Comparison of techniques to evaluate adiposity in stunted and nonstunted children

Associations between Stunting, Wasting and Body Composition: A Longitudinal Study in 6- to 15-Month-Old Kenyan Children

BACKGROUND

Early growth and body composition may influence the risk of obesity and health in adulthood. Few studies have examined how undernutrition is associated with body composition in early life.

OBJECTIVES

We assessed stunting and wasting as correlates of body composition in young Kenyan children.

METHODS

Nested in a randomized controlled nutrition trial, this longitudinal study assessed fat and fat-free mass (FM, FFM) using deuterium dilution technique among children at age 6 and 15 months. This trial was registered at http://controlled-trials.com/ (ISRCTN30012997). Cross-sectional and longitudinal associations between z-score categories of length-for-age (LAZ) or weight-for-length (WLZ) and FM, FFM, fat mass index (FMI), fat-free mass index (FFMI), triceps, and subscapular skinfolds were analyzed by linear mixed models.

RESULTS

Among the 499 children enrolled, breastfeeding declined from 99% to 87%, stunting increased from 13% to 32%, and wasting remained at 2% to 3% between 6 and 15 mo. Compared with LAZ >0, stunted children had a 1.12 kg (95% CI: 0.88, 1.36; P < 0.001) lower FFM at 6 mo and increased to 1.59 kg (95% CI: 1.25, 1.94; P < 0.001) at 15 mo, corresponding to differences of 18% and 17%, respectively. When analyzing FFMI, the deficit in FFM tended to be less than proportional to children's height at 6 mo (P ≤ 0.060) but not at 15 mo (P > 0.40). Stunting was associated with 0.28 kg (95% CI: 0.09, 0.47; P = 0.004) lower FM at 6 mo. However, this association was not significant at 15 mo, and stunting was not associated with FMI at any time point. A lower WLZ was generally associated with lower FM, FFM, FMI, and FFMI at 6 and 15 mo. Differences in FFM, but not FM, increased with time, whereas FFMI differences did not change, and FMI differences generally decreased with time.

CONCLUSIONS

Overall, low LAZ and WLZ among young Kenyan children were associated with reduced lean tissue, which may have long-term health consequences.

Calibration of Bioelectrical Impedance Analysis Against Deuterium Dilution for Body Composition Assessment in Stunted Ugandan Children

BACKGROUND

BIA represents an important tool in body composition (BC) assessment, especially in low-income settings in which simple and affordable options are preferred. There is a particular need to measure BC in stunted children, in which cases population-specific BIA estimating equations are lacking.

OBJECTIVES

We calibrated an equation to estimate body composition from BIA using deuterium dilution (²H) as the criterion method in stunted children.

METHODS

We measured BC with ²H and performed BIA in stunted Ugandan children (n = 50). Multiple linear regression models were constructed to predict ²H-derived FFM from BIA-derived whole-body impedance and other relevant predictors. Model performance was expressed as adjusted R² and RMSE. Prediction errors were also calculated.

RESULTS

Participants were aged 16-59 mo, of whom 46% were girls, and their median (IQR) height-for-age z-score (HAZ) was -2.58 (-2.92 to -2.37) according to the WHO growth standards. Impedance index (height²/impedance measured at 50 kHz) alone explained 89.2% variation in FFM and had an RMSE of 583 g (precision error 6.5%). The final model contained age, sex, impedance index, and height-for-age z-score as predictors and explained 94.5% variation in FFM with an RMSE of 402 g (precision error 4.5%).

CONCLUSIONS

We present a BIA calibration equation for a group of stunted children with a relatively low prediction error. This may help evaluate the efficacy of nutritional supplementation in large-scale trials in the same population. J Nutr 20XX;xxx:xx.

