Factor analysis of the metabolic syndrome among elderly Koreans--the South-west Seoul Study

Factor analysis for the clustering of cardiometabolic risk factors and sedentary behavior, a cross-sectional study

Background

Few studies have reported on the clustering pattern of CVD risk factors, including sedentary behavior, systemic inflammation, and cadiometabolic components in the general population.

Objective

We aimed to explore the clustering pattern of CVD risk factors using exploratory factor analysis to investigate the underlying relationships between various CVD risk factors.

Methods

A total of 5606 subjects (3157 male, 51.5±11.7 y/o) were enrolled, and 14 cardiovascular risk factors were analyzed in an exploratory group (n = 3926) and a validation group (n = 1676), including sedentary behaviors.

Results

Five factor clusters were identified to explain 69.4% of the total variance, including adiposity (BMI, TG, HDL, UA, and HsCRP; 21.3%), lipids (total cholesterol and LDL-cholesterol; 14.0%), blood pressure (SBP and DBP; 13.3%), glucose (HbA1C, fasting glucose; 12.9%), and sedentary behavior (MET and sitting time; 8.0%). The inflammation biomarker HsCRP was clustered with only adiposity factors and not with other cardiometabolic risk factors, and the clustering pattern was verified in the validation group.

Conclusion

This study confirmed the clustering structure of cardiometabolic risk factors in the general population, including sedentary behavior. HsCRP was clustered with adiposity factors, while physical inactivity and sedentary behavior were clustered with each other.

Factor analyses of metabolic syndrome: A systematic review with special reference to Asian Indians

BACKGROUND

Metabolic syndrome is the constellation of cardiovascular disease risk factors and a growing public health issue affecting more than 20% of world population. Factor analysis is a powerful mathematical tool in exploring the underlying factors of any chronic diseases. Although it is most often criticized for its contrasting results for a common expression differently interpreted by the researchers yet fit the original data equally well.

OBJECTIVE

The present study aims to find out the underlying physiological domains for the phenotypic attribution of metabolic syndrome as documented in several studies.

METHODOLOGY

Literature search was done using Google Scholar, PUBMED, Research Gate and manual searching to identify relevant studies of the selected topic.

CONCLUSION

More than one physiological domain has been explored for the expression of metabolic syndrome explored in different studies. A reason for this disparity may be because most of explored factors are just mathematically significant but not biologically. Another reason may be the varied factor load concern. Therefore, a fixed factor load value is needed to be restricted for all studies across world.

Comparison of Competitive Models of Metabolic Syndrome Using Structural Equation Modeling: A Confirmatory Factor Analysis

BACKGROUND

The purpose of this study was to apply the structural equation modeling (SEM) to compare the fitness of different competing models (one, two, and three factors) of the metabolic syndrome (MetS) in Iranian adult population.

METHODS

Data are given on the cardiometabolic risk factors of 841 individuals with nondiabetic adults from a cross-sectional population-based study of glucose, lipids, and MetS in the north of Iran. The three conceptual hypothesized models (single factor, two correlated factors, and three correlated latent factors) were evaluated by using confirmatory factor analysis with the SEM approach. The summary statistics of correlation coefficients and the model summary fitting indexes were calculated.

RESULTS

The findings show that a single-factor model and a two-correlated factor model had a poorer summary fitting index compared with a three-correlated factor model. All fitting criteria met the conceptual hypothesized three-correlated factor model for both sexes. However, the correlation structure between the three underlying constructs designating the MetS was higher in women than in men.

CONCLUSION

These results indicate the plausibility of the pathophysiology and etiology of MetS being multifactorial, rather than a single factor, in a nondiabetic Iranian adult population.

Factor Analysis of Metabolic Syndrome Components in an Iranian Non-Diabetic Adult Population: A Population-Based Study from the North of Iran

OBJECTIVES

The aim of this study was to explore the underlying latent factors that can explain the observed variation of components of metabolic syndrome (MetS) in Iranian non-diabetic adult population.

METHODS

The researchers performed an exploratory factor analysis (EFA) of metabolic syndrome components, including body mass index (BMI), waist circumference (WC), systolic (SBP) and diastolic blood pressure (DBP), triglyceride (TG), high density lipoprotein (HDL), and Fasting blood sugar (FBS). These observed variables were measured from a representative sample of 841 non-diabetic participants in a cross-sectional population-based study of adults aged 20 to 70 years in the North of Iran.

RESULTS

Three factors were extracted by EFA in both genders. In males, the 3 generated factors were, 1) blood pressure factor underlying systolic and diastolic blood pressure, 2) obesity factor manifested by BMI and WC, 3) lipid/glucose factor underlying TG, HDL and FBS that explained 23.9%, 23.0% and 18.4% of variance in the observed data, respectively, in males. However, in females, BMI and WC were revealed as obesity factors, and systolic and diastolic blood pressure were characterized as hypertension factor, and TG, HDL and FBS appeared to be loaded on lipid/glucose factor, similar to males, and designated 25.6%, 25.4%, and 15.8% of the variance, respectively. Triglyceride and FBS were positively loaded, whereas HDL was loaded negatively with similar loading pattern in both genders. Overall, these 3 underlying latent factors explained 65.3% of the variance of observed clinical data sets in males and 66.8% in females. When TG and HDL were replaced by TG to HDL ratio and also SBP and DBP by mean arterial pressure (MAP), the two-factor model was generated in both genders.

CONCLUSIONS

The 2-and 3-factor models were characterized indicating a single pathogenesis that could not explain the unified clustering of MetS in non-diabetic adults.

