Biomedical subjects

Mercedes de Onis

Publications and source records attributed to Mercedes de Onis.

At least 19 recordsLinked to original sources

PubMed2007

Comparison of the WHO child growth standards and the CDC 2000 growth charts.

The evaluation of child growth trajectories and the interventions designed to improve child health are highly dependent on the growth charts used. The U.S. CDC and the WHO, in May 2000 and April 2006, respectively, released new growth charts to replace the 1977 NCHS reference. The WHO charts are based for the first time on a prescriptive, prospective, international sample of infants selected to represent optimum growth. This article compares the WHO and CDC curves and evaluates the growth performance of healthy breast-fed infants according to both. As expected, there are important differences between the WHO and CDC charts that vary by age group, growth indicator, and specific Z-score curve. Differences are particularly important during infancy, which is likely due to differences in study design and characteristics of the sample, such as type of feeding. Overall, the CDC charts reflect a heavier, and somewhat shorter, sample than the WHO sample. This results in lower rates of undernutrition (except during the first 6 mo of life) and higher rates of overweight and obesity when based on the WHO standards. Healthy breast-fed infants track along the WHO standard's weight-for-age mean Z-score while appearing to falter on the CDC chart from 2 mo onwards. Shorter measurement intervals in the WHO standards result in a better tool for monitoring the rapid and changing rate of growth in early infancy. Their adoption would have important implications for the assessment of lactation performance and the adequacy of infant feeding and would bring coherence between the tools used to assess growth and U.S. national guidelines that recommend breast-feeding as the optimal source of nutrition during infancy.

Body Height↗

PubMed2007

Field-testing the WHO child growth standards in four countries.

In April 2006 the WHO released a set of growth standards for children from birth to the age of 5 y. Prior to their release, the standards were field-tested in 4 countries. The main objective was to compare children's length/height-for-age and weight-for-length/height based on the new standards with clinician assessments of the same children. The study sampled children <5-y-old attending well-child clinics in 2 affluent populations (Argentina and Italy) and 2 less-affluent ones (Maldives and Pakistan). Length/height and weight were measured by doctors and epidemiologists who also recorded a clinical assessment of each child's length/height in relation to age and weight relative to length/height. Anthropometric indicators of nutritional status were generated based on the WHO standards. As expected, Pakistan and the Maldives had higher rates of stunting, wasting, and underweight than Italy and Argentina, and the reverse was true for overweight and obesity. Where stunting was prevalent, the children classified as short were a mean <-2 SD for height-for-age. In all sites, the children classified as thin were indeed wasted (<-2 SD for weight-for-height) and a positive association in trend was evident between weight-for-height and the line-up of groups from thin to obese. The overall concordance between clinical assessments and the WHO standards-based indicators attested to the clinical soundness of the standards.

Argentina↗

PubMed2007

Evaluation of the feasibility of international growth standards for school-aged children and adolescents.

The development of an international growth standard for the screening, surveillance, and monitoring of school-aged children and adolescents has been motivated by 2 contemporaneous events, the global surge in childhood obesity and the release of a new international growth standard for infants and preschool children by the WHO. If a prescriptive approach analogous to that taken by WHO for younger children is to be adopted for school-aged children and adolescents, several issues need to be addressed regarding the universality of growth potential across populations and the definition of optimal growth in children and adolescents. A working group of experts in growth and development and representatives from international organizations concluded that subpopulations exhibit similar patterns of growth when exposed to similar external conditioners of growth. However, based on available data, we cannot rule out that observed differences in linear growth across ethnic groups reflect true differences in genetic potential rather than environmental influences. Therefore, the sampling frame for the development of an international growth standard for children and adolescents must include multiethnic sampling strategies designed to capture the variation in human growth patterns. A single international growth standard for school-aged children and adolescents could be developed with careful consideration of the population and individual selection criteria, study design, sample size, measurements, and statistical modeling of primary growth and secondary ancillary data. The working group agreed that existing growth references for school-aged children and adolescents have shortcomings, particularly for assessing obesity, and that appropriate growth standards for these age groups should be developed for clinical and public health applications.

