Low sensitivity for the metabolic syndrome to detect uric acid elevations in females and non-Hispanic-black male adolescents: an analysis of NHANES 1999-2006

Association between asymptomatic hyperuricemia and risk of arthritis, findings from a US National Survey 2007-2018

BACKGROUND

Arthritis is thought to be closely related to serum uric acid. The study aims to assess the association between asymptomatic hyperuricemia (AH) and arthritis.

METHODS

A multistage, stratified cluster was used to conduct a cross-sectional study of adult US civilians aged≥20 years from the 2007-2018 National Health and Nutrition Examination Survey. Participants with hyperuricemia and without hyperuricemia prior to gout were included. A questionnaire was used to determine whether participants had arthritis and the type of arthritis. Logistic regression was used to investigate the association between hyperuricemia and arthritis.

RESULT

During the past 12 years, the percentage of participants with arthritis changed from 25.95% (22.53%-29.36%) to 25.53% (21.62%-29.44%). The prevalence of osteoarthritis (OA) increased from 8.70% (95% CI: 6.56% to 10.85%) to 12.44% (95% CI: 9.32% to 15.55%), the prevalence of AH changed from 16.35% (95% CI: 14.01% to 18.40%) to 16.39% (95% CI: 13.47% to 19.30%). Participants with AH were associated with onset of arthritis (OR=1.34, 95% CI: 1.07 to 1.69), but the association was muted after adjusting demographic and socioeconomic factors. For participants aged 40-49 years, AH is associated with incident arthritis (OR=1.96, 95% CI: 1.23 to 2.99) and the relationship remained after adjusting for education level, income to poverty ratio, body mass index, diabetes, hypertension and smoking (OR=2.00, 95% CI: 1.94 to 3.36). Compared with male, female participants with AH are more likely to develop arthritis, especially in OA (OR=1.35, 95% CI: 1.14 to 1.60).

CONCLUSION

Our data identified AH as the risk factor for incident arthritis, especially for OA, which might be exaggerated in aged population and female population.

The serum uric acid level in females may be a better indicator of metabolic syndrome and its components than in males in a Japanese population

BACKGROUND

Although the level of uric acid (UA) is higher in males, increased UA level in females was reported to be closely associated with prevalence of metabolic syndrome (Mets) leading to atherosclerotic cardiovascular disease (ASCVD). Few data exist regarding the gender diferences in relationship between the serum UA levels and cardo-metabolic risk in the Japanese population, which generally contains a lower proportion of obesity than Western populations.

METHODS

This cross-sectional study was designed to investigate, by gender, the association between the serum UA level and abdominal obesity, and thereby cardio-metabolic risk i.e. presence of Mets and its components using a sample of 8567 apparently healthy subjects females: n = 3334, males: n = 5233 at the Health Planning Center of Nihon University Hospital between September 2015 and August 2016.

RESULTS

Receiver operating characteristic analysis was performed to reveal the accuracy of serum UA level as a predictor of abdominal obesity based on the Japanese criteria of Mets (females vs. males: area under the curve, 0.751 vs 0.609). Furthermore, the serum UA level and proportion of abdominal obesity rose with increasing age in females; in males, however, these parameters did not change in parallel with age. Furthermore, the serum UA levels in females reflected a status of cardio-metabolic risk when compared with males in a multi-logistic regression analysis. It is particularly worth noting that in the above-mentioned multivariate logistic regression analysis, the odds ratio of hyperuricemia in females was generally 1.3-2.5 times higher than that in males.

CONCLUSIONS

Compared with males, increased serum UA level in females might be involved in abdominal obesity and cardio-metabolic risk, possibly leading to the development of ASCVD even in a Japanese population. This may be due to gender differences affecting the development of abdominal obesity and changes in the serum UA levels with age.

CLINICAL TRIAL REGISTRATION

UMIN (http://www.umin.ac.jp/) Study ID:　UMIN000035901retrospectively registered 1 March 2018.

