Estimation of body fatness by air displacement plethysmography in African American and white children

The purpose of this study was to determine the ability of air displacement plethysmography (ADP) to estimate body fatness in prepubertal and early pubertal African American and white children. One hundred nineteen nonoverweight and overweight boys (N = 56) and girls (N = 63), age (mean +/- SD) 9.8 +/- 1.7 y, body mass index 25.9 +/- 7.6 kg/m2 (range, 14.2-47.0 kg/m2), and mean percent body fat (%BF) by dual-energy x-ray absorptiometry (DXA) 39.2 +/- 11.7% (range, 12.2-57.5%), were studied. %BF by ADP was compared with DXA %BF estimates and with body fat by several field methods: skinfold thicknesses using the Slaughter et al. equations (Hum Biol 60: 709-723, 1988), bioelectrical impedance analysis (BIA) using the Houtkooper et al. equation (J Appl Physiol 72: 366-373, 1992), and a predictive equation using skinfold thicknesses, BIA, and weight (Goran et al.: Am J Clin Nutr 63: 299-305, 1996). All methods used to estimate %BF were significantly correlated with DXA (all p < 0.0001), with r2 ranging from 0.85 (skinfold measurements) to 0.95 (ADP). ADP using the Siri equation underestimated %BF by -1.9% (p < 0.001); the Bland-Altman limits of agreement (defined as +/-2 SD) were +/-7.4%. %BF by ADP-Siri underestimated %BF by DXA by 3.0% for girls (p < 0.001) and by 0.6% for boys (NS). Agreement between body fat estimation by ADP and DXA did not vary with age, race, or pubertal stage. Application of the age-adjusted Lohman model to ADP significantly increased the magnitude of the underestimation to -6.9% (p < 0.0001). Prediction of %BF by the Slaughter skinfold thickness equation showed no significant mean bias for the overall data, but significantly underestimated %BF in girls (-3.7%) while overestimating %BF in boys (+2.4%) with wide limits of agreement (+/-17.7%, p < 0.01 versus ADP). %BF by the Houtkooper BIA equation or Goran model underestimated %BF to a significantly greater degree than ADP (Houtkooper, -8.1%; Goran, -10.1%; both p < 0.0001 versus DXA or ADP). Determination of %BF from ADP using the Siri model slightly underestimates %BF as determined by DXA in girls, but appears to be superior to existing field methods both in accuracy and limits of agreement. Because of the ease with which it can be performed, ADP may prove useful for investigations of adiposity in children.     

Fat mass by air-displacement plethysmography and impedance in obese/non-obese children and adolescents.

OBJECTIVE: To determine the level of agreement between measurements of body composition by air-displacement plethysmography (ADP) and bioelectrical impedance analysis (BIA) in obese/non-obese children and adolescents. METHODS: Fat mass (FM) and fat free mass (FFM) were measured by ADP using the BOD-POD system and foot-to-foot BIA in 187 children and adolescents (75 males and 112 females, aged 5 to 22 years). Obesity was defined as a percentage FM (determined by BOD-POD), as a percentage (%) higher than 25%-35%. Sixty-four subjects were obese and 123 non-obese. RESULTS: Lin's Concordance Coefficient (Rc) between estimates of FM (%) and FFM (kg) was 0.79 (95% CI: 0.73; 0.83) by BIA and 0.96 (95% CI: 0.95; 0.97) by ADP. For the group of patients as a whole, the mean difference (p < 0.001) between methods (the BIA measurement minus the ADP measurement) was -3.39 (95% CI: -4.13; -2.65) for FM (%) and 1.54 (95% CI: 1.10; 1.98) for FFM (kg) (p < 0.001). The limits of agreement were -13.70; 6.90 for FM (%) and 1.40; 7.60 for FFM (kg). In the obese group, the mean difference between methods was -5.01 (95% CI: -6.21; -3.81) for FM (%) and 2.58 (95% CI: 3.45; 1.71) for FFM (kg) (p < 0.001). In the non-obese group, these mean differences were 2.49 (95% CI: -3.41; -1.57) and 0.96 (95% CI: 1.43; 0.50), respectively (p < 0.001). CONCLUSIONS: Compared with ADP, foot-to-foot BIA overestimates FFM and underestimates FM in obese and non-obese children of either sex. ADP and BIA estimates of FFM and FM are highly correlated for both obese/non-obese children. However, the large limits of agreement suggest that these methods should not be used interchangeably.     

