Prediction of fat-free mass using bioelectrical impedance analysis in young adults from five populations of African origin

Measurement of body composition in postpartum South African women living with and without HIV infection

Background

While several methodologies are available to measure adiposity, few have been validated in sub-Saharan African (SSA) and none in postpartum African women living with HIV (WLHIV). We compared bioelectrical impendence analysis (BIA) and air displacement plethysmography (ADP) against dual x-ray absorptiometry (DXA) in South African women and examined differences by HIV and body mass index (BMI) status.

Methods

Lin's concordance correlation coefficient (CCC) test was used to examine fat mass (FM), fat free mass (FFM), and total body fat percent (%BF) difference between BIA vs. DXA, and ADP vs. DXA in women living with HIV (n = 57) and without HIV (n = 25). The Bland Altman test was used to assess mean differences and the direction of bias.

Results

The median age was 31 years (IQR, 26-35) and months postpartum were 11 (IQR, 7-16), 44% of the women had obesity. Lin's CCC for BIA and ADP vs. DXA were both 0.80 for %BF and 0.97 for FM, and 0.86 and 0.80 for FFM, respectively. Mean differences (DXA-BIA and ADP estimates) were 0.22 ± 4.54% (p = 0.54) and 3.35 ± 3.27% (p < 0.01) for %BF, -0.82 ± 3.56 kg (p = 0.06) and 1.43 ± 2.68 kg (p = 0.01) for FM, -1.38 ± 3.61 kg (p = 0.01) and - 3.34 ± 2.37 kg (p < 0.01) for FFM, respectively. BIA overestimated %BF in WLHIV and underestimated it in women with obesity.

Conclusion

Body composition measurements using BIA and ADP correlated well with DXA, thereby providing alternative, safe tools for measuring postpartum FM and FFM in SSA women, including WLHIV.

The bioelectrical impedance analysis (BIA) international database: aims, scope, and call for data

BACKGROUND

Bioelectrical impedance analysis (BIA) is a technique widely used for estimating body composition and health-related parameters. The technology is relatively simple, quick, and non-invasive, and is currently used globally in diverse settings, including private clinicians' offices, sports and health clubs, and hospitals, and across a spectrum of age, body weight, and disease states. BIA parameters can be used to estimate body composition (fat, fat-free mass, total-body water and its compartments). Moreover, raw measurements including resistance, reactance, phase angle, and impedance vector length can also be used to track health-related markers, including hydration and malnutrition, and disease-prognostic, athletic and general health status. Body composition shows profound variability in association with age, sex, race and ethnicity, geographic ancestry, lifestyle, and health status. To advance understanding of this variability, we propose to develop a large and diverse multi-country dataset of BIA raw measures and derived body components. The aim of this paper is to describe the 'BIA International Database' project and encourage researchers to join the consortium.

METHODS

The Exercise and Health Laboratory of the Faculty of Human Kinetics, University of Lisbon has agreed to host the database using an online portal. At present, the database contains 277,922 measures from individuals ranging from 11 months to 102 years, along with additional data on these participants.

CONCLUSION

The BIA International Database represents a key resource for research on body composition.

