Factor analysis of ethnic variation in the multiple metabolic (insulin resistance) syndrome in three Canadian populations

Contributions to chronic disease prevention and control: studies among the Kivalliq Inuit since 1990

A population-based health interview and examination survey of 8 Inuit communities in the Kivalliq region of Nunavut, Canada, during the early 1990s has resulted in an increased understanding of the burden and extent of cardiovascular diseases and diabetes and their risk factors such as genetics, obesity, lipids, blood pressure and fatty acids. A recent national health interview survey which included a sample from Nunavut indicates that the Inuit still enjoy some advantages relative to other Canadians (lower level of self-reported diabetes and hypertension) and disadvantages (higher level of smoking, obesity, and heavy drinking). The pattern of health and disease among the Inuit is rapidly evolving, as the traditional lifestyle becomes further eroded. A long-term prospective cohort study that monitors this trend, investigates the etiology, and identifies potential interventions is urgently needed.

Body proportions in healthy adult Inuit in East Greenland in 1963

OBJECTIVES

It is important to know the starting point when describing changes in Inuit in transition.

STUDY DESIGN

The original charts of 1,852 individuals from the epidemiological investigation in East Greenland around 1963 performed by Littauer and colleagues were recovered recently. They included height, weight and a physical investigation.

METHODS AND RESULTS

The focus of this paper was adult Inuit body proportions in 1963 by ten-year age groups excluding participants with disabilities affecting body build. Relatively stable values were seen in both genders with age. Median values in men/women aged 20 years and above were: height 164/153.5 cm, weight 64/54 kg and BMI 23.7/23.1. Men aged 50 years and above had a little lower height and weight than young men. Women aged 40-49 years had a higher weight and BMI, but this evened out in the older age groups. Median BMI was relatively high compared to WHO definition.

CONCLUSIONS

The data from 1963 gives a starting point for evaluating changes in Inuit body build and the prevalence of overweight. Furthermore, they indicate a need for Inuit-specific normal BMI delineation.

Clustering of cardiac risk factors associated with the metabolic syndrome and associations with psychosocial distress in a young Asian Indian population

The metabolic syndrome is a precursor for coronary heart disease. However, its pathophysiology is not clear, its phenotypic expression may vary by region; also, the phenotypic manifestation may be exacerbated by psychosocial distress and family history. The purpose of the current study was to assess the factor structure of the metabolic syndrome in young urban Asian Indians. Asian Indian youth (N = 112) were evaluated for body mass index (BMI), waist-hip ratio, blood pressure (systolic: SBP; diastolic: DBP), blood sugar, triglycerides, cholesterol, insulin, psychosocial distress and family health history. Factor analyses were computed on components of the metabolic syndrome. Three factors were identified for the entire sample: hemodynamic-obesity (SBP, DBP, waist-hip ratio), Lipid (cholesterol, triglyceride), and insulin-obesity (blood sugar, BMI, insulin). Similar to previous research with this population, three distinct factors with no overlap were identified. Factors did not correlate with psychosocial distress or family history. Lack of correlation with family history and psychosocial distress may be a function of the young age and demographics of the sample.

A principal component model of medical health: implications for cognitive deficits and decline among adults in a population-based sample

Longitudinal blood- and cognitive data from 879 adults were analyzed to extract a multidimensional health structure for prediction of cognitive change. Six health components were identified and replicated at two waves. Following, cognitive outcomes were regressed on the health components. Large proportions of cognitive age related variations were accounted for by baseline health in both cross-sectional and prospective analyses. Less variation was accounted for when health change and cognitive change were contrasted. Cardiovascular health was particularly important for prediction of cognitive change. Our study underlines causal relations between health and cognitive functions, and suggests that some effects are long term.

Central Adiposity Determines Prevalence Differences of the Metabolic Syndrome

OBJECTIVE

To compare the expression of the metabolic syndrome in Spain and San Antonio, TX, two populations with major differences regarding their cardiovascular risk profile.

