Validity of body adiposity index in predicting body fat in a sample of Brazilian women

BODY COMPOSITION ASSESSED BY DUAL-ENERGY X-RAY ABSORPTIOMETRY ON METABOLIC PROFILE AND CARDIOVASCULAR RISK IN OBESE PATIENTS PRIOR TO BARIATRIC SURGERY

BACKGROUND

Fat, muscle, and bone are endocrine organs capable of affecting the metabolic profile and cardiovascular risk. Relating these components is important to the establishment of early intervention strategies for overweight patients.

AIMS

This study aimed to evaluate the influence of body mass components on the metabolic profile and cardiovascular risk in the preoperative period of bariatric surgery.

METHODS

A cross-sectional study was conducted with patients admitted for bariatric surgery at a university hospital in the city of Recife, Brazil, between 2018 and 2019. Body composition was determined using dual-energy x-ray absorptiometry. Cardiovascular risk was assessed using the Framingham risk score. Data were collected on anthropometric, clinical, and lifestyle characteristics. The lipid profile (total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides), blood glucose, and vitamin D were determined using the standard methods of the hospital laboratory.

RESULTS

A total of 60 patients were analyzed, 86.7% of whom had comorbidities, 33.3% had moderate/high cardiovascular risk, and 71.4% had vitamin D insufficiency/deficiency. Lower lean body mass (adjusted PR 3.24; 95%CI 1.19-5.77) was independently associated with the severity of obesity. The body mass index and waist circumference were negatively correlated with lean body mass (r=-0.52; p<0.01)/r=-0.36; p<0.01). Lean body mass was negatively correlated with fat mass (r=-0.26; p<0.05), trunk fat (r=-0.29; p<0.05), fasting glucose (r=-0.26; p<0.05), and bone mineral density (r=-0.26; p<0.05). A total of 84.2% of individuals with less trunk fat tended to have low cardiovascular risk (p=0.05). However, physical inactivity (adjusted PR 2.14; 95%CI 1.19-5.54) and the risk of alcohol dependence (adjusted PR 2.41; 95%CI 1.76-4.15) were the only variables independently associated with cardiovascular risk.

CONCLUSION

Obese patients in the preoperative period of bariatric surgery with less trunk fat tended to have low cardiovascular risk. However, the other components of body mass were also not associated with cardiovascular risk.

Performance of Body Adiposity Index and Relative Fat Mass in Predicting Bioelectric Impedance Analysis-Derived Body Fat Percentage: A Cross-Sectional Study among Patients with Type 2 Diabetes in the Ho Municipality, Ghana

Objective

The study sought to determine the diagnostic accuracy of body adiposity index (BAI) and relative fat mass (RFM) to predict BIA-derived BFP among patients with type 2 diabetes in the Ho municipality. Materials and Method. This hospital-based cross-sectional study involved 236 patients with type 2 diabetes. Demographic data, including age and gender were obtained. Height, waist circumference (WC), and hip circumference (HC) were measured using standard methods. BFP was estimated on a bioelectrical impedance analysis (BIA) scale. The validity of BAI and RFM as alternative estimates for BIA-derived BFP was evaluated based on mean absolute percentage error (MAPE), Passing-Bablok regression, Bland-Altman plots, receiver-operating characteristic curve (ROC), and kappa statistics analyses. A p value less than 0.05 was considered statistically significant.

Results

BAI showed systematic bias in estimating BIA-derived BFP in both genders, but this was not evident between RFM and BFP among females (t = -0.62; p = 0.534). While BAI showed "good" predictive accuracy in both genders, RFM exhibited "high" predictive accuracy for BFP (MAPE: 7.13%; 95% CI: 6.27-8.78) among females according to MAPE analysis. From the Bland-Altman plot analysis, the mean difference between RFM and BFP was acceptable among females [0.3 (95% LOA: -10.9 to 11.5)], but both BAI and RFM recorded large limits of agreement and low Lin's concordance correlation coefficient with BFP (Pc < 0.90) in the two gender populations. The optimal cut-off, sensitivity, specificity, and Youden index for RFM were >27.2, 75%, 93.75%, and 0.69, respectively, while those of BAI were >25.65, 80%, 84.37%, and 0.64, respectively, among males. Among females, the values for RFM were >27.26, 92.57%, 72.73%, and 0.65, whereas those of BAI were >29.4, 90.74%, 70.83%, and 0.62, respectively. The accuracy of discriminating between BFP levels was higher among females [BAI (AUC: 0.93) and RFM (AUC: 0.90)] compared to males [BAI (AUC: 0.86) and RFM (AUC: 0.88)].