Associations of Low Muscle Mass and the Metabolic Syndrome in Caucasian and Asian Middle-aged and Older Adults

OBJECTIVE

Age-related declines in skeletal muscle mass may confer significant metabolic consequences for older adults. Associations of low muscle mass and metabolic syndrome (MetS) in Caucasians, and comparisons with associations observed in Asian populations, have not been reported. We examined associations of low muscle mass and metabolic syndrome (MetS) in Asian and Caucasian middle-aged and older men and women using criteria for low muscle mass.

DESIGN, SETTING AND PARTICIPANTS

Two population-based studies of Australian (Tasmanian Older Adult Cohort Study; TASOAC; N=1005) and Korean (Korean Sarcopenic Obesity Study; KSOS; N=376) community-dwelling adults, mean age 62 and 58 years, respectively.

MEASUREMENTS

Appendicular lean mass (aLM) determined by dual-energy X-ray absorptiometry and normalised to height squared (aLM/Ht2), weight (aLM/Wt) or body mass index (aLM/BMI). Participants in the lowest sex-specific 20% for aLM measures were defined as having low muscle mass. MetS was defined according to National Cholesterol Education Program Adult Treatment Panel III criteria.

RESULTS

Although Australians demonstrated generally unfavourable anthropometric and metabolic characteristics compared to Koreans, prevalence of MetS was similar (29.5% in Australians and 31.4% in Koreans, respectively). Low aLM/Ht2 was associated with significantly reduced likelihood of MetS in both Australians (OR: 0.30, 95% CI 0.19 - 0.46) and Koreans (OR: 0.31, 95% CI 0.16 - 0.62). Conversely, low aLM/BMI was associated with increased odds for MetS in Australians (OR: 1.78, 95% CI 1.12 - 2.84), but not Koreans (OR: 1.33, 95% CI = 0.67 - 2.64).

CONCLUSION

Low aLM/BMI is associated with significantly increased likelihood of MetS in Australian adults, but not Koreans, suggesting potential differences in effects of low muscle mass relative to body mass on cardiometabolic health in Caucasian and Asian middle-aged and older adults. Low muscle mass relative to height is associated with reduced likelihood of MetS in both populations.

Predictive Mortality Index for Community-Dwelling Elderly Koreans

There are very few predictive indexes for long-term mortality among community-dwelling elderly Asian individuals, despite its importance, given the rapid and continuous increase in this population. We aimed to develop 10-year predictive mortality indexes for community-dwelling elderly Korean men and women based on routinely collected clinical data.We used data from 2244 elderly individuals (older than 60 years of age) from the southwest Seoul Study, a prospective cohort study, for the development of a prognostic index. An independent longitudinal cohort of 679 elderly participants was selected from the Korean Genome Epidemiology Study in Ansan City for validation.During a 10-year follow-up, 393 participants (17.5%) from the development cohort died. Nine risk factors were identified and weighed in the Cox proportional regression model to create a point scoring system: age, male sex, smoking, diabetes, systolic blood pressure, triglyceride, total cholesterol, white blood cell count, and hemoglobin. In the development cohort, the 10-year mortality risk was 6.6%, 14.8%, 18.2%, and 38.4% among subjects with 1 to 4, 5 to 7, 8 to 9, and ≥10 points, respectively. In the validation cohort, the 10-year mortality risk was 5.2%, 12.0%, 16.0%, and 16.0% according to these categories. The C-statistic for the point system was 0.73 and 0.67 in the development and validation cohorts, respectively.The present study provides valuable information for prognosis among elderly Koreans and may guide individualized approaches for appropriate care in a rapidly aging society.

Factor analysis of metabolic syndrome components and predicting type 2 diabetes: Results of 10-year follow-up in a Middle Eastern population

BACKGROUND

The relationship among components of metabolic syndrome (MetS) and their association with diabetes is unclear in West Asia. The aim of the present study was to conduct factor analysis of MetS components and the effect these factors have on the incidence of type 2 diabetes (T2D) in a population-based cohort study of the Tehran Lipid and Glucose Study (TLGS).

METHODS

The present study enrolled 1861 men and 2706 women (20-60 years of age), from Tehran (Iran) who were free of diabetes at baseline and followed them for 10 years. A principal component analysis was performed to extract standardized factors from MetS components. Logistic regression was used to detect associations between the extracted factors and the incidence of diabetes. A propensity score was used to correct differential selection bias resulting from loss to follow-up.

RESULTS

Factor analysis identified three factors (blood pressure, lipids and glycemia). Waist circumference was shared in three all factors. Blood pressure, lipids and glycemia were related to the incidence of diabetes with odds ratios (95% confidence intervals) of 2.23 (1.31-3.78), 1.89 (1.27-3.67), and 7.54 (4.09-13.91), respectively, in men and 2.13 (1.34-3.40), 2.06 (1.35-3.15), and 13.91 (7.29-26.51), respectively, in women for the third versus the first tertile of these standardized factors.

CONCLUSIONS

Central adiposity may have a pivotal role in MetS linking other risk factors together. Glycemia had a high impact on the incidence of diabetes, whereas blood pressure and lipid had a similar moderate effect on the incidence of diabetes.