RESEARCH METHODS AND PROCEDURES

Cross-sectional analysis of population-based, epidemiological surveys using the metabolic syndrome definition of the National Cholesterol Education Program. In San Antonio, we limited our analysis to non-Hispanic whites because non-Hispanic whites are largely of European ancestry (n = 1339 in San Antonio and 2947 in Spain)

RESULTS

In men, increased central adiposity was more prevalent in San Antonio than in Spain (29.7 vs. 23.0%, p < 0.0001); in women, it was less prevalent in San Antonio than in Spain (40.2 vs. 66.4%, p < 0.0001). The metabolic syndrome followed that same pattern: more prevalent in men (28.9 vs. 20.8%, p = 0.019) and less in women from San Antonio (27.1 vs. 30.9%, p < 0.0001). In subjects with the metabolic syndrome, most women had increased central adiposity (92.6% in San Antonio and 97.5% in Spain), and most men had either increased central adiposity or blood pressure (99.2% in San Antonio and 95.0% in Spain).

DISCUSSION

Contrary to men, the metabolic syndrome is more prevalent in Spanish women than in women from San Antonio with differences that mirror differences in central adiposity. Central adiposity and blood pressure may be used to exclude the metabolic syndrome. Considering recent secular trends in obesity, we predict there will be an increase in the prevalence of the metabolic syndrome in both populations in the coming years.

A comparison of the metabolic response to abdominal obesity in two Canadian Inuit and First Nations population

Inuit and Cree populations are known for high obesity rates despite markedly different rates of type 2 diabetes (T2DM). To document this apparent discrepancy we evaluated the impact of body size parameters and fasting insulin (FI) on several T2DM risk factors among Inuit and Cree populations (Québec, Canada). A total of 1,104 adults (≥18 years) Inuit and Cree individuals participated in a cross-sectional investigation. Interestingly, across both genders, across all levels of waist circumference (WC), Inuit showed lower levels of FI (age-adjusted, P < 0.0001) and fasting glucose (P < 0.0001) than Cree individuals. In both groups, a comparison of multi-sample structural equation models confirmed the predominant influence of WC on other traditional risk factors, compared to BMI. A preponderant direct impact of WC was observed on blood pressure (BP) parameters (P < 0.0001), high-density lipoprotein cholesterol (HDL-C) (P < 0.0001), and FI (P < 0.0001). Fasting glucose level appear to be influenced by WC via FI in both ethnic groups (P < 0.0001), while triacylglycerol (TAG) level was predominantly impacted by WC via FI, but only in Cree individuals (P < 0.0001). The main ethnic difference found was the strength of the impact of WC on FI, which was considerably higher among the Cree (λ = 2.4, P < 0.0001) than the Inuit (λ = 1.8, P < 0.0001). These results confirm the predominant role of abdominal adiposity in the complex and tenuous links of different traditional T2DM determinants. However, the ethnic difference in the impact of abdominal obesity on insulin levels across all WCs needs to be explored further.

Factor analysis of risk variables associated with metabolic syndrome in adult Asian Indians

BACKGROUND

Several studies hinted about the clustering of risk variables of the metabolic syndrome (MS) and suggested that the underlying genetic polymorphisms could be responsible for the increasing incidence of coronary heart disease (CHD) in people of Indian origin. Therefore, identification of the components of the MS along with the genetic factors could be one of the aspects to make an attempt to prevent the increasing incidence of CHD.

MATERIALS AND METHODS

Principal component factor analysis (PCFA) was undertaken to identify the components or factors of the MS among the adult (≥30 years) Asian Indians living in and around Calcutta, India. The study comprised 350 adult Asian Indians. Anthropometric measurements were taken, and lipid profiles, blood pressure and fasting blood glucose were measured for each participant. Two genetic polymorphisms, namely, angiotensin converting enzyme (ACE) gene polymorphism (insertion/deletion [I/D]) or ACE (I/D) and apolipoproteinE (Hha I) were also studied.

RESULTS

PCFA revealed 3 factors that cumulatively explained 65.39% of the observed variance of the MS by measured variables. The 3 factors identified were lipids and lipoprotein (Factor 1), centripetal fat and blood pressure (Factor 2), and ACE (I/D) polymorphism with blood pressure (Factor 3). Moreover, the first 2 factors, that is, lipids, lipoprotein, centripetal fat, and blood pressures cumulatively explained ~46% (45.94%) of the observed variance of MS in this population.