Conclusion

RFM had a better predictive accuracy of BIA-derived BFP in females. However, both RFM and BAI failed as valid estimates for BFP. Furthermore, gender-specific performance in the discrimination of BFP levels for RFM and BAI was observed.

Criterion-Related Validity of Field-Based Methods and Equations for Body Composition Estimation in Adults: A Systematic Review

PURPOSE OF REVIEW

Overweight and obesity are associated to health prognosis. Therefore, body composition assessment is an important health outcome, especially in adult population. We analyzed the criterion-related validity of existing field-based methods and equations for body composition estimation in adults aged 19-64 years.

RECENT FINDINGS

One hundred studies met inclusion criteria. The field-based methods, waist circumference (WC), body adiposity index (BAI), and body mass index (BMI) are valid to indicate body adiposity. Likewise, several equations, including the classical Durnin/Womersley equation, Jackson/Pollock equation (males), and Jackson, Pollock, and Ward equation (females), are valid to estimate total body fat mass or body fat percentage. Anthropometric field methods can provide a simple, quick, and easy informative indicators of adiposity in adults. Classical equations, such as Durnin/Womersley equation, Jackson/Pollock equation, and Jackson, Pollock, and Ward equation, are still valid to estimate total body fat mass or body fat percentage in adult population. When choosing estimation equations, specific population characteristics, such as age, weight status, or race ethnicity, should be taken into account. (Trial Registration: Registered on PROSPERO (CRD42020194272)).

The Body Adiposity Index is not applicable to the Brazilian adult population

Background

Obesity is a serious disease that burdens public health systems around the world. It is a risk factor for the development of several non-communicable chronic diseases that are related to the amount and distribution of body fat. Body composition assessment using simple and low-cost techniques can help in the early detection of excess fat, allowing for the prevention and treatment of both obesity and associated diseases. Thus, identifying and proposing valid anthropometric indices for this purpose can be a great ally of health programs.

Objective

To verify the validity of the Body Adiposity Index (BAI) in relation to Dual Energy X-Ray Absorptiometry (DXA) for estimating body fat percentage in Brazilian adults, as well as to propose a new mathematical model to estimate the fat-free mass of this population.

Methods

In a cross-sectional study, 424 subjects (of which 220 were women), aged between 20 and 59 years, were evaluated by BAI and DXA, then randomly divided into two groups stratified by sex: the development group (n = 283) and the cross-validation group (n = 141). Statistical analyses to test the validity of BAI as a predictor of fat mass, in addition to proposing a new mathematical model for estimating fat-free mass, using DXA as a reference method. The analysis included paired t-test, stepwise multiple regression, coefficient of concordance correlation, and Bland-Altman plots.

Results

The BAI validity analysis showed a low correlation coefficient of agreement [CCC = 0.626; ρ (precision) = 0.795; C_b(accuracy) = 0.787]; in addition, the mean difference in the Bland-Altman plot was different from zero in the cross-validation group (p < 0.01) and limits of agreement (LOA) ranged between−8.0 and 14.4 kg, indicating a poor agreement between the BAI and the reference method. The new mathematical model for estimating FFM showed a high correlation coefficient of agreement (CCC = 0.952; ρ = 0.953; C_b = 0.999), in addition to acceptable LOA in the Bland-Altman plot (-6.7 and 6.7).

Conclusion

In the studied sample, the BAI showed low validity for estimating body fat, while the new proposed model was found to be a good option to assess the body composition of Brazilian adults.