Elevated serum ferritin and mercury concentrations are associated with hypertension; analysis of the fourth and fifth Korea national health and nutrition examination survey (KNHANES IV-2, 3, 2008-2009 and V-1, 2010)

The impact of simultaneously elevated serum ferritin and mercury concentrations on hypertension in the general population is not known. To determine the association of serum ferritin and mercury concentrations with hypertension, 6213 subjects (3060 men and 3153 women) over 20 years of age from 2008 to 2010 Korea National Health and Nutrition Examination Survey were divided into tertiles according to serum ferritin and mercury concentrations in each gender. Serum ferritin (258.2 vs. 94.8 pmol/L) and mercury concentrations (28.4 vs. 19.9 nmol/L) were higher in men than in women. Serum ferritin (men; P = 0.029, women; P < 0.001) and mercury (men; P < 0.001, women; P = 0.003) concentrations were significantly associated with the prevalence of hypertension. In addition, significant correlation between serum ferritin and mercury concentrations in both men (r = 0.193, P < 0.001) and women (r = 0.145, P < 0.001) were found. Also, the increase of serum ferritin concentrations were more prominent in men (P < 0.001) than in women (P = 0.017) as the serum mercury tertiles increased after proper adjustments. Furthermore, significantly higher odds ratios of hypertension were found in the second (OR = 1.86, 95% CI; 1.05-3.30), and third (OR = 1.84, 95% CI; 1.01-3.36) tertiles of serum ferritin with the top tertile of serum mercury in men. The current study indicate that serum ferritin and mercury concentrations are associated with the prevalence of hypertension and that simultaneously elevated serum ferritin and mercury concentrations are related to the risk for hypertension in men.

Composition of metabolic syndrome among korean adults in a lifestyle modification intervention

Objectives

The aim of this study was to examine the composition of metabolic syndrome (MetS) components among middle-aged and older Koreans.

Methods

A total of 263 participants (age 40 + years) in a lifestyle modification intervention program who met the MetS definition of National Cholesterol Education Program (NCEP) – Adult Treatment Panel (ATP) III criteria were included in the study. The frequent patterns and clustering of MetS components were investigated. Clustering of changes in individual components, through a lifestyle modification intervention, was also identified. All characteristics were stratified by and compared between sexes.

Results

Approximately 80% of the participants had three of five MetS risk factors at baseline. The prevalence of each risk differed by sex. MetS composition patterns that do not include low high-density lipoprotein (HDL) cholesterol were more noticeable in men because of the low prevalence of low HDL cholesterol. In women, with higher prevalence of low HDL cholesterol, more patterns that include low HDL cholesterol were observed. The most common combination was “elevated blood pressure + abdominal obesity + impaired fasting glucose” in both sexes. Clustering of MetS risks was also found with most of the frequent combinations of MetS components. Through the lifestyle intervention, the greatest change was observed in HDL cholesterol among men and blood pressure among women. Triglycerides and HDL cholesterol were likely to be improved with blood pressure in men and abdominal obesity in women.

Conclusion

Differences in the prevalent patterns of MetS compositions were observed prior to and after the intervention, along with during-intervention changes. It is recommended that intervention strategies and guidelines for MetS management consider the MetS composition patterns for effectiveness.

Sarcopenia as a determinant of blood pressure in older Koreans: findings from the Korea National Health and Nutrition Examination Surveys (KNHANES) 2008-2010

BACKGROUND

Blood pressure (BP) is directly and causally associated with body size in the general population. Whether muscle mass is an important factor that determines BP remains unclear.

OBJECTIVE

To investigate whether sarcopenia is associated with hypertension in older Koreans.

PARTICIPANTS

We surveyed 2,099 males and 2,747 females aged 60 years or older.

MEASUREMENTS

Sarcopenia was defined as an appendicular skeletal muscle mass divided by body weight (ASM/Wt) that was <1 SD below the gender-specific mean for young adults. Obesity was defined as a body mass index (BMI) ≥ 25 kg/m(2). Subjects were divided into four groups based on presence or absence of obesity or sarcopenia. Hypertension was defined as a systolic BP (SBP) ≥ 140 mmHg, a diastolic BP (DBP) ≥ 90 mmHg, or a self-reported current use of antihypertensive medications.

RESULTS

The overall prevalence of hypertension in the four groups was as follows 49.7% for non-obese non-sarcopenia, 60.9% for non-obese sarcopenia, 66.2% for obese non-sarcopenia and 74.7% for obese sarcopenia. After adjustment for age, gender, regular activity, current smoking and alcohol use, the odds ratio (OR) for having hypertension was 1.5 (95% confidence interval (CI) = 1.23-1.84) in subjects in the non-obese sarcopenia group, 2.08 (95% CI = 1.68-2.57) in the obese non-sarcopenia group and 3.0 (95% CI = 2.48-3.63) in the obese sarcopenia group, compared with the non-obese non-sarcopenia group (p for trend <0.001). Controlling further for body weight and waist circumference did not change the association between hypertension and sarcopenia. The association between sarcopenia and hypertension was more robust in the subjects with diabetes mellitus.

CONCLUSION

Body composition beyond BMI has a considerable impact on hypertension in elderly Koreans. Subjects with sarcopenic obesity appear to have a greater risk of hypertension than simply obese or sarcopenia subjects.

Higher mortality in metabolically obese normal-weight people than in metabolically healthy obese subjects in elderly Koreans

OBJECTIVE

The purpose of this study was to investigate the impact of body mass index (BMI) and the presence of metabolic syndrome (MetS) on all-cause and cardiovascular mortality in elderly Korean men and women, and especially to compare metabolically obese normal-weight (MONW) and metabolically healthy obese (MHO) subjects.

PATIENTS AND METHODS

A total of 2317 elderly people (over 60 years of age) were studied using follow-up data from the South-West Seoul (SWS) Study, a prospective cohort study. Mortality from all causes and cardiovascular disease (CVD) were evaluated according to the combination of the presence or absence of MetS and Asian-specific body mass index (BMI) criteria (BMI <23 kg/m²; normal weight, BMI 23-24·9 kg/m²; overweight, BMI ≥25 kg/m²; obesity).

