What is the most common indication of nutritional status in infants and children?

Percentage of children stunted, wasted, and underweight, and mean z-scores for stunting, wasting and underweight

Definition

Percentage of children under 5 years of age, by nutritional status:

1)     Stunted.

2)     Wasted and overweight.

3)     Underweight and overweight for age.

4)     Mean z-score for height-for-age, weight-for-height, and weight-for-age.

Coverage:

Population base: Living children born 0-59 months before the survey (PR file)

Time period: Current status at time of survey

Numerators:

Stunting:

1)     Severely stunted: Number of children whose height-for-age z-score is below minus 3 (‑3.0) standard deviations (SD) below the mean on the WHO Child Growth Standards (hc70 < ‑300)

2)     Moderately or severely stunted: Number of children whose height-for-age z-score is below minus 2 (‑2.0) standard deviations (SD) below the mean on the WHO Child Growth Standards (hc70 < -200)

3)     Mean z-score for height-for-age: Sum of the z-scores of children with a non-flagged height for age score (∑ hc70/100, if hc70 < 9990)

Wasting and overweight:

4)     Severely wasted: Number of children whose weight-for-height z-score is below minus 3 (‑3.0) standard deviations (SD) below the mean on the WHO Child Growth Standards (hc72 < ‑300)

5)     Moderately or severely wasted: Number of children whose weight-for-height z-score is below minus 2 (‑2.0) standard deviations (SD) below the mean on the WHO Child Growth Standards (hc72 < -200)

6)     Overweight: Number of children whose weight-for-height z-score is above plus 2 (+2.0) standard deviations (SD) above the mean on the WHO Child Growth Standards (hc72 > 200 & hc72 < 9990)

7)     Mean z-score for weight for height: Sum of the z-scores of children with a non-flagged weight for height score (∑ hc72/100, if hc72 < 9990)

Underweight and overweight for age:

8)     Severely underweight: Number of children whose weight-for-age z-score is below minus 3 (‑3.0) standard deviations (SD) below the mean on the WHO Child Growth Standards (hc71 < -300)

9)     Moderately underweight: Number of children whose weight-for-age z-score is below minus 2 (‑2.0) standard deviations (SD) below the mean on the WHO Child Growth Standards (hc71 < ‑200)

10)  Overweight for age: Number of children whose weight-for-age z-score is above plus 2 (+2.0) standard deviations (SD) above the mean on the WHO Child Growth Standards (hc71 > 200 & hc71 < 9990)

11)  Mean z-score for weight for age: Sum of the z-scores of children with a non-flagged weight for age score (∑ hc71/100, if hc71 < 9990)

Denominators:

Number of de facto living children between ages 0 and 59 months before the survey (hv103 = 1 & hc1 in 0:59) who have:

1)     Stunting: valid non-flagged height for age z-scores (hc70 < 9990)

2)     Wasting and overweight: valid non-flagged weight for height z-scores (hc72 < 9990)

3)     Underweight and overweight for age: valid non-flagged weight for age z-scores (hc71 < 9990)

Variables: PR file.

Calculation

The assignment of anthropometric z-scores based on the WHO Child Growth Standards is done through a complicated interpolation function that takes into account sex, age (measured by difference in date of birth and date of interview, both precise to day of month), height in centimeters, and weight in kilograms (precise to 100 grams). As part of the creation of a recode file, variables with the z-scores are calculated and included in that file. The z-scores are calculated using software based on the WHO Anthro program and the macros for statistical packages at http://www.who.int/childgrowth/software/en/.

If the WHO Anthro program or the WHO igrowup macros are used to recalculate z-scores, then exclude cases without a month and year of birth recorded (hc33>1). Additionally, when the data are collected the weight variable includes two decimal places for weight (e.g. 10.65). This is rounded in the recode file to one decimal (variable hc2) (e.g. 10.7) and so recalculated z-scores may differ slightly.

In the process of assigning the z-scores, checks are made on their plausibility. Z-scores for height-for-age and weight-for-age are assigned special values to children with incomplete date of birth (month or year missing or “don’t know”) as the z-scores are sensitive to changes in age. Children with height-for-age z-scores below -6 SD or above +6 SD, with weight-for-age z-scores below -6 SD or above +5 SD, or with weight for height z-scores below -5 SD or above +5 SD are flagged as having invalid data.

The percentage of children stunted, wasted, and underweight are equal to the specific numerators divided by the appropriate denominators and multiplied by 100.

The mean z-scores are equal to the numerator divided by the appropriate denominator.

Handling of Missing Values

Children who were not weighed and measured and children whose values for weight and height were not recorded are excluded from both the denominators and the numerators. Children whose month or year of birth are missing or unknown are flagged and excluded from both the denominators and the numerators for anthropometry indices that use age in the calculation (i.e. height-for-age and weight-for-age). Children whose day of birth is missing or unknown are assigned day 15. Children who are flagged for out-of-range z-scores or invalid z-scores are excluded from both the denominator and the numerators.