Quelle méthode alternative à l'absorptiométrie biphotonique (DEXA) utiliser pour évaluer la composition corporelle des adolescents en surpoids ou obèses ?

CONTEXT: Professionals in charge of overweight and obese children and adolescents need a simple, reliable and precise method for assessing body composition. OBJECTIVES: To compare body composition as assessed by dual-energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA) and the skinfold thickness (SFT) method in overweight and obese adolescents, and to establish and validate new predictive equations of body composition from BIA measurements using DXA as standard method. SUBJECTS AND METHODS: Body composition was assessed in 143 obese adolescents (Z-score = 3.2 +/- 1.4) aged 12 to 17 years by DXA, BIA (RJL System, Analycor and Analycor XF models) and SFT (Siri and Slaughter's equations). New prediction equations of fat mass (FM) as assessed by DXA were computed from BIA measurements in a calibration group, and validated in an homologous group of subjects. Results. - The Bland-Altman test showed that compared to DXA, BIA underestimated FM by 2.8 +/- 2.0 kg and 2.3 +/- 2.1 kg using the RJL System and Analycor impedancemeter, respectively (P < 0.001).With the Analycor XF model, FM was underestimated by 3.3 +/-2.6 kg in boys, and over-valued by 0.6 +/- 2.4 kg in girls. On the contrary, the predictive equation of Wabitsch et al. overvalued FM by 6.2 +/- 2.9 kg. The SFT method overvalued FM by 2.1 +/- 5.0 kg in boys and underestimated FM by 2.3 +/- 3.5 kg in girls using Slaughter et al. equation, while Siri's equation underestimated FM by 4.0 +/- 2.9 kg (P < 0.001). The alternative to the DXA method to assess FM was BIA with new prediction equations including gender, body weight, height(2)/resistance and reactance. CONCLUSION: DXA, BIA and the SFT method were not directly interchangeable. The SFT method was inadequate to assess body composition in overweight and obese adolescents. BIA and new prediction equations could be an alternative to the DXA method in overweight and obese adolescents.     

Cross-calibration of multi-frequency bioelectrical impedance analysis with eight-point tactile electrodes and dual-energy X-ray absorptiometry for assessment of body composition in healthy children aged 6–18 years

Background:  In diagnosis and treatment of obesity, body composition analysis including percent body fat (%BF) is useful in the clinical setting. Because bioelectrical impedance analysis (BIA) could be used quickly, easily and was non-invasive in clinical setting, the purpose of the present study was to evaluate the usefulness of multi-frequency BIA with eight-point tactile electrodes (MF-BIA8; InBody 720, Biospace) compared with dual-energy X-ray absorptiometry (DXA) in healthy children and adolescents.
Methods:  A total of 166 children and adolescents under 18 (male, n  = 86; female, n  = 80) were recruited. Height, weight, body mass index (BMI) and Tanner stage were measured for each subject. The body composition such as fat-free mass (FFM), fat mass (FM), and %BF was measured on BIA and DXA and compared.
Results:  On linear regression analysis, DXA FFM = 1.006(BIA FFM) + 0.554, R ² = 0.99 and the standard error of the estimate (SEE) was 1.16 kg; DXA FM = 0.971(BIA FM) – 0.596, R ² = 0.93; SEE, 1.34 kg; and DXA %BF = 0.940(BIA %BF) – 1.026, R ² = 0.858; SEE, 3.03%. Limit of agreement in FFM, FM, and %BF was 0.7 ± 2.3 kg, −0.9 ± 2.9 kg and –2.2 ± 6.1%, respectively.
Conclusions:  Although the %BF was not interchangeable with DXA, MF-BIA8 (InBody 720; Biospace) could be used to measure body composition of children and adolescents in the clinical field because of its high precision.     

