Evaluation of body mass index percentiles for assessment of malnutrition in children with cystic fibrosis

OBJECTIVE: To compare the performance of recently released body mass index percentiles (BMIp) with standard anthropometric indexes, including height-for-age percentile (HAP), weight-for-age percentile (WAP) and percent ideal body weight (%IBW), as measures for nutritional failure in children with cystic fibrosis (CF). DESIGN: Cross-sectional analysis of growth and lung function data from 4577 children with CF reported to the German CF quality assurance (CFQA) project from 1995 to 2004. RESULTS: Frequency distribution of HAP (mean+/-s.d.: male 30.0+/-27.5; female 31.3+/-27.4) and WAP (male 28.9+/-27.0; female 29.6+/-26.7) were skewed, with significant numbers of patients below the fifth percentiles of a healthy reference population. However, because deficits occurred in both measures simultaneously, mean %IBW (male 97.0+/-12.1; female 98.1+/-12.3) assumed subjects weight close to the nominal weight-for-height at all ages. In contrast, mean BMIp was markedly reduced (male 35.7+/-27.9; female 35.6+/-27.2) and steadily declined with age. Ideal weight-for-age was significantly lower when predicted by %IBW compared with BMIp method, particularly in subjects with shorter-than-average stature. Consequently, less CF children were identified with nutritional failure according to %IBW method (male 20.5%; female 22.7%) compared with BMIp method (male 30.4%; female 28.7%). The clinical relevance of these findings was confirmed by stronger correlation of BMIp with impaired %forced expiratory volume/s, a marker for disease progression in CF. CONCLUSION: BMIp predicts nutritional failure more sensitively and accurately than conventional anthropometric indexes, at least in children with CF. Screening of CF patients by BMIp could provide an early warning sign and allow for timely therapeutic intervention.     

Comparison of ideal body weight equations and published height-weight tables with body mass index tables for healthy adults in the United States.

The purpose of this paper was to compare the ideal body weight (IBW) formulas and published height-weight tables for healthy adults in the United States with the body mass index (BMI) of 22 kg/m2, which is associated with lowest mortality. There are numerous formulas and published height-weight tables available to determine IBW, but there are no published studies comparing the validity of formulas with each other or comparing formulas with BMIs. Data from height-weight tables, weight for specific heights determined by IBW formulas, and weight for BMIs of 20, 22, 25, and 30 kg/m2 at different heights were plotted for both men and women. Slopes based on a range of heights were determined for each formula using relational database software. The value for each slope obtained by linear regression was compared with the BMIs to determine which fit best with BMI of 22 kg/m2. Most height-weight tables and formulas predicted IBWs within the range of BMI of 20-25 kg/m2. However, for shorter heights the formulas were closer to BMI 20 kg/m2 and for taller heights, were closer to BMI 25 kg/m2. Height-weight tables' slopes were closer to the BMI slopes than formula slopes. Robinson's formula appears to be the best equation for calculating desirable/healthy weights in men; however, no formula predicted close to a BMI of 22 kg/m2 for women. Thus, in practice it might be more useful to use BMI ranges instead of IBW formulas for men and women.     

Physiological and psychosocial contributors to malnutrition in children with cystic fibrosis: review

Malnutrition was once thought to be an inevitable consequence of cystic fibrosis (CF). It is now considered preventable but still contributes considerable morbidity in children. Malnutrition is linked to poorer pulmonary function, reduced survival and quality of life. As the anticipated lifespan of children with CF continues to lengthen, the prevention of malnutrition attains greater importance. This review explores the complex organic and psychosocial factors implicated in the aetiology of malnutrition associated with CF.     

