Risk-Factor Burden Impacts Lifetime Risk of CVD

In the past 20 years, short-term (approximately 10 years) risk estimates of cardiovascular disease (CVD) have been used to help reduce the burden of CVD on healthcare resources. However, according to researchers, the majority of US adults who are considered to be at low risk for CVD in the short term are actually at high risk across their remaining lifespan. Because estimates of the lifetime risk of CVD take into account the risks of CVD as well as competing risk (eg, death from cancer) until participants reach an advanced age, “such estimates can help guide public health policy, allowing projections of the overall burden of [CVD] in the population,” the researchers said. The Cardiovascular Lifetime Risk Pooling Project was designed to collect and pool data from longitudinal epidemiologic cohort studies conducted in the United States in the past 50 years. Pooling the data enabled the researchers to calculate estimates of the lifetime risk of CVD according to age, sex, race, and other risk factors across multiple birth cohorts. Results were reported in the New England Journal of Medicine [2012;366(4):321-329]. The meta-analysis included data from 17 cohort studies involving 67,890 participants whose risk factors for CVD were measured at the ages of 45, 55, 65, and 75 years. Participants were stratified according to risk-factor levels or status as assessed within 5 years of each index age. Risk factors were diabetes, current smoking status, total cholesterol, and systolic blood pressure. Risk-factor level or status was classified into 5 mutually exclusive categories: (1) all risk factors optimal; (2) ≥1 risk factor not optimal; (3) ≥1 risk factor (cholesterol level or blood pressure) elevated; (4) 1 major risk factor present; and (5) ≥2 major risk factors present. The analyses revealed marked differences in the lifetime risks of CVD across risk-factor strata. For participants 55 years of age at baseline, during up to 731,615 person-years of follow-up, there were 5912 deaths from CVD, 5062 fatal or nonfatal myocardial infarctions, 2295 fatal or nonfatal strokes, and a total of 9391 events related to atherosclerotic CVD. Among men and women 55 years of age at baseline, a higher burden of risk factors was associated with a higher lifetime risk of death from CVD. At all index ages, lifetime risks were very low among participants who had an optimal risk-factor profile. When any 1 risk level or status became not optimal, lifetime risks became substantially higher, with stepwise increases in remaining lifetime risk across groups with less favorable profiles for aggregate risk. For the most part, the lifetime risk of death from CVD and coronary heart disease or of nonfatal myocardial infarction was approximately twice as high among men as the risk among women. There were no substantial differences in the lifetime risks of fatal stroke or nonfatal stroke according to sex. In the cohort of those 55 years of age at baseline, the risk of death from CVD through 80 years of age for those with an optimal risk-factor profile was substantially lower than for those with ≥2 major risk factors (4.7% vs 29.6% among men; 6.4% vs 20.5% among women). In addition, those with an optimal risk-factor profile have lower lifetime risks of fatal coronary heart disease or of nonfatal myocardial infarction (3.6% vs 37.5% among men; <1% vs 18.3% among women) and fatal or nonfatal stroke (2.3% vs 8.3% among women; 5.3% vs 10.7% among women). In summary, the researchers said, “the presence of elevated levels of risk factors at all ages translated into markedly higher lifetime risks of cardiovascular disease across the lifespan. These findings were consistent across risk-factor strata among blacks and whites and across multiple birth cohorts."