Retaining Race in Chronic Kidney Disease Diagnosis and Treatment

The best overall measure of kidney function is glomerular filtration rate (GFR) as commonly estimated from serum creatinine concentrations (eGFRcr) using formulas that correct for the higher average creatinine concentrations in Blacks. After two decades of use, these formulas have come under scrutiny for estimating GFR differently in Blacks and non-Blacks. Discussions of whether to include race (Black vs. non-Black) in the calculation of eGFRcr fail to acknowledge that the original race-based eGFRcr provided the same CKD treatment recommendations for Blacks and non-Blacks based on directly (exogenously) measured GFR. Nevertheless, the National Kidney Foundation and the American Society of Nephrology Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease removed race in CKD treatment guidelines and pushed for the immediate adoption of a race-free eGFRcr formula by physicians and clinical laboratories. This formula is projected to negate CKD in 5.51 million White and other non-Black adults and reclassify CKD to less severe stages in another 4.59 million non-Blacks, in order to expand treatment eligibility to 434,000 Blacks not previously diagnosed and to 584,000 Blacks previously diagnosed with less severe CKD. This review examines: 1) the validity of the arguments for removing the original race correction, and 2) the performance of the proposed replacement formula. Excluding race in the derivation of eGFRcr changed the statistical bias from +3.7 to -3.6 ml/min/1.73m2 in Blacks and from +0.5 to +3.9 in non-Blacks, i.e., promoting CKD diagnosis in Blacks at the cost of restricting diagnosis in non-Blacks. By doing so, the revised eGFRcr greatly exaggerates the purported racial disparity in CKD burden. Claims that the revised formulas identify heretofore undiagnosed CKD in Blacks are not supported when studies that used kidney failure replacement therapy and mortality are interpreted as proxies for baseline CKD. Alternatively, a race-stratified eGFRcr (i.e., separate equations for Blacks and non-Blacks) would provide the least biased eGFRcr for both Blacks and non-Blacks and the best medical treatment for all patients.

Differences in calculated body fat percentage estimated from published equations based on bioelectric impedance analysis in healthy young South African adults

Background

Adult overweight and obesity, in addition to the intake of saturated fat and total serum cholesterol must be monitored as biological risk factors for non-communicable diseases (NCDs). Bioelectric impedance analysis (BIA) provides data on body fat for use in epidemiological settings. However, optimized equations should be used to calculate percentage body fat (%BF). The purpose of this study was to assess the differences between %BF calculated using different published BIA equations and %BF measured by BIA in young South African adults.

Design and methods

In this observational study, differences in calculated %BF were assessed, with different BIA equations retrieved from the literature used in 1128 healthy young adults aged 20-30 years. The %BF (measured by BIA) was compared between equations, between Black and White men and women, respectively.

Results

The results showed statistically significant differences in the %BF calculated from published BIA equations when used in young South African adults (χ² = 946, χ² = 2528, χ² = 2088, respectively, p < 0.0001). In Black and White men and women, respectively, %BF levels were significantly higher when calculated by equations, than when measured by BIA (p < 0.0001).

Conclusion

There seem to be large discrepancies in estimating %BF by BIA equations and these values cannot be used interchangeably for young South African adults. A South African age, ethnicity and sex-specific BIA equation needs to be developed to accurately estimate %BF in young South African adults.

Comparison of Several Prediction Equations Using Skinfold Thickness for Estimating Percentage Body Fat vs. Body Fat Percentage Determined by BIA in 6-8-Year-Old South African Children: The BC-IT Study

Body composition measurement is useful for assessing percentage body fat (%BF) and medical diagnosis, monitoring disease progression and response to treatment, and is essential in assessing nutritional status, especially in children. However, finding accurate and precise techniques remains a challenge. The study compares %BF determined by bioelectrical impedance analysis (BIA) and calculated from available prediction equations based on skinfolds in young South African children. A cross-sectional study performed on 202 children (83 boys and 119 girls) aged 6-8 years. Height and weight, triceps and subscapular skinfolds were determined according to standard procedures. %BF was determined with BIA and three relevant available equations. SPSS analyzed the data using paired samples tests, linear regression, and Bland-Altman plots. Significant paired mean differences were found for BIA and Slaughter (t₂₀₁ = 33.896, p < 0.001), Wickramasinghe (t₂₀₁ = 4.217, p < 0.001), and Dezenberg (t₂₀₁ = 19.910, p < 0.001). For all of the equations, the standards for evaluating prediction errors (SEE) were above 5. The Bland-Altman plots show relatively large positive and negative deviations from the mean difference lines and trends of systematic under- and over-estimation of %BF across the %BF spectrum. All three equations demonstrated a smaller %BF than the %BF measured by BIA, but the difference was smallest with the Wickramasinghe equation. In comparison, a poor SEE was found in the three %BF predicted equations and %BF derived from BIA. As such, an age-specific %BF equation incorporating criterion methods of deuterium dilution techniques or 'gold-standard' methods is needed to refute these findings. However, in the absence of developed %BF equations or 'gold-standard' methods, the available prediction equations are still desirable.

