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Revised Pooled Cohort Equations (2018)

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This tool estimates the 10-year risk for atherosclerotic cardiovascular disease  (ASCVD) which is defined as coronary death or nonfatal myocardial infarction, or fatal or nonfatal stroke.   Yadlowsky S, Hayward RA, et al.  stated that the previous 2013 pooled cohort equations overestimated the 10-year risk for atherosclerotic CVD by an average of 20% across risk groups.
Age:     Race:   Gender:
Total cholesterol (mg/dL)   HDL Cholesterol:   (mg/dL)
Systolic Blood Pressure mmHg
Diabetes :   Treatment for Hypertension :   Smoker :
Estimates of 10-year risk for atherosclerotic cardiovascular disease (ASCVD) are valid for ages 40 through 79. 1

Background Info

Key facts1:

  • In order to estimate the risk for atherosclerotic cardiovascular disease, the following information is required:
    • Age,
    • Gender,
    • Race,
    • Total cholesterol,
    • HDL cholesterol,
    • Systolic blood pressure,
    • Blood pressure lowering medication use,
    • Diabetes status, and
    • Smoking status
  • "Ten-year risk is defined as the risk of developing a first ASCVD event, defined as nonfatal myocardial infarction or coronary heart disease (CHD) death, or fatal or nonfatal stroke, over a 10-year period among people free from ASCVD at the beginning of the period."
  • The 2013 ACC/AHA Guideline focuses on the following:
    • The large proportion of the adult population WITHOUT clinical signs or symptoms of ASCVD that require evaluation for the primary prevention of atherosclerotic cardiovascular disease (ASCVD).
    • The guidelines do not apply to individuals with clear clinical signs and symptoms of atherosclerotic cardiovascular disease (ASCVD) who require alternative approaches or diagnostic strategies rather than an assessment of risk.
    • "The recommendations were not developed for use in specific subgroups of asymptomatic individuals at unusually high risk, such as those with genetically determined extreme values of traditional risk factors."
  • The Pooled Cohort Equations  were derived and validated by the ACC/AHA Work Group by using state-of-the-art statistical methods.  Only variables that were found to be statistically significant were included in the equations such as age, total and HDL-cholesterol, systolic BP (including treated or untreated status), diabetes, and current smoking status.
  • Several other factors and potential risk factors were reviewed for possible inclusion, however, many of these factors did not provide the necessary additional guidance needed for inclusion.  In some cases the data was insufficient during the validation studies and may be revisited in the future.
  • The final Pooled Cohort Equations have been "subjected to more rigorous validation than other currently available equations, and they are the only risk assessment equations that include significant numbers of African Americans and focus on estimation of 10-year risk."
  • Other ethnic groups:  The pooled cohort equations were created for either non-Hispanic white men or women ages 40 through 79 years. The results may be OVER or UNDER estimated for other groups. Groups likely to be underestimated include American Indians some Asian Americans and some Hispanics e.g. Puerto Ricans. Overestimates may occur in some Asian Americans - east Asian ancestry and some Hispanics - e.g. Mexican Americans.
  • Future goals:  The ACC/AHA Work Group will continue to expand on the current research and will hopefully develop new equations for other ethnic groups and provide further validation and enhancements to the currently released pooled cohort equations.

pooled

In many cases direct quotes are used from the primary reference: 
Stone NJ, Robinson J, Lichtenstein AH, Bairey Merz CN, Lloyd-Jones DM, Blum CB, McBride P, Eckel RH, Schwartz JS, Goldberg AC, Shero ST, Gordon D, Smith SC Jr, Levy D, Watson K, Wilson PW. 2013 ACC/AHA Guideline on the Treatment of Blood Cholesterol to Reduce Atherosclerotic Cardiovascular Risk in Adults: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2013 Nov 7. pii: S0735-1097(13)06028-2. doi: 10.1016/j.jacc.2013.11.002.