Adolescent↗

PubMed2006

Comparison of the World Health Organization (WHO) Child Growth Standards and the National Center for Health Statistics/WHO international growth reference: implications for child health programmes.

OBJECTIVES: To compare growth patterns and estimates of malnutrition based on the World Health Organization (WHO) Child Growth Standards ('the WHO standards') and the National Center for Health Statistics (NCHS)/WHO international growth reference ('the NCHS reference'), and discuss implications for child health programmes. DESIGN: Secondary analysis of longitudinal data to compare growth patterns (birth to 12 months) and data from two cross-sectional surveys to compare estimates of malnutrition among under-fives. SETTINGS: Bangladesh, Dominican Republic and a pooled sample of infants from North America and Northern Europe. SUBJECTS: Respectively 4787, 10 381 and 226 infants and children. RESULTS: Healthy breast-fed infants tracked along the WHO standard's weight-for-age mean Z-score while appearing to falter on the NCHS reference from 2 months onwards. Underweight rates increased during the first six months and thereafter decreased when based on the WHO standards. For all age groups stunting rates were higher according to the WHO standards. Wasting and severe wasting were substantially higher during the first half of infancy. Thereafter, the prevalence of severe wasting continued to be 1.5 to 2.5 times that of the NCHS reference. The increase in overweight rates based on the WHO standards varied by age group, with an overall relative increase of 34%. CONCLUSIONS: The WHO standards provide a better tool to monitor the rapid and changing rate of growth in early infancy. Their adoption will have important implications for child health with respect to the assessment of lactation performance and the adequacy of infant feeding. Population estimates of malnutrition will vary by age, growth indicator and the nutritional status of index populations.

Breast Feeding↗

PubMed2006

The Spanish strategy for nutrition, physical activity and the prevention of obesity.

The prevalence and increasing trends of obesity in Spain are a matter of concern. In adults, the prevalence of obesity and overweight is 14.5 and 38.5 %, respectively, whereas in children and adolescents it is 13.9 and 26.3 %. This situation prompted the Spanish Ministry of Health and Consumer Affairs to draw up the Strategy for Nutrition, Physical Activity and the Prevention of Obesity (NAOS), which aims to improve the diet and encourage the regular practice of physical activity by all citizens, with special emphasis on children. Coordinated by the Spanish Food Safety Agency and the General Directorate of Public Health, a wide range of stakeholders participated in drafting the Strategy through a broad consultative process. Anchored on the core goal of adopting a lifelong perspective in the prevention and control of obesity, NAOS encompasses recommendations for action in four fields: family and community, schools, private sector, and the health system. Launched on 10 February 2005, the Strategy will undergo careful monitoring and evaluation. A newly created Obesity Observatory will carry out epidemiological surveillance, define indicators to measure impact of interventions, facilitate the exchange of experiences among different initiatives, identify research priorities, monitor adherence and application of the self-regulation agreements, and conduct rigorous evaluation of initiatives to identify those that are successful and should be prioritized. To our knowledge, NAOS is the first strategy of its kind in Europe and we recommend it as an example to be followed by countries that, like Spain, face the challenge of combating the pervasive epidemic of obesity.

Exercise↗

PubMed2006

The association between stunting and overweight in Latin American and Caribbean preschool children.