Valuing the Diversity of Research Methods to Advance Nutrition Science

The ASN Board of Directors appointed the Nutrition Research Task Force to develop a report on scientific methods used in nutrition science to advance discovery, interpretation, and application of knowledge in the field. The genesis of this report was growing concern about the tone of discourse among nutrition professionals and the implications of acrimony on the productive study and translation of nutrition science. Too often, honest differences of opinion are cast as conflicts instead of areas of needed collaboration. Recognition of the value (and limitations) of contributions from well-executed nutrition science derived from the various approaches used in the discipline, as well as appreciation of how their layering will yield the strongest evidence base, will provide a basis for greater productivity and impact. Greater collaborative efforts within the field of nutrition science will require an understanding that each method or approach has a place and function that should be valued and used together to create the nutrition evidence base. Precision nutrition was identified as an important emerging nutrition topic by the preponderance of task force members, and this theme was adopted for the report because it lent itself to integration of many approaches in nutrition science. Although the primary audience for this report is nutrition researchers and other nutrition professionals, a secondary aim is to develop a document useful for the various audiences that translate nutrition research, including journalists, clinicians, and policymakers. The intent is to promote accurate, transparent, verifiable evidence-based communication about nutrition science. This will facilitate reasoned interpretation and application of emerging findings and, thereby, improve understanding and trust in nutrition science and appropriate characterization, development, and adoption of recommendations.

Development of population-specific prediction equations for bioelectrical impedance analyses in Vietnamese children

There is a need for accurate, inexpensive and field-friendly methods to assess body composition in children. Bioelectrical impedance analysis (BIA) is a promising approach; however, there have been limited validation and use among young children in resource-poor settings. We aim to develop and validate population-specific prediction equations for estimating total fat mass (FM), fat free-mass (FFM) and percentage body fat (PBF) in Vietnamese children (4-7 years) using reactance and resistance from BIA, anthropometric variables and demographic information. We conducted a cross-sectional survey of 120 children. Body composition was measured using dual-energy X-ray absorptiometry (DXA), BIA and anthropometry. To develop prediction equations, we split all data into development (70 %) and validation datasets (30 %). The model performance was evaluated using predicted residual error sum of squares, root mean squared error (RMSE), mean absolute error (MAE) and R2. We identified a top performing model with the least number of parameters (age, sex, weight and resistance index or resistance and height), low RMSE (FM 0·70, FFM 0·74, PBF 3·10), low MAE (FM 0·55, FFM 0·62, PBF 2·49), high R2 (FM 0·95, FFM 0·92, PBF 0·82) and the least difference between predicted values and actual values from DXA (FM 0·03 kg or 0·01 sd, FFM 0·06 kg or 0·02 sd, PBF 0·27 % or 0·04 sd). In conclusion, we developed the first valid and highly predictive equations to estimate FM, FFM and PBF in Vietnamese children using BIA. These findings have important implications for future research on the double burden of disease and risks associated with overweight and obesity in young children.

Factors associated with stunting in healthy children aged 5 years and less living in Bangui (RCA)

Stunting remains a major public health concern worldwide. Although its global prevalence is slowly decreasing, the actual number of affected children is still rising in Sub-Saharan Africa. In the Central African Republic (CAR), about one third of all children below the age of five are stunted. Stunting is correlated with many long-term consequences, including poor cognitive development and a higher rate of morbidity and mortality, making stunting a major contributor to poverty. In CAR, little is known about the factors that contribute to stunting. This study aimed at analysing, in a cross-sectional study, the main factors associated with stunting in a group of 414 children recruited between December 2011 and November 2013, aged five years or less and living in Bangui. For all children, demographic, socio-economic and anthropometric data were recorded and asymptomatic enteropathogen carriage was assessed in stool samples using classical microbiological assays. The study group had a mean age of 14.2±10 months. Fifty-eight percent (292/414) were boys, and 36 percent (148/414) exhibited stunted growth. Of the stunted children, 51% (75/148) showed a moderate delay in linear growth for their age group [height-for-age z-score (HAZ) between -2 and -3 SD] while 49% (73/148) presented a severe delay (HAZ < -3). Factors significantly associated with stunting included gender (aOR: 1.67; 95% CI: 1.07; 2.62 for boys compared to girls) and age (aOR of 3.98 (95% CI: 2.45; 6.46) for toddlers and aOR 4.42 (95% CI: 2.36; 8.28) for children compared to infants). Most importantly, we identified being overweight [weight-for-height z-score (WHZ) > 2 SD; aOR: 3.21; 95% CI: 1.50; 6.90 of overweight compared to normal weight] as also being significantly associated with stunting. This is the first study showing that even in the poorest countries of the world there is an association of stunting with being overweight.

