Comparison of Cardiovascular Risk Factors in Obese Blacks and Whites

Blacks are known to have higher blood pressure levels, a higher prevalence of hypertension, and higher body weights than whites. However, the interrelationships of these and other cardiac risk factors have not been analyzed in an obese population. We compared blood pressure (BP) and lipid levels in 174 obese blacks and 939 obese white patients who were entering a weight loss program; we also assessed the effects of weight loss on these factors. Prevalence of treated hypertension was similar in blacks and whites (28% vs. 25%, respectively). In patients not taking BP medication, black women weighed more (108 kg) than white women (102 kg) and black and white males' weights were similar (135 kg vs. 131 kg). Systolic and diastolic BP were similar in black and white women; black males had similar SBP but a significantly lower DBP than white males (83 mmHg vs. 89 mmHg, respectively). Lipid levels were similar in black and white women except black women had lower triglycerides (1.30 mmol/L) than white women (1.58 mmol/L, p<0.05); and black males compared to white males had significantly lower total cholesterol (4.76 mmol/L vs. 5.56 mmol/L), LDL-cholesterol (3.15 mmol/L vs. 3.52 mmol/L) and triglycerides (1.31 mmol/L vs. 2.17 mmol/L, p<0.05). Adult-onset obesity adversely affected a number of cardiovascular risk factors in whites, but not in blacks. Blacks lost significantly less weight (?13 kg) than whites (?19 kg). However, controlling for the difference in weight loss, blacks sustained comparable improvement in lipids and blood pressure, except for TC/HDL-C (whites improved significantly more, ?0.36 kg/m2, than blacks, 0.03 kg/m2). Thus, the impact of obesity on cardiovascular risk factors seems ameliorated in blacks com-pared to whites.     

Testosterone and Regional Fat Distribution

The effects of testosterone treatment of abdominally obese men have been assessed by evaluating the following parameters: The metabolic activity of different adipose tissue regions in vivo (using lipid label as a tracer) and in vitro (measuring lipoprotein lipase(LPL) activity), the total and visceral adipose tissue mass, insulin sensitivity, fasting blood glucose, blood lipids, and blood pressure as well as prostate volume. Middle-aged men with abdominal obesity were treated with transdermal administration of testosterone (T), dihydrotestosterone (DHT) or placebo (P) during 9 months. The study was double-blind. Treatment with T was followed by an inhibited uptake of lipid label in adipose tissue triglycerides, a decreased LPL-activity and an increased turn-over rate of lipid label in the abdominal adipose tissue region in comparisons with the DHT and P groups. These effects on adipose tissue metabolism were not detected in the femoral adipose tissue region in any of the groups. T treatment was also followed by a specific decrease of visceral fat mass (measured by CT-scan), by increased insulin sensitivity (measured with the euglycemic glucose clamp), by a decrease in fasting blood glucose, plasma cholesterol and triglycerides as well as a decrease in diastolic blood pressure. In the DHT group an increased visceral mass was detected. No other changes in these variables were found in the DHT and P groups. There were no detectable changes in prostate volume (measured by ultra-sound), prostate specific antigen concentration, genito-urinary history or urinary flow measurements in any of the groups. It is suggested that T substitution to a selected group of men results in general metabolic and circulatory improvements. The prostate area needs further careful attention.     

Obesity and Cardiovascular Disease Risk Factors in Firefighters: A Prospective Cohort Study

