Dietary Reference Intakes for Sodium and Potassium (2019) / Chapter Skim
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Appendix C: Committee's Assessment of the "Agency for Healthcare Research and Quality Systematic Review"
Appendix C: Committee's Assessment of the "Agency for Healthcare Research and Quality Systematic Review"
Pages 431-446
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From page 431... ...
The details of the additional data analyses conducted by the committee for the purposes of the expanded assessment are included in Chapters 6 and 10. This appendix includes the committee's approach to reviewing the quality of the AHRQ Systematic Review and to expanding the assessment of the evidence as the fundamental basis for the deliberations regarding establishing Chronic Disease Risk Reduction Intakes for potassium and sodium.
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From page 432... ...
. In spite of using assessment tools that are objective and formally accepted by the scientific community, the committee recognizes that all assessments regarding determination of risk of bias for individual studies and strength of the evidence for the body of evidence for a specific outcome entail a certain 1 AMSTAR stands for A Measurement Tool to Assess Systematic Reviews.
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From page 433... ...
, the committee accepted these minor discrepancies as typical and determined that based on this limited spot check, the application of the risk-of-bias tools in the AHRQ Systematic Review was appropriate. Assessing the Application of Strength-of-Evidence Domains The committee conducted a number of checks related to the AHRQ Systematic Review, particularly for outcomes that would likely be relevant for setting DRI values (e.g., blood pressure, cardiovascular disease)
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From page 434... ...
A major difference that could have led to differences in the final determination, however, was in the application of the inconsistency domain, which refers to the unexplained heterogeneity or variability of study results in a body of evidence, or the imprecision domain. For example, the World Health Organization's 2012 systematic review concluded that randomized controlled trials on the relationship between sodium intake and blood pressure did not show a serious inconsistency (based on inconsistency in the direction or the size of the effect)
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From page 435... ...
Thus, the strength of evidence was downgraded for each conclu sion because of "unexplained heterogeneity." If the subgroup analyses that were conducted or additional subgroup analyses that were not conducted (e.g., based on different blood pressure methodology, use of antihypertensive medications, or differences in achieved sodium intake) had resulted in consistency across effect sizes as well as significant falls in heterogeneity (as indicated by the I 2 values)
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From page 436... ...
2017. Guiding prin ciples for developing Dietary Reference Intakes based on chronic disease.
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From page 437... ...
RISK OF BIAS ASSESSMENT FOR RANDOMIZED CONTROLLED TRIALS Random Sequence Generation (Selection Bias) For randomized controlled trials, is the sequence generation (recruitment)
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From page 438... ...
• High risk: Participants or investigators enrolling participants could possibly foresee assignments and thus introduce selection bias, such as allocation based on: using an open random allocation schedule (e.g., a list of random numbers) ; assignment envelopes were used without appropriate safeguards (e.g., if envelopes were unsealed or nonopaque or not sequentially numbered)
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From page 439... ...
For randomized controlled trials and clinical controlled trials, could high attrition or uneven attrition across study arms have contributed to bias? For crossover studies, only, was outcome reporting complete for all phases?
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From page 440... ...
. • High risk: Any one of the following: not all of the study's pre specified primary outcomes have been reported; one or more pri mary outcomes is reported using measurements, analysis methods or subsets of the data (e.g., subscales)
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From page 441... ...
• Low risk: For sodium or sodium-to-potassium ratio, exposure was assessed with at least one 24-hour urinary analysis with reported quality control measure. For potassium, exposure was assessed using at least one 24-hour urinary analysis with reported quality control measure, chemical analysis of diet or food diary with inter vention/exposure adherence measure, or composition of potassium supplement with intervention/exposure adherence measure.
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From page 442... ...
• Moderate risk or unclear: For sodium, 24-hour urinary analysis without reported quality control measure. Chemical analysis of diet without intervention/exposure adherence measure, or com position of potassium supplement without intervention/exposure adherence measure.
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From page 443... ...
• Moderate risk of bias: ° Two to measures or correction for regression dilution bias with four 24-hour urine specimens with reported quality control repeated 24-hour urine collection on a sample of participants Multiple days of food diaries ° Multiple nonconsecutive days (more than 4) 24-hour diet recalls ° or food records or correction for regression dilution bias with repeated (nonconsecutive)
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From page 444... ...
• Moderate risk of bias: ° Two dilution 24-hour urine specimens or correction for regres to four sion bias with repeated 24-hour urine collection on a sample of participants ° Two to four nonconsecutive 24-hour with repeated (noncon recalls/food records or correction for regression dilution bias secutive) 24-hour diet recalls for a sample of participants Food frequency questionnaire validated for potassium intake ° within a subset of the study population against duplicate diets or multiple 24-hour urine collections • High risk of bias: ° Single 24-hourthan one 24-hour urine specimen without any urine specimen Use of more ° reported quality control measures ° Timed-urine collection of less than 24 hours specified above ° Food frequency questionnaire other than that under "Moderate risk of bias" Single-day food records ° Single day of 24-hour recall ° Spot urine specimen(s)
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From page 445... ...
2018. Sodium and potassium intake: Effects on chronic disease outcomes and risks.
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