Waist circumference action levels in the identification of cardiovascular risk factors: prevalence study in a random sample

Effect of aging on the relationship between multiple risk factors and waist circumference

OBJECTIVE

To examine the relationship between various coronary risk factors and the different levels of fat distribution in younger (<65 years) and older (> or = 65 years) men and women, using the classifications proposed by the National Heart, Lung and Blood Institute (NHLBI) and the World Health Organization (WHO).

DESIGN

Cross-sectional study of subjects enrolled in the Baltimore Longitudinal Study of Aging.

MEASUREMENTS

Systolic blood pressure, diastolic blood pressure, fasting glucose, 2-hour glucose, fasting insulin, homeostasis model assessment insulin resistance (HOMAIR), triglyceride, total cholesterol, high-density lipoprotein (HDL)-cholesterol, and low-density lipoprotein (LDL)-cholesterol were measured as risk factors. The proportion of subjects with abnormal risk factor levels by waist circumference classifications was determined in the age and gender subgroups.

RESULTS

There were significant adverse effects of age per se on all risk factors with the exception of fasting insulin and HOMAIR in both men and women, total cholesterol in men, and diastolic blood pressure in women. HDL-cholesterol was higher in older subjects. There were significant correlations between waist circumference and all of the risk factors in the younger group. Waist circumference did not have a significant correlation with total cholesterol in older men, or with total cholesterol and LDL-cholesterol in older women. The proportion of subjects with an abnormal risk factor level increased with increasing waist circumference for most risk factors in both younger and older subjects, but proportions of subjects in each individual waist group were higher in older than in younger groups for systolic blood pressure, diastolic blood pressure, fasting glucose, and 2-hour glucose in men, and for systolic blood pressure, fasting glucose, 2-hour glucose, total and LDL-cholesterol, and triglyceride in women.

CONCLUSIONS

Our data indicate that the waist circumference cutpoints proposed by NHLBI and WHO standards are useful for the prediction of cardiovascular disease risk factors in older as well as in younger men and women.

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.

Visceral obesity and metabolic syndrome

There is increasing evidence for the existence of a condition consisting of a cluster of metabolic disorders which include insulin resistance, alterations in glucose and lipid metabolism, increased blood pressure and visceral obesity. The metabolic syndrome is now the favoured definition of the cluster. Each single component of the cluster increases the cardiovascular risk, but the combination of factors is much more important. Insulin resistance is the most frequently associated factor to the singular components of the syndrome: most authors believe that it may be the common aetiological factor. However, visceral obesity seems to be the main driving factor by means of the increased production of free fatty acids whose activity, in turn, might interfere with the action of insulin. Some questions exist about the syndrome because of the frequent lack in the cluster of one of the factors. This does not mean that the missing factor does not belong to the syndrome, but only that it is not yet clinically evident. Weight gain has been shown to be a strong predictor of the metabolic syndrome. This aspect gives strength to treatment and prevention because it means that losing weight or stopping weight increase might reduce the risk of a future appearance of a factor that is still not evident. Interventions to treat visceral obesity by means of losing weight seem to be the most efficacious way to treat the metabolic syndrome thus improving the most widespread cardiovascular risk factor in western countries.

Overweight, obesity, and blood pressure: the effects of modest weight reduction

Several large epidemiological studies have shown an association between body mass index and blood pressure in normal weight and overweight patients. Weight gain in adult life especially seems to be an important risk factor for the development of hypertension. Weight loss has been recommended for the obese hypertensive patient and has been shown to be the most effective nonpharmacological treatment approach. However, long-term results of weight loss programs are disappointing with people often regaining most of the weight initially lost. In recent years, a modest weight loss, defined as a weight loss of 5% to 10% of baseline weight, has received increasing attention as a new treatment strategy for overweight and obese patients. A more gradual and moderate weight loss is more likely to be maintained over a longer period of time. Several studies have confirmed the blood pressure-lowering effect of a modest weight loss in both hypertensive and nonhypertensive patients. A modest weight loss can normalize blood pressure levels even without reaching ideal weight. In patients taking antihypertensive medication, a modest weight loss has been shown to lower or even discontinue the need for antihypertensive medication. In patients with high normal blood pressure, a modest weight loss can prevent the onset of frank hypertension. The blood pressure-lowering effect of weight loss is most likely a result of an improvement in insulin sensitivity and a decrease in sympathetic nervous system activity and occurs independent of salt restriction. In conclusion, a modest weight loss that can be maintained over a longer period of time is a valuable treatment goal in hypertensive patients.

Reliability of anthropometric measurements in overweight and lean subjects: consequences for correlations between anthropometric and other variables

OBJECTIVE

To estimate the reliability of anthropometric measurements in overweight and lean subjects, and to examine the influence of this reliability on correlations to other variables, since low reliability leads to underestimation of correlations.