RESULTS

During a median follow-up of 10·3 years, 393 subjects died, including 126 from CVD. Among subjects with MetS, all-cause and CVD mortality were significantly higher in normal-weight subjects than overweight or obese individuals in Cox proportional-hazard models adjusted for confounding factors. Furthermore, among six groups with various MetS/BMI combinations, MONW individuals had the highest risk, whereas overweight subjects without MetS had the lowest risk of death from all causes and CVD [HR = 2·2 (95% CI = 1·4-3·4), HR = 3·0 (95% CI = 1·4-6·6) respectively]. Interestingly, all-cause mortality was significantly higher in MONW than MHO individuals.

CONCLUSIONS

In contrast to MHO subjects, elderly individuals with the MONW phenotype exhibited greater all-cause mortality during 10 years of follow-up.

Remodelling of biological parameters during human ageing: evidence for complex regulation in longevity and in type 2 diabetes

Factor structure analyses have revealed the presence of specific biological system markers in healthy humans and diseases. However, this type of approach in very old persons and in type 2 diabetes (T2DM) is lacking. A total sample of 2,137 Italians consisted of two groups: 1,604 healthy and 533 with T2DM. Age (years) was categorized as adults (≤65), old (66-85), oldest old (>85-98) and centenarians (≥99). Specific biomarkers of routine haematological and biochemical testing were tested across each age group. Exploratory factorial analysis (EFA) by principal component method with Varimax rotation was used to identify factors including related variables. Structural equation modelling (SEM) was applied to confirm factor solutions for each age group. EFA and SEM identified specific factor structures according to age in both groups. An age-associated reduction of factor structure was observed from adults to oldest old in the healthy group (explained variance 60.4% vs 50.3%) and from adults to old in the T2DM group (explained variance 57.4% vs 44.2%). Centenarians showed three-factor structure similar to those of adults (explained variance 58.4%). The inflammatory component became the major factor in old group and was the first one in T2DM. SEM analysis in healthy subjects suggested that the glucose levels had an important role in the oldest old. Factorial structure change during healthy ageing was associated with a decrease in complexity but showed an increase in variability and inflammation. Structural relationship changes observed in healthy subjects appeared earlier in diabetic patients and later in centenarians.

Vitamin D deficiency is an independent risk factor for cardiovascular disease in Koreans aged ≥ 50 years: results from the Korean National Health and Nutrition Examination Survey

Vitamin D deficiency is a risk factor for metabolic syndromes. We examined whether vitamin D deficiency altered the prevalence of cardiovascular disease (CVD) in older Koreans. Cross-sectional analysis of data from the Korean National Health and Nutrition Examination Survey IV 2008-2009 was used to examine the association between serum 25-hydroxyvitamin D (25(OH)D) levels and the prevalence of CVD in a representative population-based sample of 5,559 men and women aged ≥ 50 years. CVD was defined as angina pectoris, myocardial infarction, or stroke. The prevalence of CVD (7.0%) in the older Korean population was lower than that in the older US population, although average serum 25(OH)D levels were much lower in the Korean population. Additionally, serum 25(OH)D levels did not differ significantly between the CVD and non-CVD groups. However, subjects in the lowest category (< 25 nmol/l) of serum 25(OH)D level had the greatest prevalence of CVD, about two-fold higher than subjects in the highest category (> 75 nmol/l), after adjusting for age, gender, body mass index, education level, residence location, and region. The prevalence of other risk factors for CVD, including higher waist circumference, fasting glucose, low-density lipoprotein (LDL) cholesterol, and triglyceride levels and lower high-density lipoprotein (HDL) cholesterol levels, was also higher among subjects in the lowest category than among those in the highest category. In conclusion, low serum 25(OH)D may be an independent risk factor for CVD in older Koreans.

Increased serum ferritin predicts the development of hypertension among middle-aged men

BACKGROUND

We aimed to examine the relationship between iron status and hypertension as few studies have addressed this.

METHODS

We analyzed the association between ferritin/total iron-binding capacity (TIBC) and the subsequent development of hypertension. A total of 8,580 men who visited the Health Promotion Center for a medical checkup in 2005 were followed-up after 4 years.

RESULTS

Of the 8,580 men who were not hypertensive at baseline, 818 were found to be hypertensive at the 4-year follow-up. Compared with those who remained normotensive, these hypertensive subjects had higher levels of ferritin and TIBC at baseline, but had no significant difference in iron levels. After adjustment for age and body mass index (BMI), the odds ratios (OR) was substantially higher for new hypertension (OR 1.54, 95% confidence intervals (CIs) 1.26-1.88; P for trend <0.001) in subjects with the highest ferritin quartiles compared with those in the lowest quartiles. The association of serum ferritin levels with the incidence of hypertension was unchanged after adjustment for baseline blood pressure (BP). Adjustment for insulin resistance as measured by the homeostasis model assessment and the presence of a fatty liver reduced the magnitude of the OR for hypertension (first quartile reference, fourth quartiles OR 1.24, 95% CI 1.01-1.53, P for trend = 0.012), but did not affect their statistical significance.

CONCLUSION

Serum ferritin, but not iron level, was a significant predictor of hypertension in middle-aged Korean men. Fatty liver disease and insulin resistance may be mediators of this high ferritin-hypertension association.