Metabolic syndrome severity and lifestyle factors among adolescents

The continued rise of pediatric obesity globally has raised concerns for related sequalae. One marker of risk is the metabolic syndrome, a cluster of cardiovascular risk factors that is associated with future cardiovascular disease and type 2 diabetes. MetS has at its core visceral adipocytes exhibiting dysfunction as a result of excess fat content. MetS in children and adolescents is linked to unhealthy lifestyle practices such as sedentary lifestyles and excess consumption calories. As such, the optimal means of addressing MetS is targeting a decrease in adiposity through lifestyle modification, a decrease in MetS following increases in physical activity and improvements in the quality and content of food intake. Efforts remain needed in increasing motivation to these changes and maintaining adherence to avoid long-term sequelae.

Longitudinal Associations of Metabolic Syndrome Severity Between Childhood and Young Adulthood: The Bogalusa Heart Study

BACKGROUND

Childhood metabolic syndrome (MetS) is associated with insulin resistance and increased risk for later development of type 2 diabetes (T2DM) and cardiovascular disease (CVD). In using MetS severity z-scores, our objective was to assess longitudinal associations in MetS severity, fasting insulin levels as a sign of insulin resistance and risk for T2DM, and uric acid levels as a biomarker of oxidative stress leading to CVD.

METHODS

We used linear regression to analyze longitudinal data from 285 white and black participants from the Bogalusa Heart Study evaluated at baseline at ages 5-19 and as young adults after a mean of 12.0 years follow-up. We assessed correlations between childhood MetS severity and young-adult MetS severity, fasting insulin, and uric acid levels, both overall and by sex- and racial subgroups.

RESULTS

Overall, childhood MetS z-scores were positively associated with young-adult MetS z-scores (r = 0.52), insulin (r = 0.34), and uric acid (r = 0.28) (all P < 0.001). These associations were consistent across all sex- and racial subgroups, except for young adult uric acid in white males in which childhood MetS-z was not associated (r = 0.15, P = 0.243). There was a strong cross-sectional association of young-adult MetS z-scores with insulin (r = 0.70) and uric acid (r = 0.57) (both P < 0.001), which was consistent for all sex- and racial subgroups.

CONCLUSIONS

These positive longitudinal correlations between childhood MetS z-scores and markers of later insulin resistance and oxidative stress suggest long-term durability of risk for CVD and T2DM. This suggests potential for MetS severity to serve as an indicator to monitor for future risk of T2DM and CVD.

Use of BMI as the marker of adiposity in a metabolic syndrome severity score: Derivation and validation in predicting long-term disease outcomes

BACKGROUND

Estimates of adiposity in evaluating the metabolic syndrome (MetS) have traditionally utilized measures of waist circumference (WC), whereas body mass index (BMI) is more commonly used clinically. Our objective was to determine if a MetS severity Z-score employing BMI as its measure of adiposity (MetS-Z-BMI) would perform similarly to a WC-based score (MetS-Z-WC) in predicting future disease.

METHODS

To formulate the MetS-Z-BMI, we performed confirmatory factor analysis on a sex- and race/ethnicity-specific basis on MetS-related data for 6870 adult participants of the National Health and Nutrition Survey 1999-2010. We then validated this score and compared it to MetS-Z-WC in assessing correlations with future coronary heart disease (CHD) and Type 2 diabetes mellitus (T2DM) using Cox proportional hazard analysis of 13,094 participants of the Atherosclerosis Risk in Communities study and Jackson Heart Study.

RESULTS

Loading factors, which represent the relative contribution of each component to the latent MetS factor, were lower for BMI than for WC in formulating the two respective scores (MetS-Z-BMI and MetS-Z-WC). Nevertheless, MetS-Z-BMI and MetS-Z-WC exhibited similar hazard ratios (HR) toward future disease. For each one standard-deviation-unit increase in MetS-Z-BMI, HR for CHD was 1.76 (95% confidence interval [CI]: 1.65, 1.88) and HR for T2DM was 3.39 (CI 3.16, 3.63) (both p < 0.0001). There were no meaningful differences between the MetS-Z-WC and MetS-Z-BMI scores in their associations with future CHD and T2DM.

CONCLUSIONS

A MetS severity Z-score utilizing BMI as its measure of adiposity operated similarly to a WC-based score in predicting future CHD and T2DM, suggesting overall similarity in MetS-based risk as estimated by both measures of adiposity. This indicates potential clinical usefulness of MetS-Z-BMI in assessing and following MetS-related risk over time.