Objective: Obesity, despite being a significant determinant of fitness for duty, is reaching epidemic levels in the workplace. Firefighters’ fitness is important to their health and to public safety. Research Methods and Procedures: We examined the distribution of BMI and its association with major cardiovascular disease (CVD) risk factors in Massachusetts firefighters who underwent baseline (1996) and annual medical examinations through a statewide medical surveillance program over 5 years of follow‐up. We also evaluated firefighters’ weight change over time. Results: The mean BMI among 332 firefighters increased from 29 at baseline to 30 at the follow‐up examination (2001), and the prevalence of obesity increased from 35% to 40%, respectively (p < 0.0001). In addition, the proportion of firefighters with extreme obesity increased 4‐fold at follow‐up (from 0.6% to 2.4%, p < 0.0001). Obese firefighters were more likely to have hypertension (p = 0.03) and low high‐density lipoprotein‐cholesterol (p = 0.01) at follow‐up. Firefighters with extreme obesity had an average of 2.1 CVD risk factors (excluding obesity) in contrast to 1.5 CVD risk factors for normal‐weight firefighters (p = 0.02). Finally, on average, normal‐weight firefighters gained 1.1 pounds, whereas firefighters with BMI ≥ 35 gained 1.9 pounds per year of active duty over 5 years of follow‐up. Discussion: Obesity is a major concern among firefighters and shows worsening trends over time. Periodic medical evaluations coupled with exercise and dietary guidelines are needed to address this problem, which threatens firefighters’ health and may jeopardize public safety.     

Obesity in the Elderly and Its Relationship with Cardiovascular Risk Factors in Taiwan**

Objectives: The obese elderly are at increased risk of mortality, morbidity, and functional disability. In this study, we examined the prevalence of obesity and relationship between various anthropometric indices (AI) and cardiovascular disease (CVD) risk factors in the elderly. Research Methods and Procedures: A stratified multistage clustered sampling scheme was used in the Elderly Nutrition and Health Survey in Taiwan during 1999 to 2000. 2432 non‐institutionalized subjects (age, 72.8 ± 9.4 years; BMI, 23.6 ± 6.4 kg/m²) were recruited. The receiver operating characteristic analysis was used to compare predictive validity of CVD risk factors among various AI, including BMI, waist circumference (WC), and waist‐to‐hip ratio (WHR). Results: The prevalence of obesity was 29.0% in men and 36.8% in women by obesity criteria for Asians (BMI ≥ 25 kg/m²) and 13.3% in men and 21.0% in women by the Taiwanese definition (BMI ≥ 27 kg/m²). Odds ratios of acquiring various CVD risk factors increased significantly with increment of WC, WHR, and BMI. The areas under the curve predicting metabolic syndrome were all <0.8. The cut‐off values of WC corresponding to the highest sensitivity and the highest specificity in predicting various CVD risk factors were 86.2–88.0 cm in men and 82.0–84.0 cm in women, respectively. Discussion: Obesity was prevalent in the Taiwanese elderly. WC was related to CVD risk factors to a greater extent than BMI and WHR. However, none of them alone was a good screening tool for CVD risk factors. Therefore, how to apply AI prudently to screen elderly for CVD risk factors needs further research.     

Serum Urate,Metabolic Syndrome,and Cardiovascular Risk Factors. A Population-Based Study

We studied the associations between serum urate levels (determined in 503 subjects from a population of 1,344 subjects living in northern Madrid) and both the metabolic syndrome (MS) (defined by the Adult Treatment Panel III criteria) and C-reactive protein (CRP, determined in 382 subjects). MS was diagnosed in 25% (95%CI, 21–28%) and was associated with hyperuricemia (p<0.001). There was a graded increase in serum urate levels with increasing number of MS components. Urate concentrations significantly correlated with waist circumference (r=0,455, p<0.01). Serum urate was not independently associated with CRP levels. This study shows that serum urate levels are associated with the presence of MS and each of its features.     

Characterization and heritability of obesity and associated risk factors in vervet monkeys

