Ike S. Okosun

Abdominal Adiposity and Clustering of Multiple Metabolic Syndrome in White, Black and Hispanic Americans

PURPOSE The aim of this study was to evaluate the association of abdominal adiposity assessed by waist circumference (WC) with clustering of multiple metabolic syndromes (MMS) in White, Black and Hispanic Americans. MMS was defined as the occurrence of two or more of either hypertension, type 2 diabetes mellitus, dyslipidemia, hypertriglyceridemia or hyperinsulinemia. METHODS The number of MMS and fasting insulin (a surrogate measure of MMS) were each used as dependent variables in gender-specific multiple linear regression models, adjusting for age, smoking and alcohol intake. The contribution of WC to interethnic differences in clustering of MMS and fasting insulin concentration was assessed in gender-specific linear regression models. The risk of MMS due to large waist was estimated by comparing odds ratio for men with WC >/= 102 cm with those with WC < 102, and women with WC >/= 88 cm with women with WC < 88 cm in the logistic regression model adjusting for age, smoking and alcohol intake. RESULTS WC was positively and independently associated with clustering of MMS and increased fasting insulin concentration adjusting for age, smoking and alcohol intake in the three ethnic groups (p < 0.01). Black ethnicity was associated with clustering of MMS and fasting insulin concentration (p < 0.01). Hispanic ethnicity was also associated with clustering of MMS in men and associated with fasting insulin concentration in both men and women (p < 0.01). In both men and women, the risk of MMS clustering was strongly associated with increased WC in all ethnic groups independent of BMI. CONCLUSION WC appears to be a marker for multiple metabolic syndromes in these ethnic groups. The results of this investigation lend support to the view that waist measurement should be considered as a clinical variable for assessing the risk of cardiovascular diseases.

Abdominal obesity in the United States: prevalence and attributable risk of hypertension

Objective: The aim of this study was to determine the prevalence of abdominal obesity and its impact on the risks of hypertension in the US adult population. Design and methods: Data from the third US National Health and Nutrition Examination Surveys, 1988–1994, were utilised. Abdominal obesity was defined as waist circumference 102 cm in men and 88 cm in women. Hypertension was defined as mean diastolic blood pressure 90 mm Hg, systolic blood pressure 140 mm Hg or current treatment with prescribed hypertension medication. Prevalences of abdominal obesity were estimated in non-Hispanic White, non-Hispanic Black and Hispanic Americans. Gender-specific logistic regression analysis using empirical waist cut-off points was used to determine the risks of hypertension. The impact of abdominal adiposity on risk of hypertension was estimated from population-attributable risk adjusting for age, current smoking and alcohol intake. Results: The prevalences of abdominal obesity were 27.1%, 20.2% and 21.4% in White, Black and Hispanic men, respectively. The corresponding values in women were 43.2%, 56.0% and 55.4%. Abdominal obesity was found to be associated with a two to three-fold increased risk of hypertension in this population. In men, the attributable risk percent ranged from 20.9% in Hispanics to 27.3% in Whites and in women ranged from 36.5% in Whites to 56.5% in Hispanics. We estimated that 24 million adult men and 40 million adult women of Hispanic and non-Hispanic Black and White ethnicity were suffering from abdominal obesity. Conclusions: In this population, hypertension appears to be associated with abdominal obesity. The estimates of population attributable risks suggest that the risk of hypertension could be potentially reduced if waist size were reduced to <102 cm in men and <88 cm in women.

Abdominal adiposity values associated with established body mass indexes in white, black and hispanic Americans. A study from the Third National Health and Nutrition Examination Survey

PURPOSE: To determine whether white, black and hispanic young (17–39 y) and middle-aged (40–59 y) adults, and elderly (60–90 y) Americans have the same values of abdominal adiposity (estimated from waist circumference (WC) at the established levels of overweight (body mass index, BMI 25–29.9 kg/m2) and obesity (BMI≥30 kg/m2).METHODS: Data (n=16,120) from the US Third National Health and Nutrition Survey were utilized. Age-adjusted linear regression analyses were used to estimate gender- and ethnic-specific WC values corresponding to overweight and obesity. Receiver operating characteristic (ROC) curves were also employed to determine the choices of WC values corresponding to the established BMI cut-off points. With ROC, gender- and ethnic-specific cut-off points producing the best combination of sensitivity and specificity were selected as optimal thresholds for WC values corresponding to the established BMI cut-off points.RESULTS: WC values associated with the established BMI were lower in blacks and hispanics compared with whites. In men, the WC values that corresponded to overweight ranged from 89 to 106 cm, from 84 to 95 cm, and from 87 to 97 cm in whites, blacks and hispanics, respectively. The corresponding values for obesity ranged from 99 to 110 cm, from 96 to 107 cm, and from 97 to 108 cm. The WC values that corresponded to overweight in women ranged from 82 to 91 cm, from 81 in to 90 cm, and from 83 to 92 cm in whites, blacks and hispanics, respectively. The analogous values for obesity ranged from 94 to 101 cm, from 93 to 100 cm, and from 94 to 101 cm.CONCLUSIONS: The lack of higher WC values in blacks (particularly women) and hispanics at the same levels of BMI for whites challenges previously held assumptions regarding the role of abdominal adiposity in cardiovascular disease experienced by non-whites. Defining the anthropometric variables that satisfactorily describe reasons for ethnic differences in cardiovascular disease is one of the challenges for future research.

