Demographic characteristics of the study participants are reported in Table 1. As shown in Table 2, the prevalence of current smoking declined from 27.9% (95% CI, 26.4%–29.3%) in NHANES III (1988–1994) to 22.6% (95% CI, 21.3%–24.1%) in 2005–2010 (P < .001 for trend). The prevalence of adults with desirable total cholesterol levels (<200 mg/dL) and blood pressure (<120 mm Hg/<80 mm Hg) remained largely unchanged. However, the prevalence of consuming a healthy diet (≥2 healthy diet score components), having a BMI less than 25, and having a fasting glucose level less than 100 mg/dL declined significantly from 1988–1994 to 2005–2010 (P < .05).

Few participants (<2%) met all 7 cardiovascular health metrics. The prevalence of meeting 6 or more cardiovascular health metrics was 10.3% (95% CI, 9.4%–11.3%) in 1988–1994 and 8.8% (95% CI, 7.3%–10.6%) in 2005–2010, and the prevalence of meeting 1 or fewer cardiovascular health metrics increased from 7.2% (95% CI, 6.5%–8.0%) to 8.8% (95% CI, 8.0%–9.6%) (P < .05 for trend).

Of the nonpregnant adults 20 years or older with complete data on all 7 cardiovascular health metrics and complete mortality follow-up information (n=15 305), we sequentially excluded 1262 participants who reported a history of myocardial infarction, stroke, or congestive heart failure, 465 with diagnosed cancer, and 266 with BMI less than 18.5 at baseline. After these exclusions, 13 312 NHANES III participants were available for the association study. There were 2673 total, 1085 CVD, and 576 IHD deaths over 182 352 person-years of follow-up (median follow-up, 14.5 years). Younger participants, women, non-Hispanic whites, and those with higher education levels tended to meet a greater number of cardiovascular health metrics (eTable 9).

After multivariable adjustment, not smoking, being physically active, having normal blood pressure, and having an HbA_1c level less than 5.7% were independently associated with a significantly lower risk of all-cause mortality (Table 3). A similar pattern was observed for CVD mortality (Table 4). Not smoking, eating a healthy diet (≥2 healthy diet score components), and having an HbA_1c level less than 5.7% were independently associated with a significantly reduced rate of IHD mortality (Table 5).

Adjusted PAFs for all-cause mortality ranged from 10.5% (95% CI, 6.2%–14.7%) for HbA_1c level of 5.7% or greater to 30.4% (95% CI, 19.4%–40.6%) for elevated blood pressure (Table 3); PAFs for CVD mortality ranged from 8.8% (95% CI, 2.1%–15.4%) for HbA_1c level of 5.7% or greater to 40.6% (95% CI, 24.5%–54.6%) for elevated blood pressure (Table 4); PAFs for IHD mortality ranged from 7.5% (95% CI, 3.0%–14.7%) for HbA_1c level of 5.7% or greater to 34.7% (95% CI, 6.6%–57.7%) for elevated blood pressure (Table 5).

Among participants who met 1 or fewer cardiovascular health metrics, age- and sex-standardized absolute risks were 14.8 (95% CI, 13.2–16.5) deaths per 1000 person-years for all-cause mortality, 6.5 (95% CI, 5.5–7.6) for CVD mortality, and 3.7 (95% CI, 2.8–4.5) for IHD mortality. Among participants who met 6 or more cardiovascular health metrics, corresponding risks were 5.4 (95% CI, 3.6–7.3) deaths per 1000 person-years for all-cause mortality, 1.5 (95% CI, 0.5–2.5) for CVD mortality, and 1.1 (95% CI, 0.7–2.0) for IHD mortality (P < .001 for linear trends) (Figure 1).

Comparing participants with 6 or more vs 1 or fewer cardiovascular health metrics, the adjusted HR was 0.49 (95% CI, 0.33–0.74) for all-cause mortality, 0.24 (95% CI, 0.13–0.47) for CVD mortality, and 0.30 (95% CI, 0.13–0.68) for IHD mortality. Meeting a greater number of cardiovascular health metrics was associated with a significantly lower risk of all-cause, CVD, and IHD mortality (P < .001 for linear trends) (Table 6). Adjusted PAFs were 58.6% (95% CI, 33.2%–76.1%) for all-cause mortality, 63.9% (95% CI, 28.0%–84.1%) for CVD mortality, and 62.9% (95% CI, 5.3%–89.1%) for IHD mortality.