Factor analysis of modifiable cardiovascular risk factors and prevalence of metabolic syndrome in adult Taiwanese

To assess the clustering of modifiable cardiovascular risk factors among Taiwanese adults, we evaluated 579 healthy participants who underwent health examinations between May and December 2007. Exploratory factor analysis was used to examine risk factor clustering. Smoking, alcohol intake, exercise habits, body mass index, waist circumference, total cholesterol, triglycerides, high- and low-density lipoprotein cholesterol, fasting glucose, uric acid, serum hepatic enzymes, and mean arterial pressure were assessed. Separate factor analyses assessed total and low-density lipoprotein cholesterol. Principal components analysis identified five factors for a model without low-density lipoprotein cholesterol and four factors for a model without total cholesterol. Four common factors in both models explained between 51.1 and 51.8% of variance in the original 14 factors. Metabolic factors, hematological factors (white blood cells and platelets), lifestyle factors (smoking and alcohol consumption), and exercise habits and fasting blood glucose explained about 20, 11, 10, 10% of total variance, respectively. In the model without low-density lipoprotein cholesterol, total cholesterol factor explained 8.83% of variance. This study confirmed clustering of established metabolic syndrome components and revealed additional associated cardiovascular disease risk factors, including lifestyle factors, exercise and total cholesterol, which should be targeted in prevention efforts.

Combined effect of high-normal blood pressure and low HDL cholesterol on mortality in an elderly Korean population: the South-West Seoul (SWS) study

BACKGROUND

It is unclear whether prehypertension by the seventh Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-7) criteria (systolic blood pressure (SBP) 120-139 or diastolic blood pressure (DBP) 80-89 mm Hg) or high-normal blood pressure (HNBP) by the European Society of Hypertension and European Society of Cardiology (ESH/ESC) criteria (SBP 130-139 or DBP 85-89 mm Hg) predicts mortality in elderly Koreans. We compared the mortality risk between those with prehypertension and HNBP and evaluated whether the presence of components of metabolic syndrome (MetS) can improve the prediction of mortality in subjects with HNBP.

METHODS

We analyzed all-cause and cardiovascular disease (CVD) mortality according to the JNC-7 and ESH/ESC categories using follow-up data of the South-West Seoul (SWS) Study, a prospective cohort study of 2,376 elderly Koreans, aged >60 years.

RESULTS

During the median follow-up of 7.6 years, 353 deaths occurred from all causes, and 113 of these were attributed to CVD. Prehypertension was nonsignificantly associated with an increased risk of mortality (hazard ratio (HR): 1.06, 95% confidence interval (CI): 0.68-1.64). Subjects with HNBP exhibited a nonsignificantly higher risk of mortality compared with those with optimal blood pressure by the ESH/ESC guideline (HR: 1.35, 95% CI: 0.84-2.18). However, the combination of low high-density lipoprotein (HDL) cholesterol and HNBP showed a twofold higher risk of all-cause mortality (HR: 2.01, 95% CI: 1.11-3.64) independent of other risk factors.

CONCLUSIONS

Although prehypertension was not associated with increased risk of mortality, individuals in the elderly Korean population with HNBP, especially when combined with low HDL cholesterol, showed a significantly increased risk of all-cause mortality.

The association of serum vitamin D level with presence of metabolic syndrome and hypertension in middle-aged Korean subjects

OBJECTIVE

To examine the association of serum vitamin D level with metabolic syndrome (MetS) and hypertension (HTN) in middle-aged Korean subjects.

DESIGN AND SUBJECTS

We conducted a population-based, cross-sectional survey of 1330 participants aged over 40 years (median age 65.8 years) in Chungju, Korea, in 2007. The 324 subjects, who were normotensive in 2003 and who attended a follow-up visit 4 years later, were included in an analysis of the association of serum vitamin D level with the risk of HTN.

MEASUREMENTS

Serum 25-hydroxy-vitamin D [25(OH)D] and PTH were measured in a central laboratory, using chemiluminescence assays.

RESULTS

The overall prevalence of the MetS in participants of this study was 45.3%. After adjusting for various covariates, subjects in the highest quintile group (61.4-116.8 nmol/l) compared with the lowest quintile group (10.0-29.7 nmol/l) of 25(OH)D had an odds ratio (OR) for having MetS of 0.35 (95% confidence intervals, CI, 0.22-0.56; P for trend <0.001). The median level of 25(OH)D was 46.8 nmol/l among 324 subjects who were normotensive in 2003. After multiple adjustment, the OR was substantially higher for new HTN (OR 2.74; 95% CI 1.40-5.34) in subjects with serum 25(OH)D levels below the median value compared with those above median. The inverse associations of vitamin D and MetS/HTN were unchanged after adjustment for PTH and serum calcium levels. There was no association between PTH and MetS.

CONCLUSIONS

We found a strong inverse association of 25(OH)D levels with MetS and HTN in this middle-aged Korean population. Having vitamin D deficiency was associated with an increased risk of having MetS and HTN in this demographic group.