Body adiposity measured by bioelectrical impedance is an alternative to dual-energy x-ray absorptiometry in black Africans: The Africans in America Study

OBJECTIVES

The prevalence of cardiometabolic disease has risen in Africa and parallels the obesity epidemic. To assess cardiometabolic risk, body composition measurements by dual-energy X-ray absorptiometry (DXA) are ideal. In communities with limited resources, alternative measures may be useful but have not been compared extensively in black Africans. Therefore, the aim of this study was to identify alternative methods of body composition assessment, such as body adiposity index (BAI) and bioelectrical impedance analysis (BIA), for use in African-born blacks.

METHODS

This was a cross-sectional study with African-born blacks. BAI and five BIA predictive equations (using variations of height, weight, age, sex, and impedance) were compared with DXA to estimate percent fat. Participants were 266 African-born blacks (39 ± 10 y, body mass index 28 ± 4 kg/m², and 68% men) living in metropolitan Washington DC. Equivalence (90% confidence interval, -3 to 3), concordance, and Bland-Altman analyses (bias <2%, R² closest to zero) compared BAI or BIA predictive equations to DXA as the criterion method.

RESULTS

DXA percent fat was 27.2% ± 5.5% and 40.3% ± 6.9% in men and women, respectively. BAI underestimated percent fat in men (bias: 1.88 ± 4.71, R² = 0.25, P < 0.001) and women (bias: 6.47 ± 4.94, R² = 0.08, P = 0.01). Of the five BIA predictive equations, the equation reported by Sun et al. had the best agreement with DXA percent fat for men (bias: -0.91 ± 3.67, R² = 0.02, P = 0.05) and women (bias: -0.92 ± 4.02, R² = 0.003, P = 0.58). Percent fat from the Sun et al. equation best agreed with DXA percent fat.

CONCLUSION

BIA with the Sun et al. predictive equation was the best alternative to DXA for body fat assessment in African-born blacks.

A Median Analysis of Factors Influencing Body Fatness in Urban School-Age Children in Cameroon

Background

Childhood overweight/obesity is a fast growing public health problem in developing countries. The adverse health consequences of obesity have been attributed to higher body fat levels and this has drawn overwhelming attention towards more accurate assessment of body fat. The goal of this study is to evaluate the relationships between selected behavioral factors and percentage body fat (%BF) estimated using bioelectrical impedance analysis in school-age children.

Methods

A cross-sectional analysis was carried out in randomly selected 6- to 11-year-old children (507 boys and 501 girls). Percentage body fat was assessed using bioelectrical impedance analysis. The behavioral factors were reported by parents using a structured questionnaire. Multiple quantile regression analysis was used to evaluate the relationship between the selected behavioral factors and %BF.

Results

With quantile regression, the daily consumption of fruits and vegetables, daily breakfast consumption, and high physical activity (>4–7 times/week) were significantly (p < 0.001) associated with a 4.95, 3.29, and 3.66 decrease in median %BF, respectively. Also, consumption of snacks (>3 times a day) (p < 0.001), high sedentary lifestyle (>3–6 hours/day) (p < 0.001), and motorization to school (p < 0.005) significantly increased the median %BF by 3.69, 3.01, and 1.39, respectively. The largest changes in median %BF were observed in girls.

Conclusions

Efforts are needed using longitudinal studies to clarify the effects of these behavioral factors on %BF in different regions and ethnic groups of Cameroon and also to assess whether any observed differences are of clinical relevance.

Gut microbiota, short chain fatty acids, and obesity across the epidemiologic transition: the METS-Microbiome study protocol

BACKGROUND

While some of the variance observed in adiposity and weight change within populations can be accounted for by traditional risk factors, a new factor, the gut microbiota, has recently been associated with obesity. However, the causal mechanisms through which the gut microbiota and its metabolites, short chain fatty acids (SCFAs) influence obesity are unknown, as are the individual obesogenic effects of the individual SCFAs (butyrate, acetate and propionate). This study, METS-Microbiome, proposes to examine the influence of novel risk factors, the gut microbiota and SCFAs, on obesity, adiposity and weight change in an international established cohort spanning the epidemiologic transition.