Is Body Adiposity Index a Better and Easily Applicable Measure for Determination of Body Fat?

Objective: The BAI can be used to reflect %body fat. This study aimed to compare BAI with other methods used in the determination of body fat.Materials and Methods: A cross-sectional study was conducted in Turkish adults. BAI, BMI, WHR, WHtR, body weight, hip and waist circumference (WC), skinfold thicknesses (biceps, triceps, subscapular, suprailiac) were measured. Body fat was measured using Bioelectric Impedance Analysis.Results: The Bland-Altman analyses conducted in this study showed that for % body fat estimations, BIA was in excellent agreement with skinfold measurements (p = 0.131) without proportional bias (p = 0.082), but that BAI was not in agreement with BIA and skinfold measurement. There were a statistically significant positive correlation between BAI and other measurements in terms of females and males and also regardless of sex.Conclusion: BAI was not in agreement with BIA and skinfold measurement methods for % body fat estimations, it had a significantly stronger correlation with % fat calculated using BIA and skinfold thickness.

A new anthropometric index for body fat estimation in patients with severe obesity

Background

Body mass index (BMI) has been used to assess body adiposity, but it cannot adequately reflect body fat (BF) amount. The body adiposity index (BAI) has been shown a better performance than BMI for this purpose, but it can be inaccurate to estimate BF under extreme amounts of fat. Here, we propose a new anthropometric index, the Belarmino–Waitzberg (BeW) index, for specific estimation of BF in severely obese patients.

Methods

In 144 adult patients with severe obesity, BF was estimated by air displacement plethysmography (ADP), as the reference method, along with the follow anthropometric measurements: height, abdominal circumference (AC), hip circumference (HC), weight, BMI (weight/ height²) and BAI ([HC(cm) / height (m)^1.5) − 18] × 100). Patients were proportionately distributed into two distinct databases, the building model database (BMD) and the validation model database (VMD), which were applied to develop and validate the BeW index, respectively. The BeW index was tested for gender and ethnicity adjustment as independent variables. The agreement of BF% values obtained by the new index and by BAI with ADP was also assessed.

Results

The BF% was 52.05 ± 5.42 for ADP and 59.11 ± 5.95 for the BeW index (all results are expressed as the mean ± standard deviation). A positive Pearson correlation (r = 0.74), a good accuracy (Cb = 0.94), and a positive Lin’s concordance correlation (CCC = 0.70) were observed between the two groups. The 95% limits of individual agreement between the BeW index and ADP were 6.8 to 7.9%, compared to − 7.5 to 14.8% between the BAI and ADP. The new index, called the Belarmino–Waitzberg (BeW) index, showed an improvement of 2.1% for the R² value and a significant gender effect, therefore resulting in two different indexes for females and males, as follows: Female BeW = − 48.8 + 0.087 × AC(cm) + 1.147 × HC(cm) - 0.003 × HC(cm)2 and Male BeW = − 48.8 + 0.087 × AC(cm) + 1.147 × HC(cm) - 0.003 × HC(cm)2–7.195.

Conclusions

The new BeW index showed a good performance for BF estimation in patients with severe obesity and can be superior to the BAI for this purpose.

Validity of the Body Adiposity Index in Predicting Body Fat in Adults: A Systematic Review

