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Potassium and Hypertension:
Basis for a NRV-NCD
Mary R. L’Abbé, PhDEarle W. McHenry Professor and
Chair, Department of Nutritional Sciences
CRN-I Annual Symposium
Codex CCNFSDU - Kronberg, GermanyNovember 20, 2015
10%
0
5,000,000
10,000,000
15,000,000
20,000,000
25,000,000
0-29 30-69 70-80+
Communicable,maternal, perinatal andnutritional conditions
Noncommunicablediseases
Injuries
De
ath
s in
20
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In 2011, 13.8 million people, between age of 30-70, died from NCDs: More than 85% of these deaths occurred in developing countries
Source: WHO, Sept 2014
GENERAL PRINCIPLES FOR
ESTABLISHING NRVs
For individuals older than 36 months
Daily intake values refer to nutrient intakes provided by FAO/WHO (or other recognized scientific bodies) … that are based on a recent review of the science should be taken into consideration as the primary source in establishing NRVs
INL98 is the daily intake reference value to meet the nutrient requirement of 98% of the population
Source: Codex Alimentarius GUIDELINES ON NUTRITION LABELLING
CAC/GL 2-1985 (rev 2015)
3
SELECTION OF NUTRIENTS AND
APPROPRIATE BASIS FOR NRVS-NCD
Convincing/ generally accepted scientific evidence or the
comparable level of evidence under the GRADE
classification
relationship between a nutrient and NCD risk, including
validated biomarkers for the disease risk, for at least one
major segment of the population (e.g. adults).
Public health importance of the nutrient-NCD
relationship(s)
Relevant and peer-reviewed scientific evidence for
quantitative reference values for daily intake
Source: Codex Alimentarius GUIDELINES ON NUTRITION LABELLING
CAC/GL 2-1985 (rev 2015)
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WHO REPORTS
Source: http://www.who.int/nutrition/publications/guidelines/potassium_intake/en/
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Nutrition Guidelines Led by the WHO Dept. of Nutrition for Health and
Development
WHO Nutrition Guidance Expert Advisory Group (NUGAG) Subgroup on Diet and Health (15 members)
• Multidisciplinary, regional representation
• Subject and technical experts/methodologists without competing conflicts of interest
• No commercial or industry representatives
• Plus 7 External Resource persons who did not participate in decision making
External groups provided comments on: • Priority questions; and
• Draft guidelines
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PROCESS ISSUESTaken from my experiences with WHO
Nutrition Guidance Expert Advisory Committee – Subcommittee on Diet and
Chronic Disease (NUGAG)*
*With information provided by Dr. Joerg Meerpohl, Co-Director, Cochrane
Germany; University of Freiburg, GRADE Methodology External Resource
Person
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SYSTEMATIC REVIEW OF
ALL THE EVIDENCE …
THE GRADE PROCESS
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Guideline Development ProcessPrioritize Problems, establish panel
Systematic Review
Evidence Profile
Relative importance of outcomes
(Overall) quality of evidence
Benefit – downside evaluation
Strength of recommendation
Implementation and evaluation of guidelines
GRADE
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Quality of Evidence
Likelihood of,
and
confidence in
an outcome
10
Simple hierarchies are (too) simplistic
STUDY DESIGN
• Randomized Controlled Trials
• Prospective Cohort Studies and
Case Control Studies
• Case Reports and Case Series,
Non-systematic observations
• Ecologic studies
BIAS
Exp
ert Op
inio
n
Adapted from Schünemann & Bone, 2003
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GRADE – Assessment of quality
Quality of evidence
Study design Rating down if… Rating up if…
High randomized study (RCT)
study limitations-1 serious-2 very seriousinconsistency- 1 serious- 2 very seriousindirectness-1 serious-2 very seriousimprecision-1 serious-2 very seriouspublication bias-1 likely-2 very likely
magnitude of effect+ 1 large+ 2 very large
dose-response gradient+ 1 evidence of an
application outcome relationship
all plausible confounding+ 1 would reduce a
demonstrated effect + 1 would suggest a spurious
effect when results show no effect
Middle
Low observational study
Very low
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Study Design and Execution
From Cates , CDSR 2008
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Is the evidence sound? Observational
Studies
Overall judgment required
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Inconsistency of results - heterogeneity
Look for explanations
• patients, intervention(s), outcome, methods
Judgment of consistency
• variation in size of effect
• poor overlap in confidence intervals
• statistical significance of heterogeneity
• high I2
Unexplained inconsistency downgrade quality
Guyatt et al. JCE 2011
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Rating up quality of evidenceparticularly relevant for observational studies
3 categories:
• Magnitude of effect
– large: RR > 2 (< 0,5): rate up +1
– very large: RR > 5 (< 0,2): rate up +2
– Particulary if there are more than two observational
studies without plausible confounders and consistent
results
• existence of a dose-response gradient for the outcome of
interest: rate up +1
• all remaining, plausible confounding would reduce the
estimated effect or suggest a spurious effect when results
show no effect: rate up +1
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Systematic review
F
PICO
Outcome
Outcome
Outcome
Outcome
Critical
Important
Critical
NotSummary of findings & estimate of effect for each outcome
Grade overall quality of evidence
across a variety of outcomes
1. Risk of bias2. Inconsistency3. Indirectness4. Imprecision5. Publication
bias
Gra
de
d
ow
nG
rad
e u
p 1. Large effect2. Dose
response3. Opposing bias/
Confounders
Very low
Low
Moderate
High
Governments and OthersScientific Review
Quality of evidence
Balance benefits/harms
Risk Management
Values and preferences
Intended use/application
Resource use (cost)
WHO Guidelines
OOO
O
OO
National Policy RecommendationsCodex Guidelines
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Outcome – Resting Systolic BP
Summary
21 Studies
-3.06
(-4.70 to -1.42)
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Greatest impact, when achieved a potassium intake of 90–120 mmol/ day (3510
– 4680 mg) 5.82 mmHg (95%CI: -0.79, 12.43) (quality of evidence moderate).