DESIGN

Replicate measurements by two observers in 26 overweight and 25 lean subjects measured at two occasions.

MEASUREMENTS

Sagittal abdominal diameter (SAD), waist circumference (waist), waist-to-hip ratio (W/H) and skinfold measurements.

RESULTS

Intra-class correlation coefficients (ICCs) for SAD and waist were higher than for W/H (0.98 vs. 0.90, P<0.001, and 0.97 vs. 0.90, P = 0.001, respectively). For waist, the ICC was lower for overweight than for lean subjects (0.85 vs 0.95, P=0.030), but the ICC values were comparable for SAD and W/H (0.92 vs. 0.95 and 0.78 vs. 0.83, respectively). Intra-observer variations (IOV) for SAD and waist were lower than for W/H (coefficients of variation; 1.6%, 1.4% and 2.3%, respectively), as were intra-subject variations (ISV) (2.7%, 3.0% and 3.4%, respectively). ICC values ranged from 0.84 to 0.93 and were lower for overweight than for lean subjects for biceps, subscapular and umbilical skinfolds (P=0.031, P<0.001 and P=0.048, respectively). Coefficients of variations for skinfold measurements ranged between 7.3% and 16.0% for IOV and between 14.9% and 20.8% for ISV.

CONCLUSIONS

The low ICC values imply that correlations can be underestimated in overweight groups. We propose that, because of their higher reliability, SAD and waist have a higher predictive capacity for cardiovascular risk than W/H. SAD is the only measurement with high reliability in both weight groups and its use is recommended.

Obesity as a medical problem

Obesity is now so common within the world's population that it is beginning to replace undernutrition and infectious diseases as the most significant contributor to ill health. In particular, obesity is associated with diabetes mellitus, coronary heart disease, certain forms of cancer, and sleep-breathing disorders. Obesity is defined by a body-mass index (weight divided by square of the height) of 30 kg m(-2) or greater, but this does not take into account the morbidity and mortality associated with more modest degrees of overweight, nor the detrimental effect of intra-abdominal fat. The global epidemic of obesity results from a combination of genetic susceptibility, increased availability of high-energy foods and decreased requirement for physical activity in modern society. Obesity should no longer be regarded simply as a cosmetic problem affecting certain individuals, but an epidemic that threatens global well being.

Sagittal abdominal diameter compared with other anthropometric measurements in relation to cardiovascular risk

BACKGROUND

Abdominal adiposity has been described as an independent risk factor for coronary heart disease. Sagittal abdominal diameter has been found to be closely related to the amount of visceral adipose tissue.

AIM

To compare the sagittal abdominal diameter with other anthropometric measures regarding their relationships to risk factors for coronary heart disease (CHD).

DESIGN

A study of 885 men and women participating in a health survey.

MEASUREMENTS

Sagittal abdominal diameter, body mass index (BMI), waist and hip circumferences, waist-to-hip ratio, serum concentrations of risk factors for CHD, blood pressure.

RESULTS

In men the sagittal abdominal diameter showed stronger correlations to the CHD risk factors serum cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, glucose, insulin, apolipoprotein B (apoB), plasminogen activator inhibitor tissue-type plasminogen activator (t-PA) and lipid-corrected alpha tocopherol, and to systolic and diastolic blood pressures than the other anthropometric measurements. In women, compared with the other anthropometric measurements the sagittal abdominal diameter was more strongly correlated to serum cholesterol, LDL cholesterol, LDL/HDL (high-density lipoprotein), apo B and t-PA, and to systolic and diastolic blood pressure. The sagittal abdominal diameter showed a stronger correlation to 'total risk' for cardiovascular disease (+ 0.66 for men, 0.62 for women), than waist circumference (+ 0.63 for men, + 0.57 for women) and waist-to-hip ratio (+ 0.61 for men and +0.48 for women; P <0.0001 for all correlations). This diameter was also more strongly correlated to 'metabolic risk' (+ 0.64 for men, + 0.59 for women) than waist circumference (+ 0.60 for men, + 0.59 for women) and waist-to-hip ratio (+ 0.58 for men, + 0.52 for women)(P < 0.0001 for all correlations). In a regression analysis including the anthropometric measurements and the risk values, the sagittal diameter was the strongest measure of cardiovascular risk in both men and women.

CONCLUSIONS

Among both men and women in this study the sagittal abdominal diameter showed stronger correlations to cardiovascular risk and to other risk factors in the metabolic syndrome than other anthropometric variables such as waist circumference, waist-to hip ratio and BMI.