The Body Adiposity Index (BAI) is a practical anthropometric method used to measure body fat (BF) percentage (BF%). Recently developed, the validity and precision of BAI has been studied with adult samples of men and women, populations from different countries and ethnicities, varying amounts of BF, and sensitivity to detecting change over time. However, it is still necessary to determine its potential use in clinical practice and epidemiologic studies. Thus, our objective was to verify, through a systematic review, the validity of the BAI in predicting BF% in adults. Two independent researchers performed a search using PubMed, Web of Science, Science Direct, and Scopus databases. In order to be included, the studies had to use dual-energy X-ray absorptiometry (DXA) as a reference method. We excluded studies with samples from individuals with diseases or syndromes that alter the regional distribution of BF%. We included 19 studies with samples on individuals from different continents, varied ethnicities, both sexes, and a wide age range (18-83 y). The concordance of the BAI with DXA assessed by Lin's concordance correlation coefficient showed results classified as poor (pc < 0.90). Bland-Altman plots showed that the BAI produced large individual errors when predicting BF% in all studies using this analysis. The studies were consistent in affirming that the BAI showed limited capacity to estimate BF% in adults. The BAI shows wide individual errors, in agreement with the reference method, and a lack of sensitivity in detecting change in BF% over time. The method presents a systematic error of BF% overestimation in individuals with ≤20% of BF, and underestimation in individuals with >30% of BF, regardless of sex, age, and ethnicity. The results of this systematic review show enough evidence that the BAI does not present satisfying results, and its use is not recommended for BF% determination in adults.

TRUNK BODY MASS INDEX: A NEW REFERENCE FOR THE ASSESSMENT OF BODY MASS DISTRIBUTION

BACKGROUND

Body mass index (BMI) has some limitations for nutritional diagnosis since it does not represent an accurate measure of body fat and it is unable to identify predominant fat distribution.

AIM

To develop a BMI based on the ratio of trunk mass and height.

METHODS

Fifty-seven patients in preoperative evaluation to bariatric surgery were evaluated. The preoperative anthropometric evaluation assessed weight, height and BMI. The body composition was evaluated by bioimpedance, obtaining the trunk fat free mass and fat mass, and trunk height. Trunk BMI (tBMI) was calculated by the sum of the measurements of the trunk fat free mass (tFFM) and trunk fat mass (tFM) in kg, divided by the trunk height squared (m2)). The calculation of the trunk fat BMI (tfBMI) was calculated by tFM, in kg, divided by the trunk height squared (m2)). For the correction and adjustment of the tBMI and tfBMI, it was calculated the relation between trunk extension and height, multiplying by the obtained indexes.

RESULTS

The mean data was: weight 125.3±19.5 kg, height 1.63±0.1 m, BMI was 47±5 kg/m2) and trunk height was 0.52±0,1 m, tFFM was 29.05±4,8 kg, tFM was 27.2±3.7 kg, trunk mass index was 66.6±10.3 kg/m², and trunk fat was 32.3±5.8 kg/m². In 93% of the patients there was an increase in obesity class using the tBMI. In patients with grade III obesity the tBMI reclassified to super obesity in 72% of patients and to super-super obesity in 24% of the patients.

CONCLUSION

The trunk BMI is simple and allows a new reference for the evaluation of the body mass distribution, and therefore a new reclassification of the obesity class, evidencing the severity of obesity in a more objectively way.

Fatores associados e índice de adiposidade corporal (IAC) em adultos: estudo de base populacional

Resumo Objetivou-se analisar os fatores associados ao índice de adiposidade corporal. Um estudo transversal de base populacional foi conduzido com 964 adultos, de 20 e 59 anos, em Viçosa, MG, Brasil. Aplicou-se questionários domiciliares e medidas antropométricas para se obter os dados. A análise múltipla foi realizada por meio de regressão linear, ajustada pelo efeito do desenho amostral. A prevalência de excesso de adiposidade corporal foi 36,89 (IC 30,81–43,43), sendo mais elevada nos homens (48,18% - IC 39,09–57,34). Associou-se positivamente com o índice de adiposidade corporal o sexo feminino (p = 0,002), idade em anos (p < 0,001), aqueles que viveram com companheiro (p = 0,022) e com insatisfação com a imagem corporal (p < 0,001). A autoavaliação da saúde positiva (p = 0,048) esteve associada negativamente com o índice de adiposidade corporal. A prevalência de excesso de adiposidade corporal foi elevada, sendo o sexo, a faixa etária, o estado civil, a autoavaliação da saúde e a insatisfação com a imagem corporal fatores determinantes para o aumento da adiposidade corporal, nesta população, indicando um forte risco para doenças crônicas não transmissíveis decorrentes do excesso de adiposidade.

