Body composition in Chinese subjects: comparison with data from North America

Body mass index and waist-to-hip ratio misclassification of overweight and obesity in Chinese military personnel

BACKGROUND

The rising prevalence of obesity in military personnel has raised great concerns. Previous studies suggest that body mass index (BMI)- and waist-to-hip ratio (WHR)-based obesity classifications in US military personnel and firefighters have high false negative and subsequently cause obesity misclassification.

OBJECTIVE

To determine whether BMI and WHR could reflect the fat mass of Chinese military personnel.

METHODS

Three hundred fifty-three male Chinese military personnel and 380 age-matched male adults were recruited. Obesity classification was defined by BMI, WHR, and body fat percentage (BFP).

RESULTS

Chinese military personnel had extremely low obesity rate determined by either BFP (0.3%) or BMI (0.6%). By combining overweight and obese individuals, BMI- and WHR-determined prevalence of overweight/obesity was 22.4% and 17.0% compared to BFP-based standard (4.0%) (P < 0.05). In reference to BFP, BMI and WHR have high false-positive rate compared to the control group. Further analysis showed that Chinese military personnel consisted of high percentage of BFP^lowBMI^high and/or BFP^lowWHR^high subpopulations. Eighty-one percent of BMI^high and 78.3% of WHR^high of them were BFP low.

CONCLUSIONS

Chinese military personnel has extremely low obesity rate. BMI and WHR have high false-positive rates in reference to BFP, which cannot accurately reflect the mass of adipose tissue and leads to obesity misclassification.

Identifying cut-points in anthropometric indexes for predicting previously undiagnosed diabetes and cardiovascular risk factors in the Tongan population

SUMMARY

There is growing concern that a single standard definition of overweight and obesity may not suit all ethnic groups. This study aimed to evaluate different anthropometric cut-points as indicators of risk for Type 2 diabetes (T2DM), hypertension and dyslipidaemia in a cross sectional, representative sample of the population of the Kingdom of Tonga (767 subjects: 314 males, 453 females). Anthropometric measurements included weight, height, waist circumference (WAIST), waist-to-hip ratio (WHR), weight-to-height ratio (WhgtR) and percentage body fat (%fat) using bioelectrical impedance. Risk factors investigated were systolic (sBP) and diastolic blood pressure (dBP), plasma glucose, total cholesterol, HDL cholesterol and triglycerides, hypertension and T2DM. The best predictive cut-points were identified using receiver operating characteristic (ROC) curves. The cut-points identified in this cross-sectional study contrast with those from studies in Caucasian and Asian populations. Optimal cut-points for predicting risk for T2DM, dyslipidaemia and hypertension in men were 29.3-31.7 kg/m(2) for BMI; 98.8-102.9 cm for WAIST; 0.91-0.93 for WHR and 0.56-0.60 for WhgtR. For women, the cut-points were 34.0-35.0 kg/m(2) (BMI), 100.0-102.8 cm (WAIST), 0.83-0.86 (WHR) and 0.60-0.62 (WhgtR). Mean area under the curve (AUC) measurements for each index ranged between 0.57 and 0.75 for men and 0.49 and 0.72 for women. The indexes with the highest AUCs for men were WAIST, WhgtR and BMI; and for women were WAIST and WhgtR. Use of a 100 cm tape for measuring WAIST is recommended as a simple public health and clinical indicator of risk until longitudinal follow-up studies can confirm findings of this study.:

Applicability of chronic kidney disease epidemiology collaboration equations in a Chinese population

BACKGROUND

Accurate estimated glomerular filtration rates (eGFR) is an important step in the diagnosis of chronic kidney disease (CKD). The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, based on creatinine alone (eGFRcr), was developed to improve on the Modification of Diet in Renal Disease equation, in particular by addressing the systematic underestimation of high GFR. Whether the CKD-EPI equation, based on cystatin C alone (eGFRcys), or the combined creatinine-cystatin C CKD-EPI equation (eGFRcr-cys C), actually perform better than the CKD-EPI equation based on creatinine (eGFRcr) remains unknown, especially in Asians including Chinese populations, where eGFR equations may overestimate true GFR.

METHODS

A standard dual plasma sampling method (DPSM) of estimating (99m)Tc-diethylene triamine penta-acetic acid clearance was used to determine the reference or measured GFR (mGFR). Linear regression analysis, Bland-Altman analysis, bias, absolute bias and accuracy (P30) were used to compare the performance of the combined creatinine-cystatin C equation (eGFRcr-cys) and equations based on each marker alone (eGFRcr and eGFRcys) in Chinese subjects, including both patients with CKD and healthy individuals.