Objective: The objective was to determine the prevalence and heritability of obesity and risk factors associated with metabolic syndrome (MS) in a pedigreed colony of vervet monkeys. Design: A cross‐sectional study of plasma lipid and lipoprotein concentrations, glycemic indices, and morphometric measures with heritability calculated from pedigree analysis. A selected population of females was additionally assessed for insulin sensitivity and glucose tolerance. Subjects: All mature male (n = 98), pregnant (n = 40) and non‐pregnant female (n = 157) vervet monkeys were included in the study. Seven non‐pregnant females were selected on the basis of high or average glycated hemoglobin (GHb) for further characterization of carbohydrate metabolism. Measurements: Morphometric measurements included body weight, length, waist circumference, and calculated BMI. Plasma lipids [total cholesterol (TC), triglycerides (TG), high‐density lipoprotein cholesterol (HDL‐C)] and glycemic measures (fasting blood glucose, insulin, and GHb) were measured. A homeostasis model assessment index was further reported. Glucose tolerance testing and hyperinsulinemic‐euglycemic clamps were performed on 7 selected females. Conclusion: Vervet monkeys demonstrate obesity, insulin resistance, and associated changes in plasma lipids even while consuming a low‐fat (chow) diet. Furthermore, these parameters are heritable. Females are at particular risk for central obesity and an unfavorable lipid profile (higher TG, TC, and no estrogen‐related increase in HDL‐C). Selection of females by elevated GHb indicated impaired glucose tolerance and was associated with central obesity. This colony provides a unique opportunity to study the development of obesity‐related disorders, including both genetic and environmental influences, across all life stages.     

Comparison of Overall Obesity and Body Fat Distribution in Predicting Risk of Mortality

Results of studies comparing overall obesity and abdominal adiposity or body fat distribution with risk of mortality have varied considerably. We compared the relative importance and joint association of overall obesity and body fat distribution in predicting risk of mortality. Participants included 5,799 men and 6,429 women aged 30–102 years enrolled in the third National Health and Nutrition Examination Survey who completed a baseline health examination during 1988–1994. During a 12‐year follow‐up (102,172 person‐years), 1,188 men and 925 women died. In multivariable‐adjusted analyses, waist‐to‐thigh ratio (WTR) in both sexes (P_trend <0.01 for both) and waist‐to‐hip ratio (WHR) in women (P_trend 0.001) were positively associated with mortality in middle‐aged adults (30–64 years), while BMI and waist circumference (WC) exhibited U‐ or J‐shaped associations. Risk of mortality increased with a higher WHR and WTR among normal weight (BMI 18.5–24.9 kg/m²) and obese (BMI ≥30.0 kg/m²) adults. In older adults (65–102 years), a higher BMI in both sexes (P_trend <0.05) and WC in men (P_trend 0.001) were associated with increased survival, while remaining measures of body fat distribution exhibited either no association or an inverse relation with mortality. In conclusion, ratio measures of body fat distribution are strongly and positively associated with mortality and offer additional prognostic information beyond BMI and WC in middle‐aged adults. A higher BMI in both sexes and WC in men were associated with increased survival in older adults, while a higher WHR or WTR either decreased or did not influence risk of death.     

Impact of Visceral Fat on Blood Pressure and Insulin Sensitivity in Hypertensive Obese Women

Objective: The relationship among body fat distribution, blood pressure, serum leptin levels, and insulin resistance was investigated in hypertensive obese women with central distribution of fat. Research Methods and Procedures: We studied 74 hypertensive women (age, 49.8 ± 7.5 years; body mass index, 39.1 ± 5.5 kg/m²; waist-to-hip ratio, 0.96 ± 0.08). All patients were submitted to 24-hour blood pressure ambulatory monitoring (24h-ABPM). Abdominal ultrasonography was used to estimate the amount of visceral fat (VF). Fasting blood samples were obtained for serum leptin and insulin determinations. Insulin resistance was estimated by homeostasis model assessment insulin resistance index (HOMA-r index). Results: Sixty-four percent of the women were postmenopausal, and all patients showed central distribution of fat (waist-to-hip ratio > 0.85). The VF correlated with systolic 24h-ABPM values (r = 0.28, p = 0.01) and with HOMA-r index (r = 0.27; p = 0.01). VF measurement (7.5 ± 2.3 vs. 5.9 ± 2.2 cm, p < 0.001) and the systolic 24h-ABPM (133 ± 14.5 vs. 126 ± 9.8 mm Hg, p = 0.04), but not HOMA-r index, were significantly higher in the postmenopausal group (n = 48) than in the premenopausal group (n = 26). No correlations were observed between blood pressure levels and HOMA-r index, leptin, or insulin levels. In the multiple regression analysis, visceral fat, but not age, body fat mass, or HOMA-r index, correlated with the 24h-ABPM (p = 0.003). Discussion: In centrally obese hypertensive women, the accumulation of VF, more often after menopause, is associated with higher levels of blood pressure and insulin resistance. The mechanism through which VF contributes to higher blood pressure levels seems to be independent of leptin or insulin levels.     