ESTIMATION OF FEMALE BODY FAT PERCENTAGE BASED ON BODY CIRCUMFERENCES

ABSTRACT Introduction: The increase in the prevalence of obesity entails the need for accurate low-cost methods to estimate body fat percentage (BF%). Objective: The aim of this study was to develop mathematical models to estimate the BF% of young women from southern Brazil using inexpensive equipment, based on body circumferences (BC), considering the shortage of specific studies of this population. Methods: Subjects were women (n=130) aged 18 to 35 years (26.06±4.41 years), from the city of Curitiba. Body mass and stature were measured and used to estimate body mass index (BMI), while BC measurements of the arm, forearm, waist (narrowest point and umbilicus), abdomen, hip, thigh and leg were taken for use in the mathematical models. Dual-Energy X-Ray Absorptiometry (DXA) equipment recorded the BF%. Pearson’s correlation was used for anthropometric variables and age in association with BF%. The indicators with best correlations were used to estimate linear regression mathematical models for prediction of BF%. The results of the two models and of nine anthropometric equations were compared to those obtained with the DXA using Pearson’s correlation coefficient and paired t-test. Results: Age was not significantly correlated with BF% (r=0.113 and p=0.200). The BCs with the highest correlations with BF% were abdomen, hip and waist - umbilicus (r=0.697, 0.682, 0.660, respectively, and p<0.001). Eight equations showed positive correlation with BF%, but only the results obtained with the models estimated in this study did not differ from those of DXA, with paired t-test. Mathematical models were developed with three (r=0.744, r²=0.554; t=0.16 and p=0.869) and six (r=0.768, r²=0.591; t=-0.04 and p=0.967) anthropometric variables. Conclusion: The use of mathematical models developed for estimating BF% based on body circumference and body mass is considered feasible. Level of Evidence II; Diagnostic studies - Investigating a diagnostic test.

Anthropometric Indicators of Adiposity Related to Body Weight and Body Shape as Cardiometabolic Risk Predictors in British Young Adults: Superiority of Waist-to-Height Ratio

Frequently reported poor dietary habits of young adults increase their risk of metabolic syndrome (MetS). Excess adiposity is the most established predictor of MetS, and numerous anthropometric measures have been proposed as proxy indicators of adiposity. We aimed to assess prevalence of MetS in young adult population and to make comparison between weight- and shape-oriented measures of adiposity to identify the best index in association with measured body fat and as a risk predictor for MetS. Healthy males and females aged 18-25 years from the Northwest of England were recruited using convenience sampling (n=550). As part of the assessment of the overall health of young adults, the biochemical variables and adiposity measures BMI, waist circumference (WC), waist-to-height ratio (WHtR), waist-to-hip ratio (WHR), new BMI, Body Adiposity Index (BAI), Clinica Universidad de Navarra-Body Adiposity Estimator (CUN-BAE), and A Body Shape Index (ABSI) were assessed. Linear regression analysis was used to investigate the association between the proxy indices of adiposity and measured percentage body fat. The odds ratio with 95% confidence interval was used to investigate the relationship between cardiometabolic (CM) risk factors and proxy measures of adiposity. The discriminatory power of these measures for diagnosis of MetS was investigated using area under the receiver operating characteristic curve. Body weight-related indicators of adiposity, particularly CUN-BAE, had stronger association with measured body fat compared with body shape-related indices. In relation with MetS, body shape-related indices, particularly elevated WC and WHtR, had stronger associations with CM risk compared with body weight-related measures. Amongst all indices, the best predictor for CM risk was WHtR, while ABSI had the weakest correlation with body fat, MetS, and CM risk. Indices directly associated with WC and specifically WHtR had greater diagnostic power in detection of CM risk in young adults.