RESULTS

We enrolled 617 Chinese participants (49.11% female, 47.11 ± 17.25 years old), with a mean mGFR of 73.80 ± 37.55 mL/min/1.73 m(2). The predictive abilities (r), the accuracy (P15, P30, P50), bias and absolute bias of the eGFRcr-cys equation were superior to eGFRcr equation and the eGFRcys equation in overall samples. Bland-Altman analysis also demonstrated a consistent result. When compared in subgroups, the accuracy (P30) of all three equations exceeded 90% at mGFR ≥90 mL/min/1.73m(2); the eGFRcr-cys equation had the highest accuracy (P30: 95.56%). At mGFR 60-89 mL/min/1.73 m(2), the accuracies (P30) of the eGFRcr-cys and eGFRcr equations exceeded the acceptable level (≥70%), and there was no significant difference between them (P = 0.58). At mGFR <60 mL/min/1.73 m(2), the accuracy (P30) of all three equations was below 70%, but the eGFRcr-cys equation had the greatest precision.

CONCLUSIONS

The performances of the eGFRcr-cys and eGFRcr equations were similar to superior to that of the eGFRcys equation at higher GFR levels in an Asian population, especially in normal and mild to moderate kidney disease. Further improvement is needed for these equations at GFR <60 mL/min per 1.73 m(2).

Ethnic differences in body composition and obesity related risk factors: study in Chinese and white males living in China

The purpose of this cross-sectional observational study was to identify ethnic differences in body composition and obesity-related risk factors between Chinese and white males living in China. 115 Chinese and 114 white male pilots aged 28-63 years were recruited. Fasting body weight, height and blood pressure were measured following standard procedures. Whole-body and segmental body composition were measured using an 8-contact electrode bioimpedance analysis (BIA) system. Fasting serum glucose, fasting plasma total cholesterol (TC), high-density lipoprotein (HDL) cholesterol, and triglycerides (TG) were assessed using automatic biochemistry analyzer. After adjusting for age and body mass index (BMI), Chinese males had significantly higher percentage of body fat (PBF) both with respect to whole body (Chinese: 23.7%±0.2% vs. Whites: 22.4%±0.2%) and the trunk area (Chinese: 25.0%±0.3% vs. Whites: 23.2%±0.3%) compared to their white counterparts. At all BMIs, Chinese males had significantly higher fasting glucose levels (Chinese: 5.7±1.0 mmol/L vs. Whites: 5.2±1.0 mmol/L) but lower high-density lipoprotein levels (Chinese: 0.8±1.0 mmol/L vs. Whites: 1.0±1.0 mmol/L) than white males. In addition, a marginally significantly higher diastolic blood pressure was found among Chinese men than that among white men (Chinese: 80±1.0 mmHg vs. Whites: 77±1.0 mmHg). Chinese males had more body fat and a greater degree of central fat deposition pattern than that seen in white males in the present study. Furthermore, data on blood pressure, fasting glucose and blood lipids suggest that Chinese men may be more prone to obesity-related risk factors than white men.

Mild to moderate renal impairment is associated with increased left ventricular mass

BACKGROUND

Mild to moderate renal impairment (MMRI) is associated with an excess cardiovascular mortality but the reason for this is unclear. Increased left ventricular mass (LVM) is associated with severe renal dysfunction and a higher cardiovascular mortality. However, whether increased LVM also occurs in patients with milder renal dysfunction is unknown.

METHODS

336 consecutive patients under investigation for chest pain who underwent concurrent coronary angiography, serum creatinine (Cr) and LVM assessment, were recruited from a university hospital in Shanghai, China. The main outcome measures were: LVM normalised for body surface area (NLVM), renal function determined by Cr, creatinine clearance (CrCl) (Cockroft-Gault equation) and glomerular filtration rate (GFR) (Modification of Diet in Renal Disease equation).

