Assessing Cardiovascular Risk: Guideline Synthesis

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Assessing Cardiovascular Risk: Guideline Synthesis

Agency for Healthcare Research and Quality (AHRQ)

Posted: 03/01/2012

Guidelines Being Compared

  1. Greenland P, Alpert JS, Beller GA, et al; American College of Cardiology Foundation; American Heart Association. 2010 ACCF/AHA guideline for assessment of cardiovascular risk in asymptomatic adults: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2010;56:e50-e103.
  2. National Academy of Clinical Biochemistry. Emerging Biomarkers for Primary Prevention of Cardiovascular Disease and Stroke. Washington, DC: National Academy of Clinical Biochemistry; 2009.
  3. US Preventive Services Task Force. Using nontraditional risk factors in coronary heart disease risk assessment: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2009;151:474-482.

Areas of Agreement and Difference

A direct comparison of recommendations for cardiovascular risk assessment in asymptomatic adults using nontraditional risk factors is provided below. The recommendations assume that a global risk assessment incorporating multiple traditional risk factors (e.g., the Framingham Model) has been performed.

The US Preventive Services Task Force (USPSTF) recommendation specifically applies to those determined to be at intermediate (10%-20%) 10-year risk using traditional factors and with no history of coronary heart disease (CHD), diabetes, or any CHD risk equivalent. The American College of Cardiology Foundation/American Heart Association (ACCF/AHA) and National Academy of Clinical Biochemistry (NACB) make selected recommendations for higher-risk groups (e.g., those with known diabetes or hypertension); these topics, however, are beyond the scope of this synthesis.

Areas of Agreement

Lipoprotein and apolipoprotein assessments. According to ACCF/AHA, measurement of lipid parameters, including lipoproteins, apolipoproteins, particle size, and density, beyond a standard fasting lipid profile is not recommended. NACB similarly found insufficient evidence to recommend routine measurement of lipoprotein subclasses, lipoprotein(a), and apo B.

Situations cited by NACB in which measurement of lipoprotein (a) may be appropriate include if patient is at intermediate risk and uncertainty remains as to the use of preventive therapies and to identify individuals having a genetic predisposition toward cardiovascular disease (CVD) if there is a strong family history of premature CVD (identified during global risk assessment). NACB also states that the apo B/apo A-I ratio can be used as an alternative to the usual total cholesterol/high-density lipoprotein cholesterol (HDL-C) ratio to determine lipoprotein-related risk for CVD.

The USPSTF addresses only lipoprotein(a) and makes no recommendation owing to insufficient evidence.

C-reactive protein. All three groups address measurement of -reactive protein (CRP) for CVD risk assessment in intermediate-risk adults. The USPSTF makes no recommendation owing to insufficient evidence. ACCF/AHA states that it may be reasonable in men ≤50 and women ≤60. According to NACB, if global risk is intermediate and uncertainty remains about the use of preventive therapies, high-sensitivity CRP (hsCRP) measurement might be useful for further stratification into a higher or lower risk category.

ACCF/AHA also addresses CRP measurement for the selection of patients for statin therapy, stating that it can be useful in men ≥50 years and women ≥60 with a low-density lipoprotein cholesterol (LDL-C) level < 130 mg/dL; not on lipid-lowering, hormone replacement, or immunosuppressant therapy; without clinical CHD, diabetes, chronic kidney disease (CKD), severe inflammatory conditions, or contraindications to statins.

ACCF/AHA and NACB address measurement of CRP in patients at other risk stratifications, with ACCF/AHA recommending against measurement in high-risk adults and in low-risk men <50 years and low-risk women ≤60 years. NACB recommends against measurement in adults with a 10-year predicted risk < 5%.

Lipoprotein-associated phospholipase A2 (Lp-PLA2). ACCF/AHA examined Lp-PLA2 and concluded that it might be reasonable for assessment in intermediate-risk asymptomatic adults. According to NACB, although Lp-PLA2 seems promising, complete evaluation was not possible at the time of guideline publication because of the large amount of pending data.

