WHO Child Growth Standards

WHO Child Growth Standards: Evolution, Concepts, Overview Challenges, Issues and Options Dr Arvind Mathur MD,DHA,DNB Cluster Focal Point Family & Community Health WHO-India Direct Indicators: INDICATORS OF NUTRITIONAL STATUS -- Nutritional Anthropometry -- Clinical Assessment -- Bio-chemical Estimations -- Biophysical Tests Indirect Indicators: -- Dietary assessment -- Prevalence of Morbidities -- Vital Statistics In addition, Secondary Data: -- Socio-economic -- Demographic -- Environmental NUTRITIONAL ANTHROPOMETRY Nutritional Anthropometry Weight : - Total Body mass - Simple, widely used - Sensitive to small changes in nutrition - Environmentally influenced - Stunting Reflects long duration undernutrition Height : - Genetically Determined MUAC : - Reflects muscle/fat - Easy to measure, used for quick screening - Independent of age (1-5 years) Fat Fold Thickness:- Measures body fat -Correlates well with total body fat REQUIREMENTS FOR NUTRITIONAL ANTHROPOMETRY Standard equipment: - Accuracy / Consistency, Appropriate techniques: - Training & Standardization Correct assessment of age: - Wrong age vitiates the results Reference values: - For comparison and computation of indices Classification: - For grading nutritional status Reference Values Anthropometric measurements obtained on statistically adequate number of individuals who are well nourished, representing cross section of community living in an environment free from constraints of any sort and have capacity to reach maximum growth potential at each age group/Gender. - National E.g. Well-to-do Hyderabad pre-school children - International E.g. NCHS, Harvard, MGRS Growth charts • Consist of a series of percentile curves that illustrate the distribution of selected body measurements in the study population • Used to track the growth of children from infancy thru adolescence • Indicates the state of the child's health, nutrition and well being Growth monitoring • By using growth charts-screening tool for diagnosis of nutritional, chronic systemic and endocrine diseases Need for growth charts Individual level • Monitoring &documenting growth • Comparison with references std • To detect growth faltering • Monitoring health status Community level • Performance of programs • Comparison over time • Identification of problem areas • National/international comparisons National level Scientists • Research tool Community level • Early identification of children’s growth failure for detection of malnutrition and taking appropriate interventions • Early identification-overweight/obesity • Sensitize health workers • Educate parents and allay their anxiety by showing normal growth in chart What needs to be monitored at community level First 2 years • Length/age • Weight/age • Weight /height or BMI • Head circumference/age 2 –10 years • • • Height/age Weight/age BMI/age >10 years • Above in relation to pubertal development WHO Child Growth Standards Why? 1 year 2 years 3 years 4 years 5 years Why Children Should Grow Healthy? • Child undernutrition or failure of children to grow properly in early childhood , results in greatly increased child mortality. • At more than 3000 infants a day, the death toll from undernutrition by far exceeds even the Tsunami or Bhuj. • Those children that survive do so with a greatly reduced capacity to lead productive and healthy lives. Rationale for the development of the WHO child growth standards The recommended NCHS/WHO international reference is inappropriate for assessing nutritional status:  Individual infants interferes with sound nutritional management of breastfed infants, increasing their risk of morbidity and mortality  Populations provides inaccurate estimates of undernutrition and overweight New WHO growth standards The international growth standards established by the WHO in April 2006 directly confront the notion that ethnicity is a major factor in how children grow. The new standards demonstrate that children born in different regions of the world , when given an optimum start in life , have the potential to grow and develop within the same range of height and weight for age. (ECHUI 2006 Global Framework for Action) Why should we adopt new charts? • The new Child Growth Standards is a crucial development in improving infant and young child nutrition globally. Unlike the old growth charts, the new standards (1) describe how children "should grow," (2) establish breastfeeding as the biological "norm," and (3) provide international standards for all healthy children, as human milk supports not only healthy growth, but also optimal cognitive development and long-term health. Rationale for change to new WHO standards Corrects the historical fallacy of using formula fed children from single ethnic group in one country as global standard for assessment of nutritional