Four 'Statin Benefit Groups' have been identified that have the potential to reduce the risk of atherosclerotic cardiovascular disease.  The benefit of therapy has been found to clearly exceed the potential for adverse effects in adults.   The four groups are as follows:

  1. Individuals with clinical ASCVD (Secondary prevention):   Clinical ASCVD Atherosclerotic Cardiovascular Disease is defined by the inclusion criteria for the secondary prevention statin RCTs (acute coronary syndromes, or a history of MI, stable or unstable angina, coronary or other arterial revascularization, stroke, TIA, or peripheral arterial disease presumed to be of atherosclerotic origin). 

  2. Individuals with primary elevations of LDL-C geq190 mg/dL.

  3. Individuals 40 to 75 years of age with diabetes and LDL-C 70-189 mg/dL. For the primary prevention of ASCVD in individuals with diabetes (diabetes mellitus type-1 and type-2), estimated 10-year ASCVD risk can also be used to guide the intensity of statin therapy.

  4. Individuals without clinical ASCVD or diabetes who are 40 to 75 years of age with LDL-C 70- 189 mg/dL and an estimated 10-year ASCVD risk of 7.5% or higher.   Data has shown that statins used for primary prevention have substantial ASCVD risk reduction benefits across the range of LDL-C levels of 70-189 mg/dL.


Flowchart:3
Initial steps: Counseling on a heart healthy lifestyle forms the foundation of ASCVD prevention.  Pooled Cohort equations:   Individuals not receiving cholesterol-lowering drug therapy, should have their estimated 10-year ASCVD risk calculated initially, and then every 4 to 6 years in individuals aged 40 to 75 years without clinical Atherosclerotic Cardiovascular Disease or diabetes and with LDL-C 70-189 mg/dL.

Decision point:
1] Adults age >21 years old and a candidate for statin therapy [if Yes] AND Diagnosis: Clinical
       ASCVD  [if YES] --> 2 paths:
    (a) Age leq75 years  - [if YES]  Start High-intensity statin (Use Moderate-intensity statin if not a candidate for high-intensity
       statin).

Background:  (direct quotes)  3
Moderate-intensity statin therapy should be used in individuals in whom high-intensity statin therapy would otherwise be recommended when characteristics predisposing them to statin associated adverse effects are present. Characteristics predisposing individuals to statin adverse effects include, but are not limited to: 

  • Multiple or serious comorbidities, including impaired renal or hepatic function.  
  • History of previous statin intolerance or muscle disorders.  
  • Unexplained ALT elevations >3 times ULN. 
  • Patient characteristics or concomitant use of drugs affecting statin metabolism. 
  • >75 years of age.


     (b) Age >75y or if not candidate for high-intensity statin-->[if YES]  start moderate-intensity statin.

Decision point:
2] LDL-C geq 190?  -->[if YES]  -->  Start high-intensity statin  (Moderate-intensity statin if not a candidate for high-intensity statin).

Decision point:
3] Diabetes type 1 or 2 AND age 40-75y AND LDL-C 70-189 mg/dL.?  [ if YES] --> Start Moderate-intensity statin  [support for high-intensity: "Giving a maximally tolerated statin intensity should receive primary emphasis because it most accurately reflects the data that statins reduce the relative risk of ASCVD events similarly in individuals with and without diabetes, and in primary and secondary prevention in those with diabetes, along with evidence that high-intensity statins reduce ASCVD events more than moderate-intensity statins."]

Decision point:
4] No to all above?  -->[if YES] Estimate the 10-year ASCVD risk with the Pooled Cohort Equations --> 
Is the estimated 10-y risk geq7.5  AND age 40-75 [if YES] --> Start Moderate to high intensity statin.  

 IF NO e.g. estimated 10-y risk <7.5   -->  ASCVD prevention benefit of statin therapy may be less clear in other groups.  In selected individuals, consider the following:

  • Review additional factors influencing ASCVD risk
  • Review potential ASCVD treatment risks, benefits and adverse effects
  • Review potential drug-drug interactions
  • Determine patient preferences for statin treatment.


