The metabolic syndrome: prevalence and associated risk factor findings in the US population from the Third National Health and Nutrition Examination Survey, 1988-1994

BACKGROUND

The metabolic syndrome is an important cluster of coronary heart disease risk factors with common insulin resistance. The extent to which the metabolic syndrome is associated with demographic and potentially modifiable lifestyle factors in the US population is unknown.

METHODS

Metabolic syndrome-associated factors and prevalence, as defined by Adult Treatment Panel III criteria, were evaluated in a representative US sample of 3305 black, 3477 Mexican American, and 5581 white men and nonpregnant or lactating women aged 20 years and older who participated in the cross-sectional Third National Health and Nutrition Examination Survey.

RESULTS

The metabolic syndrome was present in 22.8% and 22.6% of US men and women, respectively (P =.86). The age-specific prevalence was highest in Mexican Americans and lowest in blacks of both sexes. Ethnic differences persisted even after adjusting for age, body mass index, and socioeconomic status. The metabolic syndrome was present in 4.6%, 22.4%, and 59.6% of normal-weight, overweight, and obese men, respectively, and a similar distribution was observed in women. Older age, postmenopausal status, Mexican American ethnicity, higher body mass index, current smoking, low household income, high carbohydrate intake, no alcohol consumption, and physical inactivity were associated with increased odds of the metabolic syndrome.

CONCLUSIONS

The metabolic syndrome is present in more than 20% of the US adult population; varies substantially by ethnicity even after adjusting for body mass index, age, socioeconomic status, and other predictor variables; and is associated with several potentially modifiable lifestyle factors. Identification and clinical management of this high-risk group is an important aspect of coronary heart disease prevention.

Prevalence of the metabolic syndrome defined by the International Diabetes Federation among adults in the U.S

OBJECTIVE

The International Diabetes Federation (IDF) has proposed a new definition of the metabolic syndrome that emphasizes central adiposity as determined by ethnic group-specific thresholds of waist circumference. The objective of this study was to estimate the prevalence of this syndrome using the IDF definition among U.S. adults and to compare it with the prevalence estimated using the definition of the National Cholesterol Education Program (NCEP).

RESEARCH DESIGN AND METHODS

A total of 3,601 men and women aged > or =20 years from the National Health and Nutrition Examination Survey 1999-2002 were included in the analyses.

RESULTS

Based on the NCEP definition, the unadjusted prevalence of the metabolic syndrome was 34.5 +/- 0.9% (percent +/- SE) among all participants, 33.7 +/- 1.6% among men, and 35.4 +/- 1.2% among women. Based on the IDF definition, the unadjusted prevalence of the metabolic syndrome was 39.0 +/- 1.1% among all participants, 39.9 +/- 1.7% among men, and 38.1 +/- 1.2% among women. The IDF definition led to higher estimates of prevalence in all of the demographic groups, especially among Mexican-American men. The two definitions similarly classified approximately 93% of the participants as having or not having the metabolic syndrome.

CONCLUSIONS

In the U.S., the use of the IDF definition of the metabolic syndrome leads to a higher prevalence estimate of the metabolic syndrome than the estimate based on the NCEP definition.

Prevalence of the metabolic syndrome in American adolescents: findings from the Third National Health and Nutrition Examination Survey

BACKGROUND

Metabolic syndrome (MetS) is defined by the Third Report of the Adult Treatment Panel (ATP III) using criteria easily applied by clinicians and researchers. There is no standard pediatric definition.

METHODS AND RESULTS

We defined pediatric MetS using criteria analogous to ATP III as > or =3 of the following: (1) fasting triglycerides > or =1.1 mmol/L (100 mg/dL); (2) HDL <1.3 mmol/L (50 mg/dL), except in boys aged 15 to 19 years, in whom the cutpoint was <1.2 mmol/L (45 mg/dL); (3) fasting glucose > or =6.1 mmol/L (110 mg/dL); (4) waist circumference >75th percentile for age and gender; and (5) systolic blood pressure >90th percentile for gender, age, and height. MetS prevalence in US adolescents was estimated with the Third National Health and Nutritional Survey 1988 to 1994. Among 1960 children aged > or =12 years who fasted > or =8 hours, two thirds had at least 1 metabolic abnormality, and nearly 1 in 10 had MetS. The racial/ethnic distribution was similar to adults: Mexican-Americans, followed by non-Hispanic whites, had a greater prevalence of MetS compared with non-Hispanic blacks (12.9%, [95% CI 10.4% to 15.4%]; 10.9%, [95% CI 8.4% to 13.4%]; and 2.5%, [95% CI 1.3% to 3.7%], respectively). Nearly one third (31.2% [95% CI 28.3% to 34.1%]) of overweight/obese adolescents had MetS.