In addition to obesity and insulin resistance, microalbuminuria and diminished insulin secretion are linked with the metabolic syndrome in community-dwelling nondiabetic Taiwanese subjects

Although insulin resistance and obesity are currently considered primary factors underlying development of the metabolic syndrome, microalbuminuria and inadequate insulin secretion may also be involved. The present study is the first to examine intercorrelations among these factors in a community-based Taiwanese population. An epidemiological survey of chronic diseases conducted in 1996 was utilized to evaluate 1340 community-dwelling, nondiabetic adults. Principal component factor analyses involving varimax orthogonal rotation of transformed continuously distributed variables were performed. Sex-specific factor analyses yielded four separate factors in women (obesity/insulin resistance, lipid, blood pressure and insulin resistance/secretion factors) and three in men (obesity/insulin resistance/secretion, lipid and blood pressure factors). For men the corrected insulin response clustered with obesity, and insulin resistance loaded on the same factor, explaining 31% of variance; however, microalbuminuria was closely linked with blood pressure variables, and the corrected insulin response loaded on the same factor, explaining 13.2% of variance. Obesity and insulin resistance were confirmed as central anomalies of all features of the metabolic syndrome. The observed linkage of impaired beta-cell function and microalbuminuria with the metabolic syndrome should facilitate prediction of the onset of cardio-vasculo-metabolic disorders. Inadequate beta-cell function and microalbuminuria are plausible components of the metabolic syndrome in Taiwanese subjects.

Components of the metabolic syndrome and incidence of diabetes in elderly Italians: The Italian Longitudinal Study on Aging

The aim of this study was to explore the relationship among components of the metabolic syndrome and their role in the development of diabetes. We included 2295 subjects, aged 65-84 years, participating in the Italian Longitudinal Study on Aging, a population-based study conducted in 1992 and with a follow-up in 1996. Factor analysis was conducted, separately for diabetic and non-diabetic men and women, using the principle components method and varimax rotations. Factor scores for the baseline were used as independent variables in logistic regressions models to determine risk factors predicting the development of diabetes. Factor analysis among non-diabetic elderly showed two factors for men (body size/insulin resistance, blood pressure/lipids) and three for women (body size, lipids, blood pressure). Among diabetic subjects, three factors emerged for men (body size/lipids/insulin resistance, body size/blood pressure, glucose) and four for women (body size/lipids/insulin resistance, lipids, body size/glucose/insulin resistance, lipids/blood pressure). For non-diabetic men and women, the body size factor (body size/insulin resistance factor for men) was strongly associated with diabetes incidence (OR=2.30, 95% CI 1.41-3.74 and OR=2.06, 95% CI 1.33-3.17, respectively). This study confirms that the metabolic syndrome (MetS) does not recognize one single underlying factor in an elderly cohort and that the obesity factor is a strong predictor of development of new onset diabetes.

A pathophysiological approach to metabolic syndrome using factor analysis in an adult Romanian population

The aim of the study was to examine the role of insulin resistance in etiopathogenesis of metabolic syndrome in an adult Romanian population using exploratory factor analysis. We analyzed 228 non-diabetic subjects randomized in respect to the age and sex distribution of the general population. For each patient, age, sex, body mass index (BMI), systolic and diastolic blood pressure (SBP, DBP), HDL-cholesterol (HDL), plasma triglycerides (TG), fasting plasma glucose (FPG) and fasting insulin were obtained. Factor analysis was performed using principal component analysis, with Varimax rotation of the major determinants of metabolic syndrome. Mean age was 48.9 +/- 12.7 years; 107 (46.9%) were men and 121 (53.1%) women. We found three major factors, which are correlated with metabolic syndrome and may explain its variance. Factor 1 comprises SBP and DBP in men and SBP, DBP and BMI in women. Factor 2 comprises BMI, HDL, TG and FPG in men and BMI, TG and FPG in women. Factor 3 comprises fasting insulin in men and fasting insulin, TG and HDL in women. The finding of more than one factor suggests that insulin resistance is not the only pathophysiological mechanism involved. These factors appear to work independently of each other in men, but they intersect in women, suggesting that the pathophysiology of metabolic syndrome may be different in women compared with men.

Factor analysis of lifestyle-related factors in 12,525 urban Japanese subjects

This study describes the clustering patterns of several lifestyle-related factors in urban Japanese subjects. The effect of aging on these patterns was also investigated. Data of 8 factors that included body mass index (BMI), blood pressure (BP), fasting plasma glucose (FPG), serum total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDLc), gamma-glutamyl-transferase (GGT), and cigarette smoking were analyzed for 12,525 individuals (4,591 men and 7,934 women) aged either 40, 50, or 60 years. Factor analysis showed eight factors clustered into 3 unrelated groups. BMI and BP were excluded in subjects aged 60 years. Our data showed that the effect of obesity on the prevalence of type 2 diabetes mellitus was age dependent. In spite of the established inverse relationship between TG and HDLc, we found that TG had an association with GGT. These results indicated that aging may have a major influence on the expression of multiple risk factors. The influence of BMI on the lifestyle-related factors appeared to be mostly expressed in younger people, while these factors appeared to be independent of BMI at age 60.

An evaluation of the metabolic syndrome in a large multi-ethnic study: the Family Blood Pressure Program

BACKGROUND

The Family Blood Pressure Program is an ongoing, NHLBI-sponsored, multi-center program to study the genetic determinants of high blood pressure. The goal of this particular study was to study patterns of metabolic syndrome (MetS) in four ethnic groups: African Americans, Caucasians, Hispanics, and Asians.

METHODS

A major part of participants in three networks GENOA, HyperGEN and SAPPHIRe were recruited mainly through hypertensive probands. MetS was defined as a categorical trait following the National Cholesterol Education Program definition (c-MetS). MetS was also characterized quantitatively through multivariate factor analyses (FA) of 10 risk variables (q-MetS). Logistic regression and frequency tables were used for studying associations among traits.

