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Risk Factors, Not Race, Determine Lifetime Heart Risks

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Myths About Age, Race Debunked

I applaud the approach taken by the investigators of this meta-analysis. Many in the field have been troubled by the tendency to use 10-year risk estimates.

Nobody wants to live just 10 years, so it’s important to be able to provide younger patients with a broader picture of lifetime risk. This study does not give us the ability to calculate 20- and 30-year risk, but it does introduce that concept.

It also introduces the intriguing and somewhat novel concept of primordial prevention, that is, preventing the development of risk factors.

The study’s findings that the effects of traditional risk factors are consistent between races and across birth cohorts is not surprising. In fact, they emphasizes the classic risk factor model we’ve talked about all along, and debunks some myths about age, race, and other factors. I think that’s a useful message.

However, although the concept of primordial prevention is intriguing, the findings don’t obviate the need for maintaining a focus on primary prevention. The treatment effects mentioned by the investigators are small, but given the number of patients who get heart disease, they represent an enormous effect.

Paul D. Thompson, M.D., is director of cardiology at Hartford Hospital. He is a consultant, has done research, or has received speaking honoraria numerous manufacturers of lipid-lowering drugs, including GlaxoSmithKline, Merck, Pfizer, and AstraZeneca.


 

FROM THE NEW ENGLAND JOURNAL OF MEDICINE

Adults with an optimal cardiovascular risk profile at age 55 have a substantially lower risk of death from cardiovascular disease through age 80 years, and a lower lifetime risk of fatal coronary heart disease, nonfatal myocardial infarction, and stroke, compared with those who have two or more major risk factors, according to a meta-analysis of 18 studies involving more than 257,000 adults.

The findings, which have important disease prevention and public health implications, were consistent across race and diverse birth cohorts, Dr. Jarett D. Berry of the University of Texas Southwestern Medical Center, Dallas and his colleagues report in the Jan. 26 issue of The New England Journal of Medicine.

The investigators conducted their meta-analysis at the individual level using data from studies that included black men and women and white men and women who were assessed for cardiovascular risk factors at ages 45, 55, 65, and 75 years. Patients were stratified into five mutually exclusive risk categories based on blood pressure, cholesterol level, smoking status, and diabetes status; only about 5% of participants comprised the optimal risk category, and about two-thirds comprised the two highest-risk groups.

The risk of cardiovascular disease-related death through age 80 years was 4.7% and 6.4% in men and women, respectively, who were nonsmokers without diabetes, and who had a total cholesterol level of less than 80 mg/dL, and blood pressure less than 120 mm Hg systolic and 80 mm Hg diastolic at age 55 years. The risk was 30% and 21% in men and women, respectively, with two or more major risk factors at that age, they said (N. Engl. J. Med. 2012;366:321-9).

The risk of fatal coronary heart disease or nonfatal MI was 3.6% and less than 1% in men and women, respectively, with the optimal risk factor profile, compared with 37.5% and 18.3% in men and women, respectively, with two or more major risk factors. The risk of fatal or nonfatal stroke was 2.3% and 5.3% in men and women with the optimal profile, compared with 8.3% and 10.7% in those with at least two major risk factors.

Similar patterns were seen based on assessments at other ages.

Significant, but expected, differences in the burden of risk factors were seen between older and younger birth cohorts, such as a higher prevalence of diabetes, a lower prevalence of smoking, and lower mean total cholesterol and systolic blood pressure in 55-year-old men born after 1920, compared with those born before 1920. Also, the burden of risk factors was higher among blacks than among whites, when participants were stratified according to race.

This approach to characterizing the lifetime risk of cardiovascular disease provides a more comprehensive assessment of overall disease burden in the general population than does the more common approach that calculates global, 10-year risk estimates, the investigators said, explaining that the majority of adults in the U.S. who are considered to be at low risk in the short-term, are actually at high risk across their lifespan.

According to the investigators, the findings "strongly reinforce the influence of traditional risk factors on the lifetime risk of cardiovascular disease" and despite the development of notable secular trends in the prevalence of risk factors over the past 4 decades, the effect of those risk factors remained remarkably consistent across birth cohorts, they said.

In fact, they concluded that it is the presence or absence of traditional risk factors, rather than race or birth cohort, that appears to be the most consistent determinant of long-term cardiovascular disease risk – a conclusion based in part on a finding that despite an overall higher prevalence of risk factors in black than in whites, the lifetime risks of end points related to cardiovascular disease were similar in blacks and whites when risk factor profiles were similar.

The findings, according to the investigators, have important implications for clinical disease prevention and public health practice.

"First, the effect of untreated risk factors has been fairly constant for decades. Therefore, the present estimates of lifetime risk, made on the basis of current or projected risk-factor levels, may be important in estimating the future burden of cardiovascular disease in the general population. Second, efforts to lower the burden of cardiovascular disease will require prevention of the development of risk factors (primordial prevention) rather than the sole reliance on the treatment of existing risk factors (primary prevention)," they wrote.

Also, the findings are consistent with prior observations that the decline in cardiovascular event rates in the general population reflect changes in risk factor prevalence as opposed to treatment effects alone.

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