Dyslipidemia and abdominal obesity: an assessment in three general populations

Several studies show a relationship between abdominal obesity and cardiovascular diseases, partially mediated through an altered metabolism of dyslipidemia. The present study was aimed at testing the robustness of this association across three contrasted populations and at assessing the performances of abdominal obesity as a screening tool for dyslipidemia. Data were drawn from three population health surveys recently conducted in two regions of a developed country (Switzerland, mostly of Caucasian origin, n = 2650) and in a less developed country (Seychelles, Indian Ocean, mostly of black descent, n = 806). Dyslipidemia was defined as a ratio of total cholesterol to high-density lipoprotein cholesterol (TC-HDL) greater than 5. Two anthropometric circumference measurements, waist-to-hip ratio (WHR) and waist circumference (WC), were used to define abdominal obesity either as WHR >/= 0.9 in men and WHR >/= 0.8 in women or as WC >/= 94 cm and WC >/= 80 cm, respectively. A consistent direct association between abdominal obesity and dyslipidemia (odds ratios varying from 1.85 to 4.56) was found in the three populations, independently of gender, age, body mass index, blood pressure, and smoking. This consistency across ethnicities and environments strengthens the hypothesis of a common etiopathological mechanism. The sensitivity for detecting dyslipidemia was generally higher for abdominal obesity, based on either WHR or WC, than for criteria based on the other risk factors under study. In addition, the sensitivity was higher in the study populations with a low prevalence of dyslipidemia (Swiss women and Seychellois of both sexes) than in the others. These findings support that WHR and WC may be useful as simple and inexpensive screening tools to select individuals eligible for more sophisticated and costly serum lipid determinations, especially in developing countries.

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. International Journal of Obesity (2000) 24, 180-186

Somatotype and angiographically determined atherosclerotic coronary artery disease in men

The relationship between somatotype and somatotype components with coronary artery disease (CAD) and regional adiposity was considered in 58 males (age 60.2 +/- 9.4 years) undergoing investigative coronary angiography for suspected atherosclerotic CAD. Severity of CAD was determined in terms of both the degree of stenosis and the anatomical position of the lesions on the coronary arteries (myocardial score). Six patients had negative angiographic findings but three of these had impaired left ventricular function as determined by left ventriculography. The mean (+/-SD) somatotype of the group was 5.7 / 5.6 / 1.2 (1.7 / 1.4 / 1.0), illustrating a clear dominance of the first two somatotype components. Canonical correlation analysis showed that somatotype was not significantly related to the angiography results (P > 0.05). However, correlations between the somatotype components and the angiography results with their respective first canonical variates showed that the somatotype variate was one of high mesomorphy and low ectomorphy and the angiography variate was essentially one of a high myocardial score. After adjustment for the confounding interrelationship among the somatotype components, endomorphy was significantly correlated with abdominal circumference (r = 0.65, P < 0.001), the abdomen-to-hip ratio (r = 0.53, P < 0.001) and the abdominal sagittal diameter (r = 0.60, P < 0.001). Mesomorphy was not related to these indicators of android or abdominal adiposity following partial adjustment. Ectomorphy was inversely related to the indices of general and regional adiposity. This study suggests that adiposity and muscularity are important features in terms of increased CAD risk, whereas linearity is beneficial. Am. J. Hum. Biol. 12:128-138, 2000. Copyright 2000 Wiley-Liss, Inc.

Weight loss, weight maintenance, and improved cardiovascular risk factors after 2 years treatment with orlistat for obesity. European Orlistat Obesity Study Group

OBJECTIVE

To determine the effect of orlistat, a new lipase inhibitor, on long-term weight loss, to determine the extent to which orlistat treatment minimizes weight regain in a second year of treatment, and to assess the effects of orlistat on obesity-related risk factors.

RESEARCH METHODS AND PROCEDURES

This was a 2-year, multicenter, randomized, double-blind, placebo-controlled study. Obese patients (body mass index 28 to 43 kg/m2) were randomized to placebo or orlistat (60 or 120 mg) three times a day, combined with a hypocaloric diet during the first year and a weight maintenance diet in the second year of treatment to prevent weight regain. Changes in body weight, lipid profile, glycemic control, blood pressure, quality of life, safety, and tolerability were measured.

RESULTS

Orlistat-treated patients lost significantly more weight (p<0.001) than placebo-treated patients after Year 1 (6.6%, 8.6%, and 9.7% for the placebo, and orlistat 60 mg and 120 mg groups, respectively). During the second year, orlistat therapy produced less weight regain than placebo (p = 0.005 for orlistat 60 mg; p<0.001 for orlistat 120 mg). Several obesity-related risk factors improved significantly more with orlistat treatment than with placebo. Orlistat was generally well tolerated and only 6% of orlistat-treated patients withdrew because of adverse events. Orlistat leads to predictable gastrointestinal effects related to its mode of action, which were generally mild, transient, and self-limiting and usually occurred early during treatment.