Physiology of Hyperuricemia and Urate-Lowering Treatments

Gout is the most common form of inflammatory arthritis and is a multifactorial disease typically characterized by hyperuricemia and monosodium urate crystal deposition predominantly in, but not limited to, the joints and the urinary tract. The prevalence of gout and hyperuricemia has increased in developed countries over the past two decades and research into the area has become progressively more active. We review the current field of knowledge with emphasis on active areas of hyperuricemia research including the underlying physiology, genetics and epidemiology, with a focus on studies which suggest association of hyperuricemia with common comorbidities including cardiovascular disease, renal insufficiency, metabolic syndrome and diabetes. Finally, we discuss current therapies and emerging drug discovery efforts aimed at delivering an optimized clinical treatment strategy.

Geographical variation in the prevalence of obesity, metabolic syndrome, and diabetes among US adults

Cardiovascular disease (CVD) and type 2 diabetes remain significant public health concerns. Targeting of prevention efforts by geographical location has been suggested by the Institute of Medicine to coincide with the presence of area-based risk. The metabolic syndrome (MetS) is a stronger risk factor than is obesity for the prediction of future CVD and diabetes, yet its prevalence has not previously been described geographically. Our objective is to determine geographical variation in the prevalence of obesity, MetS, and diabetes among US adults. We assessed the prevalence of obesity, MetS, and diabetes by US census division, and the prevalence of obesity, MetS, and diabetes for each sex and racial/ethnic group by US region among 9826 US non-Hispanic white, non-Hispanic black, and Hispanic adults aged 20–65 years participating in the National Health and Nutrition Examination Survey 1999–2014. We also compared a sex- and race/ethnicity-specific MetS severity score by geographical area. The prevalence of obesity, MetS, and diabetes varied by US census division and region, with overall similarity by geographical area in the prevalence of each of these conditions. The prevalence of MetS was particularly high (≥35%) in the West North Central, West South Central, and East South Central and low (30%) in the Pacific, New England, and Mid-Atlantic divisions. Some of the geographical variation appeared due to differences among non-Hispanic white females, who had a high prevalence of MetS (>32%) in the Midwest and South and a low prevalence of MetS (24%) in the West and Northeast. Geographical differences in MetS imply variation in the risk for future CVD and diabetes, with more elevated risk in the center of the United States. As MetS is a stronger risk factor for prediction of CVD and T2DM than is obesity, these differences are potentially important for prompting public health efforts toward surveillance and prevention in high-risk areas.

Correlation of metabolic syndrome severity with cardiovascular health markers in adolescents

BACKGROUND AND OBJECTIVES

The presence of metabolic syndrome (MetS) in childhood is a significant risk factor for later cardiovascular disease (CVD). Recent data showed temporal decreases in a sex- and race/ethnicity-specific MetS severity z-score among U.S. adolescents. Our goal was to characterize the relationship of this MetS z-score with other CVD risk indicators and assess their temporal trends and lifestyle influences.

METHODS

We analyzed 4837 participants aged 12-20years from the National Health and Nutrition Examination Survey by 2-year waves from 1999 to 2012. We used linear regression to compare MetS z-score and dietary factors with serum levels of low-density lipoprotein (LDL), apolipoprotein-B (ApoB), high-sensitivity C-reactive protein (hsCRP) and uric acid.

RESULTS

MetS severity z-score was positively correlated with LDL, ApoB, hsCRP, and uric acid measurements (p<0.0001 for all). These correlations held true among individual racial/ethnic groups. LDL, ApoB, and hsCRP measurements decreased over time among U.S. adolescents (p=0.002, p<0.0001, and p=0.024, respectively). Saturated fat consumption was positively correlated with LDL (p=0.005) and ApoB (p=0.012) and inversely related to serum uric acid (p=0.001). Total caloric intake was inversely related to LDL (p=0.003) and serum uric acid (p=0.003). Unsaturated fat, carbohydrate, and protein consumption were not related to LDL, ApoB, hsCRP, or serum uric acid.

CONCLUSIONS

There is a positive correlation between MetS severity and all four CVD risk indicators studied. LDL, ApoB, and hsCRP showed favorable temporal trends, which could be related to similar trends in MetS z-score. These data support the importance of considering multiple inter-related factors in clinical CVD risk assessment.