Fibrinogen and white blood cells (WBC). NACB found that while both fibrinogen and WBC are independent markers of CVD risk, measurement of either is not recommended for this purpose. USPSTF also examined WBC, and makes no recommendation for its measurement owing to insufficient evidence.

Homocysteine level. USPSTF and NACB address homocysteine level screening. USPSTF makes no recommendation because of insufficient evidence; NACB states that screening is not warranted in healthy individuals.

Natriuretic peptides. Of the two groups to address natriuretic peptides, ACCF/AHA and NACB, neither recommend measurement for CVD risk assessment in asymptomatic adults.

Areas of Difference

Carotid intima-media thickness (IMT), ankle-brachial index (ABI), calcium scoring methods. ACCF/AHA and USPSTF address measurement of carotid -IMT, -ABI, and CAC for cardiovascular risk assessment in asymptomatic adults at intermediate risk. According to ACCF/AHA, all three are reasonable. The USPSTF, however, makes no recommendation owing to insufficient evidence.

Comparison of Recommendations: Lipoprotein and Apolipoprotein Assessments

ACCF/AHA (2010)

Lipoprotein and Apolipoprotein Assessments.

Class III: No Benefit.

Measurement of lipid parameters, including lipoproteins, apolipoproteins, particle size, and density, beyond a standard fasting lipid profile is not recommended for cardiovascular risk assessment in asymptomatic adults (Ip et al, 2009). (Level of Evidence: C)

NACB (2009)

Recommendations for LDL Subclasses and Particle Size

  1. Lipoprotein subclasses, especially the number or concentration of small, dense LDL particles, have been shown to be related to the development of initial CHD events, but the data analyses of existing studies are generally not adequate to show added benefit over standard risk assessment for primary prevention. (Classification of recommendation: III [lipoprotein subclass determination is not recommended], Level of evidence: A)
  2. There are insufficient data that measurement of lipoprotein subclasses over time is useful to evaluate the effects of treatments. (Classification of recommendation: III; Level of evidence: C)
  3. Several methods are available to assess lipoprotein subclasses. Standardization is needed for this technology. (Classification of recommendation: IIa; Level of evidence: C)

Recommendations for Lipoprotein(a)

  1. Lipoprotein (a) screening is not warranted for primary prevention and assessment of cardiovascular risk. (Classification of recommendation: III [against measurement]; Level of evidence: A)
  2. If risk is intermediate (10% to 20%) and uncertainty remains as to the use of preventive therapies such as statins or aspirin, then lipoprotein (a) measurement may be done at the physician’s discretion. (Classification of recommendations: IIb; Level of evidence: C)
  3. After global risk assessment, lipoprotein (a) measurements in patients with a strong family history of premature CVD may be useful for identifying individuals having a genetic predisposition of CVD. (Classification of recommendation: IIb; Level of evidence: C)
  4. The benefits of therapies based on lipoprotein (a) concentrations are uncertain. If both lipoprotein (a) and LDL-C are highly increased, an attempt can be made at the physician’s discretion to lower lipoprotein (a) level by lowering the elevated LDL-C. (Classification of recommendation: IIb; Level of evidence: C)

Recommendations for Apolipoproteins A-I and B

  1. The first step to monitor efficacy of lipid lowering therapies is to measure LDL-C (and non-HDL-C in patients with elevated triglycerides). (Classification of recommendation: I; Level of evidence: A)
  2. Although apo B measures atherogenic lipoproteins and is a good predictor of CVD risk (equal at least to LDL-C and non-HDL-C), it is only a marginally better predictor than the current lipid profile and should not be routinely measured at this time for use in global risk assessment. (Classification of recommendation: IIa [against measurement]; Level of evidence: B)
  3. Measurement of apo B can be used to monitor efficacy of lipid-lowering therapies as an alternative to non-HDL-C. (Classification of recommendation: IIb; Level of evidence: B)
  4. The apo B/apo A-I ratio can be used as an alternative to the usual total cholesterol/HDL-C ratio to determine lipoprotein-related risk for CVD. (Classification of recommendation: IIa; Level of evidence: A)

USPSTF (2009)

The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of using the nontraditional risk factors discussed in this statement* to screen asymptomatic men and women with no history of CHD to prevent CHD events. This is an I statement.