BACKGROUND: Although some segments of the population continue to suffer from undernutrition, other groups exhibit excess weight gain, resulting in the coexistence of undernutrition and obesity and leading to a dual nutritional burden. OBJECTIVE: To explore the association between stunting and overweight in preschool children from Latin American and Caribbean countries. METHODS: We analyzed cross-sectional data from children 0 to 5 years of age from 79 nationally representative surveys, compiled by the World Health Organization (WHO) Global Database on Child Growth and Malnutrition. This database defines stunting as low height-for-age and overweight as high weight-for-height. These variables were explored with the use of simple and multiple regression models. RESULTS: There were significant differences between subregions in the prevalence of stunting: the prevalence was 7.4% in the Caribbean, 11.3% in South America, and 20.4% in Central America (p < .001). In contrast, the estimated prevalence of overweight was similar between subregions. The overall prevalence rates of stunting and overweight in Latin America and the Caribbean in the year 2000 were 13.7% and 4.3%, respectively. We found an inverse relationship (r = -0.3) between the prevalence rates of overweight and stunting, overall and within subregions. South America exhibited the highest slope and intercept on the regression of overweight on stunting. CONCLUSIONS: Different subregions of Latin America and the Caribbean have different prevalence rates of childhood stunting but similar prevalence rates of overweight. There is an inverse relationship between stunting and overweight. The South American subregion had the highest increase and prevalence of overweight of the Latin American region.

Body Height↗

PubMed2006

Growth status and academic performance in Brazilian school age children: growth retardation impairs mathematical, but not reading and spelling abilities.

AIM: To assess the effect of child growth status on academic achievement and the association between child growth and academic standing. METHOD: The heights of 722 middle-school children were measured using standard procedures and height-for-age z (HAZ) scores were calculated based on an international reference. Academic performance was assessed by an adaptation of the Wide Range Achievement Test (WRAT3) composed of Reading, Arithmetic and Spelling. RESULTS: Children in the group with higher HAZ scores performed better than children in the group with lower HAZ scores only on the Arithmetic subtest. This finding was confirmed by a multiple regression model analysis of the data. In addition, only performance on the Arithmetic subtest was positively associated with HAZ. CONCLUSION: These results indicate that growth retardation impacts specifically on the development of arithmetic (numeracy) skills and are consistent with a three-fold model of life course influences on health including latency, cumulative and pathway effects.

Achievement↗

PubMed2005

Differential improvement among countries in child stunting is associated with long-term development and specific interventions.

Stunting represents growth failure resulting from poor nutrition and health during the pre- and postnatal periods. Initiatives since 1980 have steadily reduced malnutrition and consequent retardation of child growth, but 1 of 3 preschool children worldwide remains stunted. Countries have varied substantially in progress achieved in reducing stunting. This study aimed to understand which underlying (i.e., proximal) and basic (i.e., distal) national factors have been most important in explaining this variation among countries, and the relation between the 2 sets of factors. Eighty-five developing countries with at least 2 surveys for stunting >4 y apart were included from the WHO Global Database on Child Growth. The analytic data set with independent variables from several sources was constructed to match closely by year for each country to initial and final stunting data. Full-information maximum likelihood estimated multiple linear regression models while accounting for missing data in independent variables. The final model explained 65.5% of the variance of change in stunting, and included both underlying and basic variables: initial and change in immunization rate, initial and change in safe water rate, initial female literacy rate, initial government consumption, initial income distribution, and the initial proportion of the economy devoted to agriculture. Although factors that were important for reducing stunting in the past may not necessarily be the ones that are important in the future, these results suggest that it possible for substantial progress to be made in reducing the current high prevalence of stunting by investing in both long-term development and in specific interventions.

Agriculture↗

PubMed2004

Growth status, behavior and neuropsychological performance: a study of Brazilian school age children.

AIM: To assess the association between child growth and teacher-reported behavior and academic standing, and neuropsychological performance. METHOD: The heights of 344 public-school children were measured using standard procedures. Teachers were requested to complete two behavioral and one academic performance rating scales. Neuropsychological assessment consisted of the Edinburgh Handedness Inventory, the Steadiness Test and the Purdue Pegboard. Height-for-age z (HAZ) scores were calculated based on an international reference. Standard (z) scores for each factor of the first two behavioral rating scales and for each neuropsychological variable were computed for each child based on locally-derived norms. RESULTS: HAZ scores were negatively correlated with factors related to hyperactivity, conduct problem, impulsivity and inattention of the behavioral rating scales. In addition, the lower the HAZ score the worse the academic performance. CONCLUSION: These results add to the existing evidence indicating a strong association between growth status and child behavior and academic performance.