Composition of Dietary Fat Affects Blood Pressure and Insulin Responses to Dietary Obesity in the Dog

Cardiovascular and metabolic parameters were evaluated in 15 female spayed dogs before and after they became obese on either a saturated fat (LD, lard, n=8) or unsaturated fat (CO, corn oil, n=7) diet. Body weight and body fat increased significantly in both groups, although no differences occurred between diet groups. Dogs receiving the LD diet exhibited a greater increase in mean arterial pressure than those receiving the CO diet (p<0. 01; 15. 9 ± 2. 1 vs. 9. 8 ± 3. 3 mm Hg increase). The CO diet stimulated a greater increase in heart rate than the LD diet (p<0. 05; 32. 8 ± 7. 8 vs. 14. 1 ± 5. 8 bpm increase). Ganglionic blockade with chlorisondamine caused an increase in HR in both lean groups and in the obese CO group, but not the obese LD group, consistent with a decrease in parasympathetic tone to the heart in the dogs overfed saturated fat. Obesity enhanced the heart rate response to β-badrenergic stimulation by isoproterenol in the LD, but not CO group. The LD diet increased circulating insulin and decreased insulin sensitivity, whereas the CO diet had no effect on either parameter. These findings suggest that the composition of dietary fat can modulate the autonomic and metabolic adaptations induced by dietary obesity.     

Total and Regional Fat and Serum Cardiovascular Disease Risk Factors in Lean and Obese Children and Adolescents

Objective: This study was conducted to evaluate the association of total and central adiposity with serum cardiovascular disease (CVD) risk factors in lean and obese Portuguese children and adolescents. Research Methods and Procedures: A total of 87 girls (13.2 ± 1.6 years old, 29.9 ± 6.4% body fat [mean ± SD]) and 72 boys (13.2 ± 1.6 years old, 20.8 ± 9.9% body fat) volunteered for the study. Whole‐body composition and fat distribution, from DXA and anthropometry, and serum lipids, lipoproteins, and apolipoproteins were evaluated. Results: The sum of three trunk skinfolds (STS) was highly correlated with total trunk fat mass measured by DXA (p < 0.001). Body mass index, DXA‐measured percentage of body fat, trunk fat mass, STS, and the waist‐to‐height ratio were generally found to be associated with triacylglycerol, the ratio of total cholesterol (TC) to high density lipoprotein‐cholesterol (HDL‐C), low density lipoprotein‐cholesterol (LDL‐C), and apolipoprotein B levels, (significant age‐adjusted r between 0.16 and 0.27, p < 0.05). Body mass index, STS, and the waist circumference were also associated with HDL‐C (p < 0.05), whereas no body composition variable significantly correlated with TC or apolipoproteins A‐I. The STS was significantly correlated with HDL‐C (p < 0.01), TC/HDL‐C (p < 0.05), and apolipoproteins A‐I (p < 0.05) independently of whole‐body fatness. Obese subjects (n = 73) had higher TC, LDL‐C, TC/HDL‐C, and apolipoprotein B than did non‐obese subjects (n = 86), and significant associations between central adiposity and some lipid variables (triacylglycerol and HDL‐C) were found in obese children and adolescents that were not present in leaner individuals. Discussion: DXA‐ and anthropometry‐based whole‐body and central fat measures are associated with serum CVD risk factors in Portuguese boys and girls. Obese children and adolescents have a poorer lipid profile than do their leaner counterparts. Trunk skinfolds, which are easy to obtain even in large samples, predict CVD risk factors to the same extent as DXA‐based variables, in some cases, independently of total fatness.     

