Prevention

Dietary Considerations for Cardiovascular Disease Risk Reduction

Editors: Maria Sciammarella MD; Zbigniew Fedorowicz PhD, MSc, DPH, BDS, LDSRCS; Peter Oettgen MD

References

General References Used

The references listed below are used in this DynaMed topic primarily to support background information and for guidance where evidence summaries are not felt to be necessary. Most references are incorporated within the text along with the evidence summaries.

  1. Van Horn L, Carson JA, Appel LJ, et al; American Heart Association Nutrition Committee of the Council on Lifestyle and Cardiometabolic Health, Council on Cardiovascular Disease in the Young, Council on Cardiovascular and Stroke Nursing, Council on Clinical Cardiology, and Stroke Council. Recommended Dietary Pattern to Achieve Adherence to the American Heart Association/American College of Cardiology Guidelines: A Scientific Statement From the American Heart Association. Circulation. 2016 Nov 29;134(22):e505-e529, correction can be found in Circulation 2016 Nov 29;134(22):e534.
  2. United States Department of Health and Human Services, United States Department of Agriculture (DHHS/DA). Dietary Guidelines for Americans 2015-2020, 8th edition. DHHS/DA 2015 Dec PDF.
  3. Eckel RH, Jakicic JM, Ard JD, et al. 2013 AHA/ACC guideline on lifestyle management to reduce cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014 Jun 24;129(25 Suppl 2):S76-99, corrections can be found in Circulation 2014 Jun 24;129(25 Suppl 2):S100 and Circulation 2015 Jan 27;131(4):e326 .

