Dietary Behavior and Predicted 10-Year Risk for a First Atherosclerotic Cardiovascular Disease Event Using the Pooled Cohort Risk Equations Among US Adults

Abstract

Purpose:

The pooled cohort equations were developed in 2013 by the American College of Cardiology/American Heart Association Task Force to predict an individual’s 10-year risk of an atherosclerotic cardiovascular disease (ASCVD) event. The purpose of the present study was to evaluate how predicted 10-year ASCVD event risk varies as a function of daily dietary behavior.

Design:

Cross-sectional.

Setting:

National Health and Nutrition Examination Survey 2003 to 2006.

Participants:

A total of 2362 adults aged 40 to 79 years.

Measures:

The ASCVD was assessed via the pooled cohort equations, with the Healthy Eating Index calculated from self-reported dietary behavior.

Analysis:

Multivariable linear and logistic regression.

Results:

Adults in the United States consuming a healthy diet (vs those not consuming a healthy diet) had an 88% increased odds of being at low risk for a future ASCVD event within the next 10 years (odds ratio [OR] = 1.88; 95% confidence interval [CI]: 1.35-2.68; P < .001). Similarly, those eating a healthy diet had a 44% reduced odds of being at high risk for a future ASCVD event within the next 10 years (OR = 0.56; 95% CI: 0.34-0.93; P = .02).

Conclusion:

Among adults who were free of cardiovascular disease, those with a healthy diet had reduced odds of being at high risk for a 10-year ASCVD event.

Keywords

epidemiology diet cardiovascular disease

Purpose

Healthy eating has been implicated as a preventive behavior to reduce the risk of cardiovascular disease (CVD).¹ Living a sedentary lifestyle and eating an unhealthy diet may consequently lead to an increased overweight and obese population, which increases an individual’s risk for CVD.² Further, and with regard to dietary behavior, reduced sodium consumption has been shown to be associated with a 25% to 30% decreased risk of experiencing negative cardiovascular outcomes within the next 10 to 15 years.³ An overall healthy dietary pattern has also been shown to be associated with reduced CVD risk.⁴

A new set of cardiovascular risk equations (pooled cohort equations), developed from longitudinal designs, were introduced in the United States in 2013.⁵ The pooled cohort equations were originally developed to predict an individual’s 10-year risk of developing a first-time atherosclerotic cardiovascular disease (ASCVD) event (eg, nonfatal myocardial infarction or stroke).⁵ Recent work from our group supports the predictive validity of these equations, demonstrating significant positive associations between predicted 10-year ASCVD event risk and CVD–specific mortality,⁶ cancer-specific mortality,⁷ and all-cause mortality.⁶ Additionally, we have recently demonstrated associations between individual health behaviors, such as moderate to vigorous physical activity and sedentary behavior levels, with predicted 10-year risk of an ASCVD event (as determined via the pooled cohort equations).^8
-10 The objective of this applied research brief confirmatory study was to examine how 10-year predicted risk of an ASCVD event varies as a function of dietary behavior among adults in the United States. The present brief study is the first to specifically examine the association between dietary behavior and 10-year predicted cardiovascular risk using the pooled cohort equations. Statistically examining the predicted 10-year risk for an ASCVD-related event as a dependent health outcome enables the identification of health behaviors that may be associated with this risk. This approach may serve to enhance preventive health guidelines aimed at reducing the risk of ASCVD and related events that could occur within the upcoming decade of an individual’s life.

Methods

Study Design and Participants

The National Health and Nutrition Examination Survey (NHANES) is an ongoing survey conducted by the Center for Disease Control and Prevention designed to evaluate the health status of US adults through a complex, multistage, stratified clustered probability design. Data from the 2003 to 2006 cycles were utilized herein as these cycles had complete data on the study variables. Participants were interviewed in their homes and then subsequently examined in a mobile examination center (MEC). Further information on NHANES methodology and data collection is available on the NHANES website (http://www.cdc.gov/nchs/nhanes.htm). Procedures were approved by the review board of National Center for Health Statistics. Consent was obtained from all participants prior to data collection. A total of 2362 consented adults provided data on the study variables.

