The two main findings of applying the AHA 2020 cardiovascular health goal metrics to this long-term prospective study of cardiovascular health in middle-aged adults were that (1
) the AHA metrics indeed reflect well subsequent risk of CVD, as reflected by a graded CVD incidence rate in relation to the number of ideal health metrics, and (2
) virtually no one had ideal cardiovascular health in this community-based study in 1987–89. Previous studies documenting that CVD incidence rates are low in those with optimal cardiovascular health metrics1–8 studied fewer metrics and usually employed narrower CVD incidence definitions, such as CHD alone. In ARIC, for example, we estimated previously that 70% of CHD and stroke events and 77% of heart failure might be eliminated through avoidance of just four factors -- high blood pressure, high cholesterol, diabetes, and smoking (7
). We extended previous findings to the new AHA definition of cardiovascular health in relation to a combined CVD endpoint that included CHD, heart failure, and stroke. The data further demonstrate that much of CVD might be eliminated through primordial prevention whereby people avoid CVD risk factors and risk behaviors in the first place.
The AHA goal to improve cardiovascular health by 20% by 2020 (9
) is bold and forward-thinking, but achievement of the 2020 goal will be challenging. What is clear from our data and previous studies is that most US middle-aged adults have poor cardiovascular health, and few have ideal cardiovascular health. In fact, by the new AHA definition, only 0.1% of ARIC participants in 1987–89 had ideal cardiovascular health. There clearly also is some incongruency that almost no one in middle-age has ideal cardiovascular health, yet the lifetime probabilities of staying free of CHD were nearly 50% for Framingham men and nearly 70% for women (20
), 79% and 80% respectively for heart failure (21
), and 83% and 80% respectively for stroke (22
). Yet, certainly, metrics like AHA’s are needed to monitor the cardiovascular health of the population, even if the US population is currently a long way from ideal. Indeed, formulating a definition of cardiovascular health and establishing specific goal levels, even if challenging to achieve, provides an expanded view of CVD prevention.
A point that ARIC Study investigators made previously (7
) is worth re-emphasizing. Although African Americans have higher rates of CVD than white Americans, this is mainly due to their lower frequency of ideal cardiovascular health metrics (). At similar levels of health metrics, African Americans and whites actually had similar CVD incidence rates in ARIC (). Yet, none of the 3,107 African Americans studied here had ideal cardiovascular health. Other factors, such as socioeconomic disadvantages, stress, or genetics, may contribute additionally to high CVD rates in African Americans, but clearly their low prevalence of “traditional” ideal cardiovascular health metrics is alarming.
We chose to focus on ARIC participants free of CVD at baseline, because we wanted to calculate subsequent CVD incidence rates. Although we excluded participants with self-reported physician diagnosed stroke, MI, or coronary revascularization, as well as MI by ECG or symptoms or treatment for heart failure, we did not have valid measures to exclude some other prevalent cardiovascular diseases (e.g., medically-treated angina), and we did not try to exclude subclinical CVD. Nevertheless, in middle-aged adults our baseline exclusion criteria likely eliminated most clinically important CVD from the cohort. Had we not excluded people with prevalent CVD, the percent prevalence of ideal cardiovascular health in the ARIC sample would be even lower than the observed 0.13%, because CVD patients can only achieve intermediate cardiovascular health, not ideal (9
Drawbacks of our study warrant consideration. First, the ARIC sample is community-based but not nationally-representative. Most of the African Americans were from one center, so their lower prevalence of ideal cardiovascular health than ARIC whites, while consistent with national patterns (23
), might be due to geographic or socioeconomic differences and should not be attributed to race, per se. Furthermore, ARIC has no cardiovascular health information on other minority groups. Such information needs to be documented in minority cohort studies and national surveys. Second, while measurement of major risk factors is well standardized and therefore they are quite generalizable from study to study, measurement of diet and physical activity are not. The instruments we employed were validated (11
) but brief. For example, “fish” included deep fried and other types of fish that probably have widely varying health effects. In addition, sodium intake was likely quite underestimated by this brief food frequency questionnaire. Of course, if ARIC had asked about additional food items or activities, the prevalences of adults meeting ideal diet metrics might have been different. Nevertheless, our estimates for healthy diet and physical activity were close to national estimates (9
). Third, we used a single measure of cardiovascular health. Changes in risk factor levels undoubtedly occurred over two decades of follow-up and would have typically led to underestimation of the true biological associations between cardiovascular health metrics and CVD incidence. This underestimation tends to be larger for behavioral factors than for biological risk factors. Fourth, we studied risk factors in from 1987–89. Yet, the 1987–89 prevalence estimates for ARIC are not greatly different from those for the U.S., currently (9
). Using a more recent value, for example at ARIC Visit 4 in 1996–98, may have given different estimates of the prevalence of ideal health. Because the cohort would have been 9 years older then, likely the prevalence of ideal cardiovascular health would have been even lower. Finally, using the later ARIC exam data also would have shortened the follow-up time for CVD events, resulting in poorer precision of incidence rates.