Development of body proportions in achondroplasia: Sitting height, leg length, arm span, and foot length.

The aims of this study was to construct references for sitting height, leg length, arm span, relative sitting height (sitting height/height), and foot length and to discuss the development for these anthropometric variables in achondroplasia. Sex-specific references covering ±2 SD are presented for ages 2-20 years. Legs and arms in achondroplasia are already at 2 years of age considerably shorter than in the general population and this deviation increases with age. At adult ages, legs are almost 50% shorter than in the general population and arm span roughly 35% shorter. As sitting height is only mildly affected, relative sitting height position develops far beyond normal ranges. Foot length is also not as affected as limbs.

Physical growth and diets of school children: Trends from 2001 to 2015 in rural West Java, Indonesia.

OBJECTIVES: This study aimed to assess changes in physical growth and diets of school children in rural West Java, Indonesia, between 2001 and 2015, a period of rapid socioeconomic change. METHODS: In 2001 and 2015, anthropometric measurements (height, weight, mid-upper arm circumference, skin-fold thickness), food consumption surveys, and questionnaires on socioeconomic status were completed by fourth-grade school children in a rural village in West Java. RESULTS: Height increments of 5.9 cm for boys and 4.7 cm for girls during this 14-year period were calculated as 4.21 cm per decade for boys and 3.36 cm per decade for girls, which is equivalent to height increments observed during rapid economic development periods in other countries. Weights also increased by 3.8 kg for boys and 2.0 kg for girls during this period. Variations in weight status significantly increased in 2015; while 98% of the children were within the 'normal' range in 2001, the prevalence of overweight increased from 2.4% in 2001 to 13.7% in 2015 and that of thinness was 4.3% in 2015. Energy, protein, and fat intakes significantly increased in 2015. In 2015, a significant correlation between nutritional intake and weight status was observed, especially among boys. CONCLUSIONS: Socioeconomic changes between 2001 and 2015 caused increased heights and weights and greater variation in weight status, especially among boys.

Intergenerational changes in limb circumferences in children and adolescents aged 3-18 from Kraków (Poland) from 1983 to 2010.

OBJECTIVES: Measurements of body circumferences are often used in anthropology. The research on this topic, however, rarely concerns limb girths or secular trends. The main aim of this study was to investigate the occurrence of secular trends in selected limb circumferences among children and adolescents. METHODS: The research was based on measurements from two cross-sectional studies carried out in 1983 and 2010 with children and adolescents aged 3-18 from Krakow, Poland. The circumferences of the arm, forearm, thigh and calf, as well as the sum of circumferences and selected indicators, were analyzed. The series were compared using the two-way anova test. RESULTS: In most age groups of both sexes, a positive secular trend was observed for the majority of studied traits. The exception was the thigh circumference, for which, among girls, measurements in both series were similar, and negative intergenerational changes were recorded in the youngest age groups of both sexes as well as among the oldest girls. Most observed discrepancies were statistically significant in pre-school children and adolescents. CONCLUSIONS: The presence of positive secular trends shows that limb circumferences were increasing in subsequent generations, especially in boys. Contemporary girls, particularly in the older age groups, were more determined to have a slim figure and practiced conscious weight control. Summarizing, observed tendencies resulted from the improvement of socio-economic conditions, but were also related to the low level of physical activity.

Muscle quality characteristics of muscles in the thigh, upper arm and lower back in elderly men and women.

PURPOSE: The ratio of fat within skeletal muscle is an important parameter that is indicative of muscle quality, and can be assessed using ultrasonography to measure echo intensity (EI). Muscle EI indicates muscle strength and risk of physical dysfunction; however, this observation was determined following examinations of only selected muscle. The purpose of this study was to investigate the EI characteristics of muscles in several regions in elderly men and women, using physical function tests and serum cholesterol levels. METHODS: Twenty-two men and women (age 78 ± 8 years) participated in this study. The EIs were calculated from rectus femoris (RF), biceps femoris (BF) triceps brachii (TB) and multifidus (MF) using B-mode transverse ultrasound images. Seven functional tests (isometric knee-extension peak torque, functional reach, sit-to-stand, 5-m normal/maximal speed walking, handgrip strength and timed up-and-go) and blood lipid components including adipocytokines were measured in all participants. RESULTS: A statistically significant correlation between EI of the RF, TB and BF was observed (r = 0.46-0.50, P < 0.05), but not between EI of the MF and that of other muscles. EI of muscles of the limbs, which was averaged EI for RF, TB and BF, was negatively correlated with leptin levels (adjusted R2 = 0.27, P < 0.01), and EI of the MF was correlated with muscle mass and performance in the timed up-and-go test (adjusted R2 = 0.61, P < 0.01). CONCLUSION: These results suggest that EI might be influenced by specific parameters depending on the location of the muscle.