农村女性超重肥胖体质指数与体脂率法评价比较

目的 采用WHO体脂率标准评价中国现行体质指数诊断超重和肥胖标准的准确性。方法 于2013年5-7月横断面调查河北省玉田县648名18~59岁中青年农村女性,采用标准方法测量人体学指标,生物电阻抗法测量体脂率(BF%);体质指数(BMI)参照《中国成人超重和肥胖预防控制指南》,体脂率参照WHO标准。结果 调查对象平均BMI为(24.74±3.97) kg/m²,平均体脂率为(28.54±7.04)%;依据体脂率(>35%)和BMI(≥28.0 kg/m²)标准,调查对象肥胖检出率分别为18.98%和20.06%,差异无统计学意义(P>0.05)。以体脂率30%为超重标准,BMI 24 kg/m²的灵敏度和特异度分别为87.38和79.06%,诊断一致性(Kappa值)为0.66;以体脂率35%为肥胖标准,BMI 28 kg/m²的灵敏度和特异度分别为71.54和92.00%,Kappa值为0.62。BMI与体脂率呈二次曲线关系(R²=0.614,P<0.001)。结论 《中国成人超重和肥胖预防控制指南》推荐的超重和肥胖标准与WHO体脂率超重和肥胖标准的准确度和诊断一致性均较好。     

Prepregnancy body mass index and gestational weight gain in relation to child body mass index among siblings

There is increasing evidence that in utero effects of excessive gestational weight gain may result in increased weight in children; however, studies have not controlled for shared genetic or environmental factors between mothers and children. Using 2,758 family groups from the Collaborative Perinatal Project, the authors examined the association of maternal prepregnancy body mass index (BMI) and gestational weight gain on child BMI at age 4 years using both conventional generalized estimating equations and fixed-effects models that account for shared familial factors. With generalized estimating equations, prepregnancy BMI and gestational weight gain had similar associations with the child BMI z score (β = 0.09 units, 95% confidence interval (CI): 0.08, 0.11; and β = 0.07 units, 95% CI: 0.04, 0.11, respectively. However, fixed effects resulted in null associations for both prepregnancy BMI (β = 0.03 units, 95% CI: -0.01, 0.07) and gestational weight gain (β = 0.03 units, 95% CI: -0.02, 0.08) with child BMI z score at age 4 years. The positive association between gestational weight gain and child BMI at age 4 years may be explained by shared family characteristics (e.g., genetic, behavioral, and environmental factors) rather than in utero programming. Future studies should continue to evaluate the relative roles of important familial and environmental factors that may influence BMI and obesity in children.     

Energy expenditure and the body cell mass in cystic fibrosis

Poor nutritional status in patients with cystic fibrosis (CF) is associated with severe lung disease, and possible causative factors include inadequate intake, malabsorption, and increased energy requirements. Body cell mass (which can be quantified by measurement of total body potassium) provides an ideal standard for measurements of energy expenditure. The aim of this study was to compare resting energy expenditure (REE) in patients with CF with both predicted values and age-matched healthy children and to determine whether REE was related to either nutritional status or pulmonary function. REE was measured by indirect calorimetry and body cell mass by scanning with total body potassium in 30 patients with CF (12 male, mean age = 13.07 +/- 0.55 y) and 18 healthy children (six male, mean age = 12.56 +/- 1.25 y). Nutritional status was expressed as a percentage of predicted total body potassium. Lung function was measured in the CF group by spirometry and expressed as the percentage of predicted forced expiratory volume in 1 s. Mean REE was significantly increased in the patients with CF compared with healthy children (119.3 +/- 3.1% predicted versus 103.6 +/- 5% predicted, P < 0.001) and, using multiple regression techniques, REE for total body potassium was significantly increased in patients with CF (P = 0.0001). There was no relation between REE and nutritional status or pulmonary disease status in the CF group. In conclusion, REE is increased in children and adolescents with CF but is not directly related to nutritional status or pulmonary disease.     