Combination of BMI and Waist Circumference for Identifying Cardiovascular Risk Factors in Whites

Objective: BMI (kilograms per meters squared) and waist circumference (WC) (measured in centimeters) are each associated with the risk of developing cardiovascular disease (CVD). Therefore, a combination of the two may be more effective in identifying subjects at risk than either alone. The present study sought to identify the combination of BMI and WC that has the strongest association with CVD risk factors in whites. Research Methods and Procedures: Subjects were 8712 white men and women from the Third National Health and Nutrition Examination Survey. The optimal combination of BMI and WC was developed using logistic regression models with BMI and WC as predictors and CVD risk factors as outcomes. The combined measure of BMI and WC using current cut‐off points was also examined. Sensitivity, specificity, and receiver operating characteristics curves were compared between the combined measures and BMI alone. Results: For white men, the optimal combination of BMI and WC for identifying CVD risk factors was 0.68 × BMI + 0.32 × WC. This combination generated a score that better estimated the odds of having CVD risk factors than either alone. For white women, WC alone largely determined the likelihood of having CVD risks. The combination of BMI and WC using current cut‐off points may provide an improved measure of CVD risk. Combined measures showed a higher sensitivity or a shorter distance in receiver operating characteristic curves in the identification of CVD risk factors. Discussion: Combined measures of BMI and WC may provide a higher overall test performance for CVD risk factors and may be useful in some ethnic groups as an improved means of screening subjects for further evaluation in the clinical setting.     

Relationships between Dietary Fat,Body Fat,and Serum Lipid Profile in Prepubertal Children

KU, CHING YI, BARBARA A. GOWER, TIM R. NAGY, MICHAEL I. GORAN. Relationships between dietary fat, body fat, and serum lipid profile in prepubertal children. Obes Res. 1998;6:400–407. Objective : The purpose of the study was to test the hypothesis that dietary fat components were associated with the serum lipid profile independent of ethnicity, body fat, and fat distribution in prepubertal children. Research Methods and Procedures : Sixty-six children (45 African American and 21 Caucasian), aged from 4 to 10 years, were recruited into the study. Dietary total fat, saturated fat, monounsaturated fat, and polyunsaturated fat were estimated by averaging two 24-hour diet recalls. Fasting serum triacylglycerol, total cholesterol, and high-density lipoprotein cholesterol were analyzed, and low-density lipoprotein cholesterol (LDL-C) was calculated by the method of Friedewald. Body composition and fat distribution were measured by dual energy X-ray absorptiometry and computed tomography. Results : Children in both ethnic groups tended to overreport their dietary intake relative to total energy expenditure by 18%. African American children consumed more energy from total fat (35.3% vs. 31.5%, p<0.05), saturated fat (13.7% vs 12.2%, p<0.05), protein (16.4% vs. 13.2%, p = 0.02), and less from carbohydrate (48% vs. 57.1%, p<0.01) than Caucasian children. There was no significant correlation between dietary fat and either serum lipids or body fat indices after adjusting for nonfat energy intake and total lean tissue mass. Total body fat (r = 0.32), subcutaneous abdominal adipose tissue (r = 0.39), and intraabdominal adipose tissue (r = 0.42) were positively related to serum triacylglycerol; these associations remained significant in a multiple linear regression model in which body fat indices were adjusted for ethnicity, total lean tissue, dietary total fat, and nonfat intake. Discussion : Our results do not support a link between dietary fat and serum lipids; instead, our data suggest that body fat may play a more important role than dietary fat in the course of cardiovascular disease development in prepubertal children.     