Development and the evolvability of human limbs.

The long legs and short arms of humans are distinctive for a primate, the result of selection acting in opposite directions on each limb at different points in our evolutionary history. This mosaic pattern challenges our understanding of the relationship of development and evolvability because limbs are serially homologous and genetic correlations should act as a significant constraint on their independent evolution. Here we test a developmental model of limb covariation in anthropoid primates and demonstrate that both humans and apes exhibit significantly reduced integration between limbs when compared to quadrupedal monkeys. This result indicates that fossil hominins likely escaped constraints on independent limb variation via reductions to genetic pleiotropy in an ape-like last common ancestor (LCA). This critical change in integration among hominoids, which is reflected in macroevolutionary differences in the disparity between limb lengths, facilitated selection for modern human limb proportions and demonstrates how development helps shape evolutionary change.

Familial concordance for height and its components: analyses from the Breakthrough Generations Study.

OBJECTIVES: To assess familial resemblance for height, arm span, and components of these, and differences between concordance for short and tall heights. METHODS: We examined whether female relatives were similar for six anthropometric measurements (height, arm span, leg, trunk and arm length, and leg:trunk length ratio). Subjects were 31,622 related individuals aged 16-102 yr participating in the UK Breakthrough Generations Study. Height and arm span were self-reported, limb and trunk length were measured in a subset (N = 508) by study investigators, and paternal height was reported by the daughter. Data were analyzed using correlations and Poisson regression. RESULTS: Correlation coefficients within families were 0.4 for height, 0.3 for arm span, and 0.5 for leg length, trunk length, leg:trunk ratio, and arm length. Women had a relative risk (RR) of being short (i.e., in the lowest height quintile) of 2.3 (95% confidence interval [CI] = 2.1-2.5) if their mother was short, 2.1 (95% CI = 1.9-2.3) if their father was short, and 3.7 (95% CI = 3.4-4.0) if both parents were short. RRs of being tall (i.e., in the highest height quintile) were 2.3 (95% CI = 2.1-2.5), 2.4 (95% CI = 2.2-2.6), and 4.4 (95% CI = 4.1-4.8) if their mother, father or both were tall, respectively. CONCLUSIONS: We have shown, for the first time, that leg:trunk length ratio and arm length aggregate within families. Concordance seemed to be stronger for tall than short heights.

Child size and household characteristics in rural Timor-Leste.

OBJECTIVES: The main objective was to determine those characteristics of the family and household that affects child health (as measured by child size for age) in the rural Ossu area of Timor-Leste. METHODS: Interviews of parents in 102 households assessed reproductive histories, the amount and type of resources available and family composition (number, sex, and age of members). Height, weight, and mid-upper arm circumference were measured for all children in the household. To standardize for age and sex, raw measures were transformed into WHO Z scores and compared across households. RESULTS: Children were low in both height and weight relative to international standards and older children compared with international standards more poorly than under-fives. There was no evidence of sex difference in relative growth. The number of children in a household was negatively associated with height but not weight and positively with BMI. Children living in the villages more distant from Ossu town center had significantly lower Z scores for height than children in town. No crop or livestock indices were related to growth. Fostered children did not show growth different from biological children, but biological children in households with fostered children were slightly larger for age. CONCLUSIONS: Short stature inflates BMI and harvest season measures may have captured short-term increases in children's energy balance. Social networks may increase child well-being by moving children toward resource richer households. Social and cultural factors influence resource allocations among children and their health in rural Timor-Leste.

Meat and milk intakes and toddler growth: a comparison feeding intervention of animal-source foods in rural Kenya.