Ethnic differences in the relationship between body mass index and percentage body fat among Asian children from different backgrounds

Overweight and obesity in Asian children are increasing at an alarming rate; therefore a better understanding of the relationship between BMI and percentage body fat (%BF) in this population is important. A total of 1039 children aged 8-10 years, encompassing a wide BMI range, were recruited from China, Lebanon, Malaysia, The Philippines and Thailand. Body composition was determined using the 2H dilution technique to quantify total body water and subsequently fat mass, fat-free mass and %BF. Ethnic differences in the BMI-%BF relationship were found; for example, %BF in Filipino boys was approximately 2 % lower than in their Thai and Malay counterparts. In contrast, Thai girls had approximately 2.0 % higher %BF values than in their Chinese, Lebanese, Filipino and Malay counterparts at a given BMI. However, the ethnic difference in the BMI-%BF relationship varied by BMI. Compared with Caucasian children of the same age, Asian children had 3-6 units lower BMI at a given %BF. Approximately one-third of the obese Asian children (%BF above 25 % for boys and above 30 % for girls) in the study were not identified using the WHO classification and more than half using the International Obesity Task Force classification. Use of the Chinese classification increased the sensitivity. Results confirmed the necessity to consider ethnic differences in body composition when developing BMI cut-points and other obesity criteria in Asian children.     

Introduction: the use of body mass index to assess obesity in children.

The International Obesity Task Force (IOTF) was established in 1994 to address the increase in the worldwide prevalence of obesity. The goals of the IOTF are to 1) raise awareness in the population and among governments that obesity is a serious medical condition, 2) develop policy recommendations for a coherent and effective global approach to the management and prevention of obesity, and 3) implement appropriate strategies to manage and prevent obesity on a population basis worldwide. To assess the global prevalence of obesity in children and adolescents, the IOTF convened a workshop on childhood obesity to determine the most appropriate measurement to assess obesity in populations of and adolescents around the world. At the workshop, a variety of issues related to this problem were considered--including the best measure of fatness, the effect of application of a variety of existing standards on the prevalence of obesity in the same population, and the role of factors such as visceral adiposity and natural history in the definition of obesity. This article and those that follow represent the information presented at the workshop. The workshop concluded that the body mass index (BMI; in kg/m2) offered a reasonable measure with which to assess fatness in children and adolescents and that the standards used to identify overweight and obesity in children and adolescents should agree with the standards used to identify grade 1 and grade 2 overweight (BMI of 25 and 30, respectively) in adults.     

Classification of the degree of obesity by body mass index or by deviation from ideal weight

BACKGROUND: The purpose of this study was to compare classifications of subjects as underweight, normal weight, or obese by body mass index (BMI) and the ratio of body weight to ideal weight (W/IW). METHODS: We performed a theoretical comparison of the 2 indices. We compared classifications of the degree of obesity in 1839 women and 5914 men who were followed up in the primary care clinics of a United States federal hospital. Information was extracted from computerized records. Subjects were classified as underweight (BMI < 18.5 kg/m2, W/IW < 0.9), obese (BMI > or = 30.0 kg/m2, W/IW > or = 1.2), or normal weight (BMI, W/IW values between the cutoff values for underweight and obesity). W/IW values were computed assuming small, medium, and large skeletal frame for all. We compared the classifications of subjects as underweight, normal weight, or obese by BMI and W/IW. We used Cohen's kappa ratio to evaluate the agreement between these classifications. RESULTS: Theoretically, the cutoff values of BMI and W/IW for underweight and obesity are not in agreement. Patient data revealed substantial differences in the classifications of subjects as underweight, normal weight, or obese. Kappa ratios ranged between 0.18 (poor agreement) and 0.71 (reasonable, but not high degree of agreement). In general, kappa ratios were higher when assuming large or medium skeletal frame versus small frame. CONCLUSIONS: There are substantial discrepancies in classifying the subjects of a population as underweight, normal weight, or obese by BMI or W/IW. These discrepancies may cause confusion when 2 or more indices are used simultaneously to classify the degree of obesity.     

