New Guidelines for Assessing CV Risk Stir Controversy
A collaborative review panel comprised of the American Heart Association, the American College of Cardiology, and other organizations has published new recommendations for physicians assessing cardiovascular disease risk. The guidelines encompass four major areas aimed at reducing risk: obesity, overall risk assessment, lifestyle factors, and lipids. Health care analysts generally consider the biggest changes to be in the lipids risk assessment area, where many suggest the guideline changes could lead to significant changes in clinical practice.
For example, the new obesity recommendations for clinicians de-emphasize the idea that an ideal diet will necessarily promote weight loss. Instead—and not all that surprisingly—they want doctors to promote and supervise intensive lifestyle changes in their patients for at least six months.
In the risk-assessment category, the biggest change was the promotion of a new calculator to measure 10-year risk. For lifestyle, the guidelines uncontroversially continue to emphasize heart-healthy diets rich in vegetables, fruits, and whole grains and incorporating some low-fat dairy products. Recommended protein sources include fish, legumes, and poultry; recommended sources of fats include vegetable oils and nuts. The guidelines call for specific restrictions to saturated fats, trans fats, and sodium, all of which simply consolidate recommendations spread among several previous guidelines supporting an intensified use of diet and physical activity to improve lipid and blood pressure control. Specifically, recommendations for physical activity to reduce LDL, non-HDL cholesterol, and blood pressure include three to four sessions of moderate- to vigorous-intensity aerobic activity per week, lasting an average of 40 minutes per session.
The big change in the way clinicians assess lipid-level risk in patients is that there is no longer support for treating people down to specific LDL targets. In other words, whereas we used to be a little lipid-numbers obsessed when it came to figuring out who gets aggressive heart-disease-risk treatment, including statin prescriptions, the new guidelines are causing a stir among doctors by recommending we cease targeting specific LDL levels for people. The recommendation stems from evidence that many patients' risks do not necessarily decrease with solely better lipid lab results. Randomized trials showing the benefits of statins generally have examined fixed-dose statin therapy, rather than titrated therapy, to achieve prespecified LDL goals.
Instead of relying heavily on this metric, the panel urges clinicians to determine whether a patient falls into one of four mutually exclusive high-risk groups and then initiate statin therapy as follows:
- Patients with clinical atherosclerotic cardiovascular disease should receive high-intensity or moderate-intensity statin therapy (the former group being younger than 75 years old, and the latter aged 75 or above).
- Patients with LDL levels at or above 190 mg/dL should receive high-intensity statin therapy.
- Diabetic patients aged 40 to 75 with LDL levels of 70 to 189 mg/dL, and without clinical atherosclerotic CVD, should receive at least moderate-intensity statin therapy.
- Patients without clinical atherosclerotic CVD or diabetes but with LDL levels of 70 to 189 mg/dL and estimated 10-year atherosclerotic CVD risk at or above 7.5 percent should receive moderate- or high-intensity statin therapy.
The 7.5-percent CVD risk threshold for primary prevention was selected based on analyses suggesting that benefit from treatment emerges at this threshold. The panel rightly acknowledges that this would put many more people on drug therapy than before. This has been a cause for concern among many clinicians, but the key here is to recognize that the guidelines are just that, a point of departure for an in-depth discussion with your doctor about your potential benefits from drug therapy, after improved lifestyle choices have been aggressively promoted first. In this way, theoretically not everyone at this threshold would necessarily get treated with statin therapy.
Also notably, with few exceptions use of lipid-modifying drugs other than statins has been discouraged. And lifestyle modification is recommended for all patients, regardless of cholesterol-lowering drug therapy.
It's important to remember the release of these new guidelines is not accompanied by a new finding—in that sense, this is not an emergency. The guidelines seek to further refine our thinking about CVD risk and treatment. Perhaps they are best viewed as an attempt to codify a rapidly evolving practice. By assessing a patient's overall risk, relying strictly on proven drugs, de-emphasizing lipid-level targets, and stressing lifestyle changes customized to each patient, these guidelines provide the launching pad from which we may hopefully achieve increased public cardiovascular health.