status of preschool children and consequent problems in interpretation of data . WHO Child Growth Standards HOW? Milestones in the development of the WHO child growth standards 1991-1993 WHO Working Group on Infant growth  Comprehensive review shows growth patterns of healthy breastfed infants differ from the current NCHS/WHO international reference A new growth reference is needed to improve infant health management The reference population should reflect health recommendations in view of the frequent use of references as “standards”   Milestones in the development of the WHO child growth standards 1993 WHO Expert Committee  Recommends development of a new international growth reference Based on an international sample of “healthy” infants Endorses need for new reference Requests it to be based on breastfed infants  1994 WHA resolution (WHA 47.5)   A Growth Curve for the 21st Century The WHO Multicentre Growth Reference Study Approaches for developing growth references • Descriptive approach: defines growth on the basis of representative samples of healthy groups, i.e., without identifiable disease • Prescriptive approach: defines growth on the basis of health and feeding practices known to promote optimal growth and selects the sample accordingly WHO Growth Reference Study Prescriptive Approach  Optimal Nutrition – Breastfed infants – Appropriate complementary feeding  Optimal Environment – No microbiological contamination – No smoking  Optimal Health Care – Immunization – Pediatric routines Optimal Growth MGRS study design Longitudinal (0-24 months) year 1 year 2 year 3 Cross-sectional (18-71 mo) WHO Child Growth Standards Construction growth standards 1 year 2 years 3 years 4 years 5 years Mean length from birth to 24 months for the six MGRS sites Brazil Ghana India Norway Oman USA Mean of Length (cm) 50 0 60 70 80 200 400 Age (days) 600 WHO Multicentre Growth Reference Study Group. Assessment of linear growth differences among populations in the WHO Multicentre Growth Reference Study. Acta Paediatr Suppl Length at selected centiles for the pooled sample and the sample following the exclusion of Norway Length (cm) Pooled P3 Pooled P25 Pooled P50 Pooled P75 Pooled P97 Exc Norway P3 Exc Norway P25 Exc Norway P50 Exc Norway P75 Exc Norway P97 50 0 60 70 80 90 200 400 Age (days) 600 WHO Multicentre Growth Reference Study Group. Assessment of linear growth differences among populations in the WHO Multicentre Growth Reference Study. Acta Paediatr Suppl Length at selected centiles for the pooled sample and the sample following the exclusion of India Length (cm) Pooled P3 Pooled P25 Pooled P50 Pooled P75 Pooled P97 Exc India P3 Exc India P25 Exc India P50 Exc India P75 Exc India P97 50 0 60 70 80 90 200 400 600 Age (days) WHO Multicentre Growth Reference Study Group. Assessment of linear growth differences among populations in the WHO Multicentre Growth Reference Study. Acta Paediatr Suppl 2006;450:56-65. Construction of growth curves • The rigorous methods of data collection yielded very highquality dataset • State-of-art statistical methods applied in a methodical way: – Detailed examination of 30 existing methods, including types of distributions and smoothing techniques; – Selection of a software package flexible enough to allow comparative testing of alternative methods and the actual generation of the curves; – Systematic application of the selected approach to the data to generate models that resulted in the best fit • Ongoing statistical review by external expert panel WHO Child Growth Standards • Attained growth  Weight-for-age  Length/height-for-age  Weight-for-length/height  Body mass index-for-age  Mid-upper arm circumference-forage  Triceps skinfold-for-age  Subscapular skinfold-for- age  Head circumference-for-age  Weight  Length/height  Head circumference • Arm circumference • Growth velocity Prevalence of stunting (below -2 SD length/height-for-age) by age based on the WHO standards and the NCHS reference in Bangladesh NCHS 80 70 60 50 % WHO 40 30 20 10 0 0-5 6-11 12-23 24-35 Age (months) 36-47 48-60 0-60 Source: de Onis M, Onyango AW, Borghi E, Garza C, Yang H, for the WHO Multicentre Growth Reference Study Group. Comparison of the WHO Child Growth Standards and the NCHS growth reference: implications for child health programs. Public Health Nutrition 2006;9:942-947. Prevalence of underweight (below -2 SD weight-for-age) by age based on the WHO standards and the NCHS reference in Bangladesh NCHS 80 70 60 50 % WHO 40 30 20 10 0 0-5 6-11 12-23 24-35 Age (months) 36-47 48-60 0-60 Source: de Onis M, Onyango AW, Borghi E, Garza C, Yang H, for the WHO Multicentre Growth Reference Study Group. Comparison of the WHO Child Growth Standards and the NCHS growth reference: implications for child health programs. Public Health Nutrition 2006;9:942-947. Mean weight-for-age