A significant milestone in evidence-based practice was reached in November 2013, when the American Heart Association and American College of Cardiology (AHA/ACC) published 4 clinical practice guidelines on the prevention of cardiovascular disease.1-4 These guidelines—on obesity, lifestyle management, cardiovascular disease (CVD) risk assessment, and cholesterol—were developed under the auspices of the National Heart, Lung, and Blood Institute (NHLBI) to update its prior guidelines on the treatment of hypertension, high cholesterol, and obesity that were published more than a decade ago.5-7 After the NHLBI had organized the respective guideline panels and progressed through most of the guideline development process (which lasted several years each), it arranged for the AHA/ACC to assume sponsorship and publication of the guidelines. The NHLBI decided its role should be to develop evidence reports, leaving the development of guidelines to professional organizations.
While the prior guidelines on hypertension and hypercholesterolemia were influential and widely cited as the standard of care, they were heavily influenced by expert opinion and were not strictly evidence based. The NHLBI sought to develop the new guidelines using more contemporary and rigorous evidence-based processes to meet standards set by the Institute of Medicine (IOM). The group started with key clinical questions, conducted comprehensive systematic reviews of the evidence, and then rated the quality of the evidence and assigned strength of recommendation ratings.8 The guidelines and evidence reports are lengthy, and are summarized below.
In December 2013, the Eighth Joint National Committee (the 5th panel organized by the NHLBI to address CVD prevention) published its updated guideline on the treatment of hypertension, which has also generated controversy. Visit www.jfponline.com to listen to an audiocast summary of these recommendations.9
Obesity and overweight
The guideline on managing obesity and overweight adults has 17 recommendations, only 3 of which are based on expert opinion.1 (TABLE 1 summarizes the strong [A] and moderate [B] recommendations.) The recommendations stress screening, diagnosis, and treatment using diet, exercise, and lifestyle modification. They also address bariatric surgery for those with a body mass index (BMI) ≥40 or a persisting BMI ≥35 despite weight loss interventions. This set of recommendations, like those of the United States Preventive Services Task Force, advises intensive interventions for weight management and additionally offers much more detail on recommended diet and exercise.
Lifestyle management
The 10 recommendations on lifestyle management to reduce cardiovascular risk, all evidence based, are limited to diet and exercise as a means to control hypertension and hypercholesterolemia.2 They do not cover other important lifestyle modifications for preventing CVD, such as smoking cessation. The guideline panel acknowledged that the interventions are aimed at those with high blood pressure and elevated cholesterol, but they encourage all adults to follow them. Although these recommendations are not particularly controversial, the 2 recommendations to reduce sodium intake are said to be based on strong or moderate strength evidence, in contrast to a recent IOM report that concluded evidence for the health benefits of salt intake <2.3 g/d is weak.10 This illustrates how separate authoritative groups can rate the strength of the same evidence differently.
Summary highlights:
• Encourage adults who would benefit from lowering either blood pressure (BP) or low-density lipoprotein cholesterol (LDL-C) to eat a diet that emphasizes vegetables, fruits, whole grains, low-fat dairy products, and other notably healthful foods, and to cut down on products high in sugar content and on red meats.
• Review, as appropriate, such options as the DASH (dietary approaches to stop hypertension) eating plan, US Department of Agriculture Food Patterns, or the American Heart Association’s diet.
• Establish a dietary plan that also incorporates nutritional requirements for an existing comorbidity, such as type 2 diabetes mellitus (T2DM).
• Lower saturated-fat intake to 5% to 6% of total calories, and reduce trans fats.
• Advise patients with high BP to reduce sodium consumption to ≤2400 mg/d; or, at the very least, to reduce daily consumption by 1000 mg.
• Promote aerobic activity to reduce either LDL-C or BP, at moderate or vigorous intensity 3 to 4 times a week with 40-minute sessions.
CVD risk assessment
The CVD risk assessment guideline3 has generated a lot of controversy. It proposes a new tool for assessing an individual’s 10-year risk of developing an atherosclerotic cardiovascular disease (ASCVD) event, defined as a fatal or nonfatal heart attack or stroke. While the tool is new, the risk factor categories it uses have been known for decades: age, gender, race, lipid levels, diabetes, smoking status, and BP. It has not performed better in validation studies than other existing tools (all of which are suboptimal), and it may be worse.11,12 Moreover, this new tool has been tested only in African Americans and non-Hispanic whites. Using it could classify 33 million adults age 40 to 79 years as having a 10-year risk of 7.5%, and 13 million a risk between 5% and 7.5%.12 The significance of this is discussed in the next section on the management of high cholesterol levels.