The Relationship Between Fat Distribution and Coronary Risk Factors in Sedentary Postmenopausal Women On and Off Hormone Replacement Therapy

The purpose of this study was to examine the relationship between fat distribution and coronary risk factors (CRF) in sedentary overweight postmenopausal women both on and off hormone replacement therapy (HRT). Medical records and information were abstracted from nonsmoking women entering a weight loss program. A total of 33 women on HRT (mean age=50.12 ± 5.2) and 51 nonusers (mean age=52.52 ± 7.8) fulfilled subject eligibility requirements and were included in the data analysis. Results showed a significantly lower waist-to-hip ratio (WHR) (p=0.009) and waist (p=0.010) and greater levels of high-density lipoprotein cholesterol (HDL-C) (p=0.035) in HRT users than in nonusers. After converting correlations to standard Z-scores and performing z-tests, the correlation between total cholesterol (T-Chol) and WHR was significantly greater in nonusers than in HRT users (p=0.038). A multiple regression analysis showed differences between groups in the ability of age and anthropometric variables to predict CRF. Although T-Chol could be predicted in nonusers(r²=0.24; ^p=0.011), very low-density lipoprotein cholesterol (VLDL-C) and systolic blood pressure (SBP) could be significantly predicted in HRT users only (r²=0.28, P=0.055 and r²=0.40, p=0.005 for VLDL-C and SBP, respectively). These data suggest that there are differences between HRT users and nonusers in predictors of CRF, central adiposity, HDL-C, and the relationship between WHR and T-Chol. It is concluded that the significantly lower levels of central adiposity observed in HRT users may have clinical benefits with regard to CRF.     

Defining Health‐Related Obesity in Prepubertal Children

Objective: The purpose of this study was to develop percentage of fat and waist circumference cut‐points in prepubertal children with the intention of defining obesity associated with cardiovascular disease (CVD) risk. Research Methods and Procedures: A cross‐sectional analysis of 87 prepubertal children aged 4 to 11 years was used. Percentage of body fat was determined by DXA. Waist circumference was measured to the nearest millimeter. Receiver Operating Characteristic analyses of percentage of fat and waist circumference were used to develop cut‐points for individuals with adverse levels of CVD risk factors. Results: The risk factors selected for analyses (i.e., fasting insulin, high‐density lipoprotein cholesterol, low‐density lipoprotein cholesterol, triglycerides, and total cholesterol/high‐density lipoprotein cholesterol) were significantly related to percentage of body fat and waist circumference. Likelihood ratios were used to identify percentage of fat and waist circumference cut‐points associated with adverse cardiovascular risk profiles. Two cut‐points, an upper cut‐point of 33% body fat and a lower cut‐point of 20% body fat, were derived. Waist circumference cut‐points indicative of adverse and normal risk‐factor profiles were 71 cm and 61 cm, respectively. Discussion: The data indicate that children with ≥33% body fat and children with a waist circumference ≥71 cm were more likely to possess an adverse CVD risk‐factor profile than a normal risk‐factor profile. The likelihood of children with <20% body fat or a waist circumference <61 cm possessing an adverse CVD risk‐factor profile as opposed to a normal risk‐factor profile was small. The cut‐points describe an adequate health‐related definition of childhood obesity.     

Mental Distress,Obesity and Body Fat Distribution in Middle-Aged Men

Previous epidemiological studies have suggested that psychiatric symptoms are associated with obesity and abdominal distribution of body fat in women. The aim of the present study was to examine this in middle-aged men. In 1992 a cluster selected cohort of 1040 men born in 1944 (participation rate 79.9%) was examined. Registrations of symptoms of depression and anxiety, sleep disturbances, psychosomatic disease as well as degree of life satisfaction were analyzed in relation to body mass index (BMI) and the waist/hip circumference ratio (WHR). In univariate analyses both BMI and WHR correlated with these factors. BMI and WHR were, however, closely interrelated (p=0.61), necessitating analyses of separate, independent relationships in multivariate analyses. When adjusted for WHR all the significant relationships with BMI disappeared. In contrast the WHR, adjusted for BMI, showed remaining significant associations with the use of anxiolytics (p=0.018), hypnotics (p=0.029), antidepressive drugs (p=0.008), degree of melancholy (p=0.002), and life satisfaction (p=0.002, negative), difficulties to sleep (p=0.014) and fall asleep (p=0.047), tendency to wake up from sleep (borderline, p=0.070) and dyspepsia (p < 0.001). Since smoking and alcohol are known to influence on the WHR, these factors were, in addition to BMI, entered into the analyses as confounding variables. The mentioned associations then remained statistical significant (use of hypnotics borderline, p=0.074) except difficulties to fall asleep and tendency to wake up. It was concluded that in contrast to BMI, the WHR is associated with symptoms of depression and anxiety with associated sleep disturbances, as well as psychosomatic symptoms and dissatisfaction. It was hypothesized that the mechanism involved might be increased secretion of Cortisol, directing storage fat to central adipose tissue depots.     