CONCLUSIONS

Our definition of pediatric MetS, designed to be closely analogous to ATP III, found MetS is common in adolescents and has a similar racial/ethnic distribution to adults in this representative national sample. Because childhood MetS likely tracks into adulthood, early identification may help target interventions to improve future cardiovascular health.

Obesity and the metabolic syndrome in developing countries

CONTEXT

Prevalence of obesity and the metabolic syndrome is rapidly increasing in developing countries, leading to increased morbidity and mortality due to type 2 diabetes mellitus (T2DM) and cardiovascular disease.

EVIDENCE ACQUISITION

Literature search was carried out using the terms obesity, insulin resistance, the metabolic syndrome, diabetes, dyslipidemia, nutrition, physical activity, and developing countries, from PubMed from 1966 to June 2008 and from web sites and published documents of the World Health Organization and Food and Agricultural Organization.

EVIDENCE SYNTHESIS

With improvement in economic situation in developing countries, increasing prevalence of obesity and the metabolic syndrome is seen in adults and particularly in children. The main causes are increasing urbanization, nutrition transition, and reduced physical activity. Furthermore, aggressive community nutrition intervention programs for undernourished children may increase obesity. Some evidence suggests that widely prevalent perinatal undernutrition and childhood catch-up obesity may play a role in adult-onset metabolic syndrome and T2DM. The economic cost of obesity and related diseases in developing countries, having meager health budgets is enormous.

CONCLUSIONS

To prevent increasing morbidity and mortality due to obesity-related T2DM and cardiovascular disease in developing countries, there is an urgent need to initiate large-scale community intervention programs focusing on increased physical activity and healthier food options, particularly for children. International health agencies and respective government should intensively focus on primordial and primary prevention programs for obesity and the metabolic syndrome in developing countries.

Neonatal anthropometry: the thin-fat Indian baby. The Pune Maternal Nutrition Study

OBJECTIVE

To examine body size and fat measurements of babies born in rural India and compare them with white Caucasian babies born in an industrialised country.

DESIGN

Community-based observational study in rural India, and comparison with data from an earlier study in the UK, measured using similar methods.

SUBJECTS

A total of 631 term babies born in six rural villages, near the city of Pune, Maharashtra, India, and 338 term babies born in the Princess Anne Hospital, Southampton, UK.

MEASUREMENTS

Maternal weight and height, and neonatal weight, length, head, mid-upper-arm and abdominal circumferences, subscapular and triceps skinfold thicknesses, and placental weight.

RESULTS

The Indian mothers were younger, lighter, shorter and had a lower mean body mass index (BMI) (mean age, weight, height and BMI: 21.4 y, 44.6 kg, 1.52 m, and 18.2 kg/m(2)) than Southampton mothers (26.8 y, 63.6 kg, 1.63 m and 23.4 kg/m(2)). They gave birth to lighter babies (mean birthweight: 2.7 kg compared with 3.5 kg). Compared to Southampton babies, the Indian babies were small in all body measurements, the smallest being abdominal circumference (s.d. score: -2.38; 95% CI: -2.48 to -2.29) and mid-arm circumference (s.d. score: -1.82; 95% CI: -1.89 to -1.75), while the most preserved measurement was the subscapular skinfold thickness (s.d. score: -0.53; 95% CI: -0.61 to -0.46). Skinfolds were relatively preserved in the lightest babies (below the 10th percentile of birthweight) in both populations.

CONCLUSIONS

Small Indian babies have small abdominal viscera and low muscle mass, but preserve body fat during their intrauterine development. This body composition may persist postnatally and predispose to an insulin-resistant state.

Visceral adiposity and the risk of metabolic syndrome across body mass index: the MESA Study

OBJECTIVES

This study sought to evaluate differential effects of visceral fat (VF) and subcutaneous fat and their effects on metabolic syndrome (MetS) risk across body mass index (BMI) categories.

BACKGROUND

The regional distribution of adipose tissue is an emerging risk factor for cardiometabolic disease, although serial changes in fat distribution have not been extensively investigated. VF and its alterations over time may be a better marker for risk than BMI in normal weight and overweight or obese individuals.

METHODS

We studied 1,511 individuals in the MESA (Multi-Ethnic Study of Atherosclerosis) with adiposity assessment by computed tomography (CT). A total of 253 participants without MetS at initial scan underwent repeat CT (median interval 3.3 years). We used discrete Cox regression with net reclassification to investigate whether baseline and changes in VF area are associated with MetS.

RESULTS

Higher VF was associated with cardiometabolic risk and coronary artery calcification, regardless of BMI. After adjustment, VF was more strongly associated with incident MetS than subcutaneous fat regardless of weight, with a 28% greater MetS hazard per 100 cm(2)/m VF area and significant net reclassification (net reclassification index: 0.44, 95% confidence interval [CI]: 0.29 to 0.60) over clinical risk. In individuals with serial imaging, initial VF (hazard ratio: 1.24 per 100 cm(2)/m, 95% CI: 1.08 to 1.44 per 100 cm(2)/m, p = 0.003) and change in VF (hazard ratio: 1.05 per 5% change, 95% CI: 1.01 to 1.08 per 5% change, p = 0.02) were associated with MetS after adjustment. Changes in subcutaneous fat were not associated with incident MetS after adjustment for clinical risk and VF area.