RESULTS

Mean+/-SD age was 56.8+/-9.5 years, 282 (84%) were male, mean NLVM 107.1+/-36.8 g/m(2), Cr 0.94+/-0.22 mg/dL, CrCl 82.7+/-21.7 mL/min/1.73 m(2) and GFR 89.4+/-24.6 mL/min/1.73 m(2). NLVM was related to Cr (r=-0.30), CrCl (r=0.19) and GFR (r=0.24) (all p<0.001). A multiple logistic regression model using quartile analysis of renal function showed that those patients with a Cr 1.06-2.00 mg/dL, CrCl 34.8-67.5 mL/min/1.73 m(2) and a GFR 36.2-73.4 mL/min/1.73 m(2) were significantly associated with increased NLVM, independent of other variables. Using definitions derived from the National Kidney Foundation Guidelines multiple regression analysis showed MMRI to be independently associated with increased NLVM: Cr 1.2-1.9 mg/dL, odds ratio (OR) 2.77 (CI 1.04-7.40) (p=0.04); CrCl 30-89.9 mL/min/1.73 m(2), OR 1.63 (CI 0.91-2.93) (p=0.11); GFR 30-89.9 mL/min/1.73 m(2), OR 1.76 (CI 1.07-2.90) (p=0.03).

CONCLUSION

In patients being investigated for chest pain, MMRI is significantly and independently associated with increased LVM.

Application of GFR-estimating equations in Chinese patients with chronic kidney disease

BACKGROUND

To evaluate whether the Modification of Diet in Renal Disease (MDRD) equations could be applied accurately to Chinese patients with chronic kidney disease (CKD), glomerular filtration rates (GFRs) estimated by using MDRD equation 7 (7GFR), the abbreviated MDRD equation (aGFR), and the Cockcroft-Gault equation (cGFR) were compared in patients with different stages of CKD.

METHODS

The study enrolled patients with CKD diagnosed according to the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative guidelines. All patients were older than 18 years and without acute renal function deterioration, edema, skeletal muscle atrophy, or amputation. Sex, age, body height, and body weight were recorded, and plasma creatinine levels were measured by means of Jaffe's kinetic method using a Hitachi 7600 analyzer (Hitachi, Tokyo, Japan; reagents from Roche Diagnostics, Mannheim, Germany). Creatinine, urea, and albumin were measured in a single clinical laboratory. Dual plasma sampling of technetium Tc 99m-labeled diethylene triamine pentaacetic acid plasma clearance was used as the reference standard GFR (sGFR) for comparison of 7GFRs, aGFRs, and cGFRs at different stages of CKD.

RESULTS

The study enrolled 261 patients, including 146 men and 115 women. Causes of CKD included primary or secondary glomerular disease, obstructive kidney disease, chronic tubulointerstitial disease, and others. Values for 7GFR, aGFR, and cGFR were significantly greater than for sGFR in patients with CKD stages 4 to 5 (the lower the sGFR, the greater the difference); whereas 7GFR, aGFR, and cGFR were significantly lower than sGFR in patients with CKD stage 1.

CONCLUSION

Our results show that in a Chinese population with CKD, MDRD equation 7 and the abbreviated MDRD equation overestimated GFR in patients with CKD stages 4 to 5 and underestimated GFR in those with CKD stage 1. These results indicate that careful modification of these equations may be necessary in Chinese populations with CKD.

Field methods for body composition assessment are valid in healthy chinese adults

There is little information on the accuracy of simple body composition methods in non-Western populations. We determined the percentage of body fat (%BF) by isotope dilution [oxygen-18 (H(2)(18)O) and deuterium oxide ((2)H(2)O)] and anthropometry in 71 healthy, urban Chinese adults aged 35-49 y [body mass index (BMI) 18-35 kg/m(2)]. The accuracy of several prediction equations for assessment of %BF from skinfold measurements was evaluated against %BF determined by H(2)(18)O dilution. We also assessed the relationship between BMI and %BF, and the fat-free mass (FFM) hydration coefficient for our population. All skinfold equations yielded means within approximately 2%BF of H(2)(18)O-derived %BF. However, on the basis of residual plot analysis and the 95% confidence interval (CI) for the mean difference between methods, the equations of Durnin and Womersley (for assessment of body density from skinfolds) coupled with that of Brozek et al. (for assessment of %BF from body density) provided the most valid assessment for individuals. In addition, the FFM hydration coefficient averaged 0.734 +/- 0.002 (SEM), indicating that the usually assumed value of 0.732 is appropriate for this population. Finally, although BMI had high specificity (90%) for classifying individuals as having body fat within the normal range (<24%BF for men, and <35%BF for women), it had poor sensitivity (66%) for identifying individuals as having high body fat. We conclude that compared with H(2)(18)O dilution, skinfold thickness can provide an accurate and reliable assessment of body composition in healthy Chinese adults. Furthermore, using the equation of Brozek et al. may be preferable to using Siri's equation to predict %BF from body density in populations in which individuals have >30%BF.

