US: CVD and lifetime risk
Title: Lifetime risks of cardiovascular disease
Authors: J Berry, A Dyer, X Cai, D Garside, et al
Reference: N Engl J Med 2012; 366:321-329 (open access)
Reviewer: Robert Goldberg, PhD, Contributing editor, ProCor; Professor of Medicine and Epidemiology, Division of Cardiovascular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, US
Reviewer comments: Estimates of the lifetime risk of developing CVD, overall and in various demographic subgroups, provide a comprehensive measure of the burden of CVD in the general population. These estimates can be of considerable use in developing public health policies to reduce the overall burden of CVD in the population as a whole and provide insights into the impact, or lack thereof, individual and population wide efforts to reduce the magnitude of CVD predisposing factors.
The present article provides insights to the lifetime risk of fatal and nonfatal CVD events across different risk factor strata and by age. In pooling the results from a large number of prospective epidemiologic studies, the investigators demonstrated the importance of traditional coronary risk factors on the lifetime risk of CVD, and that the effect of these risk factors has remained relatively constant across the different birth cohorts examined. While the prevalence of various CVD predisposing factors was higher among blacks than whites, the lifetime risks of various CVD endpoints were essentially the same in blacks and whites when their risk factor profiles were similar.
The results of this comprehensive meta analysis provide not only an extensive amount of useful information for health care providers and CVD researchers but also reinforce the importance of maintaining an optimal coronary heat disease risk factor profile, irrespective of age, sex, and race. Indeed, having a low total serum cholesterol level, desirable level of BP, and being a nonsmoker and a diabetic were associated with a substantially lower risk for dying from CVD in men and women, blacks and whites. These data convincingly demonstrate the importance of having a desirable coronary risk factor profile and the rich dividends that this desirable risk profile will pay on the lifetime risk of experiencing either a fatal coronary heart disease event or nonfatal heart attack.
Purpose of study: To examine the lifetime risks for CVD in black and white adults of varying ages according to various risk factor strata
Location of study: Dallas, Texas, US
Study design: Meta analysis
Results: The authors carried out a meta analysis using data from 18 cohort studies that included information from more than 257,000 middle-aged and elderly black and white men and women. They referred to this effort as the Cardiovascular Lifetime Risk Pooling Project.
Studies were included in this meta analysis if they represented either community or population-based cohorts, had at least one baseline exam that measured various physiologic or anthropometric factors, and had extended follow-up (>10 years) for the ascertainment of fatal or nonfatal CVD events.
Seventeen unique cohort studies satisfied these criteria and were included in the present investigation; data from the MRFIT (Multiple Risk Factor Intervention Trial) were analyzed separately give the large size of this randomized controlled trial and number of originally screened potential study subjects.
A total of 67,890 men and women were included from the 17 studies in the pooled cohort and an additional 189,494 participants were included from MRFIT. There were nearly 30,000 men and women age 45 years, more than 42,000 people age 55 years, 31,000 people age 65 years, and nearly 14,000 people age 75 years.
The lifetime risks of dying from CVD were considerably higher among men than women but were similar between blacks and whites; 36% of white men died from CVD, 33% of black men, and 27% of white and black women. An optimal risk factor profile was considered to be present when a study subject had a total serum cholesterol level of <180 mg/dl, an untreated BP of <120/80 mmHg, the person was a nonsmoker, and the person did not have diabetes present.
In each age strata examined, a higher burden of well-established coronary risk factors was associated with a greater lifetime risk of dying from CVD. For example, among people age 45 years, the proportion of men dying from CVD in whom all of the risk factors examined were considered to be optimal was 9%; this proportion increased to 21% of men who had one major risk factor present and to 33% for men who had two or more major risk factors present. These percentages were 18%, 36%, and 39% for men who were 75 age years. Similar trends were observed among women in the four different age strata examined, though the risks of dying from CVD were considerably lower than were observed among men. Similar trends within these risk factor strata were observed among blacks and whites, though the burden of risk factors was consistently higher among blacks than among whites. Of key importance, an optimal risk factor profile was associated with a substantially lower lifetime risk of fatal CHD or nonfatal MI among both men and women.