Dietary Behavior

Two 24-hour recalls were collected, 1 occurring during the visit to the MEC and another via telephone 3 to 10 days after the MEC visit. Dietary intake may differ by weekday, especially weekend days. To capture intake on all days of the week, the 24-hour recalls were collected on every day of the week. The dietary interviewers used the Dietary Data Collection system,¹¹ which is an automated standardized interactive dietary interview and coding system. The Healthy Eating Index (HEI) was developed by the United States Department of Agriculture (USDA) as an indicator of dietary quality.¹² The HEI is comprised of 12 components (total fruit; whole fruit; total vegetable; dark green, orange vegetable, and legumes; total grain; whole grain; milk; meat and beans; oil; saturated fats; sodium; and calories from solid fats, alcoholic beverages, and added sugars) with a maximum score of 100 and with a higher score reflecting better adherence to the dietary guidelines for Americans. The HEI was derived for each of the 24-hour recall days using the MyPyramid Equivalents Database and following the methods and SAS code established by the USDA Center for Nutrition Policy and Promotion.^13

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Using the average of the 2-day HEI scores, participants at or above the 60th percentile (ie, top 40%) of HEI scores in the population were categorized as adhering to the dietary guidelines or consuming a healthy diet.¹⁷

Predicted ASCVD Risk

Predicted 10-year risk of a first ASCVD event for adults aged 40 to 79 years (age range equations were derived from) was calculated using the pooled cohort equations, developed by the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.⁵ Pregnant women or participants on cholesterol medication or who had been told by a doctor or other health professional that they had congestive heart failure, coronary heart disease (CHD), angina, heart attack, or stroke were excluded from the analyses. Separate equations were developed for black and white/other men and women, which included the following variables in the equations: age (years), concentration of total cholesterol (mg/dL), high-density lipoprotein cholesterol (mg/dL), treated or untreated systolic blood pressure (mm Hg), diabetes status (defined here as physician diagnosis or A1C ≥6.5%), and self-reported smoking status (yes/no). Participants with an ASCVD score of ≥20% were considered to be at high risk for future cardiovascular events, with an ASCVD score <7.5% considered at low risk.¹⁸ These equations have demonstrated evidence of validity. For example, Muntner et al¹⁹ demonstrated that the predicted (via the pooled cohort equations) and observed CVD incidence yielded very similar estimates (within 1%-5% of each other), demonstrating that the pooled cohort equations are well calibrated for the population they were derived from.

Covariates

Covariates included age, gender, race–ethnicity, obesity, and physical activity. Obesity was defined as measured body mass index ≥30 kg/m². Objectively measured physical activity was assessed via accelerometry, with details provided elsewhere.²⁰ Briefly, activity counts/min ≥100 was classified as physical activity.²¹

Analyses

Using Stata (version 12) and while accounting for the complex survey design used in NHANES, multivariable linear and logistic regression was used to examine the association between healthy diet and ASCVD and being at high and low risk for future cardiovascular events. Statistical significance was established as P < .05.

Results

The weighted mean age was 53.1 years (95% confidence interval [CI]: 52.3-53.8). The weighted mean ASCVD risk score was 7.04 (95% CI: 6.60-7.48). Among the 2362 adults, 372 had an elevated 10-year risk of an ASCVD event, with 1376 being at low risk.

After adjusting for age, gender, race–ethnicity, weight, and physical activity level, and when considering the ASCVD risk score as a continuous variable, healthy diet was inversely associated with the risk of an ASCVD event (β_adjusted = −1.30; 95% CI: −1.82 to −0.78; P < .001). Results examining the association between healthy diet and both low and high risk for a future ASCVD event are shown in Table 1. As shown in model 2 of Table 1, individuals eating a healthy diet had a 44% reduced odds of being classified in the “high-risk” 10-year ASCVD event group (odds ratio = 0.56; 95% CI: 0.34-0.93; P = .02). Notably, when adding in energy intake (assessed from a dietary interview spanning over 2 days of dietary assessment) as a covariate, results were unchanged (data not shown).

Table 1.

