Segregation analysis of waist circumference, hip circumference and waist-to-hip ratio in the Korean Nationwide Family Study

Metabolically healthy obesity and the risk of all-cause and cardiovascular disease mortality in a Korean population: a prospective cohort study

OBJECTIVES

This study aimed to examine the association between metabolically healthy obesity and all-cause and cardiovascular disease (CVD) mortality in a Korean population.

DESIGN

A prospective study.

SETTING

This study used data from the Korean Genome and Epidemiology Study.

PARTICIPANTS

A total of 140 137 participants were followed up over a median period of 9.2 years. Participants were categorised into four groups according to obesity (obese: body mass index ≥25 kg/m² or non-obese) and metabolic health (metabolically unhealthy: two or more metabolic abnormalities or metabolically healthy).

PRIMARY AND SECONDARY OUTCOME MEASURES

All-cause and CVD mortality of the participants until 31 December 2018 were ascertained by the National Health Insurance Service of beneficiary status of Korea.

RESULTS

Metabolically unhealthy non-obese participants were at elevated risk of all-cause mortality (HR, 1.12; 95% CI, 1.04 to 1.21; p=0.0019) and CVD mortality (HR, 1.39; 95% CI, 1.17 to 1.65; p=0.0002), particularly mortality from ischaemic heart disease (IHD) (HR, 1.54; 95% CI, 1.10 to 2.14; p=0.0116) compared with metabolically healthy non-obese participants. Surprisingly, metabolically healthy obese participants were at reduced risk of all-cause mortality (HR, 0.89; 95% CI, 0.81 to 0.98; p=0.0197). Metabolically unhealthy obese participants were at elevated risk of CVD mortality (HR, 1.51; 95% CI, 1.26 to 1.81; p<0.0001) and IHD mortality (HR, 1.88; 95% CI, 1.35 to 2.63; p=0.0002) compared with metabolically healthy non-obese participants.

CONCLUSIONS

In a Korean population, metabolically healthy obese participants had reduced risk of all-cause mortality compared with their non-obese counterparts, whereas metabolically unhealthy participants had elevated risk of CVD mortality, in particular mortality from IHD regardless of obesity.

Predictive performance of anthropometric indexes of central obesity for the risk of type 2 diabetes

BACKGROUND

In spite of several available anthropometric indexes, the relative merit of these indexes for the prediction of type 2 diabetes remains unknown. Considering that obesity and diabetes commonly coexist as co-morbidities, our objective was to directly compare the performance of measures of central and general obesity to predict the risk of type 2 diabetes.

METHODS

We conducted a case-control study of type 2 diabetes on 150 cases and 150 age- and gender-matched controls. We directly compared the predictive performance of five anthropometric indexes: four related to central obesity--waist circumference (WC), waist/hip ratio (WHR), abdominal volume index (AVI) and conicity index (CI); and one related to general obesity--body mass index (BMI). We used various statistical approaches like area under (AUC) receiver-operating characteristic (ROC) curves, likelihood ratios, logistic regression and Shannon's entropy to compare the performance of the indexes in the study sample as well as bootstrapped samples.

RESULTS

WC had the highest overall predictive accuracy that was gender insensitive (AUC=0.77 in males and 0.74 in females); a comparable information content as that of AVI (Shannon's entropy=1.81 for WC and 1.84 for AVI) and was a better predictor of the risk of type 2 diabetes than all the remaining indexes. WC also correlated strongly with the biochemical markers of diabetes like blood sugar and lipid profile.

CONCLUSIONS

WC is a simple, non-invasive and accurate predictor of the risk of type 2 diabetes that can potentially be used in screening programs in developing countries.

Which anthropometric indices best predict metabolic disorders in Taiwan?

OBJECTIVES

The aim of this survey was to assess the association between the three simple anthropometric indices (body mass index [BMI], waist-to-hip ratio (WHR), and waist circumference [WC]) and various metabolic disorders, and to identify which indices can best predict metabolic disorders in Taiwan.

METHODS

A cross-sectional hospital-based survey was carried out from January to December 2000. We retrospectively analyzed the medical records of all the patients receiving periodic health examination with scheduled items at China Medical University Hospital. Anthropometric indices, metabolic profiles, and abdominal sonography were performed. A total of 746 people aged 19 to 87 were recruited as subjects for this study. The t test, chi2 test, and stepwise multivariate logistic regression were used.

RESULTS

The subjects included 44.5% women and 55.5% men, with a mean age of 50.74 +/- 12.68 years. After controlling for the other covariables, stepwise multivariate logistic regression showed considerable statistical significance between overall obesity and hypertension, hypertriglyceridemia, hyperuricemia, and fatty liver. There is also statistical significance between abdominal obesity and abnormal ratio of total cholesterol HDL (high-density lipoprotein), hyperuricemia, and fatty liver. None of the indices revealed any association with hyperglycemia, hypercholesterolemia, abnormal low-density lipoprotein, or abnormal HDL.

CONCLUSIONS

BMI and WC can best predict some metabolic disorders. For practical reasons, the combined measurement of BMI and WC is the simple and inexpensive anthropometric index for primary health care settings in the routine physical examinations of adults. We hope this study can establish the background data for further investigation on the epidemiology of anthropometric indices in Taiwan.

Genome-wide linkage to chromosome 6 for waist circumference in the Framingham Heart Study

While several loci for BMI have been identified, it is not known whether genes underlie the process of regional fat deposition. We sought to test whether waist circumference, a measure of central adiposity, contains a genetic component. Variance components linkage analysis was performed on 330 families from the Framingham Heart Study original and offspring cohorts, using a 10-cM genome-wide linkage analysis. Overall, 2,086 subjects (51% women), mean age 48 years, were available for analysis. The overall heritability of waist circumference was 0.41. The maximum logarithm of odds (LOD) score in the full dataset was 3.3 on chromosome 6 at marker D6S1009; when subjects were limited to those aged <60 years, the peak LOD score was 3.7 at the same location. Substantial evidence exists for linkage to waist circumference, a measure of central adiposity. Potential candidate genes include ESR1, OPRM1, and NMBR. Further research is necessary to understand the genes involved in central adiposity.

Uncoupling protein 1 and 3 polymorphisms are associated with waist-to-hip ratio

Body weight regulation is a complex phenotype also depending on the action of uncoupling proteins (UCPs) that mediate the "uncoupling" of respiration leading to the dissipation of energy as heat. This study investigated whether genetic variants in the genes encoding UCP-1 and UCP-3 are associated with different obesity-related phenotypes in 162 whites with a wide range of body mass index. All subjects were genotyped for the polymorphisms UCP-1 A-3826G, UCP-1 Ala64Thr, and UCP-3 C-55T using a PCR-based restriction method with appropriate enzymes. The frequencies of the UCP-1 3826G, UCP-1 64Thr, and UCP-3 55T alleles were 27.2%, 12.0%, and 22.8%, respectively. No significant associations were observed between polymorphism and body mass index or obesity. However, after adjustment for gender, age, body mass index, and diabetes mellitus the waist-to-hip ratio was significantly associated with UCP-1 Ala64Thr ( P=0.003) and UCP-3 C-55T ( P=0.02) but not with UCP-1 A-3826G. The higher waist-to-hip ratios associated with the UCP-1 64Thr and UCP-3 55T alleles were due to higher waist circumference in these allele carriers. In conclusion, central obesity in whites as reflected by an increased waist-to-hip ratio is associated with the UCP-1 Ala64Thr and UCP-3 C-55T polymorphisms. To what extent these genotypes contribute to the overall cardiovascular risk remains to be elucidated.