CONCLUSIONS

VF is modestly associated with BMI. However, across BMI, a single measure of and longitudinal change in VF predict MetS, even accounting for weight changes. Visceral adiposity is essential to assessing cardiometabolic risk, regardless of age, race, or BMI, and may serve as a marker and target of therapy in cardiometabolic disease.

Sex-hormone-binding globulin and the free androgen index are related to cardiovascular risk factors in multiethnic premenopausal and perimenopausal women enrolled in the Study of Women Across the Nation (SWAN)

BACKGROUND

Recent clinical trials have shifted attention away from estrogens and toward androgens and sex hormone-binding globulin (SHBG) as potential mediators of increasing cardiovascular (CV) risk in women at midlife.

METHODS AND RESULTS

The correlation between reproductive hormones and CV risk factors was evaluated in a multiethnic (white, black, Hispanic, Chinese, and Japanese) sample of 3297 premenopausal and perimenopausal women. Testosterone and estradiol (E2) were evaluated along with SHBG and the free androgen index (FAI), the amount of testosterone not bound by SHBG. Low SHBG and high FAI were strongly and consistently related to elevated CV risk factors (higher insulin, glucose, and hemostatic and inflammatory markers and adverse lipids) even after controlling for body mass index (P<0.001 for all). Low levels of E2 were associated with elevated CV risk factors to a lesser degree. These observations were consistent across the 5 ethnic groups. Compared with whites, blacks had higher levels of SHBG and lower levels of FAI, and Chinese had lower levels of SHBG and higher levels of FAI.

CONCLUSIONS

Low SHBG and high FAI are strongly associated with CV risk factors in racially diverse women, and thus, androgens likely play a role in the CV risk profile of perimenopausal women.

Insulin resistance, the metabolic syndrome, and risk of incident cardiovascular disease in nondiabetic american indians: the Strong Heart Study

OBJECTIVE

Insulin resistance (IR) and the metabolic syndrome (MS) are associated with type 2 diabetes and adverse cardiovascular disease (CVD) risk factor profiles. Whether IR and MS predict CVD independently of diabetes and other CVD risk factors is not known. This study examines whether IR and/or presence of MS are independently associated with CVD in nondiabetic American Indians (AI).

RESEARCH DESIGN AND METHODS

We examined 2283 nondiabetic AI who were free of CVD at the baseline examination of the Strong Heart Study (SHS). CVD risk factors were measured, IR was quantified using the homeostasis model assessment (HOMA), and MS as defined by the National Cholesterol Education Program Adult Treatment Panel (ATP III) was assessed for each participant. Incident CVD and diabetes were ascertained during follow-up.

RESULTS

MS was present in 798 individuals (35%), and 181 participants (7.9%) developed CVD over 7.6 +/- 1.8 years of follow-up. Age, BMI, waist circumference, and triglyceride levels increased and HDL cholesterol decreased across tertiles of HOMA-IR. Risk of diabetes increased as a function of baseline HOMA-IR (6.3, 14.6, and 30.1%; P < 0.001) and MS (12.8 vs. 24.5%). In Cox models adjusted for CVD risk factors, risk of CVD did not increase either as a function of baseline HOMA-IR or MS, but individual CVD risk factors predicted subsequent CVD.

CONCLUSIONS

Among nondiabetic AI in the SHS, HOMA-IR and MS both predict diabetes, but neither predicts CVD independently of other established CVD risk factors.

Visceral fat, waist circumference, and BMI: impact of race/ethnicity

OBJECTIVE

BMI and waist circumference are used to define risk from excess body fat. Limited data in women suggest that there may be racial/ethnic differences in visceral adipose tissue (VAT) at a given BMI or waist circumference. This study tested the hypothesis that racial/ethnic differences exist in both men and women in the relationship of anthropometric measures of body composition and computed tomography (CT)-determined VAT or subcutaneous adipose tissue (SAT).

METHODS AND PROCEDURES

Subjects included 66 African American, 72 Hispanic, and 47 white men and women, aged > or =45. Waist circumference and BMI were measured using standard methods. Total abdominal and L4L5 VAT and SAT were measured using CT.

RESULTS

Among both men and women, groups did not differ in waist circumference or BMI. White men had greater L4L5 VAT than African-American men, and both white and Hispanic men had greater total VAT than African-American men. Among women, Hispanics and whites had greater L4L5 VAT than African Americans, and Hispanics had greater total VAT than African Americans. The slope of the linear relationship between BMI or waist circumference and VAT was lower in African Americans than in Hispanics and/or whites.