DISCUSSION

Orlistat administered for 2 years promotes weight loss and minimizes weight regain. Additionally, orlistat therapy improves lipid profile, blood pressure, and quality of life.

Varying sensitivity of waist action levels to identify subjects with overweight or obesity in 19 populations of the WHO MONICA Project

It has been suggested in the literature that cut-off points based on waist circumference (waist action levels) should replace cut-off points based on body mass index (BMI) and waist-to-hip ratio in identifying subjects with overweight or obesity. In this article, we examine the sensitivity and specificity of the cut-off points when applied to 19 populations with widely different prevalences of overweight. Our design was a cross-sectional study based on random population samples. A total of 32,978 subjects aged 25-64 years from 19 male and 18 female populations participating in the second MONICA survey from 1987 to 1992 were included in this study. We found that at waist action level 1 (waist circumference > or =94 cm in men and > or =80 cm in women), sensitivity varied between 40% and 80% in men and between 51% and 86% in women between populations when compared with the cut-off points based on BMI (> or =25 kg/m2) and waist-to-hip ratio (> or =0.95 for men, > or =0.80 for women). Specificity was high (> or =90%) in all populations. At waist action level 2 (waist circumference > or =102 cm and > or =88 cm in men and women, respectively, BMI > or =30 kg/m2), sensitivity varied from 22% to 64% in men and from 26% to 67% in women, whereas specificity was >95% in all populations. Sensitivity was in general lowest in populations in which overweight was relatively uncommon, whereas it was highest in populations with relatively high prevalence of overweight. We propose that cut-off points based on waist circumference as a replacement for cut-off points based on BMI and waist-to-hip ratio should be viewed with caution. Based on the proposed waist action levels, very few people would unnecessarily be advised to have weight management, but a varying proportion of those who would need it might be missed. The optimal screening cut-off points for waist circumference may be population specific.

A comparison of proxy measures of abdominal obesity in Chinese, European and South Asian adults

AIMS

To assess whether four proxy measures of abdominal obesity (waist circumference; waist-to-hip ratio (WHR); waist-to-height ratio and C index, a measure of body shape) were uniformly associated with features of the metabolic syndrome (triglycerides, high density lipoprotein (HDL) cholesterol, 2-h glucose) in three ethnic groups.

METHODS

Anthropometric and biochemical data were collected in 629 Europeans (320 men, 309 women), 380 Chinese (183 men, 197 women) and 597 South Asians (275 men, 322 women) aged 25-64 years in Newcastle upon Tyne, UK. Linear regression models were used to determine whether relationships differed between ethnic groups.

RESULTS

Linear regression analysis showed that most proxy measures of abdominal obesity were associated with features of the metabolic syndrome. There were significant interactions between WHR and ethnicity and C index and ethnicity in the relationship with log triglycerides when comparing European and Chinese women. Interactions existed between all proxy measures and ethnicity in the relationship with log triglycerides and HDL cholesterol when comparing European and South Asian women. In men, interactions between ethnicity and waist circumference, WHR and C index when comparing Europeans and South Asians, and between ethnicity and WHR and C index when comparing South Asian and Chinese for log 2-h glucose were significant (P < 0.001). All interactions remained significant when differences in smoking, alcohol and physical activity were taken into account.

CONCLUSIONS

Not all the proxy measures of abdominal obesity were consistently related to features of the metabolic syndrome across the ethnic groups studied. However, waist circumference and waist to height ratio were the most consistent and WHR the least when comparing across the ethnic groups.

Abdominal adiposity in six populations of West African descent: prevalence and population attributable fraction of hypertension

OBJECTIVES

The objective of this investigation was to examine the prevalence of abdominal adiposity and its association with the prevalence of hypertension among African descent populations in Nigeria, Cameroon, Jamaica, St. Lucia, Barbados, and the United States (US).

RESEARCH METHOD

The data for this investigation were obtained from the International Collaborative Study on Hypertension in Blacks. Hypertension was defined as mean diastolic blood pressure > or =90 mmHg, systolic blood pressure > or = 140 mmHg or current treatment with prescribed anti-hypertension medication. Abdominal overweight was defined as waist circumference (WC) > or =94 and > or =80 cm for men and women, respectively. Abdominal obesity was defined as WC > or =102 and > or =88 cm for men and women, respectively. We estimated the site-specific prevalence of abdominal overweight and obesity across age and body mass index cut-points. We also calculated the population attributable fraction (AF) of hypertension due to abdominal adiposity.