RESULTS

Using the NCEP definition, the Hispanic sample, which by design was enriched for type 2 diabetes (T2D), had a very high prevalence of MetS (73%). In contrast, its prevalence in Chinese was the lowest (17%). In African Americans and Hispanics, c-MetS was more prevalent in women than in men. Association of c-MetS with type 2 diabetes (T2D) was prominent in the Hispanics and African Americans, less pronounced in the Whites and Japanese, (although still significant), and weakest in the Chinese sample. Using FA without rotation, we found that the main factor loaded obesity (OBS) and blood pressure (BP) in African Americans; OBS and insulin (INS) in Hispanics, in Japanese, and in Whites; and OBS alone in Chinese. In Hispanics, Whites, and Japanese, BP loaded as a separate factor. Lipids in combination with INS also loaded in a separate factor. Using FA with Varimax rotation, 4 independent factors were identified: "Obesity-INS," "Blood pressure," "Lipids-INS," and "Central obesity." They explained about 60% of the variance present in the original risk variables.

CONCLUSION

MetS ethnic differences were identified. Ascertaining for hypertension or T2D increased the MetS prevalence in networks compared with the one in the US general population. Obesity was the most prominent risk factor contributing to both c-MetS and q-MetS. INS contributed in two important factors (obesity and lipids). The information imbedded into c-MetS trait /q-MetS factors scores can contribute in future research of the MetS, especially its utilization in the genetic analysis.

Greater beneficial effects of visceral fat reduction compared with subcutaneous fat reduction on parameters of the metabolic syndrome: a study of weight reduction programmes in subjects with visceral and subcutaneous obesity

AIMS

To evaluate the effect of weight reduction on parameters of the metabolic syndrome in obese patients according to their pattern of abdominal fat distribution.

METHODS

A longitudinal intervention study, consisting of a 12-week weight reduction programme, including lifestyle modification and adjuvant appetite suppressant, in 38 subjects with visceral obesity and 47 subjects with subcutaneous obesity. Visceral, subcutaneous and total adipose tissue areas were determined by CT scan at the level of L4-L5. Parameters for components of the metabolic syndrome were measured before and after weight reduction.

RESULTS

Reductions in body weight, BMI and subcutaneous adipose tissue area were greater in the subcutaneous than in the visceral obesity group. In contrast, changes in fasting plasma glucose, insulin, and HOMA score were higher in the visceral than in the subcutaneous obesity group. Changes in visceral adipose tissue area were significantly related to changes in fasting plasma glucose, triglycerides and HOMA score.

CONCLUSIONS

Visceral fat reduction induced greater beneficial effects on parameters of the metabolic syndrome than subcutaneous fat reduction. Evaluation of changes in abdominal fat distribution is necessary when obese subjects enter a weight reduction programme.

Leptin and the metabolic syndrome in Korean adolescents: factor analysis

BACKGROUND

The objectives of this study were to evaluate the relationships of leptin with the metabolic syndrome and to examine leptin's role in clustering of the metabolic components among Korean adolescents.

METHODS

A cross sectional study was carried out in 68 male and 80 female adolescents aged 13-18 years in an urban area of South Korea. Anthropometric variables were measured and blood pressure, fasting plasma glucose, low-density lipoprotein cholesterol, triglyceride, high-density lipoprotein cholesterol, and serum leptin were obtained.

RESULTS

As more metabolic components were clustered, body mass index, body fat, waist circumference, and serum leptin levels were significantly increased. Principal components factor analysis revealed three factors in males and females that explained 70% and 65%, respectively, of the observed variance of the 10 measured variables. These were obesity-leptin-lipid factor, blood pressure factor, and glucose-cholesterol factor in males and obesity-leptin-glucose factor, blood pressure factor, and cholesterol factor in females. Leptin loaded on only one factor in both genders.

CONCLUSION

Leptin did not appear to have a major role linking various components of the metabolic syndrome, even though it was strongly associated with obesity indices. Gender difference of linking of leptin with glucose or lipid was observed. There seems to be more than one pathophysiological mechanism which might underlie full expression of the metabolic syndrome among Korean adolescents.

The metabolic syndrome defined by factor analysis and incident type 2 diabetes in a chinese population with high postprandial glucose

OBJECTIVE

The aim of this study was to examine how the major components of the metabolic syndrome relate to each other and to the development of diabetes using factor analysis.

RESEARCH DESIGN AND METHODS

The screening survey for type 2 diabetes was conducted in 1994, and a follow-up study of nondiabetic individuals at baseline was carried out in 1999 in the Beijing area. Among 934 nondiabetic and 305 diabetic subjects at baseline, factor analysis was performed using the principle components analysis with varimax orthogonal rotation of continuously distributed variables considered to represent the components of the metabolic syndrome. Fasting insulin was used as a marker for insulin resistance. Of the 559 subjects without diabetes at baseline, 129 developed diabetes during the 5-year follow-up. Factors identified at baseline were used as independent variables in univariate and multivariate logistic regression models to determine risk factor clusters predicting the development of diabetes.

RESULTS

Four factors were identified in nondiabetic and diabetic subjects. Fasting insulin levels, BMI, and waist-to-hip ratio were associated with one factor. Systolic and diastolic blood pressures were associated with the second factor. Two-hour postload plasma glucose (2-h PG) and serum insulin and fasting plasma glucose were associated with the third factor. Serum total cholesterol and triglycerides were associated with the fourth factor. The first and the third factors predicted the development of diabetes. In diabetic patients at baseline, the combination of systolic and diastolic blood pressure was the most important factor, and urinary albumin excretion rate clustered with fasting and 2-h PG levels.

CONCLUSIONS

Insulin resistance alone does not underlie all features of the metabolic syndrome. Different physiological processes associated with various components of the metabolic syndrome contain unique information about diabetes risk. Microalbunuria is more likely to be a complication of type 2 diabetes or hypertension than a marker for the metabolic syndrome.