DISCUSSION

Middle-aged and older African-American men and women had lower VAT despite similar BMI and waist circumference measurements. Altered relationships between anthropometric measures and VAT may have implications for defining metabolic risk in different populations. Different waist circumference or BMI cutoff points may be necessary to adequately reflect risk in different racial/ethnic groups.

Influence of body fat content and distribution on variation in metabolic risk

OBJECTIVES

Several reports indicate that the body fat compartments, especially ip fat, predict metabolic risk better than total body fat. The objective of the study was to determine whether this can be confirmed and generalized throughout the population.

PARTICIPANTS

A representative sample of 1934 Black and White women and men of the Dallas Heart Study participated in the study.

DESIGN

We measured the fat in total body, trunk, and lower body with dual-energy x-ray absorptiometry and in abdominal compartments (sc, ip, and retroperitoneal) with magnetic resonance imaging. Other measurements included body mass index (BMI), waist circumference, blood pressure, plasma lipids, glucose, insulin (including homeostasis model), and C-reactive protein.

RESULTS

In all groups, total body fat correlated positively with key metabolic risk factors, i.e. homeostasis model, triglyceride/high-density lipoprotein-cholesterol ratios, C-reactive protein, and blood pressure; however, it explained less than one third of the variability of all the risk factors. After adjustment for total body fat, truncal fat conferred additional positive correlation with risk factors. Furthermore, with multivariable regression analysis, ip fat conferred independent correlation with plasma lipids beyond a combination of other compartments including truncal fat. Still, except for insulin levels, all combinations including ip fat still explained less than one third of the variability in risk-factor levels. Conversely, lower body fat correlated negatively with risk factors; i.e. lower body fat appeared to offer some protection against risk factors.

CONCLUSIONS

Body fat distribution has some influence on risk factors beyond total body fat content. Both waist circumference and BMI significantly predicted risk factors after adjustment for total body fat, and for clinical purposes, most of the predictive power for men was contained in waist circumference, whereas for women, BMI and waist circumference were similarly predictive. Finally, even though the correlations between combined body fat parameters and risk factors explained only a portion of the variation in the latter, the average number of categorical metabolic risk factors increased progressively with increasing obesity. Hence, obesity seemingly has more clinical impact than revealed in these correlative studies.

Association between serum uric acid, metabolic syndrome, and carotid atherosclerosis in Japanese individuals

OBJECTIVE

There are few data available on possible independent association between uric acid and carotid atherosclerosis. Here we first sought to investigate association between uric acid levels and metabolic syndrome in Japanese; second, we assessed whether there is an independent association of uric acid with prevalence of carotid atherosclerosis in individuals subdivided according to gender and metabolic syndrome status.

METHODS AND RESULTS

Cross-sectional data from 8144 individuals who underwent general health screening were analyzed. After adjusting for age, total cholesterol, and smoking status, the odds ratios (95% CI) of sex-specific quartiles of serum uric acid for metabolic syndrome were 1.0, 1.06 (0.60 to 1.87), 2.18 (1.30 to 3.64), and 4.17 (2.56 to 6.79) in women, and 1.0, 0.92 (0.74 to 1.14), 1.52 (1.25 to 1.65), and 1.97 (1.61 to 2.40) in men. After adjusting for age, serum levels, total cholesterol, and smoking status, prevalence of carotid plaque was higher in subjects in the second, third, and fourth quartiles of uric acid level with odds ratios (95% CI) of 1.24 (1.01 to 1.52), 1.37 (1.11 to 1.68), and 1.31 (1.05 to 1.63), respectively, in men without metabolic syndrome but not in men with metabolic syndrome or in women with or without metabolic syndrome.

CONCLUSIONS

The prevalence of metabolic syndrome showed a graded increase according to serum uric acid values in both genders. In men who did not have metabolic syndrome, uric acid was found to be an independent risk factor for incidence of carotid plaque.

Pediatric metabolic syndrome predicts adulthood metabolic syndrome, subclinical atherosclerosis, and type 2 diabetes mellitus but is no better than body mass index alone: the Bogalusa Heart Study and the Cardiovascular Risk in Young Finns Study

BACKGROUND

The clinical utility of identifying pediatric metabolic syndrome (MetS) is controversial. This study sought to determine the status of pediatric MetS as a risk factor for adult subclinical atherosclerosis (carotid intima-media thickness [cIMT]) and type 2 diabetes mellitus (T2DM) and compare and contrast this prediction with its individual components.