Impact of birth weight on ethnic variations in subcutaneous and central adiposity in American children aged 5-11 years. A study from the Third National Health and Nutrition Examination Survey.

OBJECTIVE: To determine the types of subcutaneous adiposity represented by different measurements of skinfold thickness that are associated with birth weight in white (n=759), Black (n=916) and Hispanic (n=813) American children aged 5–11 y. We also determined the contribution of birth weight to ethnic differences in subcutaneous and central adiposity.DESIGN AND METHODS: Data for this analysis were from the Third US National Health and Nutrition Examination Survey. The outcome measures were triceps, subscapular, suprailliac and thigh skinfold thicknesses at 5–11 y of age. Central adiposity was defined as ratios of subscapular to triceps (STR) and central–peripheral (CPR) (subscapular+suprailliac)/(triceps+thigh) skinfolds. Partial correlation analyses were used to determine the association between birth weight and measures of subcutaneous fatness, while multiple linear regression analyses were used to determine the independent contribution of birth weight to ethnicity variations in subcutaneous and central adiposity adjusting for sex, age and BMI.RESULTS: Overall, birth weight was negatively associated with subscapular skinfold and central adiposity in White, Black and Hispanic American children (P<0.05). Birth weight was also negatively associated with suprailliac skinfold in both Blacks and Hispanics (P<0.01) and with sum of the four skinfolds in Blacks (P<0.05). Compared with White, Black ethnicity was negatively associated with triceps, suprailliac thigh and sum of skinfold thicknesses controlling for birth weight, sex, age and BMI (P<0.01). Compared with White, Hispanic ethnicity was negatively associated with triceps, thigh and sum of skinfold thicknesses (P<0.01). Both Black and Hispanic ethnicity was positively associated with STR and CPR (P<0.01).CONCLUSIONS: In this population of American children, the association of birth weights with subcutaneous and central fat accumulation may be due to fetal programming. Since the impact of fetal conditions is likely to be modified by life course, defining the interaction between factors that are present at birth and subsequent exposures is one of the essential challenges for future research.

Predictive value of abdominal obesity cut-off points for hypertension in Blacks from West African and Caribbean island nations

BACKGROUND: Waist circumferences (WC) ≥94 cm for men and ≥80 cm for women (action level I) and ≥102 cm for men and ≥88  cm for women (action level II) have been suggested as limits for health promotion purposes to alert the general public to the need for weight loss. In this analysis we examined the ability of the above cut-off points to correctly identify subjects with or without hypertension in Nigeria, Cameroon, Jamaica, St Lucia and Barbados. We also determined population- and gender-specific abdominal adiposity cut-off points for epidemiological identification of risk of hypertension.METHODS: Waist measurement was made at the narrowest part of the torso as seen from the front or at midpoint between the bottom of the rib cage and 2 cm above the top of the iliac crest. Sensitivity and specificity of the established WC cut-off points for hypertension were compared across sites. With receiver operating characteristics (ROC), population- and gender-specific cut-off points associated with risk of hypertension were determined over the entire range of WC values.RESULTS: Predictive abilities of the established WC cut-off points for hypertension were poor compared to the specific cut-off points estimated for each population. Different values of WC were associated with increased risk of hypertension in these populations. In men, WC cut-off points of 76, 81, 80, 83 and 87 cm provided the highest sensitivity for identifying hypertensives in Nigeria, Cameroon, Jamaica, St Lucia and Barbados, respectively. The analogous cut-off points in women were 72, 82, 85, 86 and 88 cm.CONCLUSIONS: The waist cut-off points from this study represent values for epidemiological identification of risk of hypertension. For the purpose of health promotion, the decision on what cut–off points to use must be made by considering other additional factors including overall impact on health due to intervention (e.g. weight reduction) and potential burden on health services if a low cut-off point is employed. There is a need to develop abdominal adiposity cut-off points associated with increased risks for cardiovascular diseases in different societies, especially for those populations where the distribution of obesity and associated risk factors tends to be very different from those of the technologically advanced nations.