Measurement of body fat using leg to leg bioimpedance.

AIMS: (1) To validate a leg to leg bioimpedance analysis (BIA) device in the measurement of body composition in children by assessment of its agreement with dual energy x ray absorptiometry (DXA) and its repeatability. (2) To establish a reference range of percentage body fat in Hong Kong Chinese children. METHODS: Sequential BIA and DXA methods were used to determine body composition in 49 children aged 7-18 years; agreement between the two methods was calculated. Repeatability for the BIA method was established from duplicate measurements. Body composition was then determined by BIA in 1139 girls and 1243 boys aged 7-16 years, who were randomly sampled in eight local primary and secondary schools to establish reference ranges. RESULTS: The 95% limits of agreement between BIA and DXA methods were considered acceptable (-3.3 kg to -0.5 kg fat mass and -3.9 to 0.6% body fat). The percentage body fat increased with increasing age. Compared to the 1993 Hong Kong growth survey, these children had higher body mass index. Mean (SD) percentage body fat at 7 years of age was 17.2% (4.4%) and 14.0% (3.4%) respectively for boys and girls, which increased to 19.3% (4.8%) and 27.8% (6.3%) at age 16. CONCLUSION: Leg to leg BIA is a valid alternative method to DXA for the measurement of body fat. Provisional reference ranges for percentage body fat for Hong Kong Chinese children aged 7-16 years are provided.     

Comparison of bioelectrical impedance analysis and dual energy X-ray absorptiometry for assessment of body composition in children

BACKGROUND: There are a variety of methods for assessing body composition. Bioelectrical impedance analysis (BIA) is an easy and non-invasive technique, but has limitations in underweight and overweight subjects. Few reports have investigated the validity of BIA in children. In this report, the characteristics of BIA, especially in overweight and underweight children, are assessed and the results are compared with those of dual energy X-ray absorptiometry (DXA), as a reliable method for assessing body composition. METHODS: Determination of the fat-free mass (FFM), body fat content and percent body fat (%fat) was carried out using both BIA and DXA. The subjects (60 males and 44 females) were divided into five groups according to the percentage of ideal bodyweight (%IBW). Ten obese children, who were treated with exercise and a low-energy diet for 1 month, were also enrolled in this study. RESULTS: The %fat, FFM and body fat content showed a close correlation when measured by BIA and DXA with the correlation coefficients being 0.90, 0.95, and 0.95, respectively. In the underweight group, the %fat value determined by BIA tended to be greater than that determined by DXA, while in the overweight group, the BIA value was lower than the DXA value. The same trend was also seen in obese children before and after therapy with exercise and diet. CONCLUSION: Bioelectrical impedance analysis seems to be a reasonable method for daily clinical use, but attention should be paid to the interpretation of %fat values in underweight and overweight children.     

Measured and predicted total body water in children with myelomeningocele

OBJECTIVE: Children with myelomeningocele (MMC) have an altered body composition and an atypical distribution of total body water (TBW). The aim of the present study was to determine the accuracy of current predictive equations, based on bioelectrical impedance analysis (BIA), in determining TBW when compared with measured TBW using deuterium dilution. METHODS: Fourteen children with MMC were measured for whole body BIA and TBW (using deuterium dilution and the Plateau method). Total body water was predicted using equations based on the resistance and characteristic frequency from BIA measurements and heights of subjects. RESULTS: The mean measured TBW was 15.46 +/- 8.28 L and the mean predictions for TBW using equations based on the resistance and characteristic frequency from BIA measurements and heights of subjects were 18.29 +/- 8.41 L, 17.72 +/- 11.42 L and 12.51 +/- 7.59 L, respectively. The best correlation was found using characteristic frequency. The limits of agreement between measured and predicted TBW values using Bland-Altman analysis were large. CONCLUSIONS: The present study suggests that the prediction of TBW in children with MMC can be made accurately using the equation of Cornish et al. based on BIA measurements of characteristic frequency.     