Comparison between dual-energy X-ray absorptiometry and skinfold thickness in assessing body fat in overweigh/obese adult patients with type-2 diabetes

Percentage of body fat (%BF) is estimated in clinical practice using anthropometric equations, but little is known about their reliability in overweight/obese patients with type-2 diabetes. The aim of this study was to compare, in overweight/obese adults with type-2 diabetes, %BF estimated with several commonly used anthropometric equations and %BF measured with dual-energy X-ray absorptiometry (DXA, Hologic). The %BF was measured with DXA in 40 patients aged 40-68 years with type-2 diabetes (mean HbA1c, 7.3 ± 0.9%). Body density was estimated in the same patients by means of four anthropometric equations and converted to %BF using the Siri and Brozek equations. Paired-sample t-test and the mean signed difference procedure were used to compare anthropometric equation-derived %BF and DXA measurements. The coefficient of determination was computed. Bland-Altman analysis was used to test the agreement between methods. Among the four anthropometric equations, the Durnin-Womersley equation only showed close agreement with DXA in both female and male patients; the other equations significantly underestimated or overestimated %BF. Two new predictive equations were developed using DXA as the reference to predict total body and trunk %BF. Further comparative studies are required to confirm and refine the accuracy of practical, non-invasive methods for monitoring %BF in this population.

Comparison of Three Adiposity Indexes and Cutoff Values to Predict Metabolic Syndrome Among University Students

PURPOSE

Obesity and high body fat are related to diabetes and metabolic syndrome (MetS) in all ethnic groups. Based on the International Diabetes Federation (IDF) definition of MetS, the aim of the present study was to compare body adiposity indexes (BAIs) and to assess their various cutoff values for the prediction of MetS in university students from Colombia.

METHODS

A cross-sectional study was conducted on 886 volunteers (51.9% woman; age mean 21.4 years). Anthropometric characteristics (height, weight, waist circumference [WC], and hip circumference [HC]) were measured, and body composition was assessed by bioelectrical impedance analysis. MetS was defined as including ≥3 of the metabolic abnormalities (WC, high-density lipoprotein cholesterol [HDL-C], triglycerides, fasting glucose, and systolic and diastolic blood pressure [BP]) in the definition provided by the IDF. The BAIs (i.e., BAI-HC [BAI], BAI-WC [BAI-w], and [BAI-p]) were calculated from formulas taking into account, height, weight, and WC, and for the visceral adiposity indexes, a formula, including WC, HDL-C, and triglycerides, was used.

RESULTS

The overall prevalence of MetS was 5.9%, higher in men than in women. The most prevalent components were low HDL-C, high triglyceride levels, WC, and BP levels. The receiver operating characteristic curves analysis showed that BAI, BAI-w, and BAI-p could be useful tools to predict MetS in this population.

CONCLUSION

For women, the optimal MetS threshold was found to be 30.34 (area under curve [AUC] = 0.720-0.863), 19.10 (AUC = 0.799-0.925), and 29.68 (AUC = 0.779-0.901), for BAI, BAI-w, and BAI-p, respectively. For men, the optimal MetS threshold was found to be 27.83 (AUC = 0.726-0.873), 21.48 (AUC = 0.755-0.906), and 26.18 (AUC = 0.766-0.894), for BAI, BAI-w, and BAI-p, respectively. The three indexes can be useful tools to predict MetS according to the IDF criteria in university students from Colombia. Data on larger samples are needed.

Body Adiposity Index Performance in Estimating Body Fat Percentage in Colombian College Students: Findings from the FUPRECOL-Adults Study

Recently, a body adiposity index (BAI = (hip circumference)/((height)(1.5))-18) was developed and validated in adult populations. The aim of this study was to evaluate the performance of BAI in estimating percentage body fat (BF%) in a sample of Colombian collegiate young adults. The participants were comprised of 903 volunteers (52% females, mean age = 21.4 years ± 3.3). We used the Lin's concordance correlation coefficient, linear regression, Bland-Altman's agreement analysis, concordance correlation coefficient (ρc) and the coefficient of determination (R²) between BAI, and BF%; by bioelectrical impedance analysis (BIA)). The correlation between the two methods of estimating BF% was R² = 0.384, p < 0.001. A paired-sample t-test showed a difference between the methods (BIA BF% = 16.2 ± 3.1, BAI BF% = 30.0 ± 5.4%; p < 0.001). For BIA, bias value was 6.0 ± 6.2 BF% (95% confidence interval (CI) = -6.0 to 18.2), indicating that the BAI method overestimated BF% relative to the reference method. Lin's concordance correlation coefficient was poor (ρc = 0.014, 95% CI = -0.124 to 0.135; p = 0.414). In Colombian college students, there was poor agreement between BAI- and BIA-based estimates of BF%, and so BAI is not accurate in people with low or high body fat percentage levels.