CONCLUSIONS

Since more than 1 factor was identified for the MS phenotype, more than 1 physiogenetic mechanism could be accounted for MS in the Asian Indian population.

Metabolic syndrome: prevalence among American Indian and Alaska native people living in the southwestern United States and in Alaska

BACKGROUND

Metabolic syndrome occurs commonly in the United States. The purpose of this study was to measure the prevalence of metabolic syndrome among American Indian and Alaska Native people.

METHODS

We measured the prevalence rates of metabolic syndrome, as defined by the National Cholesterol Education Program, among four groups of American Indian and Alaska Native people aged 20 years and older. One group was from the southwestern United States (Navajo Nation), and three groups resided within Alaska. Prevalence rates were age-adjusted to the U.S. adult 2000 population and compared to rates for U.S. whites (National Health and Nutrition Examination Survey [NHANES] 1988-1994).

RESULTS

Among participants from the southwestern United States, metabolic syndrome was found among 43.2% of men and 47.3% of women. Among Alaska Native people, metabolic syndrome was found among 26.5% of men and 31.2% of women. In Alaska, the prevalence rate varied by region, ranging among men from 18.9% (western Alaska) to 35.1% (southeast), and among women from 22.0% (western Alaska) to 38.4 % (southeast). Compared to U.S. whites, American Indian/Alaska Native men and women from all regions except western Alaska were more likely to have metabolic syndrome; men in western Alaska were less likely to have metabolic syndrome than U.S. whites, and the prevalence among women in western Alaska was similar to that of U.S. whites.

CONCLUSION

The prevalence rate of metabolic syndrome varies widely among different American Indian and Alaska Native populations. Differences paralleled differences in the prevalence rates of diabetes.

Waist circumference, metabolic syndrome and coronary artery disease in a Pakistani cohort

BACKGROUND

Metabolic syndrome (M-IRS) is common in Asians. This study investigated the relationship of two definitions of M-IRS to atherosclerosis in Indian Asians with suspected coronary arterial disease (CAD).

METHODS

400 patients with chest pain selected for the presence or absence of angiographic disease were recruited from a tertiary referral centre in Pakistan into a prospective case-control study. Patients were categorized by the National Cholesterol Education Program adult treatment panel 3 (NCEP) and International Diabetes Federation (IDF) definitions of the metabolic syndrome and the relationship of these to the presence of CAD and extent of atheroma burden was investigated.

RESULTS

M-IRS was present in 53% by IDF criteria and in 44% using the Asian criteria for NCEP. The 2 populations identified were only 69% concordant. No relationship existed between the presence of NCEP M-IRS and atheroma burden. In contrast, the presence of IDF M-IRS was associated with CAD (65 vs. 34%; RR=1.88; p<0.001) and angiographic disease burden (28 [0-224] vs. 0 (0-198); RR=1.83; p<0.001). This association persisted (beta=18.4; p<0.001) after correction for C-reactive protein (beta=8.67; p<0.001), lipoprotein (a) (beta=8.14; p=0.002), and estimated glomerular filtration rate (beta=-0.22; p=0.01). Differences in presumed underlying factors were found in the 2 populations identified by the definitions though both agreed on the separate weightings given to blood pressure and HDL-C/apolipoprotein A1.

CONCLUSIONS

The specific Asian IDF and NCEP definitions of M-IRS show limited concordance in Pakistanis. The IDF criteria in contrast to the NCEP criteria are associated with the presence of CAD even after allowing for other risk factors identified in this population.

Inuit women's health in Nunavut, Canada: a review of the literature

OBJECTIVES

Inuit women face challenging health and wellness issues in Northern communities. Literature examining these contexts and the processes through which health is affected is virtually non-existent. The objective [corrected] of this review is to examine and consolidate the available literature on Inuit women's health issues from the last decade in order to identify priorities for future research.

STUDY DESIGN

This study is a review of literature from the last decade. Inuit women's health issues that have been raised in the literature and in various reports are examined within a health-determinants framework.