METHODS AND RESULTS

Using data from the population-based, prospective, observational Bogalusa Heart and Cardiovascular Risk in Young Finns studies, we examined the utility of 4 categorical definitions of youth MetS and their components in predicting adult high cIMT and T2DM among 1781 participants aged 9 to 18 years at baseline (1984 to 1988) who were then examined 14 to 27 years later (2001-2007) when aged 24 to 41 years. Youth with MetS were at 2 to 3 times the risk of having high cIMT and T2DM as adults compared with those free of MetS at youth. Risk estimates with the use of high body mass index were similar to those of MetS phenotypes in predicting adult outcomes. Comparisons of area under the receiver operating characteristic curve and net reclassification index suggested that prediction of adult MetS, high cIMT, and T2DM in adulthood with the use of youth MetS was either equivalent or inferior to classification based on high body mass index or overweight and obesity.

CONCLUSIONS

Youth with MetS are at increased risk of meaningful adult outcomes; however, the simplicity of screening for high BMI or overweight and obesity in the pediatric setting offers a simpler, equally accurate alternative to identifying youth at risk of developing adult MetS, high cIMT, or T2DM.

Features of the metabolic syndrome and diabetes mellitus as predictors of aortic valve calcification in the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Calcific aortic valve disease is common in the elderly, is correlated with common cardiovascular risk factors, and is associated with increased cardiovascular event risk; however, whether metabolic syndrome is associated with an increased prevalence of aortic valve calcium (AVC) is not known.

METHODS AND RESULTS

The prevalence of AVC, as assessed by computed tomography, was compared in 6780 Multi-Ethnic Study of Atherosclerosis (MESA) participants with metabolic syndrome (n=1550; National Cholesterol Education Program's Adult Treatment Panel III [ATP III] criteria), diabetes mellitus (n=1016), or neither condition (n=4024). The prevalence of AVC for those with neither condition, metabolic syndrome, or diabetes mellitus was, respectively, 8%, 12%, and 17% in women (P<0.001) and 14%, 22%, and 24% in men (P<0.001). Compared with those with neither condition, the adjusted relative risks for the presence of AVC were 1.45 (95% CI 1.11 to 1.90) for metabolic syndrome and 2.12 (95% CI 1.54 to 2.92) for diabetes mellitus in women and 1.70 (95% CI 1.32 to 2.19) for metabolic syndrome and 1.73 (95% CI 1.33 to 2.25) for diabetes mellitus in men. There was a graded, linear relationship between AVC prevalence and the number of metabolic syndrome components in both women and men (both P<0.001). Similar results were obtained when the International Diabetes Federation metabolic syndrome definition was used.

CONCLUSIONS

In the MESA cohort, the metabolic syndrome and diabetes mellitus are associated with increased risk of AVC, and AVC prevalence is increased with increasing number of metabolic syndrome components.

Ethnic differences in the ability of triglyceride levels to identify insulin resistance

The Metabolic Syndrome is used to predict the onset of coronary artery disease and Type 2 diabetes. As the predictive value of the Metabolic Syndrome has been challenged, alternative syndromes have been developed. All of these syndromes were developed in populations that were predominantly non-Hispanic white (NHW). They include the Enlarged Waist Elevated Triglyceride Syndrome, the Overweight-Lipid Syndrome and the Hypertriglyceridemic Waist Syndrome. The first applies to postmenopausal women, the second to overweight individuals (BMI> or =25 kg/m(2)), and the third to men. Each syndrome uses hypertriglyceridemia as a criterion. However, the definition of hypertriglyceridemia varies by syndrome i.e. TG> or =128 mg/dL for the Enlarged Waist Elevated Triglyceride Syndrome, TG> or =130 mg/dL for the Overweight-Lipid Syndrome, > or =150 mg/dL for the Metabolic Syndrome, and TG> or =176 mg/dL for the Hypertriglyceridemic Waist Syndrome. Insulin resistance and hypertriglyceridemia are highly correlated. But as insulin resistant non-Hispanic blacks (NHB) often have triglyceride (TG) levels below the thresholds set by these syndromes, the ability of either TG or these syndromes to identify high risk NHB is unknown. Using the National Health and Nutrition Examination Survey (NHANES) 1999-2002, our goals were to determine by ethnicity: (1) the prevalence of each of these syndromes; (2) the ability of fasting TG concentrations to identify insulin resistance at cut-off levels established by these syndromes, specifically 130, 150 and 176 mg/dL. Participants were 2804 adults from NHANES 1999-2002. The cohort was divided into tertiles of homeostasis model assessment. Insulin resistance was defined as the upper tertile (> or =2.73). The prevalence of each syndrome was lower in NHB than NHW or Mexican Americans (MA) (all P<0.05). Mean TG levels in NHB, non-Hispanic Whites (NHW) and Mexican Americans (MA) were: 99, 140 and 144mg/dL, respectively. The mean percents of insulin-resistant NHB, NHW and MA with TG<130mg/dL were: 64, 31 and 36. The percents of insulin-resistant NHB, NHW and MA with TG<150mg/dL were: 75, 46 and 47. The percents of insulin-resistant NHB, NHW and MA with TG<176 mg/dL were: 81, 58 and 59. Significance was P<0.001 for each comparison to NHB. In conclusion, the prevalence of syndromes that use TG as a diagnostic criterion is lower in NHB than NHW or MA. NHB are more likely than NHW or MA to be insulin-resistant and have TG levels below threshold values. As syndromes are formulated to identify individuals at high risk for conditions such as cardiovascular disease and Type 2 diabetes, ethnic differences in TG levels should be considered.