OBJECTIVE: To examine the effects of animal-source foods on toddler growth. DESIGN: A 5-month comparison feeding intervention study with one of three millet-based porridges randomized to eighteen feeding stations serving 303 children aged 11-40 months. Feeding stations served plain millet porridge (Plain group), porridge with milk (Milk group) or porridge with beef (Meat group). Anthropometry, morbidity and food intake were measured at baseline and regular intervals. Longitudinal mixed models were used to analyse growth. SETTING: Embu, Kenya. SUBJECTS: Two hundred and seventy-four children were included in final analyses. RESULTS: Linear growth was significantly greater for the Milk group than the Meat group (P = 0·0025). Slope of growth of mid-arm muscle area of the Plain group was significantly greater than in the Meat group (P = 0·0046), while the Milk group's mid-upper arm circumference growth rate was significantly greater than the Meat group's (P = 0·0418). The Milk and Plain groups' measures did not differ. CONCLUSIONS: Milk and meat porridges did not have a significantly greater effect on growth than plain porridge in this undernourished population. Linear growth was influenced by more than energy intakes, as the Plain group's total body weight-adjusted energy intakes were significantly greater than the Meat group's, although linear growth did not differ. Energy intakes may be more important for growth in arm muscle. The diverse age distribution in the study makes interpretation difficult. A longer study period, larger sample size and more focused age group would improve clarity of the results.

Age-related stature and linear body segments in children with X-linked hypophosphatemic rickets.

Children with X-linked hypophosphatemic rickets (XLH) are prone to severe stunting. A multicenter mixed-longitudinal study was conducted to assess age-related stature, sitting height, arm and leg length in XLH patients on continuous treatment with phosphate and calcitriol. Mean standard deviation scores (SDS) for all body dimensions were markedly reduced and differed significantly among each other at the initial and subsequent evaluations (baseline: stature -2.48 SDS; sitting height -0.99 SDS; arm length -1.81 SDS; leg length -2.90 SDS; each p<0.001). A strong association between stature and leg length (r (2)=0.87, p<0.001) was noted. Leg length SDS decreased progressively during childhood (2-9 years) and adolescence (12-15 years; each p<0.001). Sitting height SDS increased significantly during late childhood, indicating uncoupled growth of the legs and trunk and resulting in an ever increasing sitting height index (i.e. ratio of sitting height to stature; age 2 years 2.0 SDS; age 10 years 3.3 SDS; p<0.001) that was associated with the degree of stunting (r (2)=0.314, p<0.001). Mean serum phosphate levels were positively associated with stature and leg length, but negatively with sitting height index. Based on these results, we can conclude that growth of the legs and trunk is uncoupled in XLH and related to serum phosphate levels.

The validity of estimating triceps brachii volume from single MRI cross-sectional area before and after resistance training.

The aim of this study was to determine whether triceps brachii muscle volume can be adequately estimated from a single anatomical cross-sectional area (ACSA) and can the same model be used for prediction after training. Thirty-five healthy male non-athletes (age 21.6 ± 2.5 years, body mass index 24.8 ± 3.5 kg · m(-2)) volunteered for this study. The volumes of the upper arm extensors were calculated from magnetic resonance imaging (MRI) sequence scans and regression models were developed, which were used to predict muscle volumes from single MRI cross-sectional scans taken at different points along the humerus length. The same procedure was repeated after 12 weeks of maximal resistance training of the elbow extensors. Correlation coefficients were calculated for Model A with CSA(max), humerus length (HL), and body mass index (r = 0.919), a model with CSA(50%) and HL (r = 0.922), and a model with CSA(60%) and HL (r = 0.920) (P < 0.001). The standard error of estimate for Model A, Model CSA(50%), and Model CSA(60%) was 8.0%, 7.7%, and 7.8% respectively. Thesame prediction formula can be used for the left arm (r = 0.904). If a single ACSA is used for triceps brachii volume prediction, the best fit is with Model CSA(60%) and HL, both before and after training (r = 0.941). By introducing humerus length into the calculation, we simplify the procedure for volume measurement, since it can be obtained during MRI scanning.

Concurrent growth of phenotypic features: a phenomenological universalities approach.

Different physical features of an organism are often measured concurrently, because their correlations can be used as predictors of longevity, future health, or adaptability to an ecological niche. Since, in general, we do not know a priori if the temporal variations in the measured quantities are causally related, it may be useful to have a method that could help us to identify possible correlations and to obtain parameters that may vary from population to population. In this paper we develop a procedure that may detect underlying relationships. We do this by generalizing the recently introduced concept of phenomenological universalities to the complex field. In this generalization, allometric growth is described by a complex function, whose real and imaginary parts represent two phenotypic traits of the same organism. As particular solutions of the resulting problem, we obtain generalizations of the Gompertz and the von Bertalanffy-West growth equations. We then apply the procedure to two biological systems in order to show how to determine the existence of mutual interference between trait variations.

Predicting growth and curve progression in the individual patient with adolescent idiopathic scoliosis: design of a prospective longitudinal cohort study.