Determination of body composition in African-American children: validation of bioelectrical impedence with dual energy X-ray absorptiometry

Body compositional differences between Black and White adults are well-known. It has become increasingly apparent that these racial variations may begin in childhood. Previously, our group validated tetrapolar bioelectrical impedance (BIA) measurements against H2(18O) dilution method to develop prediction formulas of fat free mass (FFM) in healthy White-American children: FFM = 0.524 Ht2/R + 0.415 Wt 0.32. In the present study we used BIA to establish a FFM prediction equation for forty African-American children (19 males and 21 females). Of the females, six were diagnosed with polycystic ovary syndrome (PCOS) and were obese. FFM was determined by dual energy X-ray absorptiometry (DEXA). Impedence measurements by BIA showed a strong correlation with FFM determined by DEXA. In healthy Black children, FFM = 0.84 Ht2/R + 1.10 with a standard error of estimate (SEE) of 1.47 kg (R2 = 0.97). In Black females with PCOS, FFM = 0.62 Ht2/R + 0.21 Wt - 1.94 with a SEE of 1.43 kg (R2 = 0.99). The observed differences in the prediction equations of FFM between White-American and African-American children underline the importance of using race-specific formulas in evaluating body composition. With the overall increase in rates of childhood obesity and more so in the Black race, BIA is an easy and useful tool for the assessment and follow up of body compositional changes with lifestyle interventions.     

Evaluation of lean body mass in obese children

Multiple skinfold anthropometry (MSA) and bioelectrical impedance analysis (BIA) are useful as clinically non-invasive, inexpensive and portable techniques, although it is not clear if they can be used interchangeably in the same patient to routinely assess her/his body composition. In order to compare BIA, MSA and DXA in the estimation of lean body mass (LBM) of a pediatric obese population, 103 obese [body mass index (BMI) > 97th percentile] children (median age: 11 years; range: 5.4–16.7 years) underwent nutritional evaluation. After an overnight fast, the subjects’ anthropometric measurements were performed by the same investigator: body weight (BW), height, skinfold thickness (four sites); fat body mass (FBM) using Brook or Durnin equations and dual X-ray absorptiometry (DXA). BIA was performed using a bioelectrical impedance analyzer (Analicor-Eugedia, 50 kHz) and Houtkooper’s equation to calculate LBM. Linear regression analysis was performed to evaluate the relationship between the prediction of LBM by MSA, DXA and BIA. The differences between the three techniques were analysed using Student’s t-test for paired observations and the Bland and Altmann method. A considerable lack of agreement was observed between DXA- and BIA-LBM (δ = −4.37 kg LBM; δ−2σ = −11.6 kg LBM; δ+2σ = +2.8 kg LBM); between DXA- and MSA-LBM (δ = −1.72 kg LBM; δ−2σ = −8.2 kg LBM; δ+2σ = +4.8 kg LBM) and between BIA- and MSA-LBM (δ = −2.65 kg LBM; δ−2σ = −10.5 kg LBM; δ+2σ = +5.2 kg LBM). Conclusion: In obese children, DXA, BIA and MSA should not be used interchangeably in the assessment of LBM because of an unacceptable lack of agreement between them. The discrepancies between methods increase with the degree of obesity.     

Agreement between skinfold-predicted percent fat and percent fat from whole-body bioelectrical impedance analysis in children and adolescents.

