Obesity and Cardiovascular Diseases in a High-Risk Population: Evidence-Based Approach to CHD Risk Reduction.

BACKGROUND: Obesity is becoming a worldwide public health problem and it is expected to worsen as its prevalence is increasing in children and adolescents. This report examined the distribution of major cardiovascular disease (CVD) risk factors and the effect of life-style changes on coronary heart disease (CHD) risk prediction in a high risk obese African Americans. METHODS: We examined the baseline distribution of CVD risk factors in 515 obese African Americans, with mean BMI of 42.9 ± 6.8 kg/m2, and prospectively the effect of a 6-month low-salt, low-fat diet and aerobic-exercise intervention program on risk reduction. RESULTS: Prevalence of hypertension, dyslipidemia, and diabetes mellitus were 57%, 27% and 24% respectively. Metabolic syndrome was present in 36% and 39% met two features of the syndrome. The 10-year risk prediction for developing CHD ranged from 4% to 17% for women and 6% to 29% for men. After 6 months of life-style changes, many of the risk factors improved, and the CHD risk scores decreased from 6% to 4% in the women and 16% to 13% in the men. CONCLUSION: The high prevalence and increasing incidence of obesity and associated cardiovascular risk emphasizes the need to focus on obesity reduction in this high risk population.

Nocturnal blood pressure nondipping in obese African-Americans.

OBJECTIVES: Nondipping pattern of circadian blood pressure (BP) is associated with increased cardiovascular morbidity and mortality; however, limited data are available among obese African-Americans. We, therefore, aimed to evaluate the pattern of circadian BP variation and to identify clinical conditions associated with nondipping in this population. METHODS: A total of 211 obese African-Americans enrolled in a weight-reduction program underwent 24-h ambulatory BP monitoring. Nondipping was defined as a nocturnal BP reduction of less than 10%. RESULTS: Systolic BP (SBP) nondipping was present in 158 participants (74.9%) and diastolic BP (DBP) nondipping was present in 93 participants (44.1%). In multivariate logistic regression analyses, diabetes was associated with SBP nondipping (adjusted OR, 2.53; CI: 1.16-5.76; P=0.02), and increasing BMI (5 kg/m) was associated with DBP nondipping (adjusted OR, 1.46; CI: 1.17-1.83; P=0.001). In linear regression analyses, BMI was positively correlated to office, 24-h, daytime, and night-time SBP (P=0.03, 0.01, 0.03, and 0.005, respectively) and office, 24-h, daytime, and night-time PP (P=0.01, P<0.001, 0.001, and P=0.003, respectively). CONCLUSION: This study demonstrated an excessively high prevalence of nondippers and independent associations between diabetes and SBP nondipping and between BMI and DBP nondipping in an obese African-American population.

The relationship between flow-mediated dilatation of the brachial artery and intima-media thickness of the carotid artery to Framingham risk scores in older African Americans.

The objective of this study was to investigate the relationship of flow-mediated dilatation and intima-media thickness (IMT) with coronary risk in African Americans (AAs). Endothelial dysfunction and IMT of carotid arteries are considered early steps in atherosclerotic disease process and have been used as surrogate markers of subclinical atherosclerosis. Data were collected on 106 AAs with a mean age of 64.0+/-6.6 years. Carotid artery IMT was measured with B-mode ultrasonography, as was brachial artery diameter at rest, during reactive hyperemia, and after nitroglycerin. Percent change in flow-mediated dilatation (%FMD) was defined as 100x(diameter during reactive hyperemia - resting diameter)/resting diameter. Percent change in nitroglycerin-mediated dilatation (%NMD) was defined as 100x(diameter with nitroglycerin-resting diameter)/resting diameter. The Framingham 10-year risk score (FRS) was calculated for each patient using the National Cholesterol Education Program (NCEP) risk score calculator and participants were categorized into 3 groups with FRS as <10%, 10% to 20%, and >20%. Thirty-eight participants had risk scores <10%, 26 had 10% to 20%, and 42 >20%. There was a significant inverse relation between %FMD and FRS (P<.0001) and between %NMD and FRS (P<.001). IMT was not statistically different among the risk groups. Endothelial dysfunction assessed by FMD significantly correlates inversely with FRS in AAs. FMD, an index of arterial compliance, appears to be a sensitive and reliable index of cardiovascular disease.

Effect of diet and exercise on pulse pressure and cardiac function in morbid obesity: analysis of 24-hour ambulatory blood pressure.