Achievement↗

PubMed2004

Methodology for estimating regional and global trends of child malnutrition.

BACKGROUND: Child malnutrition is an important indicator for monitoring progress towards the Millennium Development Goals (MDG). This paper describes the methodology developed by the World Health Organization (WHO) to derive global and regional trends of child stunting and underweight, and reports trends in prevalence and numbers affected for 1990-2005. METHODS: National prevalence data from 139 countries were extracted from the WHO Global Database on Child Growth and Malnutrition. A total of 419 and 388 survey data points were available for underweight and stunting, respectively. To estimate trends we used linear mixed-effect models allowing for random effects at country level and for heterogeneous covariance structures. One model was fitted for each United Nation's region using the logit transform of the prevalence and results back-transformed to the original scale. Best models were selected based on explicit statistical and graphical criteria. RESULTS: During 1990-2000 global stunting and underweight prevalences declined from 34% to 27% and 27% to 22%, respectively. Large declines were achieved in Eastern and South-eastern Asia, while South-central Asia continued to suffer very high levels of malnutrition. Substantial improvements were also made in Latin America and the Caribbean, whereas in Africa numbers of stunted and underweight children increased from 40 to 45, and 25 to 31 million, respectively. CONCLUSION: Linear mixed-effect models made best use of all available information. Trends are uneven across regions, with some showing a need for more concerted and efficient interventions to meet the MDG of reducing levels of child malnutrition by half between 1990 and 2015.

Child↗

PubMed2004

Estimates of global prevalence of childhood underweight in 1990 and 2015.

CONTEXT: One key target of the United Nations Millennium Development goals is to reduce the prevalence of underweight among children younger than 5 years by half between 1990 and 2015. OBJECTIVE: To estimate trends in childhood underweight by geographic regions of the world. DESIGN, SETTING, AND PARTICIPANTS: Time series study of prevalence of underweight, defined as weight 2 SDs below the mean weight for age of the National Center for Health Statistics and World Health Organization (WHO) reference population. National prevalence rates derived from the WHO Global Database on Child Growth and Malnutrition, which includes data on approximately 31 million children younger than 5 years who participated in 419 national nutritional surveys in 139 countries from 1965 through 2002. MAIN OUTCOME MEASURES: Linear mixed-effects modeling was used to estimate prevalence rates and numbers of underweight children by region in 1990 and 2015 and to calculate the changes (ie, increase or decrease) to these values between 1990 and 2015. RESULTS: Worldwide, underweight prevalence was projected to decline from 26.5% in 1990 to 17.6% in 2015, a change of -34% (95% confidence interval [CI], -43% to -23%). In developed countries, the prevalence was estimated to decrease from 1.6% to 0.9%, a change of -41% (95% CI, -92% to 343%). In developing regions, the prevalence was forecasted to decline from 30.2% to 19.3%, a change of -36% (95% CI, -45% to -26%). In Africa, the prevalence of underweight was forecasted to increase from 24.0% to 26.8%, a change of 12% (95% CI, 8%-16%). In Asia, the prevalence was estimated to decrease from 35.1% to 18.5%, a change of -47% (95% CI, -58% to -34%). Worldwide, the number of underweight children was projected to decline from 163.8 million in 1990 to 113.4 million in 2015, a change of -31% (95% CI, -40% to -20%). Numbers are projected to decrease in all subregions except the subregions of sub-Saharan, Eastern, Middle, and Western Africa, which are expected to experience substantial increases in the number of underweight children. CONCLUSIONS: An overall improvement in the global situation is anticipated; however, neither the world as a whole, nor the developing regions, are expected to achieve the Millennium Development goals. This is largely due to the deteriorating situation in Africa where all subregions, except Northern Africa, are expected to fail to meet the goal.