Fat-free mass depletion in cystic fibrosis: Associated with lung disease severity but poorly detected by body mass index

ObjectiveMalnutrition in cystic fibrosis (CF) is associated with poorer survival, but the determinants of fat-free mass (FFM) depletion are not well-characterized. It is unknown whether routine nutritional indicators, including body mass index (BMI), are adequate for detecting FFM depletion. This study aimed to determine the prevalence of FFM depletion in adults with CF, to compare fat-free mass index (FFMI) with BMI, and to identify predictors of FFM depletion.MethodsThis was a prospective cross-sectional study of 86 adults with CF (19–59 y old). Body composition was assessed using dual-energy X-ray absorptiometry to determine FFMI and BMI. FFMI percentiles and Z-scores were derived from a reference population of 156 healthy adults. FFM depletion was defined as an FFMI below the fifth percentile for age and gender and low BMI as <18.5 kg/m². Univariate and multivariate analyses identified predictors of FFMI and FFMI Z-score.ResultsMean FFMIs were 18.3 ± 1.9 kg/m² in men with CF and 15.8 ± 1.1 kg/m² in women with CF (P < 0.0005). FFM depletion was found in 14% of adults with CF, and low BMI was found in 18.6%. The sensitivity of BMI for detecting FFM depletion was 42%. Forced expiratory volume in 1 s as a percentage of predicted was independently associated with FFMI in women (r = 0.62, P < 0.0001) and men (r = 0.28, P = 0.045) and FFMI Z-score (r = 0.41, P < 0.0001).ConclusionFFM depletion was found in 14% of adults with CF, but was undetectable by BMI in 58% of these patients. These findings, together with the association of FFMI with forced expiratory volume in 1 s predicted, suggest a role for body composition assessment in adult CF care.     

Comparison of total body chlorine, potassium, and water measurements in children with cystic fibrosis

BACKGROUND: Symptoms of cystic fibrosis (CF) may limit the utility of total body chlorine (TBCl) and total body potassium (TBK) measurements for assessing body fluid compartments of children. OBJECTIVE: This study assessed relations among independent measurements of TBCl, TBK, and total body water (TBW) in children with CF. DESIGN: We compared cross-sectional measurements of TBCl by in vivo neutron activation analysis, TBK by whole-body counting of (40)K, TBW by D(2)O dilution [TBW(D(2)O)], and TBW from TBCl and TBK [TBW(Cl + K)] in 19 prepubertal children (13 boys) aged 7.6-12.5 y who had mild symptoms of CF. Body-composition measurements were compared with data from previous studies of healthy children. RESULTS: Subjects with CF had deficits in TBCl, TBK, TBW, and body weight compared with control reference data (P < 0.05). The ratios (TBCl + TBK)/TBW and TBCl/TBK were not significantly different from control reference values, and plasma chlorine and potassium concentrations were within control reference ranges. The sum of TBCl and TBK correlated with TBW(D(2)O) (r(2) = 0.79, P < 0.001), and TBW(Cl + K) correlated with TBW(D(2)O) (r(2) = 0.78, P < 0.001). TBW(Cl + K) was similar to TBW(D(2)O) (mean +/- SEM: 19.0 +/- 0.5 compared with 19.4 +/- 0.5 L; NS). CONCLUSIONS: Prepubertal children with mild symptoms of CF can develop deficits in TBCl, TBK, and TBW that reflect chronic energy malnutrition. Mild symptoms of CF do not appear to affect normal relations among TBCl, TBK, and TBW. Measurements of TBCl and TBK may be used to assess body fluid compartments in these patients.     