Recommendation Grading Systems Used

  • American Association of Clinical Endocrinologists/American College of Endocrinology/The Obesity Society (AACE/ACE/TOS)
    • grades of recommendation
      • Grade A - best evidence level 1, or best evidence level 2 but adjusted upwards for positive subjective factors
      • Grade B - best evidence level 2, or best evidence level 1 adjusted downwards for negative subjective factors, or best evidence level 3 adjusted upwards for positive subjective factors
      • Grade C - best evidence level 3, or best evidence level 2 adjusted downwards for negative subjective factors, or best evidence level 4 adjusted upwards for positive subjective factors
      • Grade D - best evidence level 4, or best evidence level 3 adjusted downwards for negative subjective factors, or < two-thirds consensus (regardless of evidence level)
    • levels of evidence
      • Best Evidence Rating Level (BEL) 1 - randomized trials or meta-analysis of randomized trials
      • Best Evidence Rating Level (BEL) 2 - nonrandomized controlled trial, prospective cohort study, retrospective case-control study, or meta-analysis of these types of studies
      • Best Evidence Rating Level (BEL) 3 - cross-sectional study, surveillance study, consecutive case series, or single case reports
      • Best Evidence Rating Level (BEL) 4 - no evidence (theory, opinion, consensus, review, or preclinical study)
    • Reference - AACE/ACE/TOS guideline on healthy eating for prevention and treatment of metabolic and endocrine diseases in adults (Endocr Pract 2013 Sep-Oct;19 Suppl 3:1)
  • American Heart Association (AHA) grading system
    • classifications of recommendations
      • Class I - procedure or treatment should be performed or administered
      • Class IIa - reasonable to perform procedure or administer treatment, but additional studies with focused objectives needed
      • Class IIb - procedure or treatment may be considered; additional studies with broad objectives needed, additional registry data would be useful
      • Class III - procedure or treatment should not be performed or administered because it is not helpful or may be harmful
        • Class III ratings may be subclassified as Class III No Benefit or Class III Harm
    • levels of evidence
      • Level A - high-quality evidence from > 1 randomized controlled trial or meta-analysis of high-quality randomized controlled trials
      • Level B-R - moderate-quality evidence from ≥ 1 randomized controlled trial or meta-analysis of moderate-quality randomized controlled trials
      • Level B-NR - moderate-quality evidence from ≥ 1 well-designed nonrandomized trial, observational studies, or registry studies, or meta-analysis of such studies
      • Level C-LD - randomized or nonrandomized studies with methodological limitations or meta-analyses of such studies
      • Level C-EO - consensus of expert opinion based on clinical experience
    • Reference - AHA scientific statement on omega-3 polyunsaturated fatty acid (fish oil) supplementation and prevention of clinical cardiovascular disease (Circulation 2017 Apr 11;135(15):e867)
  • American College of Cardiology/American Heart Association (ACC/AHA) grading system for recommendations
    • classes of recommendations
      • Class I (Strong) - should be performed or administered; indicated/useful/effective/beneficial
      • Class IIa (Moderate) - reasonable to perform or administer; can be useful/effective/beneficial
      • Class IIb (Weak) - may be considered; usefulness/effectiveness is unknown/unclear/uncertain or not well established
      • Class III: No Benefit (Moderate) - should not be performed or administered; not indicated/useful/effective/beneficial
      • Class III: Harm (Strong) - should not be performed or administered; potentially harmful, causes harm, or associated with excess morbidity/mortality
    • levels of evidence
      • Level A - high-quality evidence from > 1 randomized controlled trial (RCT), meta-analyses of high-quality RCTs, or ≥ 1 RCTs corroborated by high-quality registry studies
      • Level B-R - moderate-quality evidence from ≥ 1 RCTs or meta-analysis of moderate-quality RCTs
      • Level B-NR - moderate-quality evidence from ≥ 1 well-designed, well-executed nonrandomized studies, observational studies, or registry studies, or meta-analysis of such studies
      • Level C-LD - randomized or nonrandomized observational or registry studies with limitations of design or execution, meta-analyses of such studies, or physiological or mechanistic studies in human subjects
      • Level C-EO - consensus of expert opinion based on clinical experience
    • PubMed30879355CirculationCirculation2019091014011e596-e646e596Reference - ACC/AHA guideline on primary prevention of cardiovascular disease (Circulation 2019 Sep 10;140(11):e596 or J Am Coll Cardiol 2019 Sep 10;74(10):1376)
  • American College of Cardiology/American Heart Association (ACC/AHA) grading system for recommendations
    • classifications of recommendations
      • Class I - procedure or treatment should be performed or administered
      • Class IIa - reasonable to perform procedure or administer treatment, but additional studies with focused objectives needed
      • Class IIb - procedure or treatment may be considered; additional studies with broad objectives needed, additional registry data would be useful
      • Class III - procedure or treatment should not be performed or administered because it is not helpful or may be harmful
        • Class III ratings may be subclassified as Class III No Benefit or Class III Harm
    • levels of evidence
      • Level A - data derived from multiple randomized clinical trials or meta-analyses
      • Level B - data derived from single randomized trial or nonrandomized studies
      • Level C - only expert opinion, case studies, or standard of care
    • Reference - 2013 ACC/AHA guideline on lifestyle management to reduce cardiovascular risk (Circulation 2014 Jun 24;129(25 Suppl 2):S76), corrections can be found in Circulation 2014 Jun 24;129(25 Suppl 2):S100 and Circulation 2015 Jan 27;131(4):e326
  • Hypertension Canada grades of recommendations
    • Grade A - recommendations based on randomized trials (or systematic reviews) with high levels of internal validity and statistical precision for which study results can be directly applied to patients because of similar clinical characteristics and clinical evidence of study outcomes
    • Grade B - recommendations based on randomized trials, systematic reviews, or prespecified subgroup analyses of randomized trials that have lower precision, or if there is a need to extrapolate from studies because of differing populations or reporting of validated intermediate/surrogate outcomes rather than clinically important outcomes
    • Grade C - recommendations from trials with lower levels of internal validity and/or precision, or that report unvalidated surrogate outcomes, or results from nonrandomized observational studies
    • Grade D - recommendations based on expert opinion alone
    • PubMed32389335The Canadian journal of cardiologyCan J Cardiol20200501365596-624596Reference - Hypertension Canada guideline on diagnosis, risk assessment, prevention, and treatment of hypertension in adults and children (Can J Cardiol 2020 May;36(5):596)
  • European Society of Cardiology/European Society of Hypertension (ESC/ESH) grading system
    • classifications of recommendations
      • Class I - evidence and/or general agreement that procedure or treatment is beneficial, useful, effective
      • Class II - conflicting evidence and/or divergence of opinion about usefulness/efficacy of given treatment of procedure
        • Class IIa - weight of evidence/opinion in favor of usefulness/efficacy
        • Class IIb - usefulness/efficacy less well established by evidence/opinion
      • Class III - evidence or general agreement that procedure or treatment is not useful/effective, and in some cases may be harmful
    • levels of evidence
      • Level A - data derived from multiple randomized clinical trials or meta-analyses
      • Level B - data derived from single randomized trial or large nonrandomized studies
      • Level C - consensus opinions of experts, and/or small studies, retrospective studies, or registries
    • Reference - ESC/ESH guideline on management of arterial hypertension (Eur Heart J 2018 Sep 1;39(33):3021)

