The ACC/AHA cholesterol guideline can be a powerful tool for making multifactorial measures of cardiovascular disease risk assessment, particularly in African American populations, but clinicians should be aware of its limitations.
In 2013, the American College of Cardiology and the American Heart Association (ACC/AHA) in collaboration with National Heart, Lung, and Blood Institutes (NHBLI) released guidelines for assessment of cardiovascular risk with lifestyle modifications to reduce risk and manage lipids. For the first time, estimates of the risk of both heart attacks and strokes with distinct spacial consideration devoted to African American populations was coordinated into guidelines along with development of a risk estimator.
The atherosclerotic cardiovascular disease (ASCVD) risk estimator was developed as an app to obtain a metric of 10-year and lifetime percentage risks for developing ASCVD. Risk values are obtained after entering age, sex, race, total cholesterol, and HDL levels along with the status of diabetes, smoking, and hypertension.
At the American College of Physicians Internal Medicine 2014 annual meeting held in Orlando, FL, Michelle A. Albert, MD, MPH, professor of medicine and chief of cardiovascular medicine at Howard University, in Washington, DC, pointed out that the ASCVD calculator, while quite useful in clinical practice, is far from perfect and not without its critics and limitations. To illustrate this point, Albert noted that a trivial change of just 1mm Hg in a patient’s blood pressure would result in a change in ASCVD lifetime risk estimation from just 5% to 36%.
Moreover, just after the release of the new guidelines, a 2013 Lancet report by Ridker and Cook revealed the ASCVD calculator overestimated expected as compared to observed risk by 75-100%, thus making approximately 30 million more Americans eligible for statin therapy.
Under the new guidelines, there is now less emphasis to focus on LCL-C and non-HDL-C as treatment goals, according to Albert. However, regular monitoring of lipid panels is still recommended.
Albert also discussed a report based on analysis of Medicare beneficiary data that indicates African American and Latino populations are 30% less likely to comply with diabetes and lipid treatment and lifestyle modification recommendations compared with white and Asian populations. These populations are also known to be at a much higher risk of ASCVD. She stressed that this lack of compliance should be addressed and that it is likely due to a combination of biological factors, cultural factors, higher levels of illiteracy, side effects, logistics, and/or cognitive impairment.
As illustrated in the example above, where even a reduction of 1 mm Hg in blood pressure exerts large impact on the lifetime risk for developing ASCVD, hypertension is the biggest risk factor for developing ASCVD. Approximately 78 million Americans have hypertension, with about 90% of all Americans developing hypertension over the course of a lifetime.
While the blood pressure targets are <140 mm Hg systolic and <90 mm Hg diastolic for most people, even lower blood pressure targets may be more desirable specifically diabetics and African Americans, according to Albert.
She stressed that “lifestyle intervention is the cornerstone of reduction in blood pressure.” For managing blood pressure, the lifestyle changes of greatest impact in reducing blood pressure in mm Hg from most to least are as follows: reduction in body mass index (8-14mm), DASH eating diet (8-14mm), and lower sodium (2-8mm).
In summary, the ASCVD risk estimator can be a powerful tool for making multifactorial measures of disease risk assessment, particularly as related to African American populations, although external validation of data is an ongoing process. The ACC/AHA guidelines no longer promote LDL-C and non-HDL-C as primary treatment goals, but still stress the importance of continual monitoring via lipid panels. Albert pointed out that the new ACC/AHA guidelines emphasize the importance of promoting lifestyle changes as a means of reducing blood pressure, but also describe pharmacological treatment regimens that depend on age, race, and blood pressure.