Association of serum uric acid level with non-alcoholic fatty liver disease: a cross-sectional study

BACKGROUND/AIM

Serum uric acid level has been suggested to be associated with factors that contribute to the metabolic syndrome. The aim of this study was to investigate the association of serum uric acid level with non-alcoholic fatty liver disease (NAFLD).

METHODS

A cross-sectional study was performed among the employees of Zhenhai Refining & Chemical Company Ltd., Ningbo, China.

RESULTS

The study included 8925 subjects (6008 men) with a mean age of 43 years. The prevalence rates of NAFLD and hyperuricemia were 11.78% and 14.71%, respectively. NAFLD patients had significantly higher serum uric acid levels than controls (370.3+/-86.6 vs. 321.1+/-82.6 micromol/L; P<0.001). The prevalence rate of NAFLD was significantly higher in subjects with hyperuricemia than in those without hyperuricemia (24.75% vs. 9.54%; P<0.001), and the prevalence rate increased with progressively higher serum uric acid levels (P value for trend <0.001). Multiple regression analysis showed that hyperuricemia was associated with an increased risk of NAFLD (odds ratio [OR]: 1.291, 95% confidence interval [CI]: 1.067-1.564; P<0.001).

CONCLUSION

Serum uric acid level is significantly associated with NAFLD, and elevated serum uric acid level is an independent risk factor for NAFLD.

Chemerin is associated with metabolic syndrome phenotypes in a Mexican-American population

CONTEXT

Chemerin is a novel adipokine previously associated with metabolic syndrome phenotypes in a small sample of subjects from Mauritius.

OBJECTIVE

The aim of the study was to determine whether plasma chemerin levels were associated with metabolic syndrome phenotypes in a larger sample from a second, unrelated human population.

DESIGN, SETTING, PATIENTS, AND INTERVENTION

Plasma samples were obtained from the San Antonio Family Heart Study (SAFHS), a large family-based genetic epidemiological study including 1431 Mexican-American individuals. Individuals were randomly sampled without regard to phenotype or disease status. This sample is well-characterized for a variety of phenotypes related to the metabolic syndrome.

MAIN OUTCOMES

Plasma chemerin levels were measured by sandwich ELISA. Linear regression and correlation analyses were used to determine associations between plasma chemerin levels and metabolic syndrome phenotypes.

RESULTS

Circulating chemerin levels were significantly higher in nondiabetic subjects with body mass index (BMI) greater than 30 kg/m(2) compared with those with a BMI below 25 kg/m(2) (P < 0.0001). Plasma chemerin levels were significantly associated with metabolic syndrome-related parameters, including BMI (P < 0.0001), fasting serum insulin (P < 0.0001), triglycerides (P < 0.0001), and high-density lipoprotein cholesterol (P = 0.00014), independent of age and sex in nondiabetic subjects.

CONCLUSION

Circulating chemerin levels were associated with metabolic syndrome phenotypes in a second, unrelated human population. This replicated result using a large human sample suggests that chemerin may be involved in the development of the metabolic syndrome.

Metabolic syndrome in urban Asian Indian adults--a population study using modified ATP III criteria

AIMS/HYPOTHESIS

To determine the prevalence of the Metabolic syndrome (MetS) using modified ATP III criteria in urban Asian Indian adults.

METHODS

475 subjects (age 20-75 years) from a population data base were studied for the MetS using ATP III criteria but with a modified waist circumference (WC) appropriate for Indians. Presence of >or=3 of the following; raised WC (Men >or=90 cm, Women >or=85 cm), triglycerides (TG) >or=1.7 mmol/l), HDL-Cholesterol (HDL-C)-<1.0 mmol/l for men, <1.3 mmol/l for women, fasting plasma glucose (FPG)>or=6.1 mmol/l and blood pressure (BP)>or=130/>or=85 mm of Hg, or using BP medication, indicated the MetS. Insulin resistance (IR) was calculated using the Homeostasis Model Assessment (HOMA) equation. Factor analysis was used to identify clusters of correlated abnormalities.

RESULTS

MetS was present in 41.1%. WC was increased in 31.4%, TG in 45.6%, low HDL-C in 65.5%, hypertension in 55.4% and raised FPG 26.7%. MetS was present in 27.9% of subjects with FPG<6.1 mmol/l and its prevalence increased to >70% with higher FPG values. MetS was more common in women than in men (46.5 vs. 36.4%, chi(2)=4.6, P=0.03) and in older people. Four distinct clusters of abnormalities were identified with some gender variations. IR was more prevalent in MetS and was a component of two clusters but it was not a core component in factor analysis.