BACKGROUND: Scoliosis is present in 3-5% of the children in the adolescent age group, with a higher incidence in females. Treatment of adolescent idiopathic scoliosis is mainly dependent on the progression of the scoliotic curve. There is a close relationship between curve progression and rapid (spinal) growth of the patient during puberty. However, until present time no conclusive method was found for predicting the timing and magnitude of the pubertal growth spurt in total body height, or the curve progression of the idiopathic scoliosis.The goal of this study is to determine the predictive value of several maturity indicators that reflect growth or remaining growth potential, in order to predict timing of the peak growth velocity of total body height in the individual patient with adolescent idiopathic scoliosis. Furthermore, different parameters are evaluated for their correlation with curve progression in the individual scoliosis patient. METHODS/DESIGN: This prospective, longitudinal cohort study will be incorporated in the usual care of patients with adolescent idiopathic scoliosis. All new patients between 8 and 17 years with adolescent idiopathic scoliosis (Cobb angle >10 degrees) visiting the outpatient clinic of the University Medical Center Groningen are included in this study. Follow up will take place every 6 months. The present study will use a new ultra-low dose X-ray system which can make total body X-rays. Several maturity indicators are evaluated like different body length dimensions, secondary sexual characteristics, skeletal age in hand and wrist, skeletal age in the elbow, the Risser sign, the status of the triradiate cartilage, and EMG ratios of the paraspinal muscle activity. Correlations of all dimensions will be calculated in relationship to the timing of the pubertal growth spurt, and to the progression of the scoliotic curve. An algorithm will be made for the optimal treatment strategy in the individual patient with adolescent idiopathic scoliosis. DISCUSSION: This study will determine the value of many maturity indicators and will be useful as well for other clinicians treating children with disorders of growth. Since not all clinicians have access to the presented new 3D X-ray system or have the time to make EMG's, for example, all indicators will be correlated to the timing of the peak growth velocity of total body height and curve progression in idiopathic scoliosis. Therefore each clinician can chose which indicators can be used best in their practice. TRIAL REGISTRATION NUMBER: NTR2048.

Practices in child growth monitoring in the countries of the Eastern Mediterranean Region.

Growth reference charts are among the most sensitive and valuable tools for assessing the health and development of children. A questionnaire survey was answered by 16 of the 21 ministries of health in the Eastern Mediterranean Region countries (EMR) about their use of growth charts for children under 5 years. Most of the countries (13/16) used the NCHS/WHO charts and weight-for-age was the most commonly used. Charts for height-for-age and head circumference-for-age were less commonly used. Problems in the use of charts were identified. The introduction of the new WHO Child Growth Standards, based on exclusively breastfed babies, is a unique opportunity to support growth monitoring and optimal feeding practices in EMR.

Arm Span and Its Relation to Height in a 2- to 17-Year-Old Reference Population and Heterozygous Carriers of ACAN Variants.

BACKGROUND/OBJECTIVES: In the clinical assessment of a short or tall child, estimating body disproportion is useful to assess the likelihood of a primary growth disorder, e.g., skeletal dysplasia. Our objectives were (1) to use data from the Maastricht study on healthy children (2-17 years) to calculate relative arm span (AS) for height (H) to serve as age references for clinical purposes; (2) to assess its age and sex dependency; and (3) to investigate relative AS adjustment for age and sex in individuals with ACAN haploinsufficiency. METHODS: The Maastricht study data (2,595 Caucasian children, 52% boys, 48% girls) were re-analysed to produce reference tables and graphs for age and sex of AS - H and AS/H. Published information on AS/H in Europeans was used as reference data for adults. Relative AS from 33 patients with ACAN haploinsufficiency were plotted against reference data and expressed as standard deviation score (SDS) for age and sex. RESULTS: Mean AS - H from 2 to 17 years increased from -1.2 to +1.5 cm in boys and from -4.8 to +1.6 cm in girls. Mean AS/H increased from 0.9848 to 1.0155 in boys and from 0.9468 to 1.0028 in girls. Mean AS/H in patients with ACAN haploinsufficiency was approximately 1.0, 1.5 and 0.5 SDS in young children, adolescents and 20- to 50-year-olds, respectively, and normal thereafter. CONCLUSIONS: These reference charts can be used for 2- to 17-year-old children/adolescents. Carriers of ACAN haploinsufficiency have an elevated mean AS/H in childhood and adolescence and a slightly elevated ratio till 50 years.