*hs-CRP, ABI, leukocyte count, fasting blood glucose level, periodontal disease, carotid IMT, CAC score on EBCT [electron-beam CT], homocysteine level, and lipoprotein(a) level.

Comparison of Recommendations: Inflammation Markers (CRP, Fibrinogen, White Blood Cell Count, Lp-PLA2)

ACCF/AHA (2010)

Recommendations for Measurement of CRP

Class II a

  1. In men 50 years of age or older or women 60 years of age or older with LDL-C less than 130 mg/dL; not on lipid-lowering, hormone replacement, or immunosuppressant therapy; without clinical CHD, diabetes, chronic kidney disease, severe inflammatory conditions, or contraindications to statins, measurement of CRP can be useful in the selection of patients for statin therapy (Ridker et al., «Rosuvastatin to prevent vascular events,» 2008). (Level of Evidence: B)

Class II b

  1. In asymptomatic intermediate-risk men 50 years of age or younger or women 60 years of age or younger, measurement of CRP may be reasonable for cardiovascular risk assessment (Ridker et al., 2007; Ridker et al., «C-reactive protein and parental history,» 2008). (Level of Evidence: B)

Class III: No Benefit

  1. In asymptomatic high-risk adults, measurement of CRP is not recommended for cardiovascular risk assessment (Baigent et al., 2005). (Level of Evidence: B)
  2. In low-risk men younger than 50 years of age or women 60 years of age or younger, measurement of CRP is not recommended for cardiovascular risk assessment (Ridker et al., 2007; Ridker et al., «C-reactive protein and parental history,» 2008). (Level of Evidence: B)

Recommendation for LpPLA2

Class II b

  1. Lp-PLA2 might be reasonable for cardiovascular risk assessment in intermediate-risk asymptomatic adults (Lp-PLA2 Studies Collaboration et al., 2007; Daniels et al., 2008; Garza et al., 2007; Koenig et al., 2004). (Level of Evidence: B)

NACB (2009)

Inflammation Biomarkers and Cardiovascular Disease Risk

Clinical Science

1a. After standard global risk assessment, if the 10-year predicted risk is <5%, hsCRP should not be measured. (Classification of recommendation: I; Level of evidence: A)

1b. If the 10-year risk is 5% to <10%, it is expected that 10% might be reclassified to a higher risk group with the test. More information is needed on clinical application, particularly in relation to longer-term lifetime risk prediction and selection of an appropriate intervention (lifestyle/medical). (Classification recommendation: II; Level of evidence: B)

1c. If risk is intermediate (10% to 20%) and uncertainty remains as to the use of preventive therapies such as statins or aspirin, then hsCRP measurement might be useful for further stratification into a higher or lower risk category. (Classification of recommendation: I; Level of evidence: A)

2. Therapies prescribed based on hsCRP concentrations should be based on clinical judgment of the physician because benefits of such treatment are uncertain. (Classification of recommendation: IIb; Level of evidence: B)

3. There are insufficient data that therapeutic monitoring using hsCRP over time is useful to evaluate effects of treatments in primary prevention. (Classification of recommendation: III [against use]; Level of evidence: C)

4. The utility of hsCRP concentrations to motivate patients to improve lifestyle behaviors has not been demonstrated. (Classification of recommendation: IIb; Level of evidence: C)

5. Evidence is inadequate to support concurrent measurement of other inflammatory markers in addition to hsCRP for coronary risk assessment. (Classification of recommendation: IIb; Level of evidence: C)

Population Science

Clinical Science/Laboratory Testing

  1. Measurement of hsCRP should be done in the fasting or nonfasting state in metabolically stable patients free of infection or acute illness. If the hsCRP concentration is <3 mg/L, it does not need to be repeated. If the value is >3 mg/dL, repeat the measurement at least 2 weeks later in metabolically stable state, free of infection or acute illness. The lower of the two results should be considered the patient’s value. If hsCRP is ≥10 mg/L this might relate to CV [cardiovascular] risk. Other conditions such as acute infection or inflammation or inflammatory disorders might be responsible. Extensive evaluations with imaging tests or other testing for these patients is not recommended unless pertinent history and physical examination findings are present, or if pursuing normal practice for age-appropriate population screening. (Classification of recommendation: IIa; Level of evidence: A)

