At ClinCalc, we’re very proud to announce the availability of both a web-based 10-year ASCVD Risk Calculator (also termed the Pooled Cohort Equations Calculator). This risk assessment tool is recommended by the newly published 2013 ACC/AHA cholesterol guidelines to estimate 10-year risk of atherosclerotic cardiovascular disease (ASCVD).
Sweeping Changes to Cholesterol Guidelines
These new ACC/AHA guidelines make sweeping changes to the outdated NCEP ATP III cholesterol guidelines, last published in 2002 (with a minor update in 2004). These new guidelines have removed the controversial “LDL goal” recommendations and instead are encouraging the use of statin therapy in four specific populations:
- Individuals with clinical ASCVD
- Individuals with primary elevations of LDL ≥ 190 mg/dL
- Individuals 40 to 75 years of age with diabetes and an LDL 70 to 189 mg/dL without clinical ASCVD
- Individuals without clinical ASCVD or diabetes who are 40 to 75 years of age with LDL 70 to 189 mg/dL and a 10-year ASCVD risk of 7.5% or higher
The fourth group represents a patient population who may be at elevated risk for primary (first-event) ASCVD. This ASCVD risk assessment is based on the following risk factors:
- Total cholesterol
- HDL cholesterol
- Systolic blood pressure
- Need for antihypertensive treatment
- Presence of diabetes
- Smoking status
The actual calculation for 10-year ASCVD is quite cumbersome (involving a multitude of linear regression models), which is exactly the reason why we have released an online-based tool to help clinicians quickly and accurately assess the Pooled Cohort Equations 10-year ASCVD risk.
What defines ASCVD, and how is this different than the Framingham risk?
ASCVD (atherosclerotic cardiovascular disease) is defined as a nonfatal myocardial infarction, coronary heart disease death, or ischemic stroke. The traditional Framingham risk (as recommended by the NCEP ATP III cholesterol guidelines from 2002) only includes myocardial infarction. Unlike Framingham, the new Pooled Cohort Equations takes into account sex and race-specific modeling, which is purported to improve accuracy in African American patients.
The “Official” ACC/AHA Risk Calculator
Upon publication of the guidelines, the ACC/AHA did provide a link to an online version of the Pooled Cohort Equations. Disappointingly, this calculator was an Excel-based document that required downloading the file onto a computer that supported Excel’s formulas (ie, not most mobile devices by default). This cumbersome, clunky, and short-sighted approach was unfortunate and highlighted the need for a ClinCalc.com-based solution.
ClinCalc’s Conclusions Regarding the New Guidelines
The new guidelines were sorely needed given the outdated, controversial NCEP ATP III document from 2002. I’m extremely happy to see the demise of the LDL goal, which was never evidence-based, but there is significant controversy regarding the most appropriate cut-point for ASCVD risk. As with most things in medicine, the risk of ASCVD is a continuous gray gradient, not a black-and-white dichotomous decision.
In patients who exceed the magical cut-point of 7.5%, a risk-benefit conversation should occur between a provider and a patient. Generally speaking, statin therapy will have a primary relative risk reduction of 30% (possibly higher for high-intensity statins). For a patient with an ASCVD risk of 7.5%, his or her benefit from statin therapy will be an absolute benefit of about 2.5% (ie, reduced risk from 7.5% to 5%, number needed to treat of 40).
Some patients may prefer to forgo the small benefit of statin therapy (ie, decide that a NNT of 40 does not outweigh the hassle of risks of statins). In other patients, particularly those with risk factors not captured by the ASCVD Pooled Cohort Equations (eg, family history, higher LDL, sedentary lifestyle, poorly controlled diabetes, obesity, etc.), the pendulum may swing in the opposite direction. Regardless, it should be a shared, informed decision balancing the patient’s personal preferences with his or her risk factor analysis.