Clinical utility of metabolic syndrome severity scores: considerations for practitioners

The metabolic syndrome (MetS) is marked by abnormalities in central obesity, high blood pressure, high triglycerides, low high-density lipoprotein-cholesterol, and high fasting glucose and appears to be produced by underlying processes of inflammation, oxidative stress, and adipocyte dysfunction. MetS has traditionally been classified based on dichotomous criteria that deny that MetS-related risk likely exists as a spectrum. Continuous MetS scores provide a way to track MetS-related risk over time. We generated MetS severity scores that are sex- and race/ethnicity-specific, acknowledging that the way MetS is manifested may be different by sex and racial/ethnic subgroup. These scores are correlated with long-term risk for type 2 diabetes mellitus and cardiovascular disease. Clinical use of scores like these provide a potential opportunity to identify patients at highest risk, motivate patients toward lifestyle change, and follow treatment progress over time.

Progression of Metabolic Syndrome Severity During the Menopausal Transition

Background

After menopause, women exhibit a higher prevalence of the metabolic syndrome (MetS) and higher risk of cardiovascular disease. However, the timing of changes in MetS severity over the menopausal transition and whether these changes differ by racial/ethnic group remain unclear.

Methods and Results

We assessed data from 1470 women from the Atherosclerosis Risk in Communities cohort who experienced transition in menopausal status over 10 years (visits 1–4). We used linear mixed models to evaluate changes by menopausal status (premenopause, perimenopause, and postmenopause) in a MetS severity Z‐score and in the individual MetS components. While there were gradual increases in MetS severity over time across menopause stages, black women in particular exhibited more rapid progression in MetS severity during the premenopausal and perimenopausal periods than during the postmenopausal period. In the postmenopausal period (compared with prior periods), white women exhibited unfavorable decreases in high‐density lipoprotein, while black women exhibited favorable alterations in the rate of change for waist circumference, triglycerides, high‐density lipoprotein, and glucose, contributing to the slowed progression of MetS severity. These changes were all observed after adjusting for hormone replacement treatment.

Conclusions

During menopausal transition, women exhibited rapid increases in MetS severity during the premenopausal and perimenopausal periods, with black women having significant reductions in this increase in severity during the postmenopausal period. These data suggest that the higher prevalence of MetS in postmenopausal women may be caused more by changes during the menopausal transition than by postmenopause. These findings may thus have implications regarding the timing of cardiovascular risk relative to menopause.

Trends in Metabolic Syndrome Severity and Lifestyle Factors Among Adolescents

BACKGROUND AND OBJECTIVES

Childhood metabolic syndrome (MetS) is a risk factor for adverse outcomes later in life. Our goal was to identify temporal trends among US adolescents in the severity of MetS, its individual components, and factors related to diet and physical activity.

METHODS

We analyzed 5117 participants aged 12 to 19 from NHANES. We used regression analysis of individual waves of data, 1999 to 2012. MetS severity was calculated using a gender- and race/ethnicity-specific MetS severity z score.

RESULTS

There was a linear trend of decreasing MetS severity in US adolescents from 1999 to 2012 (P = .030). This occurred despite a trend of increasing BMI z score (P = .005); instead, the decrease in MetS severity appeared to be due to trends in increasing high-density lipoprotein (HDL; P < .0001) and decreasing triglyceride (P = .0001) levels. In considering lifestyle factors, there was no change in physical activity over the time period. Regarding dietary patterns, total calorie consumption and carbohydrate consumption were positively associated with triglyceride levels and negatively associated with HDL levels, whereas unsaturated fat consumption exhibited the opposite associations. Consistent with these associations, there was a trend of decreasing total calorie consumption (P < .0001), decreasing carbohydrate consumption (P < .0001), and increasing unsaturated fat consumption (P = .002).

CONCLUSIONS

The healthier trend of declining MetS severity in adolescents appeared to be due to favorable increases in HDL and decreases in fasting triglyceride measurements. These were in turn associated with favorable changes in dietary patterns among US adolescents. Future studies should investigate the causality of dietary differences on changes in MetS severity in adolescents.