Body heating induced by sub-resonant (350 MHz) microwave irradiation: Cardiovascular and respiratory responses in anesthetized rats

These experiments were designed to investigate the effects of sub-resonant microwave (MW) exposure (350 MHz, E orientation, average power density 38 mW/cm², average whole-body specific absorption rate 13.2 W/kg) on selected physiological parameters. The increase in peripheral body temperature during 350 MHz exposure was greater than that in earlier experiments performed at 700 MHz (resonance). Heart rate and mean arterial blood pressure were significantly elevated during a 1 °C increase in colonic temperature due to 350 MHz exposure; respiratory rate showed no significant change. The results are consistent with other investigators' reports comparing sub-resonance exposures with those at resonance and above. Bioelectromagnetics 18:335–338, 1997. © 1997 Wiley-Liss, Inc.     

脉压、脉压指数对肥胖预测的前瞻性队列研究

目的:分析成都地区1992年时非肥胖中年居民脉压(PP)、脉压指数(PPI)对该人群15年后(2007年)肥胖发生的预测价值。方法:本研究纳入1992年时年龄处于45～60岁且BMI正常者1017人,依据PP(PP≤60mmHg及PP>60mmHg)及PP(I PPI≤0.450及PPI>0.450)分为PP/PPI正常组及增高组,分析两组人群在15年后(2007年)BMI分布特征及肥胖的患病情况。结果:①1992年PP/PPI增高人群2007年时BMI皆高于PP/PPI正常人群,t检验示BMI组间差异有统计学意义。2007年肥胖患病率亦呈类似BMI的特点,亦为PP/PPI增高组高于PP/PPI正常组,经x2检验,肥胖患病率的组间差异有统计学意义。②根据该队列人群1992年的PP增高与否计算2007年的肥胖患病率的相对危险度(RR)为4.109,P值为0.000,95%可信区间为2.874～8.847;1992年PPI与2007年肥胖患病的RR为4.998,P值为0.000,95%可信区间为2.876～8.687。③使用logistic回归模型分析1992年基线PP/PPI对2007年肥胖患病的影响,在调整了SBP、WC、BMI、HR、TG后,PP、PPI的相对危险度仍为1.040及1.044。其各自相应95%CI分别为1.017～1.065、1.025～1.063。结论:脉压、脉压指数的异常与肥胖的发生关系密切,脉压、脉压指数可以预测肥胖的发生。     

Longitudinal Analyses among Overweight,Insulin Resistance,and Cardiovascular Risk Factors in Children

Objective: It has been questioned whether insulin resistance or obesity is the central abnormality contributing to the cardiovascular risk factors dyslipidemia and hypertension in obesity. Research Methods and Procedures: We studied weight status [SD score (SDS)‐BMI], lipids (triglycerides, low‐density lipoprotein‐ and high‐density lipoprotein‐cholesterol), blood pressure, and insulin resistance index [as homeostasis model assessment (HOMA) model] over a 1‐year period in 229 obese white children (median age 12 years). Results: Any degree of decrease in HOMA was associated with significant decreases in triglycerides (p < 0.001), systolic blood pressure (p < 0.001), and diastolic blood pressure (p < 0.001), whereas the children with different changes in HOMA did not differ significantly in their weight changes. Only the children in the highest quartile of weight reduction (decrease in SDS‐BMI > 0.5) demonstrated a significant decrease in systolic blood pressure (p < 0.001), diastolic blood pressure (p < 0.001), and triglycerides (p = 0.012), and an increase in high‐density lipoprotein‐cholesterol (p = 0.023), whereas with a lower degree of weight loss, there were no significant changes in cardiovascular risk factors. In contrast with a lower degree of weight loss, a reduction of >0.5 SDS‐BMI was associated with a significant decrease in HOMA (p < 0.001). Discussion: Because blood pressure and triglycerides decreased with any degree of decrease in HOMA, independently of changes in weight status, these findings support the hypothesis that insulin resistance is the central abnormality contributing to these cardiovascular risk factors. Therefore, improving insulin resistance seems more important than reducing overweight to prevent or treat hypertension and dyslipidemia in obese children.     