Association Between Healthy Diet and 10-Year Risk of a First Atherosclerotic Cardiovascular Disease Event Using the Pooled Cohort Equations, 2003 to 2006 National Health and Nutrition Examination Survey.^a

	Odds Ratio (95% CI; P Value) for Being at Low Risk for Future ASCVD Events^b	Odds Ratio (95% CI; P Value) for Being at High Risk for Future ASCVD Events^b
Dietary behavior	Model 1	Model 2
Healthy diet versus unhealthy diet^c	1.88 (1.35-2.68; P < .001)	0.56 (0.34-0.93; P = .02)
Covariates
Age, 5-year increase	0.27 (0.23-0.30; P < .001)	4.39 (3.37-5.73; P < .001)
Female versus male	11.63 (7.88-17.17; P < .001)	0.22 (0.14-0.34; P < .001)
Race–ethnicity
MA versus NHW	0.58 (0.39-0.86; P = .009)	3.08 (1.81-5.24; P < .001)
NHB versus NHW	0.20 (0.13-0.30; P < .001)	6.28 (3.32-11.87; P < .001)
Other versus NHW	0.35 (0.18-0.64; P = .002)	3.34 (1.20-9.27; P = .02)
Obese versus not obese^d	0.70 (0.49-1.01; P = .06)	1.67 (0.94-2.97; P = .07)
PA, 60-minute increase	1.13 (1.00-1.28; P = .04)	0.86 (0.73-1.01; P = .06)

Abbreviations: ASCVD, atherosclerotic cardiovascular disease event; MA, Mexican American; NHB, non-Hispanic black; NHW, non-Hispanic white; PA, physical activity.

^aN = 2362.

^bElevated 10-year risk of future ASCVD event defined as a pooled 10-year ASCVD risk score ≥20%, with low risk defined as <7.5%.

^cHealthy diet defined as an average Healthy Eating Index ≥60th percentile.

^dObesity defined as measured body mass index ≥30 kg/m².

Discussion

Summary

The main finding of this study was that among adults who were free of CVD, those with a healthy diet had a reduced odds of being at high risk for a 10-year ASCVD event. Here, a healthy diet includes one that more closely adheres to the MyPyramid recommendations for each food group (eg, eating at least 2 cups of fruit and 2.5 cups of vegetables each day, if on a 2000 calorie/day diet plan, eating a variety of food types and consuming a diet low in fat, saturated fat, cholesterol, and sodium).²² Given that we observed significant differences between a healthy diet and 10-year risk of an ASCVD event based on any of the included covariates, we would recommend following the government recommendations for a well-balanced and healthy diet to Americans of any weight, age, gender, race–ethnicity, and with any level of physical activity.

Limitations

A limitation of this brief report is the subjective assessment of dietary behavior, which may have elicited some degree of recall bias. Notably, the HEI has been previously validated with plasma biomarkers of dietary exposure (eg, serum carotenoids, folate, and vitamin C).^23,24 A limitation to the HEI is that it measures diet quality and does not address energy balance. However, the purpose of the current study was to assess the effects of consuming a healthy versus an unhealthy diet, as opposed to the effects of differing energy balances, on 10-year risk of an ASCVD event. Notably, when we added energy intake as a covariate, results were unchanged. While using the pooled cohort equations may be considered a limitation, given that it is not a direct observation of an actual ASCVD-related event, we view it as a strength of the present study. The predictive validity of these equations has previously been demonstrated with regard to CHD incidence,¹⁹ cause-specific mortality,⁷ and all-cause mortality.⁶ As such, the pooled cohort risk score may be an attractive outcome to evaluate from a preventative health standpoint, allowing for the assessment of risk, prior to an individual developing ASCVD and experiencing a related health event. Another strength of the present study is the employed national sample.

Significance

The findings of this brief report are confirmatory and in support of other studies suggesting a protective effect of healthy eating on CVD,^1,25,26 which underscores the importance of clinicians promoting healthy eating to their patients who are free of CVD.

SO WHAT?

What is already known on this topic?

Dietary behavior is known to influence CVD risk.

What does this article add?

This study adds to the literature by providing confirmatory evidence of a favorable association between dietary behavior and risk of an ASCVD-related event. This is the first national study to evaluate this topic while using the recently developed pooled cohort equations.

What are the implications for health promotion practice or research?

These findings underscore the importance of clinicians promoting healthy eating to their patients who are free of CVD.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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