Children (<5 years) who are wasted

Number of children under 5 years of age falling below -2 standard deviations (moderate and severe) from the median weight-for-height of the reference population​

Children under 5 years of age in the surveyed population​​​ with valid weight-for-height​​ z-scores​

WHO Child Growth Standards 2006

Children 0-59 months

Modelled

Chika Hayashi

[email protected]

Child growth is an internationally accepted outcome reflecting child nutritional status. Child wasting refers to a child who is too thin for his or her height and is the result of recent rapid weight loss or the failure to gain weight. A child who is moderately or severely wasted has an increased risk of death, but treatment is possible. Child wasting is a Sustainable Development Goal (SDG target 2.2.2a) and also one of the World Health Assembly 2025 Global Nutrition Target indicators.

The official SDG indicator is wasting as assessed using weight for height. Wasting can however also be assessed with mid upper arm circumference (MUAC). Estimates of wasting based on MUAC are not considered for the joint dataset. In addition, while wasting constitutes the major form of moderate acute malnutrition (MAM), there are acutely malnourished children who may not be identified with weight-for-height or MUAC, namely those presenting bilateral pitting odema (characterized by swollen feet, face and limbs). However, in 2019, the JME updated its analysis methodology to exclude oedema data when assessing a child’s nutrition status. The reasoning for this decision is that malnutrition presenting as oedema is uncommon in many countries and, more importantly, can be easily misdiagnosed (1). A child’s weight, height and sex are thus exclusively used to assess if a child was wasted or overweight. All reanalyzed estimates have excluded oedema. However, oedema is still considered and footnoted for reported estimates, as there is no way to adjust these.

Survey estimates come with levels of uncertainty due to both sampling error and non-sampling error (e.g. mesasurement technical error, recording error etc.,). None of the two sources of errros have been fully taken into account for deriving estimates neither at country nor at regional and global levels. Surveys are carried out in a specific period of the year, usually over a few months. However, this indicator can be affected by seasonality, factors related to food availability (e.g. pre-harvest periods), disease (e.g. rainy season and diarrhoea, malaria, etc.), and natural disasters and conflicts. Hence, country-year estimates may not necessarily be comparable over time. Consequently, only latest estimates are provided.

Survey estimates are based on standardized methodology using the WHO Child Growth Standards as described elsewhere (Ref: Anthro software manual). Global and regional estimates are based on methodology outlined in UNICEF-WHO-The World Bank: Joint child malnutrition estimates – Levels and trends (UNICEF/WHO/WB 2012)

Global and regional estimates refer to the age group of children under 5 years, sexes combined. Disaggregated country data are available in a majority of household surveys and UNICEF – WHO- The World Bank Group have expanded the joint data set to include sub-national and stratified estimates (e.g. sex, age groups, wealth, mothers’ education, residence) which was released in 2018.

No imputation methodology is applied to derive estimates for countries or years where no data are available.

Countries and years are treated as missing randomly following a multilevel modeling approach (3).

Regional aggregates are available for the following classifications: UN, MDG, UNICEF, WHO, The World Bank regions and income groups.

The standard analysis approach to construct the joint data set aims for a maximum comparability of country estimates. For the inclusion of survey estimates into the JME dataset, the inter-agency group applies survey quality assessment criteria. When there is insufficient documentation, the survey is not included until information becomes available. When raw data are available, and there is a question about the analysis approach, data re-analysis is performed following the standard methodology (1). Discrepancies between results from the standardised approach and those reported may occur for various reasons, for example, the use of different standards for z-score calculations, imputation of the day of birth when missing, the use of rounded age in months, the use of different flagging systems for data exclusion. For surveys based on the previous NCHS/WHO references, and for which raw data are not available, a method for converting the z-scores to be based on the WHO Child Growth Standards is applied (4). In addition, when surveys do not cover the age interval 0-<5 years, or are only representative of the rural areas, an adjustment based on other surveys for the same country, is performed. Any adjustment or conversion is transparently stated in the annotated joint data set.

More than 150 countries.

At country level, data are provided for the years where surveys are included in the joint dataset. Survey years range from 1983 to 2019. For the global and regional levels, estimates are provided only for the latest available estimate upon release each year (i.e. in Sept 2016 edition of the Joint Malnutrition Estimates the only estimate available was for 2015 and no time series were provided).

For the majority of countries, nationally representative household surveys constitute the data source. For a limited number of countries data from surveillance systems is used if sufficient population coverage is documented (about 80%). For both data sources, the child’s height and weight measurements have to be collected following recommended standard measuring techniques (1).

UNICEF, WHO and the World Bank group jointly review new data sources to update the country level estimates. Each agency uses their existing mechanisms for obtaining data.