METHODS

Government reports and statistics, publications by Inuit organizations and publications available on MEDLINE were examined for this review.

RESULTS

Inuit women's health is a crucial part of the health of their communities. Inuit women face serious health issues related to reproductive and sexual health, such as high rates of sexually transmitted infections and challenging circumstances surrounding childbirth. Wellness, suicide and stress are more significant issues for Inuit women compared with non-Inuit women. Food security and accessibility is an issue for all Northerners. Alcohol and substance abuse and exposure to violent situations endanger both the health and safety of Inuit women in many Northern communities.

CONCLUSIONS

There exists an urgent need to better understand the mechanisms through which determinants of health affect Inuit women. As well as adding to the body of knowledge on health determinants in Canada, further examining these issues will provide valuable information for health policy decision-makers and program development in the North and facilitate the direction of resources to the necessary areas of health services provision in Nunavut.

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.

Heritability of determinants of the metabolic syndrome among healthy Arabs of the Oman family study

The metabolic syndrome, as defined by the International Diabetes Federation, was investigated in five large, extended, highly consanguineous, healthy Omani Arab families of a total of 1277 individuals. Heritability (h2) of the phenotypic abnormalities that make up the syndrome and other related traits was estimated by variance decomposition method using SOLAR software. The overall prevalence of the syndrome was 23%. The prevalence of abnormalities making the syndrome in a descending order were: obligatory waist circumference, hypertension, raised fasting blood glucose, low serum high-density lipoprotein (HDL), and raised serum triglycerides (TGs). Highly significant, but widely spread, h2 values were obtained for: height (0.68), weight (0.68), BMI (0.68), serum HDL (0.63), serum leptin (0.55), percentage body fat (0.53), total serum cholesterol (0.53), fasting serum insulin (0.51), homeostasis model assessment-insulin resistance index (0.48), serum TG (0.43), waist circumference (0.40), diastolic blood pressure (0.38), and 2-hour glucose level (0.17), whereas for the metabolic syndrome itself, h2 was 0.38. The wide spread of h2 results (0.07 to 0.68) indicates that some determinants, such as weight, BMI, and HDL level, are under significant genetic influence among the Omani Arabs. Other determinants such as insulin resistance, abdominal obesity, diastolic blood pressure, and TG levels seem to be more environmentally driven.

Factor analysis of risk variables associated with metabolic syndrome in Asian Indian adolescents

The purpose of the present cross-sectional study was to identify components of risk variables associated with metabolic syndrome in Asian Indian adolescents. The sample included 400 adolescents (boys = 200; mean age, 15.0 +/- 4.5 years; girls = 200; mean age, 14.4 +/- 3.8 years) from Calcutta, India. The following variables were considered: body mass index, waist circumference, sum of four skinfolds, subscapular/triceps ratio, total cholesterol, triglycerides, blood glucose, and systolic, diastolic, and mean arterial pressure. Principal component factor analysis revealed four uncorrelated factors for adolescent boys that cumulatively explained 76.3% of the observed variance of metabolic syndrome. Four factors with overlap between factors 1 and 2 were observed for adolescent girls that cumulatively explained 74.3% of the total variation of metabolic syndrome. The four factors identified were central body fat distribution (factor 1), centralized subcutaneous fat (factor 2), lipids-blood glucose (factor 3), and blood pressure (factor 4). Furthermore, the first two factors, i.e., central body fat distribution and centralized subcutaneous fat, cumulatively explained more than 46% (46.5% for boys; 46.4% for girls) of the observed variation of metabolic syndrome. Since more than one factor was identified for metabolic syndrome, more than one physiological mechanism could account for the clustering of risk variables of metabolic syndrome in Asian Indian adolescents. Factor analysis of Asian Indian adults also revealed four uncorrelated factors, similar to the present factors, therefore warranting intervention as early as adolescence.

