DECODING THE HYPE: Controversy Continues Regarding New Heart Disease Guidelines

Posted by The Evidence Blog on November 21, 2013

For years we were told to know our cholesterol numbers, especially our low-density lipoproteins (LDLs), also known as bad cholesterol. However, new guidelines published suggest that LDL is no longer is a key risk in preventing heart disease; however, the recommended risk calculation has led to fierce criticism among cardiology specialists.

With support from the National Heart, Lung and Blood Institute (NHLBI), the American College of Cardiology (ACC)/American Heart Association (AHA) have published 4 new guidelines, including 2 first-time recommendations that contain a mix of established advice and new perspectives on the management of adults at risk for cardiovascular disease.

  • Treatment of blood cholesterol in adults
  • Assessment of cardiovascular risk using a new, online risk calculator
  • Lifestyle management to reduce cardiovascular risk
  • Management of overweight and obesity in adults

Among the many updates across the set of guidelines include the abandonment of specific LDL- and non-HDL–cholesterol targets, the addition of stroke to cardiovascular disease risk assessment, the rise of the Mediterranean diet (over a low-fat diet), and a change to the body mass index (BMI) cutoffs used to define the initiation of therapy in obesity. Absent, however, are any guidelines regarding the prevention and treatment of hypertension; these are supposed to be published sometime later in 2014.

The most controversial of the guidelines have to do with the treatment of blood cholesterol and assessment of cardiovascular risk. Treatment to LDL targets is no longer recommended; instead, the guidelines recommend that statin treatment be initiated based on 1 of 4 mutually exclusive high-risk groups that classify patients by age; degree of clinical atherosclerotic cardiovascular heart disease (ASCVHD); LDL levels ≥ 190; and a 10-year risk score of ASCVHD ≤ 7.5%.

It is recommended that patients who fit into 1 of these high-risk guidelines—2 of which rely on the new 10-year risk score—be started on either moderate or high-intensity statin therapy; with few exceptions, lipid-modifying drugs other than statins are not recommended. It is estimated that 33 million middle-aged Americans will be targeted by these new guidelines for statin therapy.

The new online risk calculator—which incorporates age, race, gender, high blood pressure, and cholesterol—may overestimate heart risk by 75% to 150%. If that's true, then up to half of the people targeted for statin therapy may not need it.

How could this happen? One answer is that the newly proposed risk calculator uses data from clinical trials conducted in the 1990s when more people smoked, exercised less, and experienced heart attacks and strokes earlier in life. Another possibility is that the risk calculator places disproportionate emphasis on race and age. Or maybe the calculator should have been tested in clinical practice before it was released.

Two Boston-area cardiologists used data from more than 100,000 people enrolled in 3 very large primary prevention cohorts where information about patients’ ages, smoking habits, and cholesterol levels were available—as well as their heart disease outcomes. When they entered these measurements into the new risk calculator, they found that it overpredicted heart problems by 75% to 150%. Publishing in the Lancet, the 2 authors believe that could mean the difference between prescribing a statin and not prescribing one.

For now, the ACC and AHA are standing firm in supporting the calculator. Even detractors have stated that the guideline is a step in the right direction. The risk-assessment calculator is one of 4 new guidelines that also embrace lifestyle changes, weight reduction, and healthful dietary changes. Representatives of the ACC and the AHA emphasize that the calculator is a "living document" that will eventually be updated as more data are collected.

In the meantime, calculators cannot replace clinical judgment. The guidelines themselves stress the importance of using the risk information to spark a conversation between the patient and the clinician about the appropriate course of action, which may or may not include a statin. Maybe the real bottom line here is that while risk calculators are 1 tool to stratify high-need patients, you should try and “know your patient before you decide to prescribe.”

Topics: Hayes Blog

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