For WHO, see published database methodology (de Onis et al. 2004). For UNICEF, the cadre of dedicated data and monitoring specialists working at national, regional and international levels in 190 countries routinely provide technical support for the collection and analysis of data. For the past 20 years UNICEF has undertaken an annual process to update its global databases, called Country Reporting on Indicators for Goals (CRING). This exercise is done in close collaboration with UNICEF country offices with the purpose of ensuring that UNICEF global databases contain updated and internationally comparable data. UNICEF country offices are invited to submit, through an online system, nationally representative data for over 100 key indicators on the well-being of women and children, including stunting. The country office staff work with local counterparts to ensure the most relevant data are shared. Updates sent by the country offices are then reviewed by sector specialists at UNICEF headquarters to check for consistency and overall data quality of the submitted estimates and re-analysis where possible. This review is based on a set of objective criteria to ensure that only the most reliable information is included in the databases. Once reviewed, feedback is made available on whether or not specific data points are accepted, and if not, the reasons why. UNICEF uses these data obtained through CRING to feed into the joint dataset. The World Bank Group provides estimates available through the Living Standard Measurement Surveys (LSMS) which usually requires re-analysis of datasets given that the LSMS reports often do not tabulate the stunting data.

Data sources are compiled and reviewed throughout the year.

The updated country dataset as well as global and regional estimates are released annually, to coincide with SDG reporting updates by The United Nations Statistical Division (UNSD), generally in March.

Data providers vary and most commonly are ministries of health, national offices of statistics or national institutes of nutrition.

1. Recommendations for data collection, analysis and reporting on anthropometric indicators in children under 5 years old. Geneva: World Health Organization and the United Nations Children’s Fund (UNICEF), 2019. Licence: CC BY-NC-SA 3.0 IGO.

2. United Nations Children’s Fund, World Health Organization, The World Bank (2012). UNICEFWHO-World Bank Joint Child Malnutrition Estimates. (UNICEF, New York; WHO, Geneva; The World Bank, Washington, DC; 2012).

3. de Onis M, Blössner M, Borghi E, et al. (2004), Methodology for estimating regional and global trends of childhood malnutrition. Int J Epidemiol, 33(6):1260-70.

4. Yang H and de Onis M. Algorithms for converting estimates of child malnutrition based on the NCHS reference into estimates based on the WHO Child Growth Standards BMC Pediatrics 2008, 8:19 (05 May 2008) (http://www.biomedcentral.com/1471-2431/8/19).

Wasting refers to being dangerously thin for one’s height. Wasting is the result of recent rapid weight loss or the failure to gain weight and wasted children have an increased risk of death, but treatment is possible. Child wasting is a World Health Assembly 2025 global nutrition target indicator.

Country trajectories and assessment towards the stunting, wasting and overweight targets at the national level were determined using the joint malnutrition country dataset (March 2020) and are largely in alignment with the WHO-UNICEF Technical Expert Advisory Group on Nutrition Monitoring rules (‘Methodology for Monitoring Progress towards the Global nutrition Targets for 2025: Technical report’, World Health Organization and United Nations Children’s Fund, June 2017, available at . The interagency assessment on country progress was made towards the 2025 World Health Assembly targets (and not the recently proposed 2030 targets) for this exercise.

While the WHO-UNICEF 2017 rules were used as much as possible, since this report uses the same 5 categories for all SDG indicators (on track, acceleration needed, target met, insufficient trend data, and no data) (Table 1) the current report does not directly align with the latest WHO-UNICEF country assessments published elsewhere.

The ‘on track’ category follows the WHO-UNICEF rules for stunting and overweight (Table 2). For wasting the WHO-UNICEF rules applied to categorize a country as ‘on track’ are instead used to assign an assessment of ‘target met’ in this report since the rules designate a country as ‘on track’ if the prevalence is <5% which is the 2025 target; there is no assessment for ‘on track’ for wasting in this report. The ‘acceleration needed’ category is based on a combination of prevalence and average annual progress rates depending on the indicator. However, the ‘acceleration needed’ category does not exist in the WHO-UNICEF 2017 rules and was made for this report by combining two categories from the WHO-UNICEF 2017 rules of (i) off track: some progress; and (ii) off track: no progress or worsening (Table 1). This report also made an additional classification not within the WHO-UNICEF 2017 rules. This was applied to any country for which the most recent estimate between 2013 and 2019 was < 3 per cent for stunting or overweight prevalence or < 5 per cent for wasting prevalence. This category of ‘target met’ was also applied to countries which have already achieved a 40 per cent reduction in the number of stunted children according to their annual progress rates assessment (Table 2). Apart from countries in the ‘target met’ category, countries that did not have at least two data points since 2008 and at least one data point beyond 2012, were classified as having ‘insufficient trend data’. Countries without any data point after 2000 were classified as ‘no data’. Note that for stunting and overweight, the JME group is developing county level model-based estimates which are anticipated for release in 2021. The assessments presented in this report may therefore change in the near future.