Padrões de adiposidade em mulheres atendidas em um Centro Municipal de Saúde de Belo Horizonte, 2000

O objetivo do estudo consiste em definir padrões de adiposidade em mulheres. O estudo foi realizado em um Centro Municipal de Saúde de Belo Horizonte, Minas Gerais, com 827 mulheres entre 12 e 65 anos. As participantes realizaram diversas medidas antropométricas e responderam a um questionário sobre condições socioeconômicas, demográficas, história obstétrica, estilo de vida. A técnica de análise fatorial de componentes principais (ACP) foi utilizada para identificar conglomerados e independência de variáveis antropométricas na definição de padrões de adiposidade em mulheres. Os três primeiros componentes principais independentes explicaram 85,97% da variância. O primeiro foi representado pelas pregas cutâneas, o segundo pelo Índice de Massa Corporal (IMC) e pela circunferência do braço (CB) e o terceiro pela razão cintura/quadril (RCQ). Os fatores explicaram 38,42%, 29,03% e 18,52% da inércia, respectivamente. Evidenciou-se associação positiva entre todas as variáveis. Observou-se associação de maior intensidade, justificado pela alta correlação, entre as pregas da coxa, peitoral, bicipital, subescapular e supra-ilíaca (Fator 1) e a CB e o IMC (Fator 2). A variável RCQ foi identificada como principal representante do terceiro fator. Conclui-se que a análise fatorial de componentes principais identificou adequadamente três padrões de adiposidade em mulheres: periférica, global e central. A forte associação entre o IMC e CB demonstra que essa última medida poderia substituir com vantagens o IMC no rastreamento populacional da obesidade. Os critérios diagnósticos para a obesidade em mulheres seriam mais precisos se considerassem simultaneamente a CB, a RCQ e a prega da coxa.

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.

Evaluation and comparison of models of metabolic syndrome using confirmatory factor analysis

The aim of this study was to evaluate and compare three competing models of the underlying factor structure of metabolic syndrome using confirmatory factor analysis (CFA). Data from the Insulin Resistance Atherosclerosis Study (IRAS) was used, which has previously been evaluated using principal components analysis (PCA). The three models that were evaluated consisted of oblique and orthogonal two-factor models with hypothesized underlying "metabolic" and "blood pressure" factors, and a four-factor model theorizing "insulin resistance," "obesity," "lipids," and "blood pressure" as the underlying constructs. Several CFAs were performed using EQS Multivariate Software Version 5.7b with maximum likelihood estimation. The results showed that the four-factor model yielded significantly better data-model fit than two-factor models, with a comparative fit index of 0.963, and standardized root mean square residual of 0.036. Factors exhibited good construct reliability and variance extracted estimates except for the lipids factor. We concluded that the four-factor model of metabolic syndrome was the most plausible model among the three competing models.

Geographic variations of the International Diabetes Federation and the National Cholesterol Education Program-Adult Treatment Panel III definitions of the metabolic syndrome in nondiabetic subjects

OBJECTIVE

We have carried out international comparisons of the metabolic syndrome using the International Diabetes Federation (IDF) and National Cholesterol Education Program-Adult Treatment Panel III (ATP III) definitions. This analysis could help to discern the applicability of these definitions across populations.

RESEARCH DESIGN AND METHODS

Nondiabetic subjects aged 35-64 years were eligible for analysis in population-based studies from San Antonio (Mexican Americans and non-Hispanic whites, n = 2,473), Mexico City (n = 1,990), Spain (n = 2,540), and Peru (n = 346). Kappa statistics examined the agreement between metabolic syndrome definitions.

RESULTS

Because of the lower cutoff points for elevated waist circumference, the IDF definition of the metabolic syndrome generated greater prevalence estimates than the ATP III definition. Prevalence difference between definitions was more significant in Mexican-origin and Peruvian men than in Europid men from San Antonio and Spain because the IDF definition required ethnic group-specific cutoff points for elevated waist circumference. ATP III and IDF definitions disagreed in the classification of 13-29% of men and 3-7% of women. In men, agreement between these definitions was 0.54 in Peru, 0.43 in Mexico City, 0.62 in San Antonio Mexican Americans, 0.69 in San Antonio non-Hispanic whites, and 0.64 in Spain. In women, agreement between definitions was 0.87, 0.89, 0.86, 0.87, and 0.93, respectively.