Laboratory Testing

  1. Of the examined inflammatory markers for assessing CV risk, hsCRP has the analyte and assay characteristics most appropriate for use in clinical practice. (Classification of recommendation: I; Level of evidence: A)
  2. There are sufficient data that fibrinogen is an independent marker of CVD risk; however, because of analytical concerns, insufficient assay standardization, and uncertainty in identifying treatment strategies, measurement is not recommended for this application. (Classification of recommendation: III; Level of evidence: A)
  3. There are sufficient data that WBC is an independent marker of CVD risk; however, because utility in reclassifying risk level and identifying treatment strategies is not known, measurement is not recommended for this application. (Classification of recommendation: III; Level of evidence: C)
  4. hsCRP results regardless of the method used, should be expressed as mg/L. (Classification of recommendation: I; Level of evidence: C)
  5. hsCRP using standardized assays categorizes patients as follows:
    1. Low Risk <1.0 mg/L
    2. Average Risk 1.0 to 3.0 mg/L
    3. High Risk >3.0 mg/L
    4. Very High Risk ≥10.0 mg/L
      (Classification of recommendation: IIa; Level of evidence: A)
  6. Caution is recommended in application of the hsCRP categorization in recommendation 5 for risk prediction in certain populations such as nonwhites and the elderly, as the clinical utility is less established. (Classification of recommendation: IIa; Level of evidence: C)

USPSTF (2009)

The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of using the nontraditional risk factors discussed in this statement* to screen asymptomatic men and women with no history of CHD to prevent CHD events. This is an I statement.

*hs-CRP, ABI, leukocyte count, fasting blood glucose level, periodontal disease, carotid IMT, CAC score on EBCT, homocysteine level, and lipoprotein(a) level.

Comparison of Recommendations: Homocysteine Level

ACCF/AHA (2010)

No recommendations provided.

NACB (2009)

Currently homocysteine is regarded as a modest independent CVD risk factor and homocysteine screening for primary prevention and assessment of CVD risk in healthy individuals is not warranted.

USPSTF (2009)

The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of using the nontraditional risk factors discussed in this statement* to screen asymptomatic men and women with no history of CHD to prevent CHD events. This is an I statement.

*hs-CRP, ABI, leukocyte count, fasting blood glucose level, periodontal disease, carotid IMT, CAC score on EBCT, homocysteine level, and lipoprotein(a) level

Comparison of Recommendations: IMT, ABI, and Calcium Scoring Methods

ACCF/AHA (2010)

Measurement of Carotid IMT

Class II a

Measurement of carotid artery IMT is reasonable for cardiovascular risk assessment in asymptomatic adults at intermediate risk. Published recommendations on required equipment, technical approach, and operator training and experience for performance of the test must be carefully followed to achieve high-quality results (Stein et al., 2008). (Level of Evidence: B)

Measurement of ABI

Class II a

Measurement of ABI is reasonable for cardiovascular risk assessment in asymptomatic adults at intermediate risk (Ankle Brachial Index Collaboration et al., 2008). (Level of Evidence: B)

Calcium Scoring Methods

Class II a

Measurement of CAC is reasonable for cardiovascular risk assessment in asymptomatic adults at intermediate risk (10% to 20% 10-year risk) (Detrano et al., 2008; Greenland et al., 2004). (Level of Evidence: B)

Class II b

Measurement of CAC may be reasonable for cardiovascular risk assessment in persons at low to intermediate risk (6% to 10% 10-year risk) (Greenland et al., 2004; Lakoski et al., 2007; Taylor et al., 2005). (Level of Evidence: B)

Class III: No Benefit

Persons at low risk (<6% 10-year risk) should not undergo CAC measurement for cardiovascular risk assessment (Detrano et al., 2008; Greenland et al., 2004; Budoff et al., 2009). (Level of Evidence: B)

NACB (2009)

No recommendations provided.