Synthesized Recommendation Grading System for DynaMed Content

  • The DynaMed Team systematically monitors clinical evidence to continuously provide a synthesis of the most valid relevant evidence to support clinical decision-making (see 7-Step Evidence-Based Methodology).
  • Guideline recommendations summarized in the body of a DynaMed topic are provided with the recommendation grading system used in the original guideline(s) and allow users to quickly see where guidelines agree and where guidelines differ from each other and from the current evidence.
  • In DynaMed content, we synthesize the current evidence, current guidelines from leading authorities, and clinical expertise to provide recommendations to support clinical decision-making in the Overview & Recommendations section.
  • We use the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to classify synthesized recommendations as Strong or Conditional.
    • Strong recommendations may be used when, based on the available evidence, clinicians (without conflicts of interest) consistently have a high degree of confidence that the desirable consequences (health benefits, decreased costs and burdens) outweigh the undesirable consequences (harms, costs, burdens).
    • Conditional recommendations may be used when, based on the available evidence, clinicians believe that desirable and undesirable consequences are finely balanced, or appreciable uncertainty exists about the magnitude of expected consequences (benefits and harms).
    • Conditional recommendations may be used when clinicians disagree in judgments of the relative benefit and harm or have limited confidence in their judgments.
    • Conditional recommendations may also be used when the range of patient values and preferences suggests that informed patients are likely to make different choices.
  • DynaMed synthesized recommendations (in the Overview & Recommendations section) are determined with a systematic methodology.
    • Recommendations are explicitly labeled as Strong recommendations or Conditional recommendations when a qualified organization has explicitly deliberated on making such a recommendation.
    • Recommendations are phrased to match the strength of recommendation.
      • Strong recommendations use "should do" phrasing, or phrasing implying an expectation to perform the recommended action for most patients.
      • Conditional recommendations use "consider" or "suggested" phrasing.
    • Recommendations are verified by ≥ 1 editor with methodological expertise, not involved in recommendation drafting or development, with explicit confirmation that Strong recommendations are adequately supported.
    • Recommendations are published only after consensus is established with agreement in phrasing and strength of recommendation by all editors.
    • If recommendations are questioned during peer review or post publication by a qualified individual, or reevaluation is warranted based on new information detected through systematic literature surveillance, the recommendation is subject to additional internal review.

DynaMed Editorial Process

  • DynaMed topics are created and maintained by the DynaMed Editorial Team and adhere to evidence-based methodology and inclusive language standards.
  • All editorial team members and reviewers have declared that they have no financial or other competing interests related to this topic, unless otherwise indicated.
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Special Acknowledgements

  • DynaMed topics are written and edited through the collaborative efforts of the above individuals. Deputy Editors, Section Editors, and Topic Editors are active in clinical or academic medical practice. Recommendations Editors are actively involved in development and/or evaluation of guidelines.
  • Editorial Team role definitions
    Topic Editors define the scope and focus of each topic by formulating a set of clinical questions and suggesting important guidelines, clinical trials, and other data to be addressed within each topic. Topic Editors also serve as consultants for the internal DynaMed Editorial Team during the writing and editing process, and review the final topic drafts prior to publication.
    Section Editors have similar responsibilities to Topic Editors but have a broader role that includes the review of multiple topics, oversight of Topic Editors, and systematic surveillance of the medical literature.
    Recommendations Editors provide explicit review of Overview and Recommendations sections to ensure that all recommendations are sound, supported, and evidence-based. This process is described in "Synthesized Recommendation Grading."
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DynaMed Levels of Evidence

Quickly find and determine the quality of the evidence.

DynaMed provides easy-to-interpret Level of Evidence labels so users can quickly find and determine the quality of the best available evidence. Evidence may be labeled in one of three levels:

1Level 1 (likely reliable) Evidence
Representing research results addressing clinical outcomes and meeting an extensive set of quality criteria which minimizes bias.
There are two types of conclusions which can earn a Level 1 label: levels of evidence for conclusions derived from individual studies and levels of evidence for conclusions regarding a body of evidence.
2Level 2 (mid-level) Evidence
Representing research results addressing clinical outcomes, and using some method of scientific investigation, but not meeting the quality criteria to achieve Level 1 evidence labeling.
3Level 3 (lacking direct) Evidence
Representing reports that are not based on scientific analysis of clinical outcomes. Examples include case series, case reports, expert opinion, and conclusions extrapolated indirectly from scientific studies.

Grades of Recommendation

Guideline producers are now frequently using classification approaches for their evidence and recommendations, and these classifications are recognized and requested by guideline users. When summarizing guideline recommendations for DynaMed users, the DynaMed Editors are using the guideline-specific classifications and providing guideline classification approach when this is done.

Download the full version of Levels of Evidence