CONCLUSIONS

The IDF definition of the metabolic syndrome generates greater prevalence estimates than the ATP III definition. Agreement between ATP III and IDF definitions was lower for men than for women in all populations and was relatively poor in men from Mexico City.

Is the factor structure of the metabolic syndrome comparable between men and women and across three ethnic groups: the Miami Community Health Study

PURPOSE

The metabolic syndrome (MS) is conceived as a cluster of disorders that increase risk for coronary heart disease and type 2 diabetes. Studies examining its structure primarily have used an exploratory factor analytic technique, but yielded discrepant results. There also is a lack of research that investigates whether the clustering pattern is similar across sex and ethnic groups. This study uses confirmatory factor analysis to evaluate the factor structure of the MS and examines its similarity between men and women and across three ethnic groups (Caucasian, African, and Cuban Americans).

METHOD

A hierarchical four-factor model with an overarching MS factor uniting insulin resistance, obesity, lipid, and blood pressure factors was tested with 517 individuals from the Miami Community Health Study.

RESULTS

Findings show that the proposed structure was well supported (comparative fit index=0.97) and similar between men and women and across ethnic groups. The MS was represented strongly by insulin resistance, followed by obesity, lipid factors, and, to a lesser extent, a blood pressure factor.

CONCLUSIONS

This study provides empirical support for identifying and diagnosing the MS by its component factors in a diverse population.

Characteristics and prevalence of the metabolic syndrome among three ethnic groups in Canada

OBJECTIVE

To compare the characteristics and prevalence of the metabolic syndrome (MetS) among Native Indians, Inuit, and non-Aboriginal Canadians.

METHODS

The study was based on four cross-sectional studies conducted in the late 1980s and early 1990s involving three ethnic groups living in contiguous regions in central Canada: Oji-Cree Indians from several reserves in northern Ontario and Manitoba, Inuit from the Keewatin region of the Northwest Territories, and non-Aboriginal Canadians (predominantly of European heritage) in the province of Manitoba. The MetS was identified among adult subjects according to the National Cholesterol Education Program (NCEP) definition. Prevalence rates were standardized to the 1991 Canadian national population.

RESULTS

The age-standardized prevalence of the MetS varied by ethnic group, ranging from as high as 45% among Native Indian women to as low as 8% among Inuit men. Compared with Canadians of European origin, Indians had a worse metabolic profile, while Inuit had a better metabolic profile except for a high rate of abdominal obesity. The NCEP criteria in identifying individuals with the MetS were compared to those of the World Health Organization (WHO) in a subset of subjects with the requisite laboratory data. There was moderate agreement between the NCEP and WHO definitions, with a kappa value of 0.63 (95% confidence interval 0.56-0.70).

CONCLUSIONS

The results indicate that the MetS is prevalent in diverse ethnic groups in Canada but varies in the pattern of phenotypic expression. Given the diverse nature of these populations, careful consideration should be given to developing culturally appropriate community-based prevention strategies aimed at reducing the frequency of this syndrome.

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.

The metabolic syndrome in Chinese, Malays and Asian Indians. Factor analysis of data from the 1998 Singapore National Health Survey

We used factor analysis to define and compare the manner in which the various features of the metabolic syndrome are linked or clustered in Chinese, Malays and Asian Indians. One thousand nine hundred and fifty seven men (1324 Chinese, 391 Malays and 261 Asian Indians) and 2308 women (1622 Chinese, 391 Malays and 296 Asian Indians) were examined. Anthropometry, blood pressure, serum glucose, lipid concentrations, and serum insulin were measured for all subjects. These data were then subjected to factor analysis which reduced the variables examined to three factors in all ethnic groups and both genders. The first (dyslipidemia) factor was positively loaded for obesity, insulin resistance (IR), fasting triglyceride and negatively loaded for HDL-cholesterol. The second (hyperglycemia) factor was positively loaded for IR and blood glucose. The third (hypertension) factor was positively loaded for obesity and blood pressure. IR was positively loaded in the hypertension factor in Malay women but not in others. Rather than a single entity causally associated with insulin resistance (IR), our findings support a concept in which the metabolic syndrome represents several distinct entities (dyslipidemia, hypertension and hyperglycemia). It appears that Malay females may be more prone to develop hypertension in association with IR.