METHODS

The parent study; Modeling the Epidemiologic Transition Study (METS) is a well-established and ongoing prospective cohort study designed to assess the association between body composition, physical activity, and relative weight, weight gain and cardiometabolic disease risk in five diverse population-based samples in 2500 people of African descent. The cohort has been prospectively followed since 2009. Annual measures of obesity risk factors, including body composition, objectively measured physical activity and dietary intake, components which vary across the spectrum of social and economic development. In our new study; METS-Microbiome, in addition to continuing yearly measures of obesity risk, we will also measure gut microbiota and stool SCFAs in all contactable participants, and follow participants for a further 3 years, thus providing one of the largest gut microbiota population-based studies to date.

DISCUSSION

This new study capitalizes upon an existing, extensively well described cohort of adults of African-origin, with significant variability as a result of the widespread geographic distributions, and therefore variation in the environmental covariate exposures. The METS-Microbiome study will substantially advance the understanding of the role gut microbiota and SCFAs play in the development of obesity and provide novel obesity therapeutic targets targeting SCFAs producing features of the gut microbiota.

TRIAL REGISTRATION

Registered NCT03378765 Date first posted: December 20, 2017.

Independent association of resting energy expenditure with blood pressure: confirmation in populations of the African diaspora

BACKGROUND

Obesity is a major risk factor for hypertension, however, the physiologic mechanisms linking increased adiposity to elevations in blood pressure are not well described. An increase in resting energy expenditure (REE) is an obligatory consequence of obesity. Previous survey research has demonstrated that REE is an independent predictor of blood pressure, and eliminates the co-linear association of body mass index. This observation has received little attention and there have been no attempts to provide a causal explanation.

METHODS

At baseline in an international comparative study on obesity, 289 participants aged 25-44 were recruited from communities in the US, the Seychelles, Ghana and South Africa and had REE measured with indirect calorimetry. All participants were thought to be free of major illness.

RESULTS

In multivariate regression models, both systolic and diastolic blood pressure were positively associated with REE (p < 0.01), while body mass index and fat mass were negatively correlated with systolic blood pressure (p < 0.01, and p < 0.05 respectively), but not diastolic blood pressure.

CONCLUSIONS

These data confirm previous reports and suggest that a common physiologic abnormality links REE and blood pressure. Elevated catecholamines, a putative metabolic characteristic of obesity, is a possible candidate to explain this association. The direct role of excess adipose tissue is open to question.

Validation of bioelectrical impedance analysis in Ethiopian adults with HIV

Bioelectrical impedance analysis (BIA) is an inexpensive, quick and non-invasive method to determine body composition. Equations used in BIA are typically derived in healthy individuals of European descent. BIA is specific to health status and ethnicity and may therefore provide inaccurate results in populations of different ethnic origin and health status. The aim of the present study was to test the validity of BIA in Ethiopian antiretroviral-naive HIV patients. BIA was validated against the 2H dilution technique by comparing fat-free mass (FFM) measured by the two methods using paired t tests and Bland-Altman plots. BIA was based on single frequency (50 kHz) whole-body measurements. Data were obtained at three health facilities in Jimma Zone, Oromia Region, South-West Ethiopia. Data from 281 HIV-infected participants were available. Two-thirds were female and the mean age was 32·7 (sd 8·6) years. Also, 46 % were underweight with a BMI below 18·5 kg/m2. There were no differences in FFM between the methods. Overall, BIA slightly underestimated FFM by 0·1 kg (-0·1, 95 % CI -0·3, 0·2 kg). The Bland-Altman plot indicated acceptable agreement with an upper limit of agreement of 4·5 kg and a lower limit of agreement of -4·6 kg, but with a small correlation between the mean difference and the average FFM. BIA slightly overestimated FFM at low values compared with the 2H dilution technique, while it slightly underestimated FFM at high values. In conclusion, BIA proved to be valid in this population and may therefore be useful for measuring body composition in routine practice in HIV-infected African individuals.