z-scores of healthy breastfed infants relative to the NCHS, CDC and WHO curves Mean weight-for-age z-score 0.8 CDC NCHS MGRS 0.4 0 -0.4 -0.8 0 1 2 3 4 5 6 7 8 9 10 11 12 Age (months) Breastfeeding No gift • provides perfect nutrition • provides initial immunization • prevents diarrhoea • maximizes a child’s physical and intellectual potential • supports food security • bonds mother and child • helps birth spacing • benefits maternal health • saves money is more precious • is environment-friendly WHO Child Growth Standards The new standards will play a key role in the prevention and early recognition of childhood obesity Prevalence of overweight (above +2 SD weight-for-length/height) by age based on the WHO standards and the NCHS reference in the Dominican Republic NCHS 16 14 12 10 % WHO 8 6 4 2 0 0-5 6-11 12-23 24-35 Age (months) 36-47 48-60 0-60 Source: de Onis M, Onyango AW, Borghi E, Garza C, Yang H, for the WHO Multicentre Growth Reference Study Group. Comparison of the WHO Child Growth Standards and the NCHS growth reference: implications for child health programs. Public Health Nutrition 2006;9:942-947. WHO standards versus NCHS reference  Important differences that vary by age group, sex, growth indicator, specific percentile or z-score curve, and the nutritional status of index populations.  Differences are particularly important during infancy due to type of feeding and issues related to study design (eg, measurement interval)  Difference in shapes of the weight-based curves in early infancy makes interpretation of growth performance strikingly different depending on whether the WHO standard or the NCHS reference is used  Healthy breastfed infants track along the WHO weightfor-age mean z-score while appearing to falter in NCHS from 2 months onwards – implications assessment of lactation performance and adequacy of infant feeding Data charact Comparison of existing growth charts CDC Multiple different studies 1963-1994 WHO Primary data KNA Primary data Source Study period Population 1997-2003 6 Countries pooled data. healthy children & practices Birth-5yrs 1988-1991 Affluent Indian population, multicentric Birth-18 yrs US, mixed feeding, no racial/ethnic diff Birth-20 yrs Age-group Use of new WHO growth standards: Corrects the historical fallacy of using formula fed children from single ethnic group in one country as global standard and consequent problems in interpretation of data . Computed under-nutrition rates in the critical 0-6 month age group with new WHO standard are higher as compared to under -nutrition rates derived from NCHS/WHO standards – this should not be viewed with alarm Computed under-nutrition rates in 1-5 year age with new WHO standard are lower as compared to under -nutrition rates derived from NCHS/WHO standards – this should not lead to complacency Under weight prevalence in DLHS WHO vs NCHS 70 % prevalence of undernutrition 60 50 40 30 20 10 0 0-2 3-5 6-8 9-11 12-14 15-17 18-20 21-23 24-35 36-60 <-2sdWHO <-2sd NCHS Age in m onths Use of new WHO growth standards can make an important contribution in clearly bringing into focus the importance of nutrition and health education in improving infant and young child feeding and caring practices and reducing the under-nutrition in preschool children Low birth-weight rate in India is 30% Prevalence of under-weight in first three months is 30% suggesting that breast feeding in the first three months prevents deterioration in nutritional status After 3 months underweight rate rises –? due to early introduction of milk supplements Between 6 and 11 months underweight rate further rises to 45 % -?due to inadequate complementary feeding Analysis of data using new WHO norms clearly brings out importance of wrong infant feeding habits as determinants of underweight in infancy and emphasises importance of nutrition education to correct them. Progressive increase in the underweight rates in 12 to 24 months of age – ?attributable to inadequate intake of family food due to poor child feeding practices. Need for nutrition education to correct these faulty habits . With the availability of new WHO standards for weight for age, height for age and BMI for age clinicians and research workers can assess which of the three indices is the most a appropriate index for assessment of functional de-compensation in the era when both under and overnutrition are public health problems Some Questions? • Individual growth monitoring in children in India-Is it possible to achieve? • Who shall use the growth charts? – Pediatricians? Family Physicians? Anganwadi workers? ASHA? Mothers? • Capacity Building: – Training of different level of workers/volunteers – Systematic Changes/strengthening • How do we introduce the new charts in the existing program? • Are there actions that the CoP members can take? • More questions!! Thank You!