Prevalence and factor analysis of metabolic syndrome in an urban Korean population

OBJECTIVE

The aim of this study was to explore the prevalence and pattern of the metabolic syndrome and its association with hyperinsulinemia in an urban Korean population of 269 men and 505 women.

RESEARCH DESIGN AND METHODS

The National Cholesterol Education Program Adult Treatment Panel (ATP) III guidelines were used to calculate the sex-specific prevalence of the metabolic syndrome. After excluding individuals taking medication for hypertension, diabetes, or dyslipidemia, we used factor analysis to examine the pattern of the metabolic syndrome in 206 men and 449 women.

RESULTS

The prevalence of metabolic syndrome was 16.0% in men and 10.7% in women aged 30-80 years. However, ATP III criteria for central obesity are not optimal for an Asian-Pacific population; when waist circumference is reduced from 102 to 90 cm in men and 88 to 80 cm in women, the prevalence of the metabolic syndrome increased to 29.0 and 16.8%, respectively. Sex-specific factor analysis showed four factors in men (obesity, glucose intolerance, hypertension, and dyslipidemia) and three in women (obesity-hypertension, glucose intolerance, and obesity-dyslipidemia). Insulin resistance estimated from fasting insulin levels clustered with three of the four factors in men and two of the three factors in women. By ATP III or Asian-Pacific waist circumference criteria, the prevalence of the metabolic syndrome increased with increasing tertiles of insulin resistance, which was estimated by a homeostasis model assessment.

CONCLUSIONS

The metabolic syndrome is common in an urban Korean population when using Asian-Pacific waist criteria. The prevalence of the metabolic syndrome increased with increasing tertiles of insulin resistance.

Serum adiponectin concentrations predict the developments of type 2 diabetes and the metabolic syndrome in elderly Koreans

OBJECTIVE

To determine whether low serum adiponectin concentrations are able to predict the future developments of type 2 diabetes and the metabolic syndrome using the National Cholesterol Education Programme (NCEP) criteria. We also investigated the stability of adiponectin levels and the relationships between baseline adiponectin levels and changes in the parameters related to the metabolic syndrome over a period of 3 years.

PATIENTS AND MEASUREMENTS

This prospective cohort study included 372 elderly Koreans who participate in the SWS (South-West Seoul) study, which was conducted in 1999 and 2002 in Seoul, Korea. Fasting and postchallenge 2-h plasma glucose, body mass index (BMI), waist-to-hip ratio (WHR), blood pressure, lipid profiles and serum adiponectin data obtained in 1999 and 2002 were examined.

RESULTS

The within-person variation between 1999 and 2002 of serum adiponectin was not significant (P = 0.61). Serum adiponectin was closely correlated with the risks factors of cardiovascular disease (CVD), that is negatively with BMI, WHR, blood pressure, triglyceride and blood glucose levels, and positively with high density lipoprotein (HDL)-cholesterol levels. Subjects with the metabolic syndrome showed lower serum adiponectin concentrations than those without the metabolic syndrome (P < 0.0001). Baseline adiponectin levels were found to be correlated with subsequent changes in WHR, low density lipoprotein (LDL)-cholesterol, fasting and postload 2-h glucose over the 3-year period, after adjusting for baseline values. Multiple logistic regression analysis showed that lower baseline serum adiponectin concentrations were significantly associated with the developments of type 2 diabetes and the metabolic syndrome after adjusting for age, sex, obesity, history of impaired fasting glucose (IFG) or impaired glucose tolerance (IGT), hypertension and dyslipidaemia.

CONCLUSIONS

Reduced concentrations of adiponectin were found to be independently associated with increased risk of both type 2 diabetes and the metabolic syndrome in elderly Koreans.

Comparison of serum concentrations of C-reactive protein, TNF-alpha, and interleukin 6 between elderly Korean women with normal and impaired glucose tolerance

This study was performed to compare concentrations of pro-inflammatory cytokines, such as interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha) as well as acute-phase protein, such as C-reactive protein (CRP) between subjects with normal glucose tolerance (NGT) and impaired glucose tolerance (IGT). The purpose of this study was to verify whether the pro-inflammatory cytokine-induced acute-phase response is a pathogenic mechanism in type 2 diabetes in elderly Korean women. A total of 1737 elderly subjects aged over 60 years participated in a population based study in Seoul, Korea (SWS Study 1999). Amongst them, a total of 232 non-smoking and non-diabetic female subjects aged 60-89 years was randomly selected and compared with each other. Higher serum high-sensitivity CRP (hs-CRP) concentrations were shown in subjects with IGT than those with normal glucose tolerance (median 1.2 versus 0.9, P < 0.05). Moreover, a relationship between serum hs-CRP concentrations and many components of the metabolic syndrome were detected. Serum pro-inflammatory cytokine IL-6 or TNF-alpha concentrations, however, were neither increased in subjects with IGT nor closely correlated with the components of the metabolic syndrome. In multiple regression analysis with stepwise selection method using hs-CRP as a dependent variable, it was found that white blood cell (WBC) counts, body mass index (BMI), fasting insulin, post-load 2h glucose, hematocrit and LDL cholesterol were significant independent variables. Our study confirms that increased acute-phase reaction is associated with impaired glucose tolerance and the metabolic syndrome in elderly Korean women. However, the hypothesis that pro-inflammatory cytokine-induced systemic inflammation is an early metabolic defect prior to onset of type 2 diabetes, is not supported in our study of elderly Korean women.