Factor analysis of metabolic syndrome among the middle-aged Bengalee Hindu men of Calcutta, India

BACKGROUND

The prevalence of coronary heart disease (CHD) is known to be very high in the people of Indian origin. In India, rates are rising and CHD has been predicted to rank first among the causes of death in the Indian population by 2015. The reasons for the increased susceptibility of Indians to CHD are yet to be understood completely. However, studies hinted that clustering of risk variables of the metabolic syndrome (MS) could be responsible for the increasing incidence of CHD in the Indians. Therefore, identification of the components of the MS could be one aspect in the way to curb the increasing incidence of CHD among the Asian Indians.

METHODS

Principal component factor analysis (PCFA) was undertaken to identify the components or factors of the metabolic syndrome (MS) among the middle-aged Bengalee Hindu men of Calcutta, India, and was compared with the findings from other studies. The present cross-sectional study consisted of 212 Bengalee Hindu men aged 30 years and above. Besides anthropometric measures, lipid profile, blood pressure, and fasting plasma glucose (FPG) were collected from each participant. Waist-hip ratio (WHR), trunk-extremity ratio (TER), and central fat skinfold ratio (CFSR) were computed accordingly. The lipid profile measures that were included were total cholesterol (TC), fasting triglyceride (FTG), high (HDL-C), low (LDL-C), and very low density lipoprotein cholesterol (VLDL-C).

RESULTS

Principal components factor analysis revealed four uncorrelated factors that cumulatively explained 72.37% of the observed variance of the metabolic syndrome by measured variables. These four factors could be identified as central obesity (factor 1), centralized subcutaneous fat (factor 2), lipid profile blood glucose (factor 3), and blood pressure (factor 4). The present factor analysis confirms the general finding from other factor analyses of the metabolic syndrome on different ethnic groups that have identified three to four factors. Furthermore, the first two factors, that is, central obesity and centralized subcutaneous fat cumulatively explained 47% of the observed variance of metabolic syndrome in this population.

CONCLUSION

Since more than one factor was identified for the metabolic syndrome and as no observed variable loaded on all four factors, therefore, more than one physiological mechanism could be accounted for the clustering of risk variables of the metabolic syndrome among the Bengalee Hindu men.

Metabolic and inflammation variable clusters and prediction of type 2 diabetes: factor analysis using directly measured insulin sensitivity

Factor analysis, a multivariate correlation technique, has been used to provide insight into the underlying structure of the metabolic syndrome. The majority of previous factor analyses, however, have used only surrogate measures of insulin sensitivity; very few have included nontraditional cardiovascular disease (CVD) risk factors such as plasminogen activator inhibitor (PAI)-1, fibrinogen, and C-reactive protein (CRP); and only a limited number have assessed the ability of factors to predict type 2 diabetes. The objective of this study was to investigate, using factor analysis, the clustering of metabolic and inflammation variables using data from 1,087 nondiabetic participants in the Insulin Resistance Atherosclerosis Study (IRAS) and to determine the association of these clusters with risk of type 2 diabetes at follow-up. This study includes information on directly measured insulin sensitivity (S(i)) from the frequently sampled intravenous glucose tolerance test among African-American, Hispanic, and non-Hispanic white subjects aged 40-69 years. Principal factor analysis of data from nondiabetic subjects at baseline (1992-1994) identified three factors, which explained 28.4, 7.4, and 6% of the total variance in the dataset, respectively. Based on factor loadings of >or= 0.40, these factors were interpreted as 1) a "metabolic" factor, with positive loadings of BMI, waist circumference, 2-h glucose, log triglyceride, and log PAI-1 and inverse loadings of log S(i) + 1 and HDL; 2) an "inflammation" factor, with positive loadings of BMI, waist circumference, fibrinogen, and log CRP and an inverse loading of log S(i) + 1; and 3) a "blood pressure" factor, with positive loadings of systolic and diastolic blood pressure. The results were similar within strata of ethnicity, and there were only subtle differences in sex-specific analyses. In a prospective analysis, each of the factors was a significant predictor of diabetes after a median follow-up period of 5.2 years, and each factor remained significant in a multivariate model that included all three factors, although this three-factor model was not significantly more predictive than models using either impaired glucose tolerance or conventional CVD risk factors. Factor analysis identified three underlying factors among a group of inflammation and metabolic syndrome variables, with insulin sensitivity loading on both the metabolic and inflammation variable clusters. Each factor significantly predicted diabetes in multivariate analysis. The findings support the emerging hypothesis that chronic subclinical inflammation is associated with insulin resistance and comprises a component of the metabolic syndrome.