Uric Acid-Induced Inflammation Is Mediated by the Parathyroid Hormone:25-Hydroxyvitamin D Ratio in Obese Adolescents

BACKGROUND

Elevated serum uric acid (SUA) level is strongly associated with prevalence of metabolic syndrome (MS), elevated parathyroid hormone (PTH) levels, and 25-hydroxyvitamin D [25(OH)D] insufficiency in adults. We examined the relationship among SUA, [25(OH)D], PTH, and inflammation in obese adolescents, in obese adolescents with and without MS.

METHODS

Body mass index, body composition, 25(OH)D, PTH, fasting lipids, glucose, high-sensitivity C-reactive protein (hs-CRP), SUA, hemoglobin A1c (HbA1c), insulin, and the homeostatic model assessment of insulin resistance (HOMA-IR) were evaluated in 152 obese adolescents.

RESULTS

Hyperuricemia [SUA ≥ 6.0 mg/dL (357 μM)] was present in 54.6% of entire cohort without significant ethnic/racial differences. While SUA was negatively correlated with high-density lipoprotein cholesterol (HDL-C) and 25(OH)D (P < 0.01), it was positively correlated with fat mass (FM), PTH, PTH:25(OH)D, and hs-CRP (P < 0.01). Vitamin D deficiency [25(OH)D <50 nM] was present in 47.4% of subjects, and PTH and 25(OH)D were inversely correlated (P < 0.0001). FM was negatively correlated with 25(OH)D (r = -0.29; P < 0.001), but was positively correlated with PTH (P < 0.0001). MS was identified in 53.3% of cohort with higher FM, SUA, hs-CRP, HOMA-IR, PTH, and PTH:25(OH)D ratio than the non-MS subgroup (P < 0.001) with similar 25(OH)D status. Multiple regression analysis showed that the PTH:25(OH)D ratio mediated the relationship between SUA and hs-CRP (β = 0.19, P < 0.05 to β = 0.15, P = 0.19).

CONCLUSIONS

Hyperuricemia is strongly associated with PTH and hs-CRP levels independent of vitamin D status. The relationship between SUA and low-grade inflammation is mediated by the PTH:25(OH)D ratio in obese adolescents.

Severity of the metabolic syndrome as a predictor of type 2 diabetes between childhood and adulthood: the Princeton Lipid Research Cohort Study

AIMS/HYPOTHESIS

The aim of this study was to determine the long-term associations of a sex- and race/ethnicity-specific metabolic syndrome (MetS) severity z score from childhood and adulthood with a future diagnosis of type 2 diabetes mellitus.

METHODS

We performed a prospective cohort study with evaluations from the Cincinnati Clinic of the National Heart Lung and Blood Institute Lipids Research Clinic (LRC) 1973-1976 and Princeton Follow-up Study (PFS) 1998-2003, and further disease status from the Princeton Health Update (PHU) 2010-2014. We assessed MetS severity as a predictor of incident type 2 diabetes among 629 cohort participants assessed at both the LRC and PFS and 354 participants at the PHU.

RESULTS

Cohort participants had a mean age of 12.9 years at baseline (LRC), 38.4 years at the PFS and 49.6 years at the most recent follow-up. Childhood MetS z scores were associated with adult MetS z scores (p < 0.01). Compared with individuals who were disease-free at all time-points, those who developed type 2 diabetes by 1998-2003 and 2010-2014 had higher MetS severity z scores in childhood (p < 0.05). For every one-unit elevation in childhood MetS z score, the OR of developing future type 2 diabetes was 2.7 for incident disease by a mean age of 38.5 years (p < 0.01) and 2.8 for incident disease by a mean age of 49.6 years (p < 0.05). Regarding associations with the change in z score from childhood to adulthood, for every one-unit increase in MetS z score over time the OR of developing incident type 2 diabetes by a mean age of 49.6 years was 7.3 (p < 0.01).

CONCLUSIONS/INTERPRETATION

The severity of MetS in childhood was associated with the incidence of adult type 2 diabetes and the degree of increase in this severity predicted future disease. These findings provide evidence of potential clinical utility in assessing MetS severity to detect risk and follow clinical progress over time.

The severity of the metabolic syndrome increases over time within individuals, independent of baseline metabolic syndrome status and medication use: The Atherosclerosis Risk in Communities Study

BACKGROUND AND AIMS

The severity of the metabolic syndrome (MetS) is linked to future cardiovascular disease. However, it is unclear whether MetS severity increases among individuals followed over time.