PURPOSE: The purpose of the study was to determine the agreement of percent body fat estimates and obesity classification derived via whole-body bioelectrical impedance analysis (% BF-BIA) with percent body fat estimates and obesity classification from skinfolds (% BF-SF) in children and adolescents. METHODS: BIA and SF data were collected on 609 boys and 645 girls aged 7 to 14 years. RESULTS: Although moderate correlations were observed between the measures, Bland-Altman analyses revealed fixed and proportional bias, and 95% limits of agreement covered a range of over 20% BF. Agreement of obesity classification was moderately high in boys (Kq = 0.77) and girls (Kq = 0.81), but fewer children were classified as obese via % BF-BIA (14.5%) than via % BF-SF (19.8%). CONCLUSIONS: The results indicate that whole-body BIA provides % BF estimates that are systematically different from % BF estimates from skinfolds in children and adolescents.     

Pitfalls in the assessment of body composition in survivors of acute lymphoblastic leukaemia

Background: Body fat mass (FM) and fat free mass (FFM) in childhood are often estimated by conversion of a measured variable into compartmental body composition using constants or regression equations that have been previously derived in healthy individuals. Application of such constants or equations to children with disease states may lead to inappropriate conclusions since the "normal" relationships may become altered. Aims and Methods: To test this hypothesis by taking measurements of body composition using dual energy x ray absorptiometry (DEXA) as a "gold standard" method and calculating hydration and body potassium constants using isotopic water dilution and whole body potassium counting. Measurements of bioelectrical impedance (BIA) by two different analysers (RJL and Holtain) were also performed to allow comparison with body water measurements. Results: Measurements were performed in 35 children treated for acute lymphoblastic leukaemia (ALL) and compared to those in 21 children treated for a variety of other malignancies and 32 healthy sibling controls. The mean hydration and potassium content of FFM was significantly reduced in the ALL group compared to both other malignancies and controls. Application of equations derived from controls for the measurement of FFM derived from bioelectrical impedance led to an underestimation of 1.15 kg when compared to that derived from DEXA in children treated for ALL but not in other malignancies. For all groups combined, BIA was significantly different in the two analysers. Conclusion: Care needs to be taken in the application of equations derived from the normal population to body composition measurement in children treated for ALL.     

Pitfalls in the assessment of body composition in survivors of acute lymphoblastic leukaemia.

BACKGROUND: Body fat mass (FM) and fat free mass (FFM) in childhood are often estimated by conversion of a measured variable into compartmental body composition using constants or regression equations that have been previously derived in healthy individuals. Application of such constants or equations to children with disease states may lead to inappropriate conclusions since the "normal" relationships may become altered. AIMS AND Methods: To test this hypothesis by taking measurements of body composition using dual energy x ray absorptiometry (DEXA) as a "gold standard" method and calculating hydration and body potassium constants using isotopic water dilution and whole body potassium counting. Measurements of bioelectrical impedance (BIA) by two different analysers (RJL and Holtain) were also performed to allow comparison with body water measurements. RESULTS: Measurements were performed in 35 children treated for acute lymphoblastic leukaemia (ALL) and compared to those in 21 children treated for a variety of other malignancies and 32 healthy sibling controls. The mean hydration and potassium content of FFM was significantly reduced in the ALL group compared to both other malignancies and controls. Application of equations derived from controls for the measurement of FFM derived from bioelectrical impedance led to an underestimation of 1.15 kg when compared to that derived from DEXA in children treated for ALL but not in other malignancies. For all groups combined, BIA was significantly different in the two analysers. CONCLUSION: Care needs to be taken in the application of equations derived from the normal population to body composition measurement in children treated for ALL.     