Body mass index and percentage body fat as health indicators for young adults

OBJECTIVES: To investigate the validity of an axiom that body mass index (BMI) and percentage body fat (%BF), above an ideal, are health risk factors. METHODS: Participants were 2615 volunteers who participated in a health-screening program conducted in college residence halls over a consecutive 8-year period. RESULTS: Nearly half of all participants were misclassified when BMI and/or %BF were used to define better versus poorer health whether analyzing all variables together, by individual factor, or by type of variable. CONCLUSIONS: Results of this study indicate that BMI and %BF are poor indicators of health status among young adults.     

Rapid growth among term children whose birth weight was appropriate for gestational age has a longer lasting effect on body fat percentage than on body mass index

BACKGROUND: It is not clear whether and how rapid growth in infancy, a risk factor for later obesity, differentially affects growth and body-composition development throughout childhood in term children with an appropriate-for-gestational age (AGA) birth weight. OBJECTIVE: The aim was to examine the effect of rapid growth in infancy on body mass index SD score (BMI SDS) and body fat percentage (%BF) trajectories until age 7 y. DESIGN: This analysis included 206 (50.5% female) AGA term participants of the Dortmund Nutritional and Anthropometric Longitudinally Designed Study. Repeated anthropometric measurements were obtained between 0.5 and 7 y of age. RESULTS: Fifty-nine of the 206 children (28.6%) displayed rapid growth (an increase in SDS for weight of >0.67 between birth and age 2 y). From 6 mo of age, their growth trajectories diverged from normal growers, and by age 7 y they had a higher BMI, more fat mass, and a higher risk of overweight (odds ratio: 6.2; 95% CI: 2.4, 16.5; P = 0.0002). Multilevel model analyses showed that the differences in BMI were achieved within the first 2 y of life [beta (+/-SE) SDS: 1.22 +/- 0.13], after which they persisted at this level until the age of 7 y, whereas differences in %BF, which were also already discernible by age 2 y (1.52 +/- 0.34%), became progressively larger over the next 5 y (adjusted difference: 0.23 +/- 0.11%/y; P = 0.03). CONCLUSIONS: Rapid growth in infancy and early childhood results in an increased BMI and %BF throughout childhood and an increased risk of overweight at age 7 y among AGA children. Rapid growth in AGA children has a more pronounced effect on %BF than on BMI.     

A composite score combining waist circumference and body mass index more accurately predicts body fat percentage in 6- to 13-year-old children

Purpose

Body mass index (BMI) and waist circumference (WC) are widely used to predict % body fat (BF) and classify degrees of pediatric adiposity. However, both measures have limitations. The aim of this study was to evaluate whether a combination of WC and BMI would more accurately predict %BF than either alone.

Methods

In a nationally representative sample of 2,303 6- to 13-year-old Swiss children, weight, height, and WC were measured, and %BF was determined from multiple skinfold thicknesses. Regression and receiver operating characteristic (ROC) curves were used to evaluate the combination of WC and BMI in predicting %BF against WC or BMI alone. An optimized composite score (CS) was generated.

Results

A quadratic polynomial combination of WC and BMI led to a better prediction of %BF (r ² = 0.68) compared with the two measures alone (r ² = 0.58–0.62). The areas under the ROC curve for the CS [0.6 * WC-SDS + 0.4 * BMI-SDS] ranged from 0.962 ± 0.0053 (overweight girls) to 0.982 ± 0.0046 (obese boys) and were somewhat greater than the AUCs for either BMI or WC alone. At a given specificity, the sensitivity of the prediction of overweight and obesity based on the CS was higher than that based on either WC or BMI alone, although the improvement was small.

Conclusion

Both BMI and WC are good predictors of %BF in primary school children. However, a composite score incorporating both measures increased sensitivity at a constant specificity as compared to the individual measures. It may therefore be a useful tool for clinical and epidemiological studies of pediatric adiposity.     