Cardiovascular risk status of Afro-origin populations across the spectrum of economic development: findings from the Modeling the Epidemiologic Transition Study

BACKGROUND

Cardiovascular risk factors are increasing in most developing countries. To date, however, very little standardized data has been collected on the primary risk factors across the spectrum of economic development. Data are particularly sparse from Africa.

METHODS

In the Modeling the Epidemiologic Transition Study (METS) we examined population-based samples of men and women, ages 25-45 of African ancestry in metropolitan Chicago, Kingston, Jamaica, rural Ghana, Cape Town, South Africa, and the Seychelles. Key measures of cardiovascular disease risk are described.

RESULTS

The risk factor profile varied widely in both total summary estimates of cardiovascular risk and in the magnitude of component factors. Hypertension ranged from 7% in women from Ghana to 35% in US men. Total cholesterol was well under 200 mg/dl for all groups, with a mean of 155 mg/dl among men in Ghana, South Africa and Jamaica. Among women total cholesterol values varied relatively little by country, following between 160 and 178 mg/dl for all 5 groups. Levels of HDL-C were virtually identical in men and women from all study sites. Obesity ranged from 64% among women in the US to 2% among Ghanaian men, with a roughly corresponding trend in diabetes. Based on the Framingham risk score a clear trend toward higher total risk in association with socioeconomic development was observed among men, while among women there was considerable overlap, with the US participants having only a modestly higher risk score.

CONCLUSIONS

These data provide a comprehensive estimate of cardiovascular risk across a range of countries at differing stages of social and economic development and demonstrate the heterogeneity in the character and degree of emerging cardiovascular risk. Severe hypercholesterolemia, as characteristic in the US and much of Western Europe at the onset of the coronary epidemic, is unlikely to be a feature of the cardiovascular risk profile in these countries in the foreseeable future, suggesting that stroke may remain the dominant cardiovascular event.

A Useful Tool As a Medical Checkup in a General Population-Bioelectrical Impedance Analysis

Accumulation of visceral fat leads to metabolic syndrome and increases risks of cerebro-cardiovascular diseases, which should be recognized and improved at the early stage in general population. Accurate measurement of visceral fat area (VFA) is commonly performed by the abdominal cross-sectional image measured by computed tomography scan, which is, however, limited due to the radiation exposure. The bioelectrical impedance analysis (OMRON, HDS-2000 DUALSCAN^R) has been recently developed to measure VFA, which is more easily accessible modality. In the present study, we investigated the clinical usefulness of DUALSCAN^R in 226 subjects who received health examination, including blood chemistries, electrocardiography, cardio, and carotid ultrasonography. VFA was measured within only just 5 min. Average of VFA was 83.5 ± 36.3 cm² in men, and 64.8 ± 28.0 cm² in women, which was correlated to weight (r = 0.7404, p < 0.0001), body mass index (BMI) (r = 0.7320, p < 0.0001), and waist circumstance (r = 0.7393, p < 0.0001). In multivariate analyses, VFA was significantly associated with weight (p < 0.0001), BMI (p < 0.0001), and waist circumstance (p < 0.0001). Compared to the group of smaller waist and normal BMI, VFA was significantly increased (p < 0.0001) in the group of larger waist and obese subjects. In conclusion, these results indicated that DUALSCAN^R is useful to measure VFA easily in general population, even in a large number of subjects.

Resting Energy Expenditure of Black Overweight Women in South Africa Is Lower than of White Women

BACKGROUND

Overweight affects 65% of black South African women. Effective weight management requires accurate measurement or estimation of energy expenditure.

AIMS

The study aimed to determine, among overweight women, whether measured resting energy expenditure (REE) differs between black and white participants, and the performance of REE estimation equations.

METHODS

The REE of 44 black (age 39.6 ± 9.7 years, body mass index (BMI) 35.1 ± 6.2 kg/m2) and 41 white (age 38.0 ± 11.6 years, BMI 33.9 ± 7.6 kg/m2) women was measured with indirect calorimetry and estimated with equations. Body composition was assessed with multi-frequency bioelectrical impedance analysis. Differences in REE were determined with t tests (Welch), and included adjustment for fat free mass (FFM) and BMI, and for FFM index (FFMI).

