Independent effect and population impact of obesity on fatal coronary heart disease in adults

doi:10.1016/j.ypmed.2005.09.011

Preventive Medicine

Volume 42, Issue 1, January 2006, Pages 66-72

https://doi.org/10.1016/j.ypmed.2005.09.011 Get rights and content

Abstract

Background.

It is unclear whether the coronary heart disease (CHD) mortality risk associated with obesity is mediated only through traditional CHD risk factors. This analysis evaluated the independent CHD mortality risk due to obesity and determined its population attributable risk (PAR).

Methods.

Using the NHANES I Epidemiologic Follow-up Study (1971–1992, n = 10,582), a diabetes-body mass index (BMI) variable was constructed. The hazard ratios (HR) for fatal CHD in the diabetes-BMI categories (adjusting for age, sex, race, exercise, education level, smoking, hypertension, cholesterol, and alcohol use) were determined and the PARs subsequently estimated.

Results.

Compared to lean non-diabetics, the HR (95% CI) for fatal CHD is 0.8 (0.7, 1.1) in overweight non-diabetics, 1.4 (1.3, 2.0) in obese non-diabetics, 2.2 (1.2, 4.0) in lean diabetics, 2.3 (1.4, 3.9) in overweight diabetics, and 3.3 (1.9, 8.9) in obese diabetics. The PAR% is −6.8 (−15.7, 1.8) in overweight non-diabetics, 6.1 (1.7, 11.1) in obese non-diabetics, 2.0 (0.3, 4.0) in lean diabetics, 2.2 (0.6, 4.3) in overweight diabetics, and 2.2 (0.8, 3.8) in obese diabetics.

Conclusions.

Obesity is an independent risk factor for CHD mortality even after controlling for traditional CHD risk factors. The PAR for CHD death in obese non-diabetics is significant. Obesity should be aggressively treated in those without traditional CHD risk factors.

Introduction

Obesity increases the risk of death [1], [2], [3] and reduces years of life. Obesity also increases the risk of developing type 2 diabetes, dyslipidemia, and hypertension [4], [5], [6]. Whether the coronary heart disease (CHD) risk associated with excess weight is mediated only through diabetes and other traditional CHD risk factors such as hypertension, hyperlipidemia, and smoking, or has additional independent risk is still unclear. Several studies reported a persistent risk of CHD even after controlling for traditional CHD risk factors in white cohorts [2], [3], [6], [7]. In contrast, other studies found that the CHD risk related to excess weight is mediated by traditional CHD risk factors [8], [9], [10], [11].

While it may seem that the increased CHD mortality associated with obesity is well established, this literature is from restricted samples without appropriate control for physical activity or socioeconomic status [12]. To provide valid results for the whole population, this relationship must be determined in a diverse sample that includes both genders, minorities, and the elderly using appropriate statistical methods that provide population estimates [13]. Since a large proportion of obese persons lack traditional cardiovascular risk factors [5], [14], [15], the accurate determination of risk within this group has significant public health importance.

With the rapid increase in obesity among US adults, it is important to understand the relationship of obesity to increased CHD risk in the context of traditional CHD risk factors [16], [17]. This analysis tests the hypothesis that there is increased CHD mortality risk in obese US adults independent of traditional cardiovascular risk factors and evaluates the population impact of obesity.

Obesity is tightly linked to the development of diabetes which is a very strong predictor of future CHD mortality [18], [19]. Diabetes is the most potent CHD risk factor and as ominous as prevalent CHD (i.e., a CHD equivalent). Diabetes is an important mechanism through which obesity mediates CHD risk [9], [20], [21]. In order to carefully control for this powerful mediator, this analysis stratifies by presence of diabetes and analyzes the independent effect of obesity in diabetics and non-diabetics. In addition, confounders that are usually overlooked such as physical activity and education [12] are incorporated. A separate analysis excludes persons with any traditional CHD risk factor to further elucidate the independent effect of obesity on CHD death. This design-based analysis [22] of a national sample attempts to provide a public health perspective on the impact of obesity on coronary heart disease mortality in people without traditional CHD risk factors.