Skinfold thickness, body fat percentage and body mass index in obese and non-obese Indian boys

Childhood obesity is presently increasing worldwide and has created enormous concern for researchers working in the field of obesity related diseases with special interest in child health and development. Selected anthropometric measurements including stature, body mass, and skinfolds are globally accepted sensitive indicators of growth patterns and health status of a child. The present study was therefore aimed not only at evaluating the body mass index (BMI), skinfolds, body fat percentage (%fat) in obese school going boys of West Bengal, India, but also aimed to compare these data with their non-obese counterparts. Ten to sixteen year old obese boys (N = 158) were separated from their non-obese counterparts using the age-wise international cut-off points of BMI. Skinfolds were measured using skinfold calipers, BMI and %fat were calculated from standard equations. Body mass, BMI, skinfolds and %fat were significantly (P<0.001) higher for the sample of obese boys when compared to their non-obese counterparts. The obese group also showed progressive age-wise increments in all recorded anthropometric parameters. Stature (cm) showed no significant inter-group variation except in the 10 year age group (P<0.001). All data for the non-obese group were comparable with other national and international studies, but those collected for the obese group could not feasibly be compared because the availability of data on obese children is limited. Current data and prediction equations will not only serve as a reference standard, but also be of vital clinical importance in order to identify or categorize obese boys, and to take preventative steps to minimise serious health problems that appear during the later part of life.     

中国六省学龄儿童体重指数、体脂百分比评价肥胖与心血管代谢危险因素的相关性

目的 探讨单纯体重指数(BMI)、体脂百分比(FMP)分类肥胖及二者交叉分组与心血管代谢危险因素的关联,为儿童肥胖及相关代谢异常的防控提供依据。方法 基于在6省(黑龙江、内蒙古、宁夏、四川、云南和湖南)完成的横断面调查,选取10～18岁的学龄儿童11 542人为研究对象。分别以[BMI(+-)]和[FMP(+-)]单独或交叉分类肥胖状况分组,采用Logistic回归模型分析比较心血管代谢危险因素异常的风险。结果 不调整腰围(WC)的影响,[BMI(-)+FMP(+)]组低高密度脂蛋白胆固醇(HDL-C)和血糖升高风险较低,其余各组与肥胖相关代谢异常的关联较高。调整WC后,男生中 [BMI(+)+FMP(+)]组高三酰甘油(TG)[OR(95%CI):2.55(1.29~5.02)]、合并血脂异常[OR(95%CI):2.07(1.19~3.61)]和血压升高[OR(95%CI):2.20(1.29~3.77)]的风险较高。女生中[BMI(+)+FMP(+)]组合并血脂异常[OR(95%CI):2.02(1.09~3.74)]的风险较高。结论 结合FMP对儿童肥胖评价可提高对血脂异常和血压升高的筛查效果。     

Association of body mass index and weight change with all-cause mortality in the elderly

The authors explored the relation of body mass index (BMI; weight (kg)/height (m)(2)) and weight change to all-cause mortality in the elderly, using data from a large, population-based California cohort study, the Leisure World Cohort Study. They estimated relative risks of mortality associated with self-reported BMI at study entry, BMI at age 21 years, and weight change between age 21 and study entry. Participants were categorized as underweight (BMI <18.5), normal weight (BMI 18.5-24.9), overweight (BMI 25-29.9), or obese (BMI >or=30). Of 13,451 participants aged 73 years (on average) at study entry (1981-1985), 11,203 died during 23 years of follow-up (1981-2004). Relative to normal weight, being underweight (relative risk (RR) = 1.51, 95% confidence interval (CI): 1.38, 1.65) or obese (RR = 1.25, 95% CI: 1.13, 1.38) at study entry was associated with increased mortality. People who were either overweight or obese at age 21 also had increased mortality (RR = 1.17, 95% CI: 1.09, 1.25). Participants who lost weight between age 21 and study entry had increased mortality regardless of their BMI category at age 21. Obesity was significantly associated with increased mortality only among persons under age 75 years and among never or past smokers. This study highlights the influence on older-age mortality risk of being overweight or obese in young adulthood and underweight or obese in later life.