Predictive values of waist circumference for dyslipidemia, type 2 diabetes and hypertension in overweight White, Black, and Hispanic American adults

Waist circumferences (WC) >/=102 cm for men and >/=88 cm for women have been proposed by an expert panel as cut-points for identifying increased risk for the development of obesity comorbidities for most adults. The aim of this investigation was to examine the predictive values of these WC cut-points for hypercholesterolemia, low concentration of high (HDL-C), and high concentration of low (LDL-C) density lipoprotein cholesterol, hypertriglyceridemia, type 2 diabetes, and hypertension in overweight American adults. Data from NHANES III were utilized for the analysis. Predictive abilities were determined by calculating sensitivity, specificity, positive (PV+) and negative (PV-) predictive values in overweight subjects with BMI 25-29.9 kg/m(2). Sensitivity of WC cut-point was stronger for high LDL-C compared to other risk factors with the highest values recorded in the 40-59 and 60-69 year age groups in men and women, respectively. PV+ of WC cut-points for dyslipidemia, type 2 diabetes, and hypertension were low in men compared to women. PV+ tended to increase with age, from 19-39, 40-59 to 60-90 year age groups in Whites, Blacks, and Hispanic men. In men, the highest PV+ were recorded for hypertriglyceridemia in the 60-90 years old groups, with values of 71.6%, 52.5%, and 43.3% in Whites, Blacks, and Hispanics, respectively. The CVD risk factor associated with the highest PV+ in women was diabetes with values of 97.2% in Whites and 88.9% in Blacks, and hypertriglyceridemia with a value of 93.8% in the 17-39 year age group in Hispanics. Among Black men 40-59 years of age, only 32% of a population of overweight hypertensives were detected by the WC cut-points, and among Black women, 40-59 years of age, only 54% were detected. Given the low sensitivity of these cut-points for detecting hypertension, one of the major co-morbidities of obesity, these cut-points failed to provide adequate evidence for the use of WC in determining or evaluating patients as to co-morbid states. We recommend further studies to determine a set of specific cut-points associated with increased risk of CVD in different population groups.

Abdominal obesity defined as a larger than expected waist girth is associated with racial/ethnic differences in risk of hypertension

Objective: Waist circumference (WC) cut-points of ⩾102 cm and ⩾88 cm for men and women, respectively, representing abdominal obesity have been recommended for determining obesity related co-morbidities. However, these cut-points carry the component of generalised obesity estimated by body mass index (BMI). The aim of this investigation was to determine whether abdominal obesity free of the influence of overall heaviness is associated with increased risk of hypertension in a representative sample of white and black Americans.Methods: Data (n = 11114) from the Third US National Health and Nutrition Examination Survey were used in this investigation. Standardised residual values from the linear regression of WC on BMI were used to define abdominal obesity status. The risk of hypertension associated with abdominal obesity was estimated from the logistic regression model, adjusting for age, smoking and alcohol. We also estimated the public health consequences of abdominal obesity from the population attributable fraction of hypertension.Results: Relative to white, black race/ethnicity was associated with ∼1.8 and ∼2.7 greater risk of hypertension in men and women, respectively, adjusting for abdominal obesity, age, smoking and alcohol consumption. Having larger than expected waist girths were associated with 1.58 and 1.39 increased risk of hypertension in black men and black women, respectively, adjusting for confounders. Population attributable risks of hypertension due to abdominal obesity were approximately 24.9% and 15.9%, in black men and black women, respectively.Conclusions: In Americans, hypertension is a public health problem that is closely linked to abdominal adiposity. An important research challenge therefore is to determine the best way to regulate body weight under conditions of food abundance. There is a need to clarify how lifestyle habits promote large waist sizes leading to abdominal adiposity and associated cardiovascular disease in the US, particularly among black Americans.

The distribution and mortality impact of chronic energy deficiency among adult Nigerian men and women