Notes and Considerations

Stunting, based on a child’s height and age, is a measure of chronic nutritional deficiency. Wasting, based on a child’s weight and height, is a measure of acute nutritional deficiency. Underweight, based on weight and age, is a composite measure of both acute and chronic statuses. Overweight, based on weight and height, is a measure of excess weight than is optimally healthy.

The World Health Organization (WHO) released an international growth standard statistical distribution in 2006, which describes the growth of children ages 0 to 59 months living in environments believed to support optimal growth of children in six countries throughout the world, including the U.S. The distribution shows how infants and young children grow under these conditions, rather than how they grow in environments that may not support optimal growth. The WHO Child Growth Standards (WHO, 2006) have replaced the NCHS/CDC/WHO international reference standard as the standard for assessing the nutritional status of children.

Due to natural variations in a well-nourished population, 2.2 percent of children will be between ‑2.0 and ‑2.99 SD below the mean, and 0.1 percent will be ‑3.0 or more SD below the mean. The extent of malnutrition in a population should be taken by the extent the proportions moderate and severe exceed these percentages that occur in a well-fed population of children.

Changes over Time

In phases of the DHS survey before DHS-IV, only children of interviewed women and who were under 5 years old (or the cutoff for the health section of the individual questionnaire) were weighed and measured. In many surveys, only a subsample of these children were selected for anthropometry.

The later DHS surveys (DHS-V onwards) included height and weight measurements of all children born in the 5 years preceding the survey and listed in the Household Questionnaire, irrespective of the interview status of their mother.

The levels of stunting, wasting, and underweight since DHS-VI are calculated using the 2006 WHO Child Growth Standards. In earlier survey the NCHS/CDC/WHO international reference standards was used and results published in the earlier survey reports will differ from those using the newer standard. In order to assess trends in nutritional status, the earlier DHS nutrition indicators should be re-calculated using the 2006 WHO Child Growth Standards.

Prior to DHS-7 if any of the three sets of z-scores (height-for-age, weight-for-height, and weight-for-age) was flagged for a child, all were considered flagged and excluded from the numerators and denominators of the indicators. In DHS-7 this was changed so that there is a separate denominator for indicators based on height-for-age, weight-for-height and weight-for-age.

All comparisons between surveys, either over time or between countries, should take into account the possible differences in the defined population base and in the reference standard used.

References

Assaf, S., M.T. Kothari, and T.Pullum. 2015. An Assessment of the Quality of DHS Anthropometric Data. In DHS Methodological Reports No. 16. Rockville, Maryland, USA: ICF International. https://dhsprogram.com/publications/publication-mr16-methodological-reports.cfm

Black, R.E., et al. 2013. “Maternal and child undernutrition and overweight in low-income and middle-income countries.” The Lancet 382(9890):427-451. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(13)60937-X/fulltext

Corsi, D. J., J. M. Perkins, and S.V. Subramanian. 2017. “Child Anthropometry Data Quality from Demographic and Health Surveys, Multiple Indicator Cluster Surveys, and National Nutrition Surveys in the West Central Africa Region: Are We Comparing Apples and Oranges?” Glob Health Action 10(1):1328185. https://www.tandfonline.com/doi/full/10.1080/16549716.2017.1328185

Mei, Z., and L.M. Grummer-Strawn. "Standard deviation of anthropometric Z-scores as a data quality assessment tool using the 2006 WHO growth standards: a cross country analysis." Bulletin of the World Health Organization 85 (2007): 441-448.

http://www.who.int/bulletin/volumes/85/6/06-034421/en/

Roth, D.E., A. Krishna, M. Leung, J. Shi, D.G Bassani, A.J.D. Barros. 2017.

“Early childhood linear growth faltering in low-income and middle-income countries as a whole-population condition: analysis of 179 Demographic and Health Surveys from 64 countries (1993–2015).” The Lancet Global Health 5, no. 12 (2017): e1249-e1257

https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(17)30418-7/fulltext

Stevens G.A., M.M. Finucane, C.J. Paciorek, S.R. Flaxman, R.A. White, A.J. Donner A.J., M. Ezzati; Nutrition Impact Model Study Group (Child Growth). 2012. “Trends in mild, moderate, and severe stunting and underweight, and progress towards MDG 1 in 141 developing countries: a systematic analysis of population representative data.” Lancet. 380(9844): p824-34. doi: 10.1016/S0140-6736(12)60647-3. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)60647-3/fulltext

United Nations Department of Technical Co-operation for Development and Statistical Office. 1986. How to weigh and measure children: Assessing the nutritional status of young children in household surveys. United Nations, New York. https://www.popline.org/node/383898