Body Weight↗

PubMed2004

Worldwide practices in child growth monitoring.

OBJECTIVE: To describe child growth monitoring practices worldwide in preparation for the construction and application of a new international growth reference. STUDY DESIGN: A questionnaire was sent to Ministries of Health in 202 countries requesting information on growth charts used in national programs, reference populations, classification systems, problems encountered, and actions taken against growth faltering. Countries also provided hard copies of charts in current use. This information was entered and analyzed in Microsoft Access. RESULTS: Responses were received from 178 (88%) countries, 154 of which included growth charts (n=806). Two thirds of the charts covered preschool age. All countries used weight-for-age, over half relying on this index alone. The reference most commonly used (68%) was the National Center for Health Statistics/World Health Organization population, with regional variations, where most European countries used local standards. Sixty-three percent of charts classified child growth on percentiles, whereas about one fifth used z scores. Problems reported were both conceptual (eg, interpreting growth trajectories) and practical (eg, lack of equipment). CONCLUSIONS: The survey demonstrates that growth charts are used universally in pediatric care. The information gathered on current use and interpretation of growth charts provides important guidance for constructing and applying the new reference.

Anthropometry↗

PubMed2004

Undernutrition as an underlying cause of child deaths associated with diarrhea, pneumonia, malaria, and measles.

BACKGROUND: Previous analyses derived the relative risk (RR) of dying as a result of low weight-for-age and calculated the proportion of child deaths worldwide attributable to underweight. OBJECTIVES: The objectives were to examine whether the risk of dying because of underweight varies by cause of death and to estimate the fraction of deaths by cause attributable to underweight. DESIGN: Data were obtained from investigators of 10 cohort studies with both weight-for-age category (<-3 SDs, -3 to <-2 SDs, -2 to <-1 SD, and >-1 SD) and cause of death information. All 10 studies contributed information on weight-for-age and risk of diarrhea, pneumonia, and all-cause mortality; however, only 6 studies contributed information on deaths because of measles, and only 3 studies contributed information on deaths because of malaria or fever. With use of weighted random effects models, we related the log mortality rate by cause and anthropometric status in each study to derive cause-specific RRs of dying because of undernutrition. Prevalences of each weight-for-age category were obtained from analyses of 310 national nutrition surveys. With use of the RR and prevalence information, we then calculated the fraction of deaths by cause attributable to undernutrition. RESULTS: The RR of mortality because of low weight-for-age was elevated for each cause of death and for all-cause mortality. Overall, 52.5% of all deaths in young children were attributable to undernutrition, varying from 44.8% for deaths because of measles to 60.7% for deaths because of diarrhea. CONCLUSION: A significant proportion of deaths in young children worldwide is attributable to low weight-for-age, and efforts to reduce malnutrition should be a policy priority.

Body Weight↗

PubMed2004

Rationale for developing a new international growth reference.

The rationale for developing a new international growth reference derived principally from a Working Group on infant growth established by the World Health Organization (WHO) in 1990. It recommended an approach that described how children should grow rather than describing how children grow; that an international sampling frame be used to highlight the similarity in early childhood growth among diverse ethnic groups; that modern analytical methods be exploited; and that links among anthropometric assessments and functional outcomes be included to the fullest possible extent. Upgrading international growth references to resemble standards more closely will assist in monitoring and attaining a wide variety of international goals related to health and other aspects of social equity. In addition to providing scientifically robust tools, a new reference based on a global sample of children whose health needs are met will provide a useful advocacy tool to health-care providers and others with interests in promoting child health.

Anthropometry↗

PubMed2004

The WHO Multicentre Growth Reference Study: planning, study design, and methodology.