Total body water reference values and prediction equations for adults

BACKGROUND

The clinical interpretation of total body water (TBW) necessitates the availability of timely comparative reference data. The prediction of TBW volume in renal disease is critical in order to prescribe and monitor the dose of dialysis in the determination of Kt/V. In clinical practice, urea distribution (V) is commonly predicted from anthropometric equations that are several decades old and for white patients only. This article presents new reference values and prediction equations for TBW from anthropometry for white and black adults.

METHODS

The study sample included four data sets, two from Ohio and one each from New Mexico and New York, for a total of 604 white men, 128 black men, 772 white women, and 191 black women who were 18 to 90 years of age. The TBW concentration was measured by the deuterium or tritium oxide dilution method, and body composition was measured with a Lunar DXA machine. An all-possible-subsets of regression was used to predict TBW. The accuracy of the selected equations was confirmed by cross-validation.

RESULTS

Blacks had larger TBW means than whites at all age groups. The 75th TBW percentile for whites approximated the TBW median for blacks at most ages. The white men and black men and women had the largest TBW means ever reported for healthy individuals. The race- and sex-specific TBW prediction equations included age, weight, and stature, with body mass index (BMI) substituted for weight in the white men. The root mean square errors (RMSEs) and standard errors for the individual (SEIs) ranged from approximately 3.8 to 5.0 L for the men and from 3.3 to 3.6 L for the women. In both men and women, high values of TBW were associated with high levels of total body fat (TBF) and fat-free mass (FFM).

CONCLUSION

: TBW in these healthy adults is relatively stable through a large portion of adulthood. There are significant race and sex differences in TBW. These accurate and precise equations for TBW provide a useful tool for the clinical prediction of TBW in renal disease for white and black adults. These are the first TBW prediction equations that are specific for blacks.

Body fat measurement among Singaporean Chinese, Malays and Indians: a comparative study using a four-compartment model and different two-compartment models

This cross-sectional study compared body fat percentage (BF%) obtained from a four-compartment (4C) model with BF% from hydrometry (using 2H2O), dual-energy X-ray absorptiometry (DXA) and densitometry among the three main ethnic groups (Chinese, Malays and Indians) in Singapore, and determined the suitability of two-compartment (2C) models as surrogate methods for assessing BF% among different ethnic groups. A total of 291 subjects (108 Chinese, seventy-six Malays, 107 Indians) were selected to ensure an adequate representation of age range (18-75 years) and BMI range (16-40 kg/m2) of the general adult population, with almost equal numbers from each gender group. Body weight was measured, together with body height, total body water by 2H2O dilution, densitometry with Bodpod and bone mineral content with Hologic QDR-4500. BF% measurements with a 4C model for the subgroups were: Chinese females 33.5 (sd 7.5), Chinese males 24.4 (sd 6.1), Malay females 37.8 (sd 6.3), Malay males 26.0 (sd 7.6), Indian females 38.2 (sd 7.0), Indian males 28.1 (sd 5.5). Differences between BF% measured by the 4C and 2C models (hydrometry, DXA and densitometry) were found, with underestimation of BF% in all the ethnic-gender groups by DXA of 2.1-4.2 BF% and by densitometry of 0.5-3.2 BF%). On a group level, the differences in BF% between the 4C model and 2H2O were the lowest (0.0-1.4 BF% in the different groups), while differences between the 4C model and DXA were the highest. Differences between the 4C model and 2H2O and between the 4C model and DXA were positively correlated with the 4C model, water fraction (f(water)) of fat-free mass (FFM) and the mineral fraction (f(mineral)) of FFM, and negatively correlated with density of the FFM (D(FFM)), while the difference between 4C model and densitometry correlated with these variables negatively and positively respectively (i.e. the correlations were opposite). The largest contributors to the observed differences were f(water) and D(FFM). When validated against the reference 4C model, 2C models were found to be unsuitable for accurate measurements of BF% at the individual level, owing to the high errors and violation of assumptions of constant hydration of FFM and D(FFM) among the ethnic groups. On a group level, the best 2C model for measuring BF% among Singaporeans was found to be 2H2O.

The prediction of body composition in Chinese Australian females

OBJECTIVE

To determine the efficacy of applying specific body composition techniques to, and assess the relationship between body mass index (BMI) and body fat levels for Chinese Australian females.

DESIGN

Statistical comparative analysis of body composition techniques.

SUBJECTS

Australian resident females of Chinese extraction (n=40) (aged 18-45 y, mean 32.5+/-8.0; BMI range 15.7-30.9 kg/m2, mean 21.7+/-3.1 kg/m2, median 20.8 kg/m2).