USPSTF (2009)

The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of using the nontraditional risk factors discussed in this statement* to screen asymptomatic men and women with no history of CHD to prevent CHD events. This is an I statement.

*hs-CRP, ABI, leukocyte count, fasting blood glucose level, periodontal disease, carotid IMT, CAC score on EBCT, homocysteine level, and lipoprotein(a) level

Comparison of Recommendations: Natriuretic Peptides

ACCF/AHA (2010)

Class III: No Benefit

Measurement of natriuretic peptides is not recommended for CHD risk assessment in asymptomatic adults (Di Angelantonio et al., 2009). (Level of Evidence: B)

NACB (2009)

  1. Increased BNP or NT-proBNP concentrations are associated with increased mortality in the next 2 to 7 years in community-based populations. However, the benefits of therapy based on these measurements are uncertain. Measurement for CVD risk assessment in the primary prevention setting is unwarranted. (Classification of recommendation: III [against measurement], Level of evidence: B)

USPSTF (2009)

No recommendations provided.

Comparison of Recommendations: Metabolic and Renal Factors

ACCF/AHA (2010)

Class II b

Measurement of HbA1C may be reasonable for cardiovascular risk assessment in asymptomatic adults without a diagnosis of diabetes (Khaw et al., 2004; Khaw & Wareham, 2006; Knowler et al., 2002; Lachin et al., 2007; Selvin et al., 2004; Selvin et al., 2010). (Level of Evidence: B)

Class II b

In asymptomatic adults at intermediate risk without hypertension or diabetes, urinalysis to detect microalbuminuria might be reasonable for cardiovascular risk assessment (Arnlov et al., 2005). (Level of Evidence: B)

NACB (2009)

  1. CKD testing is not routinely recommended if the 10-year predicted risk is <5% without specific CKD or CVD risk factors, either for CKD detection or CVD risk assessment. (Classification of recommendation: III [against routine measurement]; Level of evidence: C)
  2. CKD testing, including serum creatinine for GFR [glomerular filtration rate] estimation and microalbuminuria, for primary prevention should be performed for all individuals with hypertension, diabetes mellitus, family history of CKD, and those at intermediate risk (10% to 20%) for CVD. In addition, measurement of serum creatinine for GFR estimation should be performed in all individuals >65 years old. Individual decisions are recommended in those with other CKD risk factors. (Classification of recommendation: IIa; Level of evidence: B)

USPSTF (2009)

No recommendations provided.

Strength of Evidence and Recommendation Grading System

ACCF/AHA (2010)

Applying Classification of Recommendations and Level of Evidence

Size of Treatment Effect

  • CLASS I
    Benefit >>> Risk
    Procedure/treatment SHOULD be performed/administered
  • CLASS II a
    Benefit >> Risk Additional studies with focused objectives needed
    IT IS REASONABLE to perform procedure/administer treatment
  • CLASS II b
    Benefit ≥ Risk
    Additional studies with broad objectives needed; additional registry data would be helpful Procedure/treatment MAY BE CONSIDERED
  • CLASS III No Benefit
    Procedure/test: Not helpful
    Treatment: No proven benefit
  • CLASS III Harm
    Procedure/test: Excess cost without benefit or harmful
    Treatment: Harmful to patients

Estimate of Certainty (Precision) of Treatment Effect

LEVEL A

Multiple populations evaluated*

Data derived from multiple randomized clinical trials or meta-analyses

Class I

  • Recommendation that procedure or treatment is useful/effective
  • Sufficient evidence from multiple randomized trials or meta-analyses

Class II a

  • Recommendation in favor of treatment or procedure being useful/effective
  • Some conflicting evidence from multiple randomized trials or meta-analyses

Class II b

  • Recommendation’s usefulness/efficacy less well established
  • Greater conflicting evidence from multiple randomized trials or meta-analyses