METHODS

We assessed changes in a sex- and race/ethnicity-specific MetS severity Z-score over a 10-year period (visits 1-4) among 9291 participants of the Atherosclerosis Risk in Communities study cohort. We compared sex- and racial/ethnic subgroups for the rate of change in the MetS severity score and MetS prevalence as assessed using traditional ATP-III MetS criteria. We further examined effects of use of medications for hypertension, diabetes and dyslipidemia.

RESULTS

Over the 10 years of follow-up, MetS severity Z-scores increased in 76% of participants from an overall mean of 0.08 ± 0.77 at baseline to 0.48 ± 0.96 at visit 4 with the greatest progression in scores observed among African-American women. Baseline MetS severity scores predicted the time until ATP-III MetS diagnosis, with a model-predicted 77.5% of individuals with a visit 1 MetS severity score of 0.75 progressing to ATP-III MetS within 10 years. The rate of increase in MetS severity score was higher among those younger at baseline but was independent of baseline MetS status or the use of medications to treat blood pressure, lipids and diabetes.

CONCLUSION

The severity of metabolic derangements as measured using this MetS severity score increases over time within individuals and predicts diagnosis of ATP-III MetS. These data may have implications for tracking MetS related risk within individuals over time.

[Hyperuricaemia and metabolic syndrome in obese children and adolescents]

INTRODUCTION

Hyperuricaemia has been suggested as an additional metabolic factor in adult obese patients, but it has not been sufficiently studied in paediatric.

OBJECTIVES

To assess the relationship between serum uric acid levels (SUAL) with the level of general and visceral obesity, and other biochemical parameters in children and adolescents of Santiago, Chile.

SUBJECTS AND METHOD

A cross sectional study was conducted on 770 children and adolescents (ages: 6-15 y.) from a public school in Santiago, Chile, of whom 227 (29%) were obese (BMI>2 SD, WHO growth standards). Ninety subjects were randomly selected and 77 with no other chronic disease (41 males) accepted to participate. Data was collected on weight, stature, abdominal circumference (AC), visceral adiposity using ultrasound, and other biochemical measurements including fasting glucose, insulin, serum lipids, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and SUAL.

RESULTS

The mean SUAL was 0.200±0.065 mmol/L, and was increased in children with hyperinsulinism (adjusted by age: 0.221±0.075 vs. 0.183±0.054 mmol/L; P<.01), with no significant differences according to HOMA. Differences were also found between children with ALT>or<26 U/mL: 0.238±0.070 vs. 0.178±0.054 mmol/L, P<.001. The logistic regression showed the increased SUAL was only associated with increased ALT. No significant differences were found in general or visceral adiposity measurements or fatty liver.

CONCLUSIONS

Children and adolescents from Santiago, Chile have higher uric acid serum uric acid levels as well as an association with increased ALT and insulin. It is demonstrated in this study that uric acid should be measured in obese children and adolescents, and in their follow up.

Low sensitivity of the metabolic syndrome to identify adolescents with impaired glucose tolerance: an analysis of NHANES 1999-2010

BACKGROUND

The presence of impaired glucose tolerance (IGT) and metabolic syndrome (MetS) are two risk factors for Type 2 diabetes. The inter-relatedness of these factors among adolescents is unclear.

METHODS

We evaluated the sensitivity and specificity of MetS for identifying IGT in an unselected group of adolescents undergoing oral glucose tolerance tests (OGTT) in the National Health and Nutrition Evaluation Survey 1999-2010. We characterized IGT as a 2-hour glucose ≥140 mg/dL and MetS using ATP-III-based criteria and a continuous sex- and race/ethnicity-specific MetS Z-score at cut-offs of +1.0 and +0.75 standard deviations (SD) above the mean.

RESULTS

Among 1513 adolescents, IGT was present in 4.8%, while ATP-III-MetS was present in 7.9%. MetS performed poorly in identifying adolescents with IGT with a sensitivity/specificity of 23.7%/92.9% for ATP-III-MetS, 23.6%/90.8% for the MetS Z-score at +1.0 SD and 35.8%/85.0 for the MetS Z-score at +0.75 SD. Sensitivity was higher (and specificity lower) but was still overall poor among overweight/obese adolescents: 44.7%/83.0% for ATP-III-MetS, 43.1%/77.1% for the MetS Z-score at +1.0 SD and 64.3%/64.3% for MetS Z-score at +0.75 SD.