Section snippets

Study design and study sample

This analysis used the First National Health and Nutritional Examination Survey (NHANES I) Epidemiological Follow-up Study (NHEFS). The baseline evaluation was conducted from 1971 to 1975 in NHANES I, which used a multistage, stratified, probability sample of the US civilian non-institutionalized population. NHANES I over sampled the poor, women 25–44 years old and persons ≥65 years. NHEFS is the cohort study of NHANES I participants aged 25–74 in 1971–1975 with follow-up surveys in 1982–1984,

Results

Table 1 presents the baseline characteristics for the diabetes-BMI categories. The mean age in years (with standard errors) were 51 (0.3) for lean non-diabetics, 52 (0.2) for overweight non-diabetics, 53 (0.3) for obese non-diabetics, 59 (1.1) for lean diabetics, 62 (0.8) for overweight diabetics, and 57 (1.1) for obese diabetics. The prevalence of obesity increased with age among diabetics, but not among non-diabetics. Among non-diabetics, obese persons were more likely than non-obese persons

Discussion

In this US population-based cohort, obesity (BMI ≥ 30) confers a substantial increased risk of CHD death. In non-diabetics, there is a significant increase in risk of CHD death among obese persons compared to lean persons. Among diabetics, there is a trend towards increased risk due to obesity. The effect is independent of baseline age, gender, hypertension, smoking, physical activity, education, and cholesterol. Each unit increase in BMI is associated with an increase in the hazard ratio for

Acknowledgments

Public use National Health and Nutritional Examination Survey Epidemiologic Follow-up Study data were obtained from the National Center for Health Statistics. The NHANES I Epidemiologic Follow-up Study was developed and funded by the National Center for Health Statistics; National Institute on Aging; National Cancer Institute; National Center for Chronic Disease Prevention and Health Promotion; National Institute of Child Health and Human Development; National Heart, Lung, and Blood Institute;

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View full text

Independent effect and population impact of obesity on fatal coronary heart disease in adults

Abstract

Background.

Methods.

Results.

Conclusions.

Introduction

Section snippets

Study design and study sample

Results

Discussion

Acknowledgments

Am. J. Cardiol.

Atherosclerosis

Prev. Med.

Am. Heart J.

J. Am. Coll. Cardiol.

Am. Heart J.

Am. Heart J.

Nutrition

Am. J. Prev. Med.

Am. J. Prev. Med.

Body-mass index and mortality in a prospective cohort of U.S. adults

N. Engl. J. Med.

Obesity as an independent risk factor for cardiovascular disease: a 26-year follow-up of participants in the Framingham Heart Study

Circulation

Body weight and mortality among women

N. Engl. J. Med.

Impact of overweight on the risk of developing common chronic diseases during a 10-year period

Arch. Intern. Med.

Overweight and obesity as determinants of cardiovascular risk: the Framingham experience

Arch. Intern. Med.

Coronary heart disease risk factors ranked by importance for the individual and community. A 21 year follow-up of 12 000 men and women from The Copenhagen City Heart Study

Eur. Heart J.

Importance of identifying the overweight patient who will benefit the most by losing weight

Ann. Intern. Med.

Abdominal adipose tissue distribution, obesity, and risk of cardiovascular disease and death: 13 year follow up of participants in the study of men born in 1913

Br. Med. J. (Clin. Res. Ed.)

Losing weight-an ill-fated new year's resolution

N. Engl. J. Med.

Sampling of populations: methods and applications

Influence of obesity on cardiovascular risk. Twenty-three-year follow-up of 22,025 men from an urban Swedish population

Int. J. Obes. Relat. Metab. Disord.

Prevalence of the metabolic syndrome among US adults: findings from the third national health and nutrition examination survey

JAMA

Prevalence and trends in obesity among US adults, 1999–2000

JAMA

Prevalence of obesity, diabetes, and obesity-related health risk factors, 2001

JAMA

Diet, lifestyle, and the risk of type 2 diabetes mellitus in women

N. Engl. J. Med.

Mortality in adults with and without diabetes in a national cohort of the U.S. population, 1971–1993

Diabetes Care

Illustration of analysis taking into account complex survey considerations: the association between wine consumption and dementia in the PAQUID study. Personnes ages quid

Am. J. Epidemiol.