Statin therapy:  monitoring therapeutic response and adherence:



Flowchart:
  • Assess medication and lifestyle adherence - fasting lipid panel etc.  Was the anticipated response achieved ?   [E.g.  high-intensity statin regimen:   geq 50 percent reduction in LDL-C from untreated baseline or moderate-intensity statin therapy- LDL-C reduction of ~30 - <50% from untreated baseline]
    • [if YES] --> - reinforce continued adherence --> follow-up in 3 to 12 months.
    • [if NO]  --> (Less than anticipated result) --> [Was there intolerance to the recommended statin dose - [YES / NO] -->
      • [if YES] - Review the section on management of statin intolerance (Stone NJ et al.  2013 ACC/AHA Guideline on the Treatment of Blood Cholesterol to Reduce Atherosclerotic Cardiovascular Risk in Adults: ....)
      • [if NO] -  reinforce medication adherence and adherence to intensive lifestyle changes. Also exclude secondary causes of hypercholesterolemia.   Follow-up in 4 to 12 weeks.


References

  1. Goff DC Jr, Lloyd-Jones DM, Bennett G, O'Donnell CJ, Coady S, Robinson J, D'Agostino RB Sr, Schwartz JS, Gibbons R, Shero ST, Greenland P, Smith SC Jr, Lackland DT, Sorlie P, Levy D, Stone NJ, Wilson PW. 2013 ACC/AHA Guideline on the Assessment of Cardiovascular Risk: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2013 Nov 12. pii: S0735-1097(13)06031-2. doi: 10.1016/j.jacc.2013.11.005.
  2. Lloyd-Jones DM, Leip EP, Larson MG, D'Agostino RB, Beiser A, Wilson PW, Wolf PA, Levy D. Prediction of lifetime risk for  cardiovascular disease by risk factor burden at 50 years of age. Circulation. 2006 Feb 14;113(6):791-8. Epub 2006 Feb 6.
  3. Stone NJ, Robinson J, Lichtenstein AH, Bairey Merz CN, Lloyd-Jones DM, Blum CB, McBride P, Eckel RH, Schwartz JS, Goldberg AC, Shero ST, Gordon D, Smith SC Jr, Levy D, Watson K, Wilson PW. 2013 ACC/AHA Guideline on the Treatment of Blood Cholesterol to Reduce Atherosclerotic Cardiovascular Risk in Adults: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2013 Nov 7. pii: S0735-1097(13)06028-2. doi: 10.1016/j.jacc.2013.11.002.
  4. Yadlowsky S, Hayward RA, Sussman JB, McClelland RL, Min YI, Basu S. Clinical Implications of Revised Pooled Cohort Equations for Estimating Atherosclerotic Cardiovascular Disease Risk. Ann Intern Med. 2018 Jul 3;169(1):20-29. doi: 10.7326/M17-3011. Epub 2018 Jun 5.  [Pubmed]

    Abstract

    Background:
    The 2013 pooled cohort equations (PCEs) are central in prevention guidelines for cardiovascular disease (CVD) but can misestimate CVD risk.

    Objective:
    To improve the clinical accuracy of CVD risk prediction by revising the 2013 PCEs using newer data and statistical methods.
    Design:

    Derivation and validation of risk equations.
    Setting:
    Population-based.
    Participants:
    26689 adults aged 40 to 79 years without prior CVD from 6 U.S. cohorts.

    Measurements:
    Nonfatal myocardial infarction, death from coronary heart disease, or fatal or nonfatal stroke.

    Results:
    The 2013 PCEs overestimated 10-year risk for atherosclerotic CVD by an average of 20% across risk groups. Misestimation of risk was particularly prominent among black adults, of whom 3.9 million (33% of eligible black persons) had extreme risk estimates (<70% or >250% those of white adults with otherwise-identical risk factor values). Updating these equations improved accuracy among all race and sex subgroups. Approximately 11.8 million U.S. adults previously labeled high-risk (10-year risk >/=7.5%) by the 2013 PCEs would be relabeled lower-risk by the updated equations.
    Limitations:

    Updating the 2013 PCEs with data from modern cohorts reduced the number of persons considered to be at high risk. Clinicians and patients should consider the potential benefits and harms of reducing the number of persons recommended aspirin, blood pressure, or statin therapy. Our findings also indicate that risk equations will generally become outdated over time and require routine updating.

    Conclusion:
    Revised PCEs can improve the accuracy of CVD risk estimates.

    Primary Funding Source:
    National Institutes of Health.

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