = diastolic blood pressure; mg/d = milligrams per day; Na = sodium; rev = revised as compared to estimate used in the AHRQ Systematic Review; SBP = systolic blood pressure.
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From page 315... ...
All estimates used the Knapp-Hartung modification. Evidence rating for intake–response Using GRADE, the committee assessed the strength of evidence that reducing sodium intake reduces chronic disease risk in the intake range above 4,100 mg/d (178 mmol/d)
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From page 316... ...
. Overall, the AHRQ Systematic Review rated the strength of evidence that sodium intake was associated with these outcomes as low or insufficient owing to their observational design and concerns about risk of bias.
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sodium intake reduction, as indicated by cardiovascular disease, hypertension, systolic blood pressure, and diastolic blood pressure, in the intake range above 4,100 mg/d (178 mmol/d)
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Eligible studies No randomized controlled trials of cardiovascular disease and hypertension involving average sodium intakes in this range were available. The one observational study of cardiovascular disease with a low risk of bias included intakes below 2,300 mg/d (100 mg/d)
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per 1,000 mg/d (43 mmol/d) sodium intake reduction.
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From page 320... ...
To convert to mmol, divide the milligram value by 23.0. DASH = Dietary Approaches to Stop Hypertension; DBP = diastolic blood pressure; mg/d = milligrams per day; Na = sodium; rev = revised as compared to estimate used in the AHRQ Systematic Review; SBP = systolic blood pressure.
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From page 321... ...
CI = confidence interval; g/d = gram per day; I2 = statistic that describes the per cent of variation across studies due to heterogeneity; mg/d = milligrams per day; Na = sodium; rev = revised as compared to estimate used in the AHRQ Systematic Review; SBP = systolic blood pressure. depend on whether or not the midpoint of the intake range was < 2,300 mg/d (< 100 mmol/d)
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From page 322... ...
To convert to mmol, divide the milligram value by 23.0. CI = confidence interval; DBP = diastolic blood pressure; g/d = gram per day; I2 = statistic that describes the percent of variation across studies due to heterogeneity; mg/d = milligrams per day; Na = sodium; rev = revised as compared to estimate used in the AHRQ Systematic Review.
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From page 323... ...
intake reduction is expected to reduce chronic disease risk, as indicated by lowering of systolic blood pressure and diastolic blood pressure. Uncertainty in this intake range is primarily attributable to indirectness of evidence, includ ing the lack of studies directly measuring cardiovascular disease or hypertension risk reduction, and lack of studies in which both control and intervention intake levels are above 4,100 mg/d (178 mmol/d)
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sodium intake reduction, as indicated by cardiovascular disease, hypertension, systolic blood pressure, and diastolic blood pressure, in the intake range below 2,300 mg/d (100 mmol/d)
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c cardiovascular disease and hypertension providing more direct evidence of reduced chronic disease risk. Imprecision No (0)
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. In this intake range, reduction in sodium intake may reduce chronic disease risk, as indicated by lowering of systolic blood pressure and diastolic blood pressure.
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Likewise, there was a moderate strength of evidence from randomized controlled trials to suggest that reducing sodium intake reduces hypertension incidence. • The committee's meta-analyses and reassessment of the evidence provided in the AHRQ Systematic Review indicated a high strength of evidence from randomized controlled trials that reducing sodium intake reduces systolic and diastolic blood pressure.
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High of-bias observational study extends reductionc into this intake range
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From page 329... ...
To convert to mmol, divide the milligram value by 23. CI = confidence interval; CVD = cardiovascular disease; DBP = diastolic blood pressure; HTN = hypertension; RCT = randomized controlled trial; SBP = systolic blood pressure.
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cTo calculate the percent reduction from the size effect ln(RR) = −0.32 in cardiovascular disease incidence the following conversion was made: RR = exp(−0.32)
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In addition, pursuant to the guidance in the Guiding Principles Report, the committee assessed the evidence by population subgroups defined by characteristics such as demographics and health status. The AHRQ Systematic Review concluded that there was insufficient strength of evidence that sex, age, ethnicity/race, diabetes status, kidney disease, or obesity and overweight moderate the effect of sodium intake on cardiovascular disease, hypertension, or blood pressure (see Boxes 10-3 through 10-5)
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From page 332... ...
, there was high strength of evidence that reducing sodium intake reduces chronic disease risk, based on evidence of reduction in cardiovascular disease incidence, reduction in hypertension incidence, and lowering of systolic and diastolic blood pressure. At sodium intake levels above 4,100–5,000 mg/d (178–217 mmol/d)
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From page 333... ...