RESULTS

The prevalence of hypertension in these populations was tightly linked to abdominal adiposity. Increases in abdominal overweight accompanied an increasing degree of Westernization, rising from 6.4% and 26.3% in Nigeria, 16.5% and 62.8% in Cameroon, 15.8% and 58.6% in Jamaica, 14.3% and 62.1% in St. Lucia, 21.4% and 70.3% in Barbados to 38.9%, and 76.4% in the US for men and women, respectively. The corresponding values for abdominal obesity were 1.6% and 12.3% in Nigeria, 5.1% and 38.9% in Cameroon, 5.5% and 34.0% in Jamaica, 2.7% and 40.7% in St. Lucia, 7.8% and 44.7% in Barbados to 21.7% and 54.1% in the US for men and women, respectively. Body mass index-adjusted estimates of AF suggest that in most of these populations, especially in females, avoidance of abdominal overweight or obesity would help to curb the development of hypertension.

DISCUSSION

An important public health challenge is to clarify how lifestyle factors influence risks of abdominal adiposity and ultimately the increased risk of cardiovascular diseases.

Obesity and diabetes

Obesity, particularly truncal obesity, is closely correlated to the prevalence of diabetes and cardiovascular disease. Plasma leptin, tumour necrosis factor-alpha and non-esterified fatty acid levels are all elevated in obesity and play a role in causing insulin resistance. Diabetic glycaemic control and insulin resistance improve with reductions in obesity, but the treatment of obesity is difficult, and sustained weight reduction rarely occurs with dietary management alone. Hypocaloric diets should be combined with education and low-impact exercise, as well as behavioural techniques used to encourage long-term changes. Weight-reducing drugs have a role in the management of obesity but only as part of such a total package. Newer anti-obesity drugs such as orlistat and sibutramine are well tolerated and have been shown to improve glycaemic control in diabetes. It is probable that drugs developed in the future will act at different sites in the pathways regulating body weight, but they may have to be used in combination.

The use of anthropometric and dual-energy X-ray absorptiometry (DXA) measures to estimate total abdominal and abdominal visceral fat in men and women

OBJECTIVE

A single-slice computed tomography (CT) scan provides a criterion measure of total abdominal fat (TAF) and abdominal visceral fat (AVF), but this procedure is often prohibitive due to radiation exposure, cost, and accessibility. In the present study, the utility of anthropometric measures and estimates of trunk and abdominal fat mass by dual-energy X-ray absorptiometry (DXA) to predict CT measures of TAF and AVF (cross-sectional area, cm2) was assessed.

RESEARCH METHODS AND PROCEDURES

CT measures of abdominal fat (at the level of the L4-L5 inter-vertebral space), DXA scans, and anthropometric measures were obtained in 76 Caucasian adults ages 20-80 years.

RESULTS

Results demonstrated that abdominal sagittal diameter measured by anthropometry is an excellent predictor of sagittal diameter measured from a CT image (r=0.88 and 0.94; Total Error [TE]=4.1 and 3.1 cm, for men and women, respectively). In both men and women, waist circumference and abdominal sagittal diameter were the anthropometric measures most strongly associated with TAF (r=0.87 to 0.93; Standard Error of Estimate (SEE)=60.7 to 75.4 cm2) and AVF (r=0.84 to 0.93; SEE=0.7 to 30.0 cm2). The least predictive anthropometric measure of TAF or AVF was the commonly used waist-to-hip ratio (WHR). DXA estimates of trunk and abdominal fat mass were strongly associated with TAF (r=.94 to 0.97; SEE=36.9 to 50.9 cm2) and AVF (r=0.86 to 0.90; SEE=4.9 to 27.7 cm2).

DISCUSSION

The present results suggest that waist circumference and/or abdominal sagittal diameter are better predictors of TAF and AVF than the more commonly used WHR. DXA trunk fat and abdominal fat appear to be slightly better predictors of TAF but not AVF compared to these anthropometric measures. Thus DXA does not offer a significant advantage over anthropometry for estimation of AVF.

An independent, inverse association of high-density-lipoprotein-cholesterol concentration with nonadipose body mass

BACKGROUND

Increasing body mass index (BMI) is associated with progressively lower serum HDL-cholesterol concentrations, although the underlying body-composition compartment accounting for this unfavorable lipid change remains uncertain.

OBJECTIVE

Because growing evidence favors a role of lean tissue in HDL homeostasis, the hypothesis was tested that non-adipose tissue components of body mass explain the inverse association of HDL cholesterol and BMI.

DESIGN

Fasting serum lipid concentrations and body composition [total, subcutaneous, and visceral adipose tissue; adipose tissue-free mass (ATFM); and skeletal muscle by whole-body magnetic resonance imaging and body cell mass by 40K counting) were evaluated in healthy adults. Body-composition compartments were expressed as height2-normalized indexes.