SBP - Effect higher in Hypertensives
Summary
16 Studies in
hypertensives
-4.68
(-6.96 to -2.40)
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Outcome – Resting Diastolic BP
Summary
21 Studies
-2.84
(-4.66 to -1.01)
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Greatest impact, when achieved a potassium intake of 90–120 mmol/ day (3510
– 4680 mg) of 3.52 mmHg (95%CI: -1.24, 8.28) (quality of evidence moderate).
DBP- Effect higher in Hypertensives
Summary
16 Studies in
hypertensives
-3.66
(-6.40 to -0.91)
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SUB-GROUP EFFECT ESTIMATES
BP Status (normotensive, hypertensive, mixed)
Achieved K intake in intervention (<70, 70-90, 90-120, >120
mmol)
Difference in achieved K intakes - intervention vs control
(<30, 30-60, >60 mmol)
K intake at baseline (40 vs 40-60 vs >60)
Na intake at baseline (<2, 2-4, >4 g/day)
Duration (<2, 2-4, >4 months)
Type of BP device (automatic, manual)
Type of BP measure (supine, seated, standing, ND)
Hypertension medication status (No, Yes, mixed/ND)
Study design (parallel vs cross-over)
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GRADE - Summary of Findings
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Resting BP reduced by 3.06 mm Hg with increased K intake
CONTEXT
Blood pressure as a valid biomarker for hard outcomes.
Hypertension is considered a major risk factor for CVD 1,
especially CHD and stroke; estimated to contribute to 49%
of all CHD and 62% of all stroke 2
Blood pressure during childhood has a significant
association with blood pressure during adulthood, and are
at high risk as adults 3 and during childhood itself 4
IOM Evaluation of Biomarkers and Surrogate Outcomes
(2010) and others
1 Lewington S, et al. Lancet, 2002 2 Mackay et al., Atlas of Heart Disease and Stroke, WHO
2004; 3 Chen X, Wang Y. Circulation, 2008; 4 Daniels et al. Circulation, 1998,
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WHO recommends an increase in potassium intake
from food to reduce blood pressure and risk of
cardiovascular disease, stroke and coronary heart
disease in adults (strong recommendation 1). WHO
suggests a potassium intake of at least 90 mmol/day
(3510 mg/day) for adults (conditional recommendation
2).
WHO suggests an increase in potassium intake from
food to control blood pressure in children (conditional
recommendation). The recommended potassium intake
of at least 90 mmol/day should be adjusted downward
for children, based on the energy requirements of
children relative to those of adults.
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WHO RECOMMENDATIONS FROM
EVIDENCE REVIEW
Examples of Typical Potassium Levels
in Foods
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Codex Guidelines on Nutrition
Labelling CAC/GL 2-1985 (rev 2015)
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10 The selection of these nutrients for the establishment of an NRV was based on “high quality” evidence for a
relationship with a biomarker for NCD risk in adults as reported in the respective 2012 WHO Guidelines on
sodium and potassium intake for adults and children.
Funding
Thank You - QuestionsMary R. L’Abbe, PhD
Earle W. McHenry Professor, and
Chair, Department of Nutritional Sciences
Faculty of Medicine, University of Toronto
FitzGerald Building, 150 College Street
Toronto, ON, Canada M5S 3E2
mary.labbe@utoronto.ca
E.W. McHenry
Endowed Chair
(M. L’Abbe)
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