RESULTS

Measured REE was 585 kJ/day (95% CI 264-905; p = 0.0005) and 861 kJ/day (95% CI 499-1,221; p < 0.0001) lower in black than in white women when adjusted for FFM and BMI, and FFMI, respectively. Out of 14 equations, 13 underestimated REE (error range 2,261 ± 727 kJ/day (Bernstein equation, white women) to 8 ± 782 kJ/day (BMI equation, black women)).

CONCLUSIONS

Black overweight women have significantly lower REE than their white counterparts. No tested estimation equation provided satisfactory results across race/ethnicity. REE measurements or development of overweight- or race/ethnicity-specific estimation equations are recommended.

A comparison of indices of glucose metabolism in five black populations: data from modeling the epidemiologic transition study (METS)

Background

Globally, Africans and African Americans experience a disproportionate burden of type 2 diabetes, compared to other race and ethnic groups. The aim of the study was to examine the association of plasma glucose with indices of glucose metabolism in young adults of African origin from 5 different countries.

Methods

We identified participants from the Modeling the Epidemiologic Transition Study, an international study of weight change and cardiovascular disease (CVD) risk in five populations of African origin: USA (US), Jamaica, Ghana, South Africa, and Seychelles. For the current study, we included 667 participants (34.8 ± 6.3 years), with measures of plasma glucose, insulin, leptin, and adiponectin, as well as moderate and vigorous physical activity (MVPA, minutes/day [min/day]), daily sedentary time (min/day), anthropometrics, and body composition.

Results

Among the 282 men, body mass index (BMI) ranged from 22.1 to 29.6 kg/m² in men and from 25.8 to 34.8 kg/m² in 385 women. MVPA ranged from 26.2 to 47.1 min/day in men, and from 14.3 to 27.3 min/day in women and correlated with adiposity (BMI, waist size, and % body fat) only among US males after controlling for age. Plasma glucose ranged from 4.6 ± 0.8 mmol/L in the South African men to 5.8 mmol/L US men, while the overall prevalence for diabetes was very low, except in the US men and women (6.7 and 12 %, respectively). Using multivariate linear regression, glucose was associated with BMI, age, sex, smoking hypertension, daily sedentary time but not daily MVPA.

Conclusion

Obesity, metabolic risk, and other potential determinants vary significantly between populations at differing stages of the epidemiologic transition, requiring tailored public health policies to address local population characteristics.

Bioelectric impedance analysis of body composition of children and adolescents with sickle cell anemia in Enugu, Nigeria

BACKGROUND

Body composition indices are widely used to evaluate growth and nutrition in children, particularly those with sickle cell anemia (SCA), who are known to have impaired growth, impaired skeletal maturation, and delayed puberty. The current study is aimed at determining the body composition of children with SCA.

METHODS

Consecutive selection of SCA children aged 6 to 18 years, who served as subjects and their age and gender matched children with HbAA (controls), selected using multi-stage systematic sampling. It was a cross-sectional descriptive study conducted at the pediatric hematology and oncology clinic. Bioelectric impedance analysis was used to determine the body composition parameters, including weight, body fat percentage (BFP), visceral fat percentage, body mass index (BMI), skeletal muscle percentage, and resting metabolic rate. Data were analyzed using SPSS 16.0 at P < 0.05.

RESULTS

One hundred and thirty-two subjects and controls respectively were studied. Subjects had lower body composition parameters compared with controls, with the older male subjects aged 10 to 18 years, having lower body composition indices (weight, height, BMI, and BFP) compared with controls. Visceral fat percentage was low in both subjects and controls.

CONCLUSIONS

Children with SCA, particularly the older males, have impaired body composition indices. There is a need to conduct further studies to determine the longitudinal aspects of growth as well as quantitative and qualitative assessment of nutritional intake in children with SCA, which will inform higher alimentation requirements for HbSS children as compared with HbAA individuals.