Modernization and the onset of overweight and obesity in Bougainville and Solomon Islands children: cross-sectional and longitudinal comparisons between 1966 and 1986

This set of cross-sectional and longitudinal data from children and young adults in certain Bougainville and Solomon Islands populations undergoing rapid modernization during the period 1966-1986 reveals very different responses to essentially the same stimuli-the introduction and widespread availability of western dietary items and reductions in habitual activity. Our analyses of over 2,000 children and young adults first measured in 1966-1972, with follow-up surveys in 1968-1970 and 1985-1986, show changes in overweight/obesity in these communities have their onset around puberty, and are not related to differences in childhood growth stunting. The prevalence of overweight and obesity increased substantially during the period of this study among young adults, particularly women, and in groups with more Polynesian affinities, where the frequency of overweight (BMI ≥ 25) tripled over this 20-year interval. However, the BMI of the more Papuan groups on Bougainville remained remarkably stable, even though they were close to the epicenter of modernization during this period, the Bougainville Copper Mine.

Estimating total body fat using a skinfold prediction equation in Brazilian children

BACKGROUND

The double burden of obesity and underweight is increasing in developing countries and simple methods for the assessment of fat mass in children are needed.

AIM

To develop and validate a new anthropometric predication equation for assessment of fat mass in children.

SUBJECTS AND METHODS

Body composition was assessed in 145 children aged 9.8 ± 1.3 (SD) years from São Paulo, Brazil using dual energy X-ray absorptiometry (DEXA) and skinfold measurements. The study sample was divided into development and validation sub-sets to develop a new prediction equation for FM (PE).

RESULTS

Using multiple linear regression analyses, the best equation for predicting FM (R(2) = 0.77) included body weight, triceps skinfold, height, gender and age as independent variables. When cross-validated, the new PE was valid in this sample (R(2) = 0.80), while previously published equations were not.

CONCLUSION

The PE was more valid for Brazilian children that existing equations, but further studies are needed to assess the validity of this PE in other populations.

Accuracy of anthropometric measurements in estimating fat mass in individuals with 21-hydroxylase deficiency

OBJECTIVE

The use of anthropometric measurements to estimate the percentage of body fat (%BF) is easy and inexpensive. However, the accuracy of these methods in patients with 21-hydroxylase deficiency (21OHD) has not been explored. The objective of this study was to evaluate the accuracy of skinfold-based models, body mass index (BMI), and waist circumference (WC) in estimations of %BF using dual-energy X-ray absorptiometry (DXA) as the reference method in individuals with 21OHD.

METHODS

Fifty-four 21OHD patients (32 women and 22 men), aged 7 to 20 y, were recruited for the study. DXA was used to determine %BF; four predictive skinfold equations, BMI, and WC were assessed for accuracy in determining %BF.

RESULTS

All predictive skinfold equations were highly associated (R, range: 0.82-0.89) with DXA %BF values. In women, BMI and WC showed moderate correlations (R = 0.69 for both BMI and WC) with DXA values. In contrast, among men there was a low explanatory power for BMI (13%) and WC (4%) and high errors (BMI, 6.9%; WC, 7.4%). All predictive equations significantly underestimated %BF (range of differences, -4.1 to -8.9) compared with DXA (women, 31.3 ± 6.1; men, 24.4 ± 7.3), and large limits of agreement were observed (range, -15.3 to 1.7 and -15.5 to 4.2 for women and men, respectively).

CONCLUSION

In children and adolescents with 21OHD, %BF as estimated by skinfold measurements was associated more strongly with DXA-assessed %BF than both BMI and WC. However, still, the skinfold-based assessment underestimated DXA %BF and showed moderate agreement.

