News

New US prevention guidelines focus on overall risk of cardiovascular disease

BMJ 2013; 347 doi: http://dx.doi.org/10.1136/bmj.f6858 (Published 14 November 2013) Cite this as: BMJ 2013;347:f6858
  1. Michael McCarthy
  1. 1Seattle

Four US expert panels have released a set of guidelines on prevention of cardiovascular disease that emphasize lifestyle factors and that substantially change the recommended approach to treating high blood cholesterol concentrations.

The guidelines were commissioned by the US National Health Lung and Blood Institute and drawn up by expert panels from the American Heart Association, the American College of Cardiology, and the Obesity Society.

The four guidelines deal with assessment of the risk of atherosclerotic cardiovascular disease; the treatment of high blood cholesterol concentrations; “heart healthy” lifestyles; and management of overweight and obese adults.

Heart disease and stroke are the leading causes of death and disability in the United States. It is estimated that about a third of US adults have elevated blood cholesterol, while a third have high blood pressure and another third are “pre-hypertensive” and at high risk of developing high blood pressure.

Currently, a quarter of people in the US over the age of 40 have been prescribed a cholesterol lowering hydroxymethyl glutaryl coenzyme A (HMG CoA) reductase inhibitor (statin).

The new risk assessment guideline uses a formula that is based on information easily collected in a primary care setting, such as age, cholesterol concentrations, blood pressure, smoking history, and diagnosis of diabetes. This information can then be entered into equations given in the guideline to create a risk score to guide patient counseling and, if warranted, treatment.1

The panel recommends that clinicians use the guideline’s risk assessment equations for patients aged 40-79 years. A person whose assessment indicates that they have a 7.5% or greater 10 year risk of cardiovascular disease is considered to be at high risk. The guideline provides a separate equation to estimate a person’s lifetime risk, which is recommended from age 20.

David C Goff, dean of the Colorado School of Public Health and co-chairman of the panel, said in a statement released with the new guidelines, “The vast majority of heart attacks and strokes could be prevented if people knew their risk and did the things we know are effective in reducing that risk, but patients and doctors alike often underestimate cardiovascular disease risk, especially when considered over the lifespan.”

Unlike previous guidelines, which were based on data only from non-Hispanic white people, the new guidelines include equations that better represent the effect of risk factors for women and African Americans.

Donald M Lloyd-Jones, chair and professor of preventive medicine at Northwestern University Feinberg School of Medicine, Chicago, and the panel’s other co-chairman, said, “There is some evidence that the risk factors we know about—age, smoking, high cholesterol, blood pressure, and diabetes—have somewhat different effects in women and men and certainly in whites and African Americans.”

The panel assessed the usefulness of a variety of other markers for cardiovascular disease but concluded that there wasn’t enough evidence for these to be included in routine risk assessment. However, the panel found that four markers may be helpful for patients in whom the need for treatment remained uncertain after evaluation by the guideline’s risk equations: coronary artery calcium scores, C reactive protein concentrations, ankle brachial indices, and family history of premature cardiovascular disease.

Goff said, “These showed the greatest promise and may help inform treatment decision making when patients or providers are on the fence after quantitative risk assessment.”

The guideline on managing blood cholesterol identifies four major groups of people for whom moderate to high intensity treatment with statins is recommended: people who have known cardiovascular disease; those with a low density lipoprotein (LDL) cholesterol concentration of 190 mg/dL (4.9 mmol/L) or higher; those aged 40-75 who have type 2 diabetes; and those aged 40-75 whose 10 year risk of developing cardiovascular disease, as estimated from the risk formulas provided in the report, is 7.5% or more.2

High intensity statin treatment would include regimens that in the clinical trials reviewed by the panel reduced LDL cholesterol concentrations on average by around 50% or more. Atorvastatin 40-80 mg a day would be one example of a high intensity regimen.

Moderate intensity statin treatment would be regimens that lowered LDL cholesterol on average by around 30% to less than 50%. An example would be simvastatin 20-40 mg a day.