Heritability of multivariate factors of the metabolic syndrome in nondiabetic Japanese americans

A rapidly growing body of evidence demonstrates important associations between the metabolic syndrome, characterized by a cluster of risk factors or phenotypes that include dyslipidemia, central obesity, hypertension, and hyperinsulinemia, and both cardiovascular disease and type 2 diabetes. The purpose of the present study was to characterize the metabolic syndrome in a sample of 432 individuals from 68 Japanese-American families, using factor analysis of quantitative phenotypes, and to estimate the heritability of these independent factors. Using nine characteristic phenotypes that included LDL particle size and C-reactive protein (CRP), factor analysis identified three multivariate factors interpreted as lipids, body fat/insulin/glucose/CRP, and blood pressure, explaining 65% of the variance. Heritability analysis revealed significant genetic effects on all of the factors: lipids (h(2) = 0.52, P < 0.001), body fat/insulin/glucose/CRP (h(2) = 0.27, P = 0.016), and blood pressure (h(2) = 0.25, P = 0.026). This analysis shows that independent, multivariate factors of the metabolic syndrome are heritable, demonstrating genetic influences on the underlying pathophysiological mechanisms of the syndrome.

A confirmatory factor analysis evaluation of the coronary heart disease risk factors of metabolic syndrome with emphasis on the insulin resistance factor

AIM

The goals of this study were: (1) to analyse the underlying associations between coronary risk factors and the metabolic syndrome and (2) to evaluate the construct validity of the variables used to measure each factor.

METHODS

The subjects were from a previously studied cohort of 284 middle-aged Caucasian males from Goteborg, Sweden, who were selected from the National Population Register. A confirmatory factor analysis was performed using EQS Multivariate Software Version 5.7b with maximum likelihood estimation. Hypertension, obesity, insulin resistance and hyperlipidaemia were the latent factors hypothesized.

RESULTS

The final, four-factor model showed good fit, with significant intercorrelations noted between all factors. The highest correlations were noted between the insulin resistance factor and the obesity factor (r = 0.887) and the insulin resistance factor and the lipid factor (r = 0.835). All factors exhibited good values for construct reliability and variance extracted except for the insulin resistance factor, which was measured with the variables of fasting insulin and fasting glucose levels.

CONCLUSIONS

A four-factor model of metabolic syndrome including the coronary heart disease risk factors of hypertension, obesity, insulin resistance and hyperlipidaemia was developed using this sample of European, middle-aged Caucasian males. Insulin resistance was not well defined using the variables of fasting insulin and fasting glucose levels. Other possible variables to include in the measurement of this factor are discussed.

Genotype, obesity and cardiovascular disease--has technical and social advancement outstripped evolution?

Teleologically, our ancestors were highly adapted hunter-gatherers. In recent history, the environment in which Homo sapiens exists has altered drastically and humans are exposed to environments for which the hunter-gatherer genotype is ill-suited. The adoption of a sedentary Western lifestyle, and the case of obtaining food of a high calorific content imposed upon a thrifty genotype, have resulted in the current global epidemic of obesity, Type 2 diabetes and the Metabolic Syndrome. The ramification of this epidemic is that cardiovascular disease is becoming a global healthcare problem, which will have its greatest impact on the developing nations. A global strategy is required to reduce the impact of the Western lifestyle on the health of developing nations and prevent obesity and Type 2 diabetes. Such an approach needs to be culturally sensitive, integrated, and multidisciplinary and involve a range of interventions that work at the individual and community levels. If lifestyle measures fail, then pharmacological intervention may be necessary. For this, novel agents such as dual PPARalpha/gamma agonists may be the therapy of the future.