How useful is BMI in predicting adiposity indicators in a sample of Maya children and women with high levels of stunting?

OBJECTIVES

Body mass index (BMI) is used frequently to estimate adiposity levels in children and adults. However, the applicability of BMI to populations with high levels of stunting has been questioned. Stunted people can have disproportionately short legs, which may increase BMI without increasing body fat because of the relatively larger trunk compared with the legs.

METHODS

A sample of 57 urban Maya schoolchildren, aged 7-9 years (31 boys), and 53 adult women underwent anthropometric assessments and bioelectrical impedance analysis. Multiple linear regression was performed to determine whether the ability of BMI to predict adiposity indicators is altered by stunting and sitting height ratio (SHR). The adiposity indicators were waist circumference, sum of skinfolds, upper arm muscle area, upper arm fat area, and arm fat index.

RESULTS

BMI was the strongest predictor of all adiposity indicators and in most cases, explained more of the variance in adiposity of Maya children than Maya women. Abdominal adiposity was better predicted by BMI than peripheral adiposity in Maya women and Maya children. Stunting was significant in predicting adiposity in some models but never substantially changed the variance explained. SHR was never a significant predictor.

CONCLUSIONS

The relationship between BMI and adiposity indicators is not changed by stunting status or body proportions in this short population of urban Maya children and women. BMI can be used as an indicator of adiposity for these children but not the women. It is recommended that BMI is used in conjunction with other estimates of body composition.

Detection of cardio-metabolic risk by BMI and waist circumference among a population of Guatemalan adults

BACKGROUND

BMI and waist circumference (WC) are used to screen for cardio-metabolic risk; however it is unclear how well these indices perform in populations subject to childhood stunting.

OBJECTIVES

To evaluate BMI and WC as indicators of cardio-metabolic risk and to determine optimal cut-off points among 1,325 Guatemalan adults (44 % stunted: 162 cm men).

METHODS

Cardio-metabolic risk factors were systolic/diastolic blood pressure 85 mmHg, glucose 5 mmol/l, TAG 7 mmol/l, ratio of total cholesterol to HDL-cholesterol 0, and the presence of two or more and three or more of the preceding risk factors. Receiver operating characteristic (ROC) curve analysis was used.

RESULTS

Areas under the ROC curve were in the range of 005978 for WC among men and 006472 among women, respectively. Optimal cut-off points for BMI were 242651 kg/m2 stunted; 242656 kg/m2 among women (262769 kg/m2 non-stunted). Optimal cut-off points for WC were 879134 cm stunted; 889333 cm among women (909486 cm non-stunted).

CONCLUSION

Optimal cut-off points for BMI were slightly higher among women than men with no meaningful differences by stature. Optimal cut-off points for WC were several centimetres lower for stunted compared with non-stunted men, and both were substantially lower than the current recommendations among Western populations. Cut-off points derived from Western populations may not be appropriate for developing countries with a high prevalence of stunting.

Relation of ratio indices of anthropometric measures to obesity in a stunted population

The ratios of anthropometric measures are used to estimate obesity while controlling for allometric scaling. A good index should be uncorrelated with its denominator; this often requires exponentiation of the denominator. The stability of the derived exponents across populations is not known. We obtained subscapular (SUBS) and triceps (TRI) skinfolds, weight (WT), height (HT), waist circumference (WC), fat mass (FM), and fat-free mass (FFM) in a population of Guatemalan adults [height 1.63 +/- 0.06 m (868 males); 1.51 +/- 0.06 m (1047 females)]. We derived exponents for the indices WT/HT(P), SUBS/TRI(P), TRI/SUBS(P), WC/HT(P), FM/WT(P), and FM/FFM(P) such that the ratios were free from association with their denominators. The derived exponents were (Men: SUBS/TRI(0.88), FM/WT(2.69), FM/FFM(2.86), WC/HT(0.68), and WT/HT(2.17); Women: SUBS/TRI(0.93), FM/WT(2.01), FM/FFM(3.37), WC/HT(0.47), WT/HT(2.03)). For all examined indices the derived exponents differed (P < 0.05) from 1 and differed (P < 0.05) between men and women. The exponents for the men also differed from those previously published for Brazilian men (JCK Wells and CG Victora [2005]: Int J Obes 29:483-489). The derived indices were not more strongly correlated with adiposity than were simple unexponentiated ratios. Although exponentiation of the denominator eliminates the association of index with its denominator, the resulting exponents lack generalizability across populations, especially those where stunting remains prevalent.