The upper arm muscle and fat area of Santal children: an evaluation of nutritional status.

AIMS: The purpose of this study is to determine the growth pattern of upper arm muscle area (UAMA), upper arm fat area (UAFA) and upper arm muscle area by height (UAMAH) and assessment of magnitude of undernutrition on the basis of these parameters in Santal children. METHODS: UAMA and UAFA of 890 (473 boys and 417 girls) Santal children aged 5-12 years were calculated from mid-upper arm circumference and triceps skinfold. RESULTS: Growth curves of UAFA-for-age and UAMA by height in Santal boys and girls are placed at lower level of reference curve indicating severe undernutrition. The growth curves of UAMA-for-age in Santal children of both sexes do not indicate severe undernutrition. 17.13% Santal boys and 20.63% girls were truly undernourished on the basis of three Z-scores of height-for-age, weight-for-height and UAMAH of each subject. Santal children have more UAMA and less UAFA compared to similar undernourished children of Sugalis. CONCLUSION: Growth curves of UAFA-for-age and UAMA by height are good indicators of nutritional status in Santal children. UAMA and UAFA may not be similarly affected in undernourished children of every community. A comprehensive approach to identify the truly undernourished child has been suggested from this study.

The effect of body shape on weight-for-height and mid-upper arm circumference based case definitions of acute malnutrition in Ethiopian children.

BACKGROUND: Nutritional anthropometry surveys from Somalia and Ethiopia have reported that standard weight-for-height z-score (WHZ) and mid-upper arm circumference (MUAC) case definitions return different estimates of the prevalence of acute malnutrition in pastoralist livelihood zones but similar estimates of the prevalence of acute malnutrition in the agrarian livelihood zones. A study undertaken in Somalia to investigate this finding reported that children from pastoralist livelihood zones tended to have longer limbs and lower SSRs than children from agrarian livelihood zones. AIM: The present study investigated the relationship between weight-for-height and body shape and the relationship between MUAC and body shape in different populations of Ethiopian children. SUBJECTS AND METHODS: Six cross-sectional nutritional anthropometry surveys were undertaken. The combined survey datasets form the study sample. Data sources were grouped according to the livelihood zone from which data originated (either settled agrarian or semi-nomadic pastoralist). Case definitions of acute malnutrition using WHZ calculated using the NCHS and WHO reference populations and MUAC uncorrected for age or height were used. The SSR was used as an index of body shape. The association between body shape and the different case definitions of acute malnutrition were investigated using standard statistical techniques. RESULTS: Weight-for-height and MUAC case definitions yielded similar estimates of the prevalence of acute malnutrition in agrarian children but different estimates of the prevalence of acute malnutrition in pastoralist children. These populations also exhibit different SSRs. The SSR is an important predictor of weight-for-height. The SSR is a poor predictor of MUAC. CONCLUSION: WHZ and WHZ case status in children are associated with body shape and may overestimate the prevalence of acute malnutrition in some populations. Consideration should be given as to whether WHZ should be replaced by MUAC for the purposes of estimating the prevalence of acute malnutrition.

First use of anatomical networks to study modularity and integration of heads, forelimbs and hindlimbs in abnormal anencephalic and cyclopic vs normal human development.

The ill-named "logic of monsters" hypothesis of Pere Alberch - one of the founders of modern evo-devo - emphasized the importance of "internal rules" due to strong developmental constraints, linked teratologies to developmental processes and patterns, and contradicted hypotheses arguing that birth defects are related to a chaotic and random disarray of developmental mechanisms. We test these hypotheses using, for the first time, anatomical network analysis (AnNA) to study and compare the musculoskeletal modularity and integration of both the heads and the fore- and hindlimbs of abnormal cyclopic trisomy 18 and anencephalic human fetuses, and of normal fetal, newborn, and adult humans. Our previous works have shown that superficial gross anatomical analyses of these specimens strongly support the "logic of monsters" hypothesis, in the sense that there is an 'order' or 'logic' within the gross anatomical patterns observed in both the normal and abnormal individuals. Interestingly, the results of the AnNA done in the present work reveal a somewhat different pattern: at least concerning the musculoskeletal modules obtained in our AnNA, we observe a hybrid between the "logic of monsters" and the "lack of homeostasis" hypotheses. For instance, as predicted by the latter hypothesis, we found a high level of left-right asymmetry in the forelimbs and/or hindlimbs of the abnormal cyclopic trisomy 18 and anencephalic human fetuses. That is, a network analysis of the organization of/connection between the musculoskeletal structures of these fetuses reveals a more "chaotic" pattern than that detected by superficial gross anatomical comparisons. We discuss the broader developmental, evolutionary, and medical implications of these results.