Predictive Validity of the Body Adiposity Index in Overweight and Obese Adults Using Dual-Energy X-ray Absorptiometry

The body adiposity index (BAI) is a recent anthropometric measure proven to be valid in predicting body fat percentage (BF%) in some populations. However, the results have been inconsistent across populations. This study was designed to verify the validity of BAI in predicting BF% in a sample of overweight/obese adults, using dual-energy X-ray absorptiometry (DEXA) as the reference method. A cross-sectional study was conducted in 48 participants (54% women, mean age 41.0 ± 7.3 years old). DEXA was used as the “gold standard” to determine BF%. Pearson’s correlation coefficient was used to evaluate the association between BAI and BF%, as assessed by DEXA. A paired sample t-test was used to test differences in mean BF% obtained with BAI and DEXA methods. To evaluate the concordance between BF% as measured by DEXA and as estimated by BAI, we used Lin’s concordance correlation coefficient and Bland–Altman agreement analysis. The correlation between BF% obtained by DEXA and that estimated by BAI was r = 0.844, p < 0.001. Paired t-test showed a significant mean difference in BF% between methods (BAI = 33.3 ± 6.2 vs. DEXA 39.0 ± 6.1; p < 0.001). The bias of the BAI was −6.0 ± 3.0 BF% (95% CI = −12.0 to 1.0), indicating that the BAI method significantly underestimated the BF% compared to the reference method. Lin’s concordance correlation coefficient was considered stronger (ρc = 0.923, 95% CI = 0.862 to 0.957). In obese adults, BAI presented low agreement with BF% measured by DEXA; therefore, BAI is not recommended for BF% prediction in this overweight/obese sample studied.

Modified body adiposity index for body fat estimation in severe obesity

BACKGROUND

The body adiposity index (BAI) comprises a simple method for estimating body fat (BF) that needs to be validated in patients with severe obesity. The present study aimed to determine BAI accuracy with respect to the determination BF in patients with severe obesity.

METHODS

A cross-sectional prospective study comparing two methods for BF estimation was conducted in 433 patients with severe obesity between August 2012 to December 2014. BF was estimated by bioelectrical impedance analysis (BIA) with specific equations developed for BF estimation in patients with severe obesity and BAI. The BF estimation in 240 patients with severe obesity (Group 1: G1) was used to evaluate BAI limitations and to develop a specific equation in this population. The new equation proposed was validated in another 158 patients with severe obesity (Group 2: G2).

RESULTS

There was a significant difference between BF determination by BIA and BAI (P = 0.039). The mean (SD) BF in G1 was 52.3% (6.1%) determined by BIA and 51.6% (8.1%) determined by BAI. Sex, waist-hip ratio (WHR) and obesity grade determined significant errors on BF estimation by BAI. A new equation (modified body adiposity index; MBAI) was developed by linear regression to minimise these errors [MBAI% = 23.6 + 0.5 × (BAI); add 2.2 if body mass index ≥ 50 kg m^-2 and 2.4 if WHR ≥ 1.05]. The new equation reduced the difference [1.2% (5.9%), P < 0.001 to 0.4% (4.12%), P = 0.315] and improved the correlation (0.6-0.7) between methods.

CONCLUSIONS

BAI present significant limitations in severe obesity and MBAI was effective for BF estimation in this population.

Validity of body adiposity index in predicting body fat in Brazilians adults

OBJECTIVES

The aim of this study was to compare various methods of assessing body compositions with body adiposity index (BAI) and to identify the validity of BAI as a predictor of body fat in Brazilian adults.