Assessment of nutritional status and body composition in children using physical anthropometry and bioelectrical impedance: influence of diurnal variations

BACKGROUND: To observe whether there are diurnal variations when assessing children's body composition, using physical anthropometric and bioelectrical impedance (BI) methods. METHODS: In 32 children (18 females and 14 males) aged between 7.1 and 14.9 years, weight, height, arm circumference (AC), four skinfolds, and total body impedance (Z) were measured at 8 A.M., 12 noon, 4 P.M., and 8 P.M. on the same day. Body mass index (BMI), skinfolds sum (SS), total body water (TBW), fat-free mass (FFM), and fat mass (FM) were also calculated at these times. RESULTS: Height at 8 P.M. was 1.156 +/- 0.54 cm less than at 8 A.M. (P < 0.001) and BMI increased 0.434 +/- 0.29 kg/m2 at 8 P.M. (P < 0.001). Weight, SS and AC underwent no significant changes in the course of the day. Z was 5.83% less at 8 P.M. than at 8 A.M. (P < 0.001), yielding a TBW and FFM increase at 8 P.M. of 0.855 +/- 1.061 and 1.173 +/- 1.47 kg, respectively (P < 0.001). CONCLUSIONS: In children there is a diurnal decrease in height, impedance and FM, and an increase in BMI, TBW, and FFM. These factors must be taken into account when using such methods for assessing nutritional status in childhood.     

Validation of Bioelectric Impedance Analysis against Dual-Energy <Emphasis Type="Italic">X</Emphasis>-ray Absorptiometry for assessment of body composition in Indian children aged 5 to 18 years

Objective

To validate body composition measurements by Bioelectric Impedance Analysis (BIA) against Dual-Energy X-ray Absorptiometry (DXA) as the reference method in healthy children and adolescents.

Design

Cross-sectional

Setting

Schools in and around Pune city, India.

Participants

A random sample of 210 (114 boys, 96 girls) apparently healthy Indian children and adolescents (5–18 y).

Methods

Weight, height, Tanner stage (TS) were recorded. Body composition measures: fat-free mass (FFM), fat mass (FM), lean mass (LM), bone mineral content (BMC) and body fat percentage (%BF) were assessed by BIA and DXA on a single day. Agreement between the methods was estimated by Pearson’s correlation, and Bland and Altman analysis.

Main outcome measures

%BF, FM, FFM, LM, BMC.

Results

BIA underestimated %BF by 6.7 (3.7)% as compared to DXA. Mean FFM, BMC and LM by BIA were significantly higher than by DXA (P<0.001). These differences remained similar after adjusting for age, BMI and TS. Mean differences between FFM (?2.32 (1.39) kg), BMC (?0.18 (0.15) kg), and LM (?2.15 (1.34) kg) by DXA and BIA were significant (P<0.01). Correlations between BIA and DXA were 0.92 for %BF, 0.96 for LM and 0.98 for FFM and BMC. Both the methods were similar in identifying normal and overfat children as per their respective cut-offs.

Conclusion

BIA and DXA techniques are not interchangeable for assessment of body composition. However, BIA may be used in the field/clinical setting preferably with ethnicity specific references.

     

Nutritional impact of antipseudomonas intravenous antibiotic courses in cystic fibrosis

OBJECTIVE: To evaluate the short term effects on nutritional status of home intravenous anti-pseudomonas antibiotic courses in cystic fibrosis (CF) patients chronically colonised with Pseudomonas aeruginosa. DESIGN: A prospective study involving 38 CF patients, mean age 10.9 (SD 4.3) years (range 4.3 to 22.2 years), presenting with pulmonary exacerbations of P aeruginosa infection. The patients received a 14 day antibiotic course of intravenous ceftazidime (200 mg/kg/day) and either amikacin (35 mg/kg/day) or tobramycin (15 mg/kg/day). Nutritional evaluation on days 1 and 14 involved measurements of weight, weight/height ratio (per cent of predicted value), energy intake (per cent of recommended daily allowances), serum prealbumin, and body composition assessed by two methods: bioelectrical analysis (BIA) and skinfold anthropometry. The non-parametric Wilcoxon t test was used for statistical analysis, with a Bland-Altman plot to assess the degree of agreement between the two methods of evaluating body composition. RESULTS: Weight increased by 1.0 (0.8) kg (p < 0.001); weight/height increased from 94.4(12.2)% to 98(12.7)% (p < 0.001), energy intake from 107(32)% to 119(41)% (p < 0.02), and prealbumin from 183 (63) to 276 (89) mg/l (p < 0.001). Fat mass increased by 0.8 (1.0) kg (p < 0.001), without any significant change in fat-free mass. The limits of agreement between BIA and anthropometry were -0.7 kg and +1.1 kg. CONCLUSIONS: Antibiotic courses allow an improvement in nutritional status in CF patients, with a gain in fat mass.     