Figure 2 shows the Kaplan-Meier survival curves for cumulative all-cause, CVD, and IHD mortality among participants meeting 0–1, 2, 3, 4, 5, and 6 or more cardiovascular health metrics (P < .001 for all log-rank tests). The patterns of the reduced risk for all-cause, CVD, or IHD mortality, in association with meeting greater numbers of cardiovascular health metrics, remained largely consistent across subgroups defined by age, sex, race/ethnicity, and educational attainments (eTables 2–5). The significant interaction between cardiovascular health metrics and age group (<60 vs ≥60 years, P < .02) on CVD mortality suggested that meeting cardiovascular health metrics might offer greater protection against premature CVD deaths among younger participants (eTable 2). However, the absolute numbers of CVD deaths that would be avoided or postponed by meeting a greater number of cardiovascular health metrics would be substantially larger among older participants because of much higher baseline risk in the older population.

Using a series of nationally representative samples of the adult population, our results indicated that prevalence of current smoking continued to decline since 1988. However, the desirable level of untreated blood pressure (<120/<80 mm Hg) and total cholesterol level (<200 mg/dL) remained unchanged, and the prevalence of desirable levels of BMI (<25) and fasting glucose (<100 mg/dL) continued to decline for the study period. The prevalence of meeting all 7 cardiovascular health metrics was low.

During a median of 14.5 years of follow-up in the NHANES III Linked Mortality File cohort, participants who met 6 or more vs 1 or fewer cardiovascular health metrics had a 51% lower risk of all-cause mortality, a 76% lower risk of CVD mortality, and a 70% lower risk of IHD mortality. In addition, meeting a greater number of cardiovascular health metrics also appeared to be associated with lower risk for all-cancer mortality (eTable 6).

Elevated blood pressure, including prehypertension and hypertension, was associated with the largest adjusted PAFs for all-cause and CVD deaths in this cohort (30.4% and 40.6%, respectively). Hypertension affected approximately 68 million individuals in the United States in 2009.²⁷ Studies suggest that for every 10% increase in hypertension treatment, an estimated 14 000 deaths would be prevented annually.²⁸ Although the awareness, treatment, and management of hypertension are extremely important in prevention of CVD incidence and mortality, our results indicated that the desirable level of blood pressure (<120/<80 mm Hg) among the adult population remained unchanged since 1988. In addition to high sodium intake,²⁹ overweight or obesity, lack of physical activity, high alcohol intake, and poor diet are other important modifiable risk factors for elevated blood pressure and hypertension, supporting the importance of primordial prevention of elevated blood pressure through behavioral and policy changes.³⁰

Smoking was associated with the second-largest adjusted PAF for all-cause mortality and significantly contributed to the CVD mortality in our study. Although the prevalence of smoking among US adult populations declined over the last 40 years,^31,32 about 1 in 5 US adults (23%) were current cigarette smokers in 2005–2010. Every 5% increase in smoking cessation would prevent 7000 deaths annually.²⁸ Continuing to implement population-based prevention strategies, operationalize tobacco control policies, and promote clinical cessation interventions would further reduce the prevalence of smoking and improve cardiovascular health in the population at large.

Many observational studies provide strong evidence to support the benefits of healthy diets and physical activity on CVD incidence and mortality.^33–35 Both diet and physical activity affect the presence and severity of CVD risk factors.^4,36–43 Despite the recommendations and well-known benefits of eating fruits and vegetables daily and engaging in regular physical activity, only about 1 in 5 adults met the AHA intermediate level of healthy diet (≥2 healthy diet score components), less than 1% met the ideal level (≥4 components), and there was no evidence of increased prevalence of healthy diet over time. Although the prevalence of physical activity has increased slightly since the late 1980s,^44–46 the majority of US adults are not physically active at levels that can promote health. Additionally, significant racial/ethnic disparities in physical activity levels have been observed.^44–47 Federal, state, and local public health agencies should continue to implement evidence-based, culturally appropriate public education and policy initiatives to further increase physical activity levels and promote healthy diets among all adults in the United States.