RESULTS

An inverse correlation was observed between serum HDL cholesterol and BMI in women (n = 68; R2 = 0.08, P = 0.023) and men (n = 61; R2 = 0.07, P = 0.046). Significant inverse correlations (P = 0.005-0.02) were also observed between HDL cholesterol and nonadipose components (ie, ATFM, skeletal muscle, and body cell mass) but not between HDL cholesterol and any adipose tissue component. The association between HDL cholesterol and ATFM remained significant after serum triacylglycerol was controlled for. When BMI was entered into the HDL cholesterol-ATFM regression model, BMI was not a significant independent variable. The strongest correlate of serum triacylglycerol was visceral adipose tissue (P = 0.002 for both women and men).

CONCLUSIONS

Lean tissues and body cell mass appear to account in part for the long-observed inverse association of HDL cholesterol and BMI. These observations suggest a link between nonadipose tissue compartments and the greater cardiovascular risk associated with high BMI.

[Waist:hips girth ratio as a predictor of arterial hypertension]

This study aims to define cut-off points for the waist:hips girth ratio (WHR), using arterial hypertension as the outcome. The data refer to 3,282 individuals over twenty years of age examined in a survey conducted in the municipality of Rio de Janeiro in 1995-1996, using a two-stage sample. Sixty census tracts were drawn initially; subsequently, 34 households were selected systematically from each tract. Stature, weight, waist and hips girths, and blood pressure were measured in the households. The criterion for hypertension was a systolic blood pressure of ( 140 mmHg or diastolic pressure of ( 90 mmHg, or use of medication to reduce blood pressure. The sensitivity and specificity of different cut-off points for WHR were calculated in the prediction of arterial hypertension according to sex, age, and presence of overweight, classified according to World Health Organization guidelines. The best cut-off points for WHR were 0.95 for men and 0.80 for women. Compared to the waist:stature ratio and waist circumference, the WHR proved more capable of predicting arterial hypertension and less correlated with body mass index.

Obesity: a growing problem

Obesity, defined as a body mass index (BMI) of 30 kg/m2 or more, is common in many parts of the world, especially in the established market economies, the former socialist economies of Europe, Latin America, the Caribbean and the Middle Eastern Crescent. As many as 250 million people worldwide may be obese (7% of the adult population) and two to three times as many may be considered overweight. The prevalence of obesity seems to be increasing in most parts of the world, even where it used to be rare. Increased fatness, measured by a high BMI, a large waist circumference or a high waist/hip circumference ratio, is associated with many chronic diseases as well as with poor physical functioning. Assessments of the prevalence of obesity, and trends in this prevalence over time, are more difficult in children than adults, due to the lack of international criteria for classifying individuals as overweight or obese. The World Health Organization has now recommended the use of BMI-for-age percentiles, but the reference curves are still under development. France. The Netherlands, the UK and the USA are among the countries that have reported recent increases in the prevalence of obesity in children and adolescents. Although there are no accurate estimates of the components of energy balance and their changes over time, the available evidence suggests that the trends in obesity rates are related more to a reduction in energy expenditure than to an increase in caloric intake. Prevention of obesity through the promotion of a healthy lifestyle is among the important challenges for the new millennium, and should start in childhood.

Treatment for morbid obesity

There is no single unifying theory to explain the aetiology of obesity but several environmental factors, such as decreased physical activity and increased fat intake may contribute to its development in genetically predisposed individuals. Dietary and pharmacological treatments of morbid obesity have been proven to be unsuccessful. Modern surgical treatments have been shown to be effective in achieving significant weight loss with consequent reduction in morbidity. Despite the fact that surgical treatment of morbid obesity is the only therapeutic form that has stood the test of time, it still remains a crisis-driven form of therapy in the UK. It is probable that a better understanding of the aetiology and physiology of obesity may lead to the development of an effective pharmacological treatment of obesity in the future. However, until then, surgical treatment of morbid obesity should be considered as an effective and efficient way of treatment in selected cases.

Self-reported waist circumference compared with the 'Waist Watcher' tape-measure to identify individuals at increased health risk through intra-abdominal fat accumulation

We evaluated the accuracy of self-reported home-assessed and self-measured waist circumference in 101 men and eighty-three women aged 28-67 years. The main outcome measures were subjects' self-reported and self-measured waist circumference, and self-classification according to the previously defined waist action level 1 (940 mm in men, 800 mm in women) and action level 2 (1020 mm in men, 880 mm in women), and waist circumference measured by the investigator using the 'Waist Watcher' tape-measure, as the reference method. The mean errors (95% CI limits of agreement) for subjects' self-reported waist circumference (self-reported minus reference; mm) were -67 (95% CI -210, 77) in men and -43 (95% CI -211, 123) in women, and for self-measured waist circumference (mm) using the 'Waist Watcher' (self-measured minus reference) were -5 (95% CI -62, 52) in men and -4 (95% CI -50, 42) in women. The proportions of subjects classified into waist action level 1 or action level 2 by the investigator were used as the reference method. Self-reported waist circumference of men and women respectively would be classified correctly in different categories based on action level 1 with sensitivities of 58.3 and 78.7%, and specificities of 92.5 and 91.7%, and action level 2 with sensitivities of 35.3 and 44.9%, and specificities of 98.5 and 90.7%. Using the 'Waist Watcher' with different colour bands based on the action levels, male and female subjects respectively classified themselves into correct categories according to action level 1 with sensitivities of 100 and 95.7%, and specificities of 95.1 and 97.2%, and according to action level 2 with sensitivities of 97.1 and 100%, and specificities of 100% for both sexes. Only 2% of the sample misclassified themselves into the wrong categories according to waist circumference action levels. In conclusion, people tend to underestimate their waist circumference, but the 'Waist Watcher' tape-measure offers advantages over self-reported home-assessed measurement, and may be used as a screening tool for self-classifying the risk of ill health through intra-abdominal fat accumulation.