Establishing a sodium CDRR at this level is expected to reduce the risk of chronic disease, as supported by evidence on the relationship between sodium intake and risk for cardiovascular disease and risk for hypertension. This intake level is further supported by evidence on the relationship between sodium intake and systolic and diastolic blood pressure, which the committee considered qualified surrogate markers for cardiovascular disease and hypertension in the context of sodium intake.
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From page 334... ...
In its identification of the lowest level of intake, the committee followed the Guiding Principles Report recommendation that a DRI based on chronic disease be based on at least moderate strength of evidence for both the causal and the intake–response relationships. Such strength of evidence existed for sodium intakes down to 2,300 mg/d (100 mmol/d)
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From page 335... ...
Extrapolation to Other DRI Age and Life-Stage Groups Adults > 70 years of age The AHRQ Systematic Review concluded that there was insufficient evidence to determine a moderating effect of age on the effects of sodium reduction on cardiovascular disease. Several of the randomized controlled trials included in the committee's analyses reported allowing participants older than 70 years of age to be included in the study (Appel et al., 2001; Cappuccio et al., 2006; Howe et al., 1994; Hwang et al., 2014; Meland and Aamland, 2009; Nakano et al., 2016; Nestel et al., 1993; Schorr et al., 1996; Wing et al., 1998)
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From page 336... ...
In addition to the randomized controlled trials included in the AHRQ Systematic Review, the committee also assessed the evidence from prospective cohort studies that examined the association of sodium intake (urinary excretion or dietary assessment) and longitudinal change in blood pressure in children and adolescents (Buendia et al., 2015; Geleijnse et al., 1990; Setayeshgar et al., 2017; Shi et al., 2014)
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From page 337... ...
Extrapolated sodium CDRRs were mathematically rounded to the nearest 100 mg/d increment. TABLE 10-13 Estimated Energy Requirements for Sedentary Children and Adolescents 1–18 Years of Age, by Age Group Age Group Average EER (kcal/d)
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From page 338... ...
SUMMARY The sodium CDRRs are established through a synthesis of evidence from sodium reduction trials and outcomes of incident cardiovascular disease, incident hypertension, systolic blood pressure, and diastolic blood pressure. The sodium CDRR is the lowest level of intake for which there was sufficient strength of evidence to characterize a chronic disease risk reduction.
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From page 339... ...
2014. Methodological issues in cohort studies that relate sodium intake to cardiovascular disease outcomes: A science advisory from the American Heart Association.
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From page 340... ...
2015. Effects of tree nuts on blood lipids, apolipoproteins, and blood pressure: Systematic review, meta analysis, and dose-response of 61 controlled intervention trials.
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1983. A randomized trial of sodium intake and blood pressure in newborn infants.
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2017. Guiding prin ciples for developing Dietary Reference Intakes based on chronic disease.
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From page 343... ...
2011. Recommendations for examining and interpreting funnel plot asymmetry in meta-analyses of randomized controlled trials.
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From page 344... ...
1982. The blood pressure-raising effects of high dietary sodium intake: Racial differences and the role of potassium.
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2001. Effects of reduced sodium intake on hypertension control in older individuals: Results from the Trial of Nonpharmacologic Interventions in the Elderly (TONE)
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Hypertension Prevention Trial Research Group. Archives of Internal Medicine 150(1)
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1997. Effects of weight loss and sodium reduction intervention on blood pressure and hypertension incidence in overweight people with high-normal blood pressure.
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Evidence Provided in the AHRQ Systematic Review Two trials were identified in the AHRQ Systematic Review (Newberry et al., 2018) that examined cardiovascular disease mortality as an endpoint of reducing sodium intake.
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. The AHRQ Systematic Review concluded that there is a low strength of evidence that sodium reduction in adults may not decrease the risk of stroke.
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From page 350... ...
Committee's Synthesis of the Evidence The committee is in agreement with the assessment of the strength of evidence in the AHRQ Systematic Review, and, therefore, myocardial infarction could not be used as an indicator to inform the sodium CDRRs. Left Ventricular Mass and Gross Morbidity Evidence Presented in the 2005 DRI Report Left ventricular mass was discussed in the 2005 DRI Report because of its potential as a predictor of cardiovascular disease morbidity and mortality, as well as it being mechanistically related to increases in blood pressure.
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From page 351... ...
The AHRQ Systematic Review could not make conclusions based on this evidence. Committee's Synthesis of the Evidence The committee is in agreement with the assessment of the evidence in the AHRQ Systematic Review, and therefore neither gross morbidity nor left ventricular mass could be used as indicators to establish the sodium CDRRs (for the committee's rationale for excluding left ventricular mass from its supplementary literature search, see Appendix D)
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From page 352... ...