The prevalence of BMI less than 25 and fasting glucose levels less than 100 mg/dL continues to decline significantly, whereas the prevalence of obesity and diabetes continues to increase among US adults, although the increase in obesity rates has slowed since mid-2000.^48–52 It is estimated that 36% of US adults are obese, 8.3% have diabetes, and more than 50% of persons with diagnosed diabetes are also obese.^51–55 The high prevalence of obesity and the increasing prevalence of diabetes could offset the positive effects of the decline in other CVD risk factors^56,57 and continue to slow improvements in cardiovascular health. To address these competing influences, public health intervention programs aimed at improving lifestyle choices, eg, increasing physical activity and promoting healthy eating, should be made more widely available. For example, translating the Diabetes Prevention Program to community-based settings has shown promising results in improving diet and physical activity, reducing body weight, and improving cardiovascular health in general.^58,59

Body mass index and total cholesterol level showed a U-shaped association with CVD mortality in this cohort.^24,25 In our sensitivity analyses using BMI less than 30 vs 30 or greater and total cholesterol level less than 240 mg/dL vs 240 mg/dL or greater, these categories of BMI and total cholesterol level were associated with lower risk of CVD mortality (eTable 7), and adjusted HRs were 0.35 (95% CI, 0.26–0.46) for all-cause mortality, 0.21 (95% CI, 0.13–0.33) for CVD mortality, and 0.19 (95% CI, 0.10–0.34) for IHD mortality, comparing participants with 6 or more vs 1 or fewer cardiovascular health metrics (eTable 8). However, the prevalence of desirable total cholesterol level (<200 mg/dL) remained unchanged since 1988. Apart from actively managing cholesterol levels with medications, comprehensive primary prevention strategies promoting a healthy diet and lifestyle to increase the prevalence of desirable total cholesterol levels will improve the cardiovascular health status of the general population.

The major strengths of our study include the use of data from a series of nationally representative samples of US adults for trend analyses of cardiovascular health metrics and from a nationally representative cohort of US adults with a long duration of follow-up (median, 14.5 years) for mortality study; the availability of 7 cardiovascular health metrics measurements or appropriate proxy measurements; detailed data on potential confounders for CVD; and the estimation of adjusted PAFs for 7 cardiovascular risk factors.

Our study has several limitations. First, the NHANES III Linked Mortality File included only the baseline measurements of cardiovascular health metrics. We were not able to quantify the effects of changes in these factors over the life course on all-cause and CVD mortality. Second, the survey questionnaire about physical activity was consistent from NHANES 1999–2004 and 2005–2006 regarding duration (minutes) for each activity. However, NHANES III included no information on duration, and we thus used METs and number of times per week to approximate the AHA definition.

Third, the FFQ in NHANES III used “past month” as the reference period, but the FFQ in NHANES 2003–2004 and 2005–2006 used “previous 12 months.” The interpretation of trends should take into account this difference. Fourth, the analyses of the effects of some modifiable risk factors, especially obesity and mortality, are subject to confounding by smoking and reverse causality because of preexisting conditions, which might have led to an underestimate of these effects on mortality.⁶⁰ In the multivariate analyses, the association for the healthy diet score was also underestimated because the effects of a healthy diet are partly mediated through intermediate cardiovascular risk factors such as blood pressure and levels of cholesterol and glucose.

Fifth, we used an HbA_1c level less than 5.7% to approximate a fasting glucose level less than 100 mg/dL, as suggested by the American Diabetes Association.²¹ This might have resulted in underestimation of the prevalence of prediabetes. Sixth, PAFs derived from an observational study could lead to biased estimates of the effects of changing CVD risk factors on deaths avoided or postponed; a well-designed randomized clinical trial would have been ideal but not feasible. In addition, it is unlikely that in reality all participants would change to meet the ideal or desirable cardiovascular health metrics; the generalized impact fraction might be a more practical evaluation of the effects of changes in risk factors.⁶¹

Seventh, the NHANES III Linked Mortality File identified causes of death through the National Death Index; the index is based on death certificates, which are subject to errors in classification of the cause of death. Eighth, our study examined the association of cardiovascular health metrics with CVD mortality but not incidence. However, the pattern of associations observed in our study was consistent with that for CVD incidence.³

Healthy People 2020 and the AHA’s national strategy to reduce CVD morbidity and mortality by 20% by 2020 through promoting ideal cardiovascular health metrics represents a great challenge but also an achievable goal.¹⁰ Coordinated efforts, such as the recently announced Million Hearts initiative, align CVD prevention and control activities across the public and private sectors, creating opportunities to reduce the burden of CVD across a large segment of the population.^62–64

In summary, our findings indicate that the presence of a greater number of cardiovascular health metrics was associated with a graded and significantly lower risk of total and CVD mortality. However, the prevalence of meeting all 7 cardiovascular health metrics was low in the adult population.