Class III

  • Recommendation that procedure or treatment is not useful/effective and may be harmful
  • Sufficient evidence from multiple randomized trials or meta-analyses

LEVEL B

Limited populations evaluated*

Data derived from a single randomized clinical trials or nonrandomized studies

Class I

  • Recommendation that procedure or treatment is useful/effective
  • Evidence from single randomized trial or nonrandomized studies

Class II a

  • Recommendation in favor of treatment or procedure being useful/effective
  • Some conflicting evidence from single randomized trial or nonrandomized studies

Class II b

  • Recommendation’s usefulness/efficacy less well established
  • Greater conflicting evidence from single randomized trial or nonrandomized studies

Class III

  • Recommendation that procedure or treatment is not useful/effective and may be harmful
  • Evidence from single randomized trial or nonrandomized studies

LEVEL C

Very limited populations evaluated*

Only consensus opinion of experts, case studies or standard of care

Class I

  • Recommendation that procedure or treatment is useful/effective
  • Only expert opinion, case studies, or standard-of-care

Class II a

  • Recommendation in favor of treatment or procedure being useful/effective
  • Only diverging expert opinion, case studies, or standard-of-care

Class II b

  • Recommendation’s usefulness/efficacy less well established
  • Only diverging expert opinion, case studies, or standard-of-care

Class III

  • Recommendation that procedure or treatment is not useful/effective and may be harmful
  • Only expert opinion, case studies, or standard-of-care

*Data available from clinical trials or registries about the usefulness/efficacy in different subpopulations, such as gender, age, history of diabetes, history of prior myocardial infarction, history of heart failure, and prior aspirin use. A recommendation with Level of Evidence B or C does not imply that the recommendation is weak. Many important clinical questions addressed in the guidelines do not lend themselves to clinical trials. Even though randomized trials are not available, there may be a very clear clinical consensus that a particular test or therapy is useful or effective.

NACB (2009)

Weight of Evidence

  1. Data derived from multiple randomized clinical trials that involved large numbers of patients
  2. Data derived from a limited number of randomized trials that involved small numbers of patients or from careful analyses of nonrandomized studies or observational registries
  3. Expert consensus was the primary basis for the recommendation

Modified American College of Cardiology/American Heart Association Classifications: Summary of Indications

  1. Conditions for which there is evidence and/or general agreement that a given procedure or treatment is useful and effective
  2. Conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness/efficacy of a procedure or treatment
    1. Weight of evidence/opinion is in favor of usefulness/efficacy
    2. Usefulness/efficacy is less well established by evidence/opinion
  3. Conditions for which there is evidence and/or general agreement that the procedure/treatment is not useful/effective and in some cases may be harmful

USPSTF (2009)

What the USPSTF Grades Mean and Suggestions for Practice

GRADE A

Grade Definition: The USPSTF recommends the service. There is high certainty that the net benefit is substantial.

Suggestions for Practice: Offer or provide this service.

GRADE B

Grade Definition: The USPSTF recommends the service. There is high certainty that the net benefit is moderate or there is moderate certainty that the net benefit is moderate to substantial.

Suggestions for Practice: Offer or provide this service.

GRADE C

Grade Definition: The USPSTF recommends against routinely providing the service. There may be considerations that support providing the service in an individual patient. There is moderate or high certainty that the net benefit is small.

Suggestions for Practice: Offer or provide this service only if other considerations support offering or providing the service in an individual patient.

GRADE D

Grade Definition: The USPSTF recommends against the service. There is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits.

Suggestions for Practice: Discourage the use of this service.

I STATEMENT

Grade Definition: The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of the service. Evidence is lacking, of poor quality, or conflicting, and the balance of benefits and harms cannot be determined.

Suggestions for Practice: Read «Clinical Considerations» section of USPSTF Recommendation Statement (see «Major Recommendations» field). If this service is offered, patients should understand the uncertainty about the balance of benefits and harms.