CONCLUSION

This lack of overlap between MetS and IGT may indicate that assessment of MetS is not likely to be a good indicator of which adolescents to screen using OGTT. These data further underscore the importance of other potential contributors to IGT, including Type 1 diabetes and genetic causes of poor beta-cell function. Practitioners should keep these potential causes of IGT in mind, even when evaluating obese adolescents with IGT.

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.

Ethnic differences in the link between insulin resistance and elevated ALT

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) exhibits tight links with insulin resistance (IR) and the metabolic syndrome (MetS), a cluster of cardiovascular risk factors. Compared with non-Hispanic whites, non-Hispanic black adolescents have more IR but a lower prevalence of NAFLD and MetS. Our hypothesis was that IR would be a better predictor of alanine aminotransferase (ALT) elevations than is MetS among non-Hispanic blacks.

METHODS

We analyzed data from 4124 adolescents aged 12 to 19 years in the 1999 to 2010 NHANES, using unexplained elevations in ALT (>30 U/L) to characterize presumed NAFLD and using a pediatric adaptation of the Adult Treatment Panel III definition of MetS.

RESULTS

Prevalence of elevated ALT varied by race/ethnicity (Hispanics 13.7%, non-Hispanic white 8.6%, non-Hispanic blacks 5.4%, P < .0001). Among non-Hispanic whites and Hispanics, a classification of MetS performed well in identifying adolescents with elevated ALT (odds ratios [ORs] 9.53 and 5.56, respectively), as did MetS-related indices. However, among non-Hispanic blacks, the association between MetS and ALT elevations was smaller in magnitude and technically nonsignificant (OR = 3.24, P = .051). Furthermore, among non-Hispanic blacks, the presence of IR and elevated waist circumference performed more poorly at identifying ALT elevations (ORs 3.93 and 2.28, respectively: significantly smaller than ORs for non-Hispanic whites, P < .05), with triglyceride elevations being a better predictor (OR = 4.44).

CONCLUSIONS

Non-Hispanic black adolescents exhibit a lower relationship between IR and elevated ALT, supporting racial/ethnic differences in the link between MetS and NAFLD. These data may have implications regarding triggers for screening for NAFLD among non-Hispanic black adolescents, focusing particularly on those with triglyceride elevations.

Positive association between perfluoroalkyl chemicals and hyperuricemia in children

Hyperuricemia in children is associated with increased risk of high blood pressure, metabolic syndrome, and future cardiovascular disease. Serum perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) levels have been shown to be positively associated with hyperuricemia in adults, but the association in children remains unexplored. We therefore examined the association between serum PFOA and PFOS levels and hyperuricemia in a representative sample of US children. A cross-sectional study was performed on 1,772 participants ≤18 years of age from the National Health and Nutrition Examination Survey 1999-2000 and 2003-2008. The main outcome of interest was hyperuricemia, defined as serum uric acid levels ≥6 mg/dL. We found that serum levels of PFOA and PFOS were positively associated with hyperuricemia, independent of age, sex, race/ethnicity, body mass index, annual household income, physical activity, serum total cholesterol, and serum cotinine levels. Compared with subjects in quartile 1 (referent), subjects in quartile 4 had multivariable-adjusted odds ratios for hyperuricemia of 1.62 (95% confidence interval: 1.10, 2.37) for PFOA and 1.65 (95% confidence interval: 1.10, 2.49) for PFOS. Our findings indicate that serum perfluoroalkyl chemical levels are significantly associated with hyperuricemia in children even at the lower "background" exposure levels of the US general population.

Relationship between uric acid and vascular structure and function in hypertensive patients and sex-related differences

BACKGROUND

We sought to analyze the relationship between uric acid (UA) and vascular structure and function based on the carotid intima-media thickness, the pulse-wave velocity (PWV), the central arterial pressure, and the augmentation index in hypertensive patients and to evaluate the sex-related differences.

METHODS

A cross-sectional study was performed with 366 hypertensive individuals aged 34-75 years (men = 61.74%). The vascular structure was assessed based on the carotid intima-media thickness, the arterial stiffness was assessed by PWV, and the vascular function was assessed using hemodynamic parameters such as the central and peripheral augmentation index and the ambulatory arterial stiffness index (AASI).