CONCLUSIONS

MetS is common in Asian Indians. Its prevalence is age-related, and is more common in women. HOMA-IR or fasting plasma insulin was not a core component of the MetS.

An examination of sex and racial/ethnic differences in the metabolic syndrome among adults: a confirmatory factor analysis and a resulting continuous severity score

OBJECTIVE

The metabolic syndrome (MetS) is typically diagnosed based on abnormalities in specific clustered clinical measures that are associated with increased risk for coronary heart disease (CHD) and Type 2 diabetes mellitus (T2DM). However, current MetS criteria result in racial/ethnic discrepancies. Our goals were to use confirmatory factor analysis (CFA) to delineate differential contributions to MetS by sub-group, and if contributions were discovered, develop sex and racial/ethnic-specific equations to calculate MetS severity.

RESEARCH DESIGN AND METHODS

Using data on adults from the National Health and Nutrition Examination Survey 1999-2010, we performed a CFA of a single MetS factor that allowed differential loadings across groups, resulting in a sex and race/ethnicity-specific continuous MetS severity score.

RESULTS

Loadings to the single MetS factor differed by sub-group for each MetS component (p<0.001), with lower factor loadings among non-Hispanic-blacks for triglycerides and among Hispanics for waist circumference. Systolic blood pressure exhibited low factor loadings among all groups. MetS severity scores were correlated with biomarkers of future disease (high-sensitivity C-reactive-protein, uric acid, insulin resistance). Non-Hispanic-black-males with diabetics had a low prevalence of MetS but high MetS severity scores that were not significantly different from other racial/ethnic groups.

CONCLUSIONS

This analysis among adults uniquely demonstrated differences between sexes and racial/ethnic groups regarding contributions of traditional MetS components to an assumed single factor. The resulting equations provide a clinically-accessible and interpretable continuous measure of MetS for potential use in identifying adults at higher risk for MetS-related diseases and following changes within individuals over time. These equations hold potential to be a powerful new outcome for use in MetS-focused research and interventions.

Metabolic syndrome and ischemic stroke risk: Northern Manhattan Study

BACKGROUND AND PURPOSE

More than 47 million individuals in the United States meet the criteria for the metabolic syndrome. The relation between the metabolic syndrome and stroke risk in multiethnic populations has not been well characterized.

METHODS

As part of the Northern Manhattan Study, 3298 stroke-free community residents were prospectively followed up for a mean of 6.4 years. The metabolic syndrome was defined according to guidelines established by the National Cholesterol Education Program Adult Treatment Panel III. Cox proportional-hazards models were used to calculate hazard ratios (HRs) and 95% CIs for ischemic stroke and vascular events (ischemic stroke, myocardial infarction, or vascular death). The etiologic fraction estimates the proportion of events attributable to the metabolic syndrome.

RESULTS

More than 44% of the cohort had the metabolic syndrome (48% of women vs 38% of men, P<0.0001), which was more prevalent among Hispanics (50%) than whites (39%) or blacks (37%). The metabolic syndrome was associated with increased risk of stroke (HR=1.5; 95% CI, 1.1 to 2.2) and vascular events (HR=1.6; 95% CI, 1.3 to 2.0) after adjustment for sociodemographic and risk factors. The effect of the metabolic syndrome on stroke risk was greater among women (HR=2.0; 95% CI, 1.3 to 3.1) than men (HR=1.1; 95% CI, 0.6 to 1.9) and among Hispanics (HR=2.0; 95% CI, 1.2 to 3.4) compared with blacks and whites. The etiologic fraction estimates suggest that elimination of the metabolic syndrome would result in a 19% reduction in overall stroke, a 30% reduction of stroke in women; and a 35% reduction of stroke among Hispanics.

CONCLUSIONS

The metabolic syndrome is an important risk factor for ischemic stroke, with differential effects by sex and race/ethnicity.

Obesity, Insulin Resistance, and the Metabolic Syndrome

Background— Insulin resistance is strongly associated with obesity and other components of the metabolic syndrome (MS). The relative importance of these components in the determination of endothelial function is unknown. Furthermore, there is conflicting evidence about whether ethnic differences exist in the relative importance of these components in regard to other cardiovascular outcomes. We evaluated the contributions of insulin resistance, obesity, and the other components of the MS to impaired endothelial function.