USPSTF Levels of Certainty Regarding Net Benefit

Definition: The U.S. Preventive Services Task Force defines certainty as «likelihood that the USPSTF assessment of the net benefit of a preventive service is correct.» The net benefit is defined as benefit minus harm of the preventive service as implemented in a general, primary care population. The USPSTF assigns a certainty level based on the nature of the overall evidence available to assess the net benefit of a preventive service.

Level of Certainty: High

Description: The available evidence usually includes consistent results from well-designed, well-conducted studies in representative primary care populations. These studies assess the effects of the preventive service on health outcomes. This conclusion is therefore unlikely to be strongly affected by the results of future studies.

Level of Certainty: Moderate

Description: The available evidence is sufficient to determine the effects of the preventive service on health outcomes, but confidence in the estimate is constrained by factors such as:

  • The number, size, or quality of individual studies
  • Inconsistency of findings across individual studies
  • Limited generalizability of findings to routine primary care practice
  • Lack of coherence in the chain of evidence

As more information becomes available, the magnitude or direction of the observed effect could change, and this change may be large enough to alter the conclusion.

Level of Certainty: Low

Description: The available evidence is insufficient to assess effects on health outcomes. Evidence is insufficient because of:

  • The limited number or size of studies
  • Important flaws in study design or methods
  • Inconsistency of findings across individual studies
  • Gaps in the chain of evidence
  • Findings not generalizable to routine primary care practice
  • A lack of information on important health outcomes.

More information may allow an estimation of effects on health outcomes.

Methodology

Click on the links below for details of guideline development methodology:

To collect and select the evidence, all three guideline developers performed searches of electronic databases; ACCF/AHA and USPSTF also performed hand-searches of published literature. A systematic review of the literature was prepared by the Oregon Evidence-based Practice Center (EPC) for use by the USPSTF in the development of its guideline. Methods used to assess the quality and strength of the evidence are similar between ACCF/AHA and NACB, with both guideline groups weighting it according to a rating scheme. USPSTF employed expert consensus.

To analyze the selected evidence, all three guideline developers reviewed published meta-analyses and performed a systematic review with evidence tables. USPSTF is the only group to have also performed its own meta-analysis.

All three groups formulated the recommendations according to expert consensus (USPSTF also used balance sheets), and all of the organizations rate the strength of the recommendations according to a scheme. To validate the guidelines, all of the guideline groups sought both internal and external peer review; USPSTF also compared its guideline with those of other groups. All of the developers provide details of the evidence selection/analysis, recommendation formulation, and guideline validation processes used.

Source(s) of Funding

ACCF/AHA (2010)

The American College of Cardiology Foundation

The American Heart Association

NACB (2009)

National Academy of Clinical Biochemistry

USPSTF (2009)

US Government

Benefits and Harms

Benefits

ACCF/AHA (2010). Appropriate and effective assessment of cardiovascular risk in asymptomatic adults

NACB (2009)

  • Appropriate utilization of emerging biochemical markers in primary prevention of cardiovascular disease and stroke
  • Identification of more people who are asymptomatic and clinically apparently free of coronary heart disease, but at sufficiently high risk for a future coronary event in order to justify more intensive risk reduction efforts

USPSTF (2009

Benefits of Screening and Additional Risk Assessment

The evidence is insufficient to determine the magnitude of any reduction in CHD events and CHD-related deaths obtained by using nontraditional risk factors in CHD screening. This constitutes a critical gap in the evidence for benefit from screening.

Harms

ACCF/AHA (2010). No harms associated with screening using the nontraditional risk factors discussed in the guideline are provided.

NACB (2009). Not stated.

USPSTF (2009)

Harms of Screening and Additional Risk Assessment

Little evidence is available to determine the harms of using nontraditional risk factors in CHD screening. Harms include lifelong use of medications without proof of benefit but with expense and potential side effects. Statins are the class of medication most commonly used; these medications have been demonstrated to be safe but are associated with the rare but serious side effect of rhabdomyolysis. Psychological and other harms may result from being put into a higher risk category for CHD events.

Status

This synthesis was prepared by ECRI Institute in October 2011. The information was verified by USPSTF on December 21, 2011, by NACB on January 3, 2012, and by ACCF/AHA on January 30, 2012.

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