RESULTS

In the bivariable analysis, the PWV (r = 0.28; P < 0.01) and AASI (r = 0.25; P < 0.01) were positively correlated with UA in women. The central augmentation index (r = -0.16; P < 0.05) and peripheral augmentation index (r = -0.18; P < 0.05) were negatively correlated with UA, whereas the maximum carotid intima-media thickness (r = 0.11; P < 0.05) was positively correlated with UA in the global analysis. In the multiple linear regression analysis, a positive association between PWV and UA was observed after adjusting for classical risk factors (β = 0.27; P = 0.01) in women only. In turn, a negative association was observed between the AASI and UA after adjusting for confounders in men (β = -0.06; P = 0.04), with a positive association in women (β = 0.11; P = 0.03).

CONCLUSIONS

Serum UA showed a positive correlation with the mean maximum intima-media thickness and PWV, and this parameter showed a negative correlation with the central and peripheral augmentation indices, although this relationship was lost after adjusting for confounding factors. AASI showed a positive association in women and a negative association in men after adjusting for confounding factors.

CLINICAL TRIALS REGISTRATION

Clinical Trials.gov Identifier: NCT01325064.

Obesity, systemic inflammation, and increased risk for cardiovascular disease and diabetes among adolescents: a need for screening tools to target interventions

Cardiovascular disease (CVD) and type 2 diabetes mellitus have their roots in childhood, particularly in obese children and adolescents, raising important opportunities for early lifestyle intervention in at-risk individuals. However, not all obese individuals are at the same risk for disease progression. Accurate screening of obese adolescents may identify those in greatest need for intensive intervention to prevent or delay future disease. One potential screening target is obesity-related inflammation, which contributes to insulin resistance, metabolic syndrome, and CVD. In adults, the inflammatory marker high-sensitivity C-reactive protein (hsCRP) has utility for risk stratification and treatment initiation in individuals of intermediate CVD risk. In adolescents, hsCRP shares many of the associations of hsCRP in adults regarding the degree of insulin resistance, metabolic syndrome, and carotid artery media thickness. However, long-term data linking increased hsCRP levels-and increased insulin or decreased adiponectin-in childhood to adult disease outcomes are lacking at this time. Future efforts continue to be needed to identify childhood clinical and laboratory characteristics that could be used as screening tests to predict adult disease progression. Such tests may have utility in motivating physicians and patients' families toward lifestyle changes, ultimately improving prevention efforts.

A confirmatory factor analysis of the metabolic syndrome in adolescents: an examination of sex and racial/ethnic differences

Objective

The metabolic syndrome (MetS) is a cluster of clinical indices that signals increased risk for cardiovascular disease and Type 2 diabetes. The diagnosis of MetS is typically based on cut-off points for various components, e.g. waist circumference and blood pressure. Because current MetS criteria result in racial/ethnic discrepancies, our goal was to use confirmatory factor analysis to delineate differential contributions to MetS by sub-group.

Research Design and Methods

Using 1999–2010 data from the National Health and Nutrition Examination Survey (NHANES), we performed a confirmatory factor analysis of a single MetS factor that allowed differential loadings across sex and race/ethnicity, resulting in a continuous MetS risk score that is sex and race/ethnicity-specific.

Results

Loadings to the MetS score differed by racial/ethnic and gender subgroup with respect to triglycerides and HDL-cholesterol. ROC-curve analysis revealed high area-under-the-curve concordance with MetS by traditional criteria (0.96), and with elevations in MetS-associated risk markers, including high-sensitivity C-reactive protein (0.71), uric acid (0.75) and fasting insulin (0.82). Using a cut off for this score derived from ROC-curve analysis, the MetS risk score exhibited increased sensitivity for predicting elevations in ≥2 of these risk markers as compared with traditional pediatric MetS criteria.

Conclusions

The equations from this sex- and race/ethnicity-specific analysis provide a clinically-accessible and interpretable continuous measure of MetS that can be used to identify children at higher risk for developing adult diseases related to MetS, who could then be targeted for intervention. These equations also provide a powerful new outcome for use in childhood obesity and MetS research.