Size at birth, infant, early and later childhood growth and adult body composition: a prospective study in a stunted population

BACKGROUND

Pre-natal and post-natal growth are associated with adult body composition, but the relative importance of growth in different periods of childhood is still unclear, particularly in stunted populations.

METHODS

We studied 358 women and 352 men measured as children in 1969-77 in four villages in Guatemala, and re-measured as adults in 2002-04 (mean age 32.7 years). We determined the associations of body mass index (BMI) and length at birth, and changes in BMI and length during infancy (0-1.0 year) and early (1.0-3.0 years) and later (3.0-7.0 years) childhood, with adult BMI ((a)BMI), percentage of body fat ((a)PBF), abdominal circumference ((a)AC) and fat-free mass ((a)FFM).

RESULTS

Prevalence of stunting was high (64% at 3 years; HAZ < -2SD). Obesity (WHZ > 2SD) prevalence in childhood was <2%, while overweight prevalence in adulthood was 52%. BMI at birth was positively associated with (a)BMI and (a)FFM while length at birth was positively associated with (a)AC and (a)FFM. Increased BMI in infancy and later childhood were positively associated with all four adult body composition measures; associations in later childhood with fatness and abdominal fatness were stronger than those with (a)FFM. Change in length during infancy and early childhood was positively associated with all four adult body composition outcomes; the associations with (a)FFM were stronger than those with fat mass.

CONCLUSIONS

Increases in BMI between 3.0 and 7.0 years had stronger associations with adult fat mass and abdominal fat than with (a)FFM; increases in length prior to age 3.0 years were most strongly associated with increases in (a)FFM.

Overweight with concurrent stunting in very young children from rural Mexico: prevalence and associated factors

OBJECTIVE

To document the prevalence of overweight or obesity concurrent with stunting in rural low-income Mexican children and to identify demographic and socio-economic characteristics that could help identify families at risk of having an overweight/obese and stunted young child in this population.

DESIGN

Cross-sectional analysis of the nutritional status of very young children, using primary data from a rural community-based survey conducted in 2003. Overweight, obesity and stunting were documented along with several maternal, household and community characteristics.

SETTING

Impoverished areas of rural Mexico.

SUBJECTS

Pre-school children (n=7555), aged 24-72 months.

RESULTS

The combined prevalence of overweight and obesity was equal to or greater than 20% in all children, as was the prevalence of stunting. The prevalence of concurrent overweight or obesity and stunting was approximately 5% in non-indigenous children, and over 10% in indigenous children 24-60 months. A multinomial logistic analysis revealed that the factors associated with coexisting stunting and overweight/obesity were lower socio-economic status (SES), lower maternal age, education, intelligence (vocabulary) and perceived social status, shorter maternal height, and larger household size. Among only stunted children, the risk of also being overweight or obese was associated with younger maternal age (relative risk ratios (RRR): 0.98, P=0.05), lower maternal perceived social status (RRR: 0.95, P<0.01) and maternal obesity (RRR: 2.93, P<0.0001) or overweight (RRR: 1.50, P=0.002).

CONCLUSIONS

These analyses highlight that concurrent overweight or obesity and stunting is an important public health issue in low-income areas of rural Mexico beginning in early childhood. Even within this impoverished population, children living in households with low relative SES are the most vulnerable.

SPONSORSHIP

Financial support for this research was provided by the National Institutes of Child Health and Human Development, the Fogarty International Center at NIH, the John D and Catherine T MacArthur Foundation 'Research Network on Socioeconomic Status and Health' and the Mexican Government.