Bioelectrical impedance for measuring percentage body fat in young persons with Down syndrome: validation with dual‐energy absorptiometry

Aim: Children with Down syndrome have an increased prevalence of obesity, although there is little work describing body composition in this population. The aims of this study were to accurately measure body fat in children with Down syndrome and to identify which existing algorithm best predicts percentage body fat in this population. Methods: Seventy children with Down syndrome had anthropometric, bioelectrical impedance analysis (BIA) and dual‐energy X‐ray absorptiometry (DXA) data collected to calculate percentage body fat (PBF). Pearson correlations were carried out to assess the relationships of various methods for measuring body fat and Bland–Altman plots to assess systematic error. Results: Mean PBF was 30.5% for girls and 22.5% for boys. A total of 38% of girls and 23% of boys were obese according to international criteria. PBF as determined by DXA correlated well with PBF by BIA in both girls and boys (r = 0.91 and 0.89, respectively, p < 0.001). Conclusion: There are high rates of obesity in children with Down syndrome. BIA can be used to accurately determine adiposity in this population. We recommend the use of the Schaeffer algorithm for calculation of PBF in children with Down syndrome.     

Nutritional impact of antipseudomonas intravenous antibiotic courses in cystic fibrosis

Accepted 21 November 1996 OBJECTIVE—To evaluate the short term effects on nutritional status of home intravenous anti-pseudomonas antibiotic courses in cystic fibrosis (CF) patients chronically colonised with Pseudomonas aeruginosa.DESIGN—A prospective study involving 38 CF patients, mean age 10.9 (SD 4.3) years (range 4.3 to 22.2 years), presenting with pulmonary exacerbations of P aeruginosa infection. The patients received a 14 day antibiotic course of intravenous ceftazidime (200 mg/kg/day) and either amikacin (35 mg/kg/day) or tobramycin (15 mg/kg/day). Nutritional evaluation on days 1 and 14 involved measurements of weight, weight/height ratio (per cent of predicted value), energy intake (per cent of recommended daily allowances), serum prealbumin, and body composition assessed by two methods: bioelectrical analysis (BIA) and skinfold anthropometry. The non-parametric Wilcoxon t test was used for statistical analysis, with a Bland-Altman plot to assess the degree of agreement between the two methods of evaluating body composition.RESULTS—Weight increased by 1.0 (0.8) kg (p < 0.001); weight/height increased from 94.4(12.2)% to 98(12.7)% (p < 0.001), energy intake from 107(32)% to 119(41)% (p < 0.02), and prealbumin from 183(63) to 276 (89) mg/l (p < 0.001). Fat mass increased by 0.8 (1.0) kg (p < 0.001), without any significant change in fat-free mass. The limits of agreement between BIA and anthropometry were -0.7 kg and +1.1 kg.CONCLUSIONS—Antibiotic courses allow an improvement in nutritional status in CF patients, with a gain in fat mass.     

Validation of Simple Epidemiological or Clinical Methods for the Measurement of Body Composition in Young Children

Objective:

The present study aimed to determine the validity of simple epidemiological and clinical methods for the assessment of body fatness in preschool children.