Physical Activity,Obesity, and Cardiovascular Risk Factors in Children. The Belgian Luxembourg Child Study II

GUILLAUME, MICHÈLE, LEIF LAPIDUS, PER BJÖRNTORP, ANDRE LAMBERT. Physical activity, obesity, and cardiovascular risk factors in children. The Belgian Luxembourg Child Study II. Physical activity was measured in relation to cardiovascular (CV) risk factors in a randomly selected population of 1028 children from Province de Luxembourg in Belgium, a mainly rural area with a high prevalence of such risk factors among adults and children. Physical activity was estimated as participation in sport activities, a major indicator of leisure-time physical activity in schoolchildren, and physical inactivity was estimated as frequency and duration of television (TV) watching. Boys participated more frequently in sport activities than girls did (p=0. 001). A majority of the children watched TV daily. After age adjustment, bodyweight (girls, p<0. 012; boys, p<0. 027) and, in boys, body mass index (BMI) (p<0. 039) were related to days per week of TV watching. No significant relationships with other CV risk factors remained after adjustments for BMI. In analyses of independent contributions of age, TV watching, and sports activity on CV risk factors, age showed highly significant relationships. In boys, TV showed relationships with BMI (P<0. 04) and (borderline) with systolic blood pressure, independent of age and sports activity, whereas the latter was significantly related to subscapular skinfold (p<0. 04) and (borderline) with triceps skinfold and cholesterol. In girls, no significant independent contributions to risk factor associations were found. The father's education was directly associated with sports activities, whereas the mother being a housewife showed negative relationships to physical activity and positive to TV watching in their children, suggesting socioeconomic influence on the activity patterns of children. Furthermore, registrations suggested less physical activity in the most rural part of the area. It is concluded that children in this mainly rural area watch TV frequently. In boys, physical inactivity, measured both as TV watching and as registrations of sports activities, contributes independently to body fat mass. In girls, no contribution or weaker contributions of physical inactivity were found. This suggests that contributory factors leading to obesity might be different in girls and boys.     

The impact of central obesity as a prerequisite for the diagnosis of metabolic syndrome

Objective: To compare the prevalence of metabolic syndrome (MS) defined according to the American Heart Association (AHA)/National Heart Lung and Blood Institute (NHLBI) and the International Diabetes Federation (IDF) and to determine the effect of the presence of central obesity on the phenotype (insulin resistance and other cardiovascular risk factors) associated with MS. Research Methods and Procedures: We studied 4723 Chinese, Malays, and Asian Indians living in Singapore. Each individual was categorized according to the five criteria for MS as defined by the AHA/NHLBI and the IDF. The population was categorized according to the presence of three or more criteria and then further subcategorized according to the presence or absence of central obesity. Characteristics of each group were compared using ANOVA and the χ² test. Results: MS was present in 20.2% (IDF) and 26.9% (AHA/NHLBI) of the population. Of the population, 6.7% exhibited three or more features of MS without central obesity. Use of the IDF definition, which requires central obesity, is associated with greater insulin resistance but similar levels of other cardiovascular disease risk factors than the use of the AHA/NHLBI definition, which does not require central obesity. Discussion: In this Southeast Asian population, the IDF and the AHA/NHLBI definitions of MS identify different segments of the MS population. The IDF definition may be more appropriate for the identification of those with insulin resistance and increased risk of type 2 diabetes. In contrast, the AHA/NHLBI definition may better identify those at increased risk of cardiovascular disease.