METHODS

This study included 706 individuals (average age 37.3 years, SD = 12.1). Anthropometric data included percent body fat obtained by skinfold thicknesses, bioelectrical impedance analysis and DXA. Body mass index (BMI), waist/hip ratio, and BAI were calculated. The correlation between variables was assessed by Pearson's correlation coefficient, and the Bland-Altman and Kaplan Meier graphic approaches were used to verify the agreement between BAI and DXA.

RESULTS

There was a strong correlation between BAI and BMI (r = 0.84 in men and r = 0.86 in women, P < .001), waist circumference (r = 0.77 in men and r = 0.75 in women, P < .001) percent fat by skinfold thicknesses (r = 0.71 in men and r = 0.71 in women, P < .001) and by DXA (r = 0.72 in men and r = 0.78 in women, P < .001). The Bland-Altman approach showed an overestimation of BAI in males and an underestimation in women using DXA as the reference method. The agreement between BAI and DXA through the Kaplan-Meier analysis was 41%.

CONCLUSIONS

It was found that BAI does not replace other measurements of body fat, but compared with more complex methods can be an alternative for estimating the body fat in the absence of these methods.

Body adiposity index performance in estimating body fat in a sample of severely obese Brazilian patients

Background/objectives

The body adiposity index (BAI) estimates the amount of body fat (BF) in humans. In Mexican-American and African-American populations, BAI has performed better than body mass index (BMI). The aim of this study was to evaluate the performance of BAI in estimating percentage (BF%) in severely obese Brazilian patients, with air displacement plethysmography (ADP) used as the reference method.

Subjects/methods

Estimation of BF% by ADP, anthropometric measurements (height, abdominal and hip circumferences, body weight, and BMI) and BAI calculation were performed in 72 obese subjects (BMI ≥ 30 kg/m²) aged 30–55 years.

Results

The mean BF% estimates ± standard deviation were 52.1 ± 5.7 % for ADP and 47.7 ± 7.4 % for BAI, with a positive Pearson correlation (r_p = 0.66) and a positive Lin’s concordance correlation (r_c = 0.479) observed between these methods. The 95 % limits of individual agreement between BAI and ADP ranged from -5.769 % to 16.036 %, with BAI exhibiting an average positive bias of 5.13 % compared to the reference method. For each studied variable, BAI exhibited a systematic bias, as evidenced by a tendency for low BF% values to be overestimated.

Conclusion

For Brazilian patients with severe obesity, BAI does not provide an accurate estimate of BF%.

Predictive validity of the body adiposity index in costa rican students

OBJECTIVE

To verify the validity of the body adiposity index (BAI) in a sample of Costa Rican students.

METHODS

Volunteers were 93 females (mean age = 18.6 ± 2.4 years) and 106 males (mean age = 19.2 ± 2.8 years). Dual-energy X-ray absorptiometry (DXA) was used as the "gold standard" to determine body fat percentage (BF%). Pearson's correlation coefficient and paired samples t-test studied the association and mean differences between BAI and DXA BF%. Concordance between BAI and DXA BF% was determined by the Lin's concordance correlation coefficient and the Bland-Altman agreement analysis.

RESULTS

Significant correlations between BAI and DXA BF% were found for females (r = 0.74) and males (r = 0.53) (P < 0.001). Differences between methods were found for females (BAI = 29.3 ± 4.1% vs. DXA = 36.5 ± 7.9%) and males (BAI = 24.8 ± 3.7% vs. DXA = 21.9 ± 8.6%; P < 0.001). Concordance was poor in females and males. Bland-Altman plots showed BAI underestimating and overestimating BF% in relation to the "gold standard" in females and males, respectively.

CONCLUSIONS

BAI presented low agreement with BF% measured by DXA; therefore, BAI is not recommended for BF% prediction in this Central American sample studied. Am. J. Hum. Biol. 28:394-397, 2016. © 2015 Wiley Periodicals, Inc.