The panel considered other cholesterol lowering drugs but found them to be not as effective as statins, said Neil J Stone, professor of medicine at Northwestern University Feinberg School of Medicine and chairman of the expert panel. “Statins were chosen because their use has resulted in the greatest benefit and the lowest rates of safety issues,” he said in a statement. Other drugs could be considered for patients who were intolerant of statins, he added.

In an important shift from current practice, the guideline does not recommend using combination therapy to try to reach specific LDL or non-HDL cholesterol concentration targets. Randomized controlled trials reviewed by the panel either compared fixed doses of statins with placebo or with untested controls or compared fixed doses of higher and lower intensity statins and were not designed to evaluate the effect of dose adjusted statin treatment to achieve pre-specified LDL or non-HDL cholesterol concentration targets.

The panel said, “Therefore, given the absence of data on titration of drug therapy to specific goals, no recommendations are made for or against specific LDL-C or non-HDL-C goals for the primary or secondary prevention of ASCVD [atherosclerotic cardiovascular disease].”

It identified three problems with the “treat to target” approach: the clinical trial data do not indicate what the target should be; the panel was not able to identify randomized controlled trials that looked at whether titrating drug therapy to specific LDL or non-HDL cholesterol goals improved outcomes in atherosclerotic cardiovascular disease; and the approach does not take into account potential adverse effects from multidrug regimens that might be used to achieve a specific goal.

“The focus for years has been on getting the LDL low,” said Stone. “Our guidelines are not against that. We’re simply saying how you get the LDL low is important. Considering all the possible treatments, we recommend a ‘heart healthy’ lifestyle and statin therapy for the best chance of reducing your risk of stroke or heart attack in the next 10 years.”

The lifestyle guideline emphasizes physical activity and eating a “heart healthy” diet. The recommended diet includes fruits, vegetables, whole grains, low fat dairy products, poultry, fish, and nuts and limits amounts of saturated and trans fats, sodium, sweets, sugar sweetened beverages, and red meat.3 For physical activity the guideline recommends moderate to vigorous intensity aerobic exercise, such as brisk walking, for an average of 40 minutes three to four times a week.

The guideline on management of adults who are overweight or obese recommends that healthcare providers calculate their patient’s body mass index at their annual visits and use the measurements as a guide to identify those whose BMI puts them at risk of heart disease and stroke.4

In the US nearly 155 million adults are overweight, defined as a BMI of 25 to 29.9, or obese, defined as having a BMI of 30 or higher.

Weight loss plans should include three key components, the guideline says: a diet with moderately reduced energy intake, increased physical activity, and use of behavioral strategies to help patients lose weight and keep it off.

The most effective behavior change programs include meetings involving two to three patients once a month for at least six months, the guideline says. Web and phone based programs are an option but have not been shown to be as effective as face to face programs, the panel found.

Donna Ryan, co-chairwoman of the guideline writing committee and professor emeritus at Louisiana State University’s Pennington Biomedical Research Center, said, “Healthcare providers should do more than advise patients affected by obesity or overweight to lose weight: they should be actively involved and help their patients reach a healthy body weight.”

Efforts should focus on achieving a sustained weight loss of 5% to 10% in the first six months. Sustained weight loss of as little as 3% could reduce the risk of diabetes and could lower concentrations of triglycerides and blood glucose and other risks of cardiovascular disease, the panel said.

Bariatric surgery may benefit patients with a BMI of 40 or more or those with a BMI of 35 or more who had diabetes, hypertension, or other cardiovascular risk factors, the panel said.

“We hope that by laying out the scientific evidence that medically supervised weight loss works and significantly reduces the risk factors for cardiovascular disease it will be more fully embraced by patients and doctors and effective programs will eventually be reimbursed by all third party payers,” said Ryan.

Notes

Cite this as: BMJ 2013;347:f6858

Footnotes

References