Methods and Results— The relationships of the MS components (as defined according the National Cholesterol Education Program) and insulin resistance (estimated using the homeostasis model) with endothelium-dependent vasodilation were examined in 42 white and 55 black subjects. Endothelium-dependent vasodilation was assessed as the increment in leg blood flow (measured by thermodilution) after exposure to methacholine chloride. Waist circumference, glucose, blood pressure, and insulin resistance distributions did not differ between ethnic groups; blacks in our sample had higher HDL cholesterol (1.31 versus 1.09 mmol/L; P <0.001) and lower triglyceride levels (1.01 versus 1.37 mmol/L; P =0.005) than white subjects. In the absence of the MS, black subjects exhibited reduced endothelium-dependent vasodilation compared with white subjects ( P =0.005), and both groups demonstrated significantly worse endothelial function when the MS was present (maximal increase in leg blood flow: blacks: 107±9% MS absent, 53±16% MS present; whites: 163±16% MS absent, 54±18% MS absent; P =0.007, MS absent versus present; P =NS for interaction of ethnicity and MS). Multivariable regression analysis examining relationships of endothelial function with the 5 MS components (analyzed as continuous variables) revealed independent relationships only with waist circumference ( P =0.01) and systolic blood pressure ( P =0.02). Waist circumference was no longer independently associated after adding insulin resistance to the modeling ( P =0.02 for log of homeostasis model index of insulin resistance, P =0.02 for systolic blood pressure). Ethnicity still exerted an independent effect on endothelial function after accounting for the above components ( P =0.04 for an additional effect of ethnic status on endothelial function), with an ethnic difference in the effect of insulin resistance on endothelial function ( P =0.046 for interaction of ethnicity and log of homeostasis model index of insulin resistance).

Conclusions— These findings suggest that insulin resistance and systolic blood pressure are the principal determinants of endothelial dysfunction in the MS and that there are ethnic differences in the relative importance of these factors. These differences may imply different benefits from treatments targeting blood pressure or insulin resistance in different ethnic groups.

Socioeconomic disparities in metabolic syndrome differ by gender: evidence from NHANES III

PURPOSE

The aim of the study is to examine whether socioeconomic position (SEP) is associated with metabolic syndrome and whether the association differs by gender and race/ethnicity.

METHODS

Study participants were from the Third National Health and Nutrition Examination Survey. SEP was measured by using education and poverty income ratio (PIR). Metabolic syndrome was measured according to the National Institutes of Health guidelines. Multivariable-adjusted logistic regression analyses were performed.

RESULTS

Low education (<12 years) was associated with metabolic syndrome in women (odds ratio [OR], 1.77; 95% confidence interval [CI], 1.39-2.24) and less so in men (OR, 1.27; 95% CI, 0.97-1.66) versus more than 12 years of education. For income, low PIR (<or=1) was related to metabolic syndrome in women (OR, 1.81; 95% CI, 1.37-2.40) and not men (OR, 0.98; 95% CI, 0.74-1.29) versus PIR greater than 3. SEP was associated with metabolic syndrome in white, black, and Mexican-American women. Education was associated with all five metabolic syndrome components in women and only three components (abdominal obesity, hypertension, and hyperglycemia) in men.

CONCLUSIONS

SEP is associated with metabolic syndrome in white, black, and Mexican-American women and is associated less strongly in men. The findings provide biologic mechanistic evidence of previously documented associations between SEP and such clinical disorders as type 2 diabetes and coronary heart disease. These results underscore the clinical significance of SEP, particularly for women.

Asian Americans have greater prevalence of metabolic syndrome despite lower body mass index

OBJECTIVE

To examine the relationship between body mass index (BMI) and metabolic syndrome for Asian Americans and non-Hispanic Whites (NHWs), given that existing evidence shows racial/ethnic heterogeneity exists in how BMI predicts metabolic syndrome.

RESEARCH DESIGN AND METHODS

Electronic health records of 43,507 primary care patients aged 35 years and older with self-identified race/ethnicity of interest (Asian Indian, Chinese, Filipino, Japanese, Korean, Vietnamese or NHW) were analyzed in a mixed-payer, outpatient-focused health-care organization in the San Francisco Bay Area.

RESULTS

Metabolic syndrome prevalence is significantly higher in Asians compared with NHWs for every BMI category. For women at the mean age of 55 and BMI of 25  kg  m(-2), the predicted prevalence of metabolic syndrome is 12% for NHW women compared with 30% for Asians; similarly for men, the predicted prevalence of metabolic syndrome is 22% for NHWs compared with 43% of Asians. Compared with NHW women and men with a BMI of 25  kg  m(-2), comparable prevalence of metabolic syndrome was observed at BMI of 19.6  kg  m(-2) for Asian women and 19.9  kg  m(-2) for Asian men. A similar pattern was observed in disaggregated Asian subgroups.

CONCLUSIONS

In spite of the lower BMI values and lower prevalence of overweight/obesity than NHWs, Asian Americans have higher rates of metabolic syndrome over the range of BMI. Our results indicate that BMI ranges for defining overweight/obesity in Asian populations should be lower than for NHWs.