Valproate, lamotrigine, and insulin-mediated risks in women with epilepsy

We recently reported the frequent occurrence of polycystic ovaries and hyperandrogenism associated with weight gain and hyperinsulinemia in women taking valproate for epilepsy. The purpose of this study was to evaluate the risks related to valproate-induced hyperinsulinemia and their reversibility after discontinuing the medication. Sixteen women with valproate-related polycystic ovaries or hyperandrogenism participated in the study. Vaginal ultrasonography was performed, and endocrine and lipid parameters were measured. Thereafter, lamotrigine was substituted for valproate and the patients were observed for 12 months. Twenty-four healthy age-matched women served as control subjects. Twelve women completed the 12-month follow-up. While still on valproate they had centripetal obesity with associated hyperinsulinemia and unfavorable serum lipid profiles. The body-mass index and fasting serum insulin and testosterone concentrations decreased during the first year after replacing valproate with lamotrigine whereas the HDL-cholesterol/total cholesterol ratios increased from 0.17 +/- 0.06 to 0.26 +/- 0.05. The total number of polycystic ovaries in these women decreased from 20 during valproate medication to 11 one year after replacing valproate with lamotrigine. Valproate induces a metabolic syndrome with centripetal obesity, hyperinsulinemia, lipid abnormalities, and polycystic ovaries/hyperandrogenism in women with epilepsy. These valproate-related risks can be reduced by substituting lamotrigine for valproate.

Impairment of health and quality of life in people with large waist circumference

BACKGROUND

Symptoms and secondary disorders associated with excess central fat distribution are being increasingly recognised. We aimed to define the symptoms and assess risks of chronic disorders in people with large waist circumferences.

METHODS

We did a cross-sectional study of 5887 men and 7018 women aged 20-59 years from the general population of Maastricht, Amsterdam, and Doetinchem, Netherlands. We assessed in health centres respiratory insufficiency, low back pain, degree of physical function, presence of non-insulin-dependent diabetes, and cardiovascular risk factors. We measured bodyweight, body-mass index, and waist circumference by action levels (men: less than action level 1 <94.0 cm, action levels 1-2 94.0-101.9 cm, more than action level 2 > or =102.0 cm; women: less than action level 1 <80.0 cm, action levels 1-2 80.0-87.9 cm) more than action level 2 > or =88.0 cm). The reference group were people with waist circumferences lower than action level 1.

FINDINGS

All symptoms and risks increased among participants higher than action level 2, after adjustment for age and lifestyle, by 3.1 (95% CI 2.5-3.7) in men and 2.7 (2.3-3.1) in women for shortness of breath when walking upstairs; 4.5 (2.5-7.8) and 3.8 (1.9-7.3) for non-insulin-dependent diabetes; and 4.2 (3.6-5.0) and 2.8 (2.4-3.2) for at least one major cardiovascular risk factor. Above action level 2, compared with the reference group, men and women were at twice the risk of difficulties in everyday activities, women were 1.5 times more likely to have low back pain or symptoms of intervertebral disc herniation, with secondary problems including hindrance to daily activities.

INTERPRETATION

People with large waist circumferences have excess burden of ill health. Waist action levels could be useful for health promotion to raise awareness of the need for weight management.