Methods:

In 89 children (42 boys, 47 girls; mean age 4.1 SD 1.3y) measures of body fatness were made using total body water (TBW), dual energy x-ray absorptiometry (DXA), air displacement plethysmography (BODPOD) and skinfold thickness. Methods were compared by Bland–Altman analysis using TBW as the reference method, and by paired comparisons and rank order correlations.

Findings:

Bias for DXA was +1.8% body fat percentage units (limits of agreement +15.5% to −11.9%), bias for BODPOD was −3.5% (limits of agreement +18.9% to −5.9%) and bias for skinfolds using the Slaughter equations was −6.5% (limits of agreement +10.0% to −23.1%). Significant rank order correlations with TBW measures of fatness were obtained for DXA estimates of fatness (r=0.54, P=0.01), but not for estimates of fat by skinfold thickness (r=0.20, P=0.2) or BODPOD (r=0.25, P=0.1). Differences between both DXA and BODPOD and the reference TBW estimates of body fatness were not significant (P=0.06 and P=0.1 respectively); however, the difference in estimated body fatness between skinfold thickness and TBW was significant (P<0.001).

Conclusion:

Estimates of body fatness in preschool children were inaccurate at the level of the individual child using all the methods, but DXA might provide unbiased estimates and a means of making relative assessments of body fatness.     

Bioelectrical impedance analysis of the body composition of Nigerian children with sickle cell disease

We used bioelectrical impedance (BIA) to investigate the body composition of children with sickle cell disease (SCD) in northern Nigeria. A total of 48 children with SCD and 51 controls between 3 and 20 years of age were studied. A significant difference was found in the weights of male subjects over the age of 10 years compared to controls (p = 0.01), but not in height. Significant differences were also observed for SCD males in the 10-18-year-old age range in body mass index (p = 0.001), fat free mass (p = 0.001), per cent fat free mass, (p = 0.02), body fat (p = 0.02), and per cent body fat (p = 0.02). No significant differences in any of these parameters between SCD subjects and controls were obtained for males under the age of 10 years. There were no significant differences in the height, weight, body mass index, or fat free mass for female SCD subjects compared to controls over the age range we studied. However, there were significant differences in the per cent fat free mass (p = 0.006), body fat (p = 0.025), and per cent body fat (p = 0.01) for female SCD subjects over the age of 10 years compared to controls. In addition to documenting differences in the body composition of adolescent boys with sickle cell disease in Nigeria, this study also demonstrated the feasibility of using bioelectrical impedance to analyse the body composition of individuals under the hot, arid conditions which prevail in sub-Saharan Africa.     

Body composition of preterm infants measured during the first months of life: bioelectrical impedance provides insignificant additional information compared to anthropometry alone

Detailed knowledge of body composition in preterm neonates during their later postnatal period may be important for the treatment process. However, little consideration has been given to test whether bioelectrical impedance analysis (BIA) is a useful bedside method to predict fat-free mass (FFM). The aim of the study is to assess whether BIA is a bedside method to measure FFM in preterm neonates. FFM of 118 white subjects (51 males, 67 females), mean gestational age of 30.1±3.1 weeks and birth weight of 1.26±0.47 kg, was measured at a gestational age of 38.6±3.8 weeks and actual body weight of 2.6±0.54 kg using dual energy X-ray absorptiometry (FFM_DXA). Weight (W), height (Ht), and bioelectric impedance (I) measurements were collected. Multiple regression analysis was performed to develop prediction equations to estimate FFM with impedance index (Ht²/I, cm²/Ω) and W (kg) as predictor variables. Bootstrap analysis was performed for validating the derived prediction equations. Correlations between FFM_DXA and weight were 0.96, 0.98, and 0.97 in boys, girls, and both sexes, respectively. Those between FFM_DXA and Ht²/I were: 0.73, 0.81, and 0.79. Equations used to predict FFM (kg) were for boys: and for girls: . Conclusions. In preterm neonates, weight is a more effective predictor of FFM than impedance index. The study provides a bedside procedure for estimating FFM, mainly based on anthropometric parameters rather than BIA.