No other studies on kidney disease outcomes met the AHRQ Systematic Review inclusion criteria. The AHRQ Systematic Review concluded there was insufficient evidence on the relationship between sodium intake and kidney disease.
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From page 353... ...
Because a nutritional intervention in healthy individuals is unlikely to lead to effects on mortality within such a short timeframe, the committee conducted a meta-analysis that restricted inclusion to studies lasting at least 1 year and in healthy participants with no preexisting cardiovascular disease. For the committee's revisions to data from individual trials, as compared to the AHRQ Systematic Review, see Box 10-2.
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From page 354... ...
China SSS = China Salt Substitute Study; CI = confidence interval; df = degrees of freedom; I2 = statistic that describes the percent of variation across studies due to heterogeneity; Na = sodium; Q = Q statistic; REML = restricted maximum likelihood; rev = revised as compared to estimate used in the AHRQ Systematic Review; TOHP = Trials of Hypertension Prevention. SOURCES: Chang et al., 2006; Cook et al., 2016; CSSSCG, 2007.
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From page 355... ...
The variance was estimated using the REML approach. CI = confidence interval; df = degrees of freedom; I2 = statistic that describes the percent of variation across studies due to heterogeneity; Na = sodium; Q = Q statistic; REML = restricted maximum likelihood; rev = revised as compared to estimate used in the AHRQ Systematic Review; TOHP = Trials of Hypertension Prevention; w/o = without.
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From page 356... ...
" or "(+2) " depending on whether upgrade is one or two levels bThis terminology was used for consistency with the AHRQ Systematic Review.
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From page 357... ...
1999. Dietary sodium intake and subsequent risk of cardiovascular disease in overweight adults.
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2010. Higher habitual sodium intake is not detrimental for bones in older women with adequate calcium intake.
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From page 359... ...
8) Pursuant to the guidance in the Guiding Principles Report, the committee explored whether blood pressure could serve as a surrogate marker for the relationship between sodium intake, hypertension, and cardiovascular disease.14 Qualification of blood pressure as a surrogate marker implies that studies measuring blood pressure as an outcome of reducing sodium intake can be used in support of establishing a CDRR.
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From page 360... ...
. This section focuses on blood pressure as the potential surrogate marker for hypertension and cardiovascular disease because of its relevance in the committee's assessment of the evidence about the relationship between sodium intake and those health outcomes (see Figure 10-13)
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From page 361... ...
. However, these issues are to be revisited in the "Utilization" step, specifically in the context of use considered for the surrogate endpoint -- in this case for interventions involving reduced sodium intake -- discussed next.
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From page 362... ...
. Therefore, the committee took into account the possibility of requiring a "lower threshold of use," particularly with respect to the extent to which effects of sodium intake reduction on blood pressure could account for the full extent of the benefits with respect to hypertension and cardiovascular disease (discussed further below in factor 5)
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From page 363... ...
suffer from high risk of bias. Therefore, no concerns are raised with respect to unintended risks that would argue against using blood pressure as a surrogate endpoint in the case of sodium intake reduction, at least as low as the Adequate Intake of 1,500 mg/d (65 mmol/d)
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From page 364... ...
, and applied rigorously by the committee in Chapter 10. One key issue has been whether blood pressure is on the causal pathway between sodium intake reduction and hypertension or cardiovascular disease risk such that it reliably predicts changes in hypertension and cardiovascular disease risk when sodium intake is reduced.
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From page 365... ...
, there remains some uncertainty as to whether blood pressure fully explains the effect of sodium intake reductions on cardiovascular risk. In considering whether blood pressure is a qualified surrogate marker for predicting the effect of sodium intakes on cardiovascular disease risk within the DRI context, this uncertainty does not negate the committee's ability to qualify blood pressure as a surrogate marker for the purposes of establishing a CDRR for sodium and cardiovascular disease.
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From page 366... ...
Summary In the main body of Chapter 10, the committee rigorously evaluated the evidence supporting the fact that blood pressure is on the causal pathway between sodium intake and cardiovascular risk and accurately predicts the directional benefits of sodium intake reduction on cardiovascular disease risk. In this annex, the committee evaluated whether blood pressure is qualified to serve as a surrogate marker within the DRI context when sodium is the intervention of interest and chronic disease is the outcome of interest (i.e., is fit for purpose)
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From page 367... ...
2017. Guiding prin ciples for developing Dietary Reference Intakes based on chronic disease.
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