Blood pressure is a major risk factor for cardiovascular events, although the role of pulse pressure, an independent predictor of arterial stiffness, has recently been emphasized. This study examines the baseline relationship between body mass index (BMI) and blood pressure indexes in 215 obese African Americans enrolled in a diet-exercise program. The subject population was 77% female, with a mean +/- SD age of 46.7+/-10.7 years and a mean BMI of 42.5+/-7.5 kg/m2. In addition, the authors prospectively examined the effect of weight loss on cardiovascular parameters in a subset of 25 participants. The results show a closer significant correlation between pulse pressure and BMI (b=1.97 kgm-1; p=0.001) than between systolic blood pressure and BMI (b=1.58 kgm-1; p=0.020). After 3 months of diet and exercise, average reductions were as follows: BMI, 4.2 kg/m2 (p<0.01); systolic blood pressure, 7.2 mm Hg (p<0.01); pulse pressure, 4.8 mm Hg (p<0.01); and cardiac output, 975 mL/min (p<0.01). Compliance index increased by 0.1 mL/mm Hg/m2 (p=0.03). The results highlight the potential value to cardiovascular health of a modest reduction in body weight in obese individuals.

The impact of body mass index on pulse pressure in obesity.

OBJECTIVE: Pulse pressure, a marker of arterial vascular properties, has been linked to cardiovascular diseases and complications. This study examined the impact of excess body mass and cardiovascular disease risk factors on pulse pressure (PP). DESIGN: Cross-sectional and prospective study. METHODS: Baseline data consist of 219 obese African Americans, with mean +/- SD age of 46.8 +/- 10.9 years enrolled in a diet and exercise program of weight reduction. A non-invasive monitoring device was used to acquire 24 hourly ambulatory blood pressures. Pulse pressure was calculated as the difference between the average 24-h systolic and diastolic blood pressure and studied as a continuous variable and according to quartiles. The cross-sectional association of pulse pressure with body mass index (BMI) was examined using multivariate linear regression and proportional odds models that controlled for cardiovascular disease risk factors. In addition, we examined prospectively, in 36 participants, the effect of weight loss on pulse pressure, using the Wilcoxon signed ranked test. RESULTS: At baseline, a 5 kg/m2 increase in BMI was independently associated with a 35% risk [relative risk (RR) = 1.35, confidence interval (CI) = 1.10-1.65, P < 0.01] in the general study population and 19% (RR = 1.19, CI = 1.07-1.56, P = 0.04) in obese normotensives for increasing PP by one quartile after adjustment for other significant variables. After 3 months of diet and exercise intervention, BMI decreased by an average of 10.6% (P < 0.01) and resulted in an 8.8% (P < 0.01) reduction in PP. CONCLUSIONS: In the context of obesity, increasing BMI is independently associated with decreasing arterial compliance, as reflected in PP. This association highlights the potential value to cardiovascular health of any reduction in body weight in obese individuals.

Obese African Americans: the prevalence of dyslipidemia, hypertension, and diabetes mellitus.

CONTEXT: The prevalence of the cardiovascular disease risk factors, dyslipidemia, hypertension, and diabetes mellitus, is increased in the setting of obesity. OBJECTIVE: To determine whether the prevalence of these risk factors increases with increasing body mass index in an obese cohort, or whether there is a threshold for their appearance. DESIGN AND SETTING: Individuals with body mass index > or = 30 kg/m2 joined a weight reduction program in the Howard University General Clinical Research Center. PARTICIPANTS: Five hundred fifteen African Americans (aged 12-74 years, mean body mass index of 42.8 +/- 8.5 kg/m2). OUTCOME MEASURES: The cohort was divided by incremental increases in body mass index of 4.99 kg/m2, and the prevalence rates of hypertension (blood pressure > or = 140/90 mm Hg), dyslipidemia (total cholesterol > 200 mg/dL, or low-density lipoprotein > 130 mg/dL, or elevated ratio of total or low-density to high-density lipoprotein cholesterol) and diabetes mellitus (fasting blood glucose > or = 126 mg/dL or random blood glucose > 200 mg/dL) were determined for each group. RESULTS: The cohort prevalence rates were: dyslipidemia, 27.0%; hypertension, 56.9%; and diabetes mellitus, 24.1%. These rates are higher than those found in the African-American population by the third National Health and Nutrition Examination Survey. After adjusting for age and sex, there were no significant differences in the prevalence rates of these risk factors according to increasing body mass index, suggesting a threshold of between 30 kg/m2-34.99 kg/m2 for maximal appearance of these risk factors. CONCLUSION: The incidence rates of dyslipidemia, hypertension, and diabetes mellitus do not increase with a greater degree of obesity above a body mass index of 34.99 kg/m2.