MEASUREMENTS

Body composition determined using bio-electrical impedance analysis (BIA), the skin-fold equations of Durnin and Womersley (D&W) and a deuterium dilution technique. Body size was calculated as the body mass index (BMI) weight/height(2) (kg/m2).

RESULTS

With a median BMI of 20.8, range 15.7-30.9, an acceptable BMI existed for 87.5% of the subjects (mean (s.d.) 21.7+/-3.1 kg/m2). Percentage fat mass (%FM) from the deuterium dilution technique (mean (s.d.) 35.6+/-6.4) suggested 75% were overweight or obese. %FM from the D&W equation (mean (s.d.) 28.0+/-3.9) and BIA (mean (s.d.) 29.4+/-5.1) also indicated a tendency towards overweight or obese. The deuterium technique was significantly correlated and significantly different to the D&W eqn, r=0.71 P=0.001; and BIA, r=0.77, P=0.001. Bland and Altman analysis indicated that bias existed between the techniques (BIA mean (s.d.)-6.7+/-4.1) and D&W equation mean (s.d.)-6+/-4.5) when compared to the deuterium method.

CONCLUSIONS

Despite a low mean BMI, body fat levels determined by the three methods suggested that, overall, an unsatisfactory body composition existed. The levels of overweight and obesity (%FM>30) were higher than reported in previous research despite a mean BMI lower than the Australian national average. Comparative analysis suggested that the body fat prediction techniques used may be precise but not accurate. Comparative results obtained for the BIA and D&W equation techniques suggest an overestimation of body fat levels for leaner individuals and under estimation for overfat individuals. The results support the notion that accurate determination of body composition and the determination of appropriate body size may require equations developed for specific ethnic populations.

The validity of predicted body composition in Chinese adults from anthropometry and bioelectrical impedance in comparison with densitometry

Body composition was measured by densitometry in a group of eighty-one Chinese males and 124 healthy Chinese females, aged 18-67 years. Biceps, triceps, subscapular and suprailiac skinfolds were measured as well as total body bioelectrical impedance at 50 kHz. Mean heights were 1.71 (SD 0.05) and 1.61 (SD 0.06) m, body weights 66.1 (SD 9.1) and 57.2 (SD 9.4) kg and BMI 22.7 (SD 3.0) and 22.0 (SD 3.3) kg/m2 in males and females respectively. Body fat values from body density were 20.1 (SD 6.2) and 29.7 (SD 7.5)% in males and females respectively. Mean predicted body-fat values from skinfolds, bioelectrical impedance and BMI, using prediction formulas developed in Western populations, did not differ or differed only slightly from body-fat values estimated from body density. The SD of the difference for each method was 5% body fat or 3.3 kg fat-free mass (CV 6%), which is approximately equal to the accuracy level of each predictive method. Compared with densitometry the predictive methods overestimated body fat at the lower levels of body fatness, whereas at the higher levels of body fat the predictive methods tended to underestimate body fatness. It is concluded that prediction formulas for estimating body fat from skinfolds, impedance or BMI developed in Western populations are applicable and valid in the adult Chinese population. However, in very lean subjects the predictive methods overestimate body fat compared with values obtained from body density.

Comparison of body composition assessments by bioelectrical impedance and by anthropometry in premenopausal Chinese women

Fat-free mass (FFM) was estimated in forty-seven premenopausal Chinese women, aged 18-43 years, from anthropometric data (skinfolds, body mass index (weight/height2; BMI)) or bioelectrical impedance, using several prediction formulas for body composition from the literature, and values compared with the mean of these three individual methods used as a frame of reference. In thirty-six women these values could be compared with FFM calculated from total body water (TBW) determined by D2O dilution. The prediction formulas used were developed from studies on Caucasian adults and their validity will have to be shown in populations with different ethnic backgrounds. The mean difference between FFM predicted from BMI and the frame of reference was 0.1 kg (95% confidence interval (CI) -0.1, 0.4), from bioelectrical impedance it was 0.5 kg (95% CI 0.3, 0.7), and from skinfolds it was -0.6 kg (95% CI -0.9, -0.4). The mean difference between FFM calculated from TBW and the frame of reference was higher (2.2 kg, 95% CI 1.2, 3.3). The results of the present study indicate that the three methods may be valid for predicting body composition in adult Chinese females, but further research is needed on development and cross-validation of prediction equations for body composition for Chinese.