Survey of musculoskeletal abnormalities in school-going children of hilly and foothill regions of Eastern Himalayas using the pediatric Gait, Arms, Legs, Spine screening method.

OBJECTIVE: To study the prevalence and pattern of musculosketetal abnormalities in school-going children living in the hilly and foothill regions of the Eastern Himalayas using the pediatric Gait, Arms, Legs, Spine (pGALS) screening tool. METHODS: Total of 3608 children, aged 3-12 years were enrolled from 16 schools (5 in the hills) in the eastern Himalayan region. After the three screening questions, the pGALS maneuvers were administered. Subjects were shown a video on pGALS before the actual testing. Those detected to have abnormality were probed in greater detail and referred for treatment as necessary. RESULTS: The pGALS examination was completed in 3463 children with a median time of 3 min (range 1.9-5.4 min). The abnormality pattern was in the order: growing pains (38.86%), hypermobility (25.54%), mechanical pains (24.46%) and others (11.14%). Among mechanical pain, back and neck problems occurred with a similar overall frequency of 7.61%. Similar order was observed considering only children from the pains. However, in hill children, the proportion of mechanical problems (32.28%) exceeded proportion of hypermobility (23.62%). Asymptomatic hypermobility was more common than symptomatic hypermobility. Maximum prevalence of hypermobility was in 6-9 year age group. Of the 94 children with hypermobility, 55.32% had some kind of joint pain. CONCLUSIONS: Pediatric Gait, Arms, Legs, Spine is an acceptable screening tool for musculoskeletal abnormalities in apparently healthy children. Growing pain is the commonest musculoskeletal complaint while hypermobility is the commonest physical abnormality in school-going children in the Eastern Himalayas. Asymptomatic hypermobility is more common than symptomatic hypermobility.

A growth reference for mid upper arm circumference for age among school age children and adolescents, and validation for mortality: growth curve construction and longitudinal cohort study.

Objectives To construct growth curves for mid-upper-arm circumference (MUAC)-for-age z score for 5-19 year olds that accord with the World Health Organization growth standards, and to evaluate their discriminatory performance for subsequent mortality.Design Growth curve construction and longitudinal cohort study.Setting United States and international growth data, and cohorts in Kenya, Uganda, and Zimbabwe.Participants The Health Examination Survey (HES)/National Health and Nutrition Examination Survey (NHANES) US population datasets (age 5-25 years), which were used to construct the 2007 WHO growth reference for body mass index in this age group, were merged with an imputed dataset matching the distribution of the WHO 2006 growth standards age 2-6 years. Validation data were from 685 HIV infected children aged 5-17 years participating in the Antiretroviral Research for Watoto (ARROW) trial in Uganda and Zimbabwe; and 1741 children aged 5-13 years discharged from a rural Kenyan hospital (3.8% HIV infected). Both cohorts were followed-up for survival during one year.Main outcome measures Concordance with WHO 2006 growth standards at age 60 months and survival during one year according to MUAC-for-age and body mass index-for-age z scores.Results The new growth curves transitioned smoothly with WHO growth standards at age 5 years. MUAC-for-age z scores of -2 to -3 and less than-3, compared with -2 or more, was associated with hazard ratios for death within one year of 3.63 (95% confidence interval 0.90 to 14.7; P=0.07) and 11.1 (3.40 to 36.0; P<0.001), respectively, among ARROW trial participants; and 2.22 (1.01 to 4.9; P=0.04) and 5.15 (2.49 to 10.7; P<0.001), respectively, among Kenyan children after discharge from hospital. The AUCs for MUAC-for-age and body mass index-for-age z scores for discriminating subsequent mortality were 0.81 (95% confidence interval 0.70 to 0.92) and 0.75 (0.63 to 0.86) in the ARROW trial (absolute difference 0.06, 95% confidence interval -0.032 to 0.16; P=0.2) and 0.73 (0.65 to 0.80) and 0.58 (0.49 to 0.67), respectively, in Kenya (absolute difference in AUC 0.15, 0.07 to 0.23; P=0.0002).Conclusions The MUAC-for-age z score is at least as effective as the body mass index-for-age z score for assessing mortality risks associated with undernutrition among African school aged children and adolescents. MUAC can provide simplified screening and diagnosis within nutrition and HIV programmes, and in research.