Objective: To determine the prevalence of chronic energy deficiency (CED) and associated mortality risk in a cohort of adult Nigerians followed from 1992 to 1997.Research methods and procedures: The data for this investigation were derived from an international collaborative study on chronic diseases in populations of the African diaspora. Body mass index (BMI) was used to define three grades of CED in 4061 men and women aged 25 years and older: Grade I (mild CED) as BMI 17.5–18.4, Grade II (moderate CED) as BMI 16.0–17.4, and Grade III (severe CED) as BMI<16.0 and BMI ≥18.5 was considered normal. The odds of mortality associated with differing grades of CED was estimated with logistic regression analysis.Results: The prevalence of CED (BMI<18.5) increased from 14.3% in 1992 to 19.6% in 1997, both genders combined. The prevalence of CED was similar for both sexes in 1992 (14%) but increased to 22.4% in men and 17.4% in women by 1997. The prevalence of CED was 8.5%, 7.6 and 3.4 for Grades I, II and III, respectively. Two hundred and seven deaths occurred during the follow-up period. The mortality rate for the 5.5 y of follow-up was 5.1% (207/4061). The odds ratios (95% Cls) for all cause mortality were 1.4 (0.5, 3.8), 2.4 (1.2, 4.9) and 2.5 (1.0, 6.2), respectively, for CED grades I, II and III adjusting for age and sex.Conclusion: Under nutrition is an increasing problem in Nigerian men and women. The economic reforms (structural adjustment program (SAP)) introduced in 1986 in combination with the continued economic woes brought on by political instability, corruption and nepotism have been advanced by several investigators as the main factors in the growing problem of inadequate calorie intake. Intervention strategies both at the government and private sectors are urgently needed to increase food availability.Sponsorship: This work was supported by grants from the National Institutes of Health (HL 45508, HL 47910, HL 53353).

Ethnic differences in the risk of type 2 diabetes attributable to differences in abdominal adiposity in American women.

Objective To determine how much of the relative difference in the risk of type 2 diabetes between White and non-White (Black and Hispanic) American women can be explained by differences in the prevalence of abdominal obesity. Methods Data from the Third National Health and Nutrition Examination Survey (n= 1572) were used in this investigation. The risk of type 2 diabetes and the population attributable fraction due to abdominal obesity were estimated using a logistic regression model adjusted for body mass index, age, smoking and alcohol consumption. The contribution of abdominal obesity to the development of diabetes within different ethnic groups and ethnic differences in the risk of diabetes were determined using the population attributable fraction and relative attributable risk, respectively, which compared Hispanic and Black women to White women. Results Abdominal obesity was associated with an increased risk of type 2 diabetes when adjusting for body mass index, age, smoking and alcohol consumption. The population attributable fractions indicated that 24.0, 39.9 and 15.7% of diabetes in White, Black and Hispanic women, respectively, could have been avoided if abdominal obesity was absent. Abdominal obesity accounted for 12.1% and 9.8% of ethnic differences in the risk of diabetes between White and Black women and between White and Hispanic women, respectively. Conclusion A reduction in the risk of diabetes among Black and Hispanic women could be possible by instituting public health measures for reducing waist size to the levels seen in White women. Intervention programmes designed for reducing overall obesity and, consequently, waist size through lifestyle modification, including exercise and diet, may have considerable public health significance in reducing the incidence of type 2 diabetes in these populations.

Association of waist circumference with ApoB to ApoAI ratio in black and white Americans.

BACKGROUND: Although numerous studies have demonstrated obesity as an aspect of the insulin resistance syndrome in cardiovascular disease (CVD), the mechanism is not clear. Central adiposity, acting through many CVD risk factors, including, plasma glucose, insulin, total cholesterol, low density lipoprotein-cholesterol (LDL-C) and lipoprotein moities-apolipoprotein B (ApoB), apolipoprotein A-I (ApoAI), by atherogenic and thrombotic mechanisms has been proposed as a possible mechanism. In this study, we examined the relationship between central fat distribution (defined by waist circumference) and the ratio of these lipoproteins (ApoB/ApoAI).SUBJECTS AND METHODS: Association between ApoB/ApoAI ratio and waist circumference was compared in Blacks (n=854) and Whites (n=2552) using the NHANES III population-based samples. Correlation analyses and multiple regression analyses were used to determine the association between ApoB/ApoAI and waist circumference, controlling for age, body mass index (BMI), race, gender, plasma glucose, insulin, serum triglyceride and total cholesterol.RESULTS: Adjusting for age, ApoB/ApoAI was significantly correlated with waist circumference (Black men: r=0.38, White men: r=0.26, Black women: r=0.20, White women: r=0.36) (all P<0.01). Adjusting for age and triglyceride or insulin, waist circumference was also positively correlated with CVD risk factors including, ApoB, LDL-C, plasma glucose and fasting insulin, and inversely correlated with ApoAI and HDL-C in Blacks and Whites (P<0.05). Overall, triglyceride and total cholesterol were the strongest predictors of ApoB/ApoAI in Blacks and Whites adjusting for age, BMI and insulin, than waist girth (P<0.01).CONCLUSIONS: The result of this study suggests the need to investigate ApoB/ApoAI as another possible facet in the insulin resistant syndrome.