Dexfenfluramine. An updated review of its therapeutic use in the management of obesity

Dexfenfluramine increases serotonergic activity by stimulating serotonin (5-hydroxytryptamine; 5-HT) release into brain synapses, inhibiting its reuptake into presynaptic neurons and by directly stimulating postsynaptic serotonin receptors. On the basis of the serotonin hypothesis of appetite control, these actions would be expected to reduce appetite and, consequently, bodyweight. Studies conducted in animals and in overweight patients with and without associated disorders have confirmed the weight-reducing efficacy and good tolerability of dexfenfluramine. In 3-month clinical studies in obese patients, weight reductions with dexfenfluramine 15mg twice daily combined with dietary support were significantly higher than those achieved with placebo and similar to those with ephedrine/caffeine 20/20mg 3 times daily, sibutramine 10mg once daily and fluoxetine 60 mg/day. Furthermore, dexfenfluramine recipients with non-insulin-dependent diabetes mellitus, hyperlipidaemia or hypertension consistently show improvements in glycaemic control, blood lipid profiles and blood pressure. 12-month trial results indicate that most weight loss occurs in the initial 6 months and appears to be maintained for a further 6 months. Weight regain after withdrawal of treatment in 12-month studies demonstrates that dexfenfluramine is effective in maintaining a stable bodyweight at a lower level than placebo and in limiting food intake over this time period. Commonly reported adverse events with dexfenfluramine include diarrhoea, tiredness, dry mouth and somnolence; these symptoms are generally mild and transient. Approximately 7 and 10% of dexfenfluramine recipients in short and long term studies withdrew because of adverse events. Dexfenfluramine was better tolerated than ephedrine/caffeine and fluoxetine in short term studies. Obesity is a chronic condition that is accompanied by a number of metabolic complications. It is a significant health problem in developed countries, and as a major risk factor for many chronic diseases, including diabetes and cardiovascular disease, the economic burden of this condition is considerable. As with other chronic conditions, there is a role for pharmacological intervention in patients with severe obesity. However, drugs should be considered as only one component of a weight-control programme, since additional lifestyle modification is required to maintain weight loss. The promising data on the long term efficacy and tolerability of dexfenfluramine as well as its favourable effects on risk factors associated with obesity requires confirmation in long term studies. In the meantime, dexfenfluramine should be considered a valuable adjunct to a reduced-calorie diet in the management of severe obesity, particularly in patients with associated disorders and those unsuccessful with conventional weight loss measures. Available data support the use of the drug for up to 1 year to maintain weight loss and thus dexfenfluramine should be considered for long term administration.

Waist percentiles: a simple test for atherogenic disease?

OBJECTIVE

To give standards for quantification of the magnitude of waist circumference in children.

METHODS

We calculated the percentiles of waist circumference by age and sex from a sample of 2858 subjects (1440 males and 1418 females, aged 6-14 years). Data were from a population survey of 15,000 school-children in Pescara, a town in Abruzzo, a region of Central Italy.

RESULTS

We reported the values of the calculated percentiles by age and sex and gave the smoothed percentile curves.

CONCLUSIONS

Some recent studies in adults have indicated that measuring waist circumference seems to be the simplest way to estimate obesity and the risk of cardiovascular disease. In children, similar evidence is emerging. To date, no example of calculating standards has been published for quantitating the magnitude of waist circumference in children; therefore, our example of standard waist measurements could be used as a practical model for selecting subjects with a value of < or = or > 2 SD from the mean. The metabolic status should then be checked by complementary laboratory examination.

Waist circumference as a screening tool for cardiovascular risk factors: evaluation of receiver operating characteristics (ROC)

To evaluate the receiver operating characteristics (ROC) to determine the cutoffs of waist circumference as a potential population directed screening tool for hypercholesterolaemia (> or = 6.5 mmol/L), low high density lipoprotein cholesterol (< 0.9 mmol/L), and hypertension (treated and/or systolic > or = 160 and/or diastolic blood pressure > or = 95 mmHg), in 2183 men and 2698 women aged 20 to 59 years selected at random from Dutch civil registries.

MAIN OUTCOME MEASURES

Height, weight, body mass index (BMI), waist circumference, total plasma cholesterol and high density lipoprotein cholesterol concentrations, and blood pressure.

RESULTS

ROC curves showed that sensitivity equalled specificity at waist circumferences between 93-95 cm in men and 81-84 cm in women for identifying individual risk factors, and 92 cm in men and 81 cm in women for identifying those with at least one risk factor. Sensitivity and specificity were equal at levels between 61% to 69% for identifying individual risk factors, with positive predictions (56.8% in men and 37.8% in women) within 2% of those using previously defined 'Action Level 1' of waist circumference 94 cm in men and 80 cm in women (58.8% in men and 37.4% in women). Risk prediction by anthropometric methods was relatively low: ROC areas for identifying each risk factor by waist varied from 55% to 60%, and reached about 65% for identifying at least one risk factor. Height accounted for less than 0.3% of variance in waist circumference. Using BMI at 25 kg/m2 gave similar prediction to waist, but its combination with waist did not improve predictive values.

CONCLUSIONS

Measurement of waist circumference 'Action Level 1' at 94 cm (37 inches) in men and 80 cm (32 inches) in women could be adopted as a simpler valid alternative to BMI for health promotion, to alert those at risk of cardiovascular disease, and as a guide to risk avoidance by self-weight management.