The World Health Organization (WHO) Multicentre Growth Reference Study (MGRS) is a community-based, multicountry project to develop new growth references for infants and young children. The design combines a longitudinal study from birth to 24 months with a cross-sectional study of children aged 18 to 71 months. The pooled sample from the six participating countries (Brazil, Ghana, India, Norway, Oman, and the United States) consists of about 8,500 children. The study subpopulations had socioeconomic conditions favorable to growth, and low mobility, with at least 20% of mothers following feeding recommendations and having access to breastfeeding support. The individual inclusion criteria were absence of health or environmental constraints on growth, adherence to MGRS feeding recommendations, absence of maternal smoking, single term birth, and absence of significant morbidity. In the longitudinal study, mothers and newborns were screened and enrolled at birth and visited at home 21 times: at weeks 1, 2, 4, and 6; monthly from 2 to 12 months; and every 2 months in their second year. In addition to the data collected on anthropometry and motor development, information was gathered on socioeconomic, demographic, and environmental characteristics, perinatal factors, morbidity, and feeding practices. The prescriptive approach taken is expected to provide a single international reference that represents the best description of physiological growth for all children under five years of age and to establish the breastfed infant as the normative model for growth and development.

Anthropometry↗

PubMed2004

Measurement and standardization protocols for anthropometry used in the construction of a new international growth reference.

Thorough training, continuous standardization, and close monitoring of the adherence to measurement procedures during data collection are essential for minimizing random error and bias in multicenter studies. Rigorous anthropometry and data collection protocols were used in the WHO Multicentre Growth Reference Study to ensure high data quality. After the initial training and standardization, study teams participated in standardization sessions every two months for a continuous assessment of the precision and accuracy of their measurements. Once a year the teams were restandardized against the WHO lead anthropometrist, who observed their measurement techniques and retrained any deviating observers. Robust and precise equipment was selected and adapted for field use. The anthropometrists worked in pairs, taking measurements independently, and repeating measurements that exceeded preset maximum allowable differences. Ongoing central and local monitoring identified anthropometrists deviating from standard procedures, and immediate corrective action was taken. The procedures described in this paper are a model for research settings.

Anthropometry↗

PubMed2004

Assessment of gross motor development in the WHO Multicentre Growth Reference Study.

The objective of the Motor Development Study was to describe the acquisition of selected gross motor milestones among affluent children growing up in different cultural settings. This study was conducted in Ghana, India, Norway, Oman, and the United States as part of the longitudinal component of the World Health Organization (WHO) Multicentre Growth Reference Study (MGRS). Infants were followed from the age of four months until they could walk independently. Six milestones that are fundamental to acquiring self-sufficient erect locomotion and are simple to evaluate were assessed: sitting without support, hands-and-knees crawling, standing with assistance, walking with assistance, standing alone, and walking alone. The information was collected by both the children's caregivers and trained MGRS fieldworkers. The caregivers assessed and recorded the dates when the milestones were achieved for the first time according to established criteria. Using standardized procedures, the fieldworkers independently assessed the motor performance of the children and checked parental recording at home visits. To ensure standardized data collection, the sites conducted regular standardization sessions. Data collection and data quality control took place simultaneously. Data verification and cleaning were performed until all queries had been satisfactorily resolved.

Brazil↗

PubMed2004

Managing data for a multicountry longitudinal study: experience from the WHO Multicentre Growth Reference Study.

The World Health Organization (WHO) Multicentre Growth Reference (MGRS) data management protocol was designed to create and manage a large data bank of information collected from multiple sites over a period of several years. Data collection and processing instruments were prepared centrally and used in a standardized fashion across sites. The data management system contained internal validation features for timely detection of data errors, and its standard operating procedures stipulated a method of master file updating and correction that maintained a clear trail for data auditing purposes. Each site was responsible for collecting, entering, verifying, and validating data, and for creating site-level master files. Data from the sites were sent to the MGRS Coordinating Centre every month for master file consolidation and more extensive quality control checking. All errors identified at the Coordinating Centre were communicated to the site for correction at source. The protocol imposed transparency on the sites' data management activities but also ensured access to technical help with operation and maintenance of the system. Through the rigorous implementation of what has been a highly demanding protocol, the MGRS has accumulated a large body of very high-quality data.

Child Development↗