WHO. 2017. Global Nutrition Monitoring Framework: Operational Guidance for Tracking Progress in Meeting Targets for 2025. http://www.who.int/nutrition/publications/operational-guidance-GNMF-indicators/en/

WHO. 2006. The WHO Child Growth Standards

http://www.who.int/childgrowth/en/ and

http://www.who.int/childgrowth/publications/technical_report_pub/en/

Resources

WHO Anthro program and macros. http://www.who.int/childgrowth/software/en/

DHS-7 Tabulation plan: Table 11.1

API Indicator IDs:

CN_NUTS_C_HA3, CN_NUTS_C_HA2, CN_NUTS_C_WH3, CN_NUTS_C_WH2, CN_NUTS_C_WHP, CN_NUTS_C_WA3, CN_NUTS_C_WA2, CN_NUTS_C_WAP

(API link, STATcompiler link)

SDG Indicator 2.2.1: Prevalence of stunting among children under 5 years of age

SDG Indicator 2.2.2: Prevalence of malnutrition among children under 5 years of age, by type (wasting and overweight)

GNMF Indicator 1: Prevalence of low height-for-age in children under five years of age

GNMF Indicator 4: Prevalence of weight-for-height >+2 SD in children under five years of age

GNMF Indicator 6: Prevalence of low weight-for-height in children under five years of age

WHO 100 Core Health Indicators: Children under 5 years who are stunted

WHO 100 Core Health Indicators: Children under 5 years who are wasted

WHO 100 Core Health Indicators: Children under 5 years who are overweight

MICS6 Indicator TC.44: Underweight prevalence

MICS6 Indicator TC.45: Stunting prevalence

MICS6 Indicator TC.46: Wasting prevalence

MICS6 Indicator TC.47: Overweight prevalence

Percentage of women by nutritional status

Definition

1)     Percentage of women age 15-49 with height under 145 cm.

2)     Percentage of non-pregnant, non-postpartum women age 15–49 by nutritional status based on specific body mass index (BMI) levels.

3)     Mean body mass index (BMI) for non-pregnant, non-postpartum women age 15–49.

Coverage:

Population base: All women age 15-49; Non-pregnant and non-postpartum women age 15–49 years at the time of the survey (IR file)

Time period: Current status at time of survey

Numerators:

1)     Number of women age 15-49 with height below 145cm (v438 < 1450, if v438 in 1300:2200)

2)     Number of non-pregnant, non-postpartum women age 15-49 with a body mass index (BMI) with the following values:

a)      Normal: 18.5 to 24.9 (v445 in 1850:2499)

b)     Total thin: less than 18.5 (v445 in 1200:1849)

c)      Mildly thin: 17.0 to 18.4 (v445 in 1700:1849)

d)     Moderately and severely thin: less than 17.0 (v445 in 1200:1699)

e)     Total overweight or obese (>=25.0) (v445 in 2500:6000)

f)       Overweight: 25.0 to 29.9 (v445 in 2500:2999)

g)      Obese: 30.0 or more (v445 in 3000:6000)

3)     Mean BMI: Sum of BMI for non-pregnant, non-postpartum women age 15–49 who were weighed and measured (∑ v445/100, if v445 in 1200:6000)

Denominator:

1)     Number of women age 15–49 with a valid height measurement (v438 in 1300:2200)

2)     Number of women age 15–49, excluding women who are pregnant or who gave birth in the 2 months preceding the date of the interview (v213 ≠ 1 and (v208 = 0 or b19_01 >= 2)), with a valid BMI (v445 in 1200:6000)

3)     Same as denominator 2

Variables: IR file.

b19_01 exists in DHS-7 surveys.  For older surveys use b19_01 = v008 - b3_01 to create its equivalent.

Calculation

The body mass index is calculated as weight in kilograms divided by the square of height in meters.

The percentages of women, by category, are equal to the category numerators divided by the denominator and multiplied by 100.

In ever-married women samples, the data in the IR file are augmented with data from the PR file for never-married women to provide nutritional status estimates for all women.  In ever-married samples (hv020 = 1), never-married women who are de facto residents and were weighed and measured (hv115 = 0 & hv103 = 1 & either ha3 in 1300:2200 or ha40 in 1200:6000 depending on the denominator) are added to the denominator, and to the numerators if their height (ha3) was below 145 cm, and if their BMI were in the appropriate categories (ha40). In ever-married samples, never-married women are assumed to not be pregnant nor to have had a recent birth.

Added variables required for ever-married samples:

The mean BMI is equal to the numerator divided by the denominator.

Handling of Missing Values

Women who were not weighed and measured and women whose values for weight and height were not recorded are excluded from both the denominator and the numerators. Women whose calculated BMI is below 12.0 or above 60.0 are flagged as out of range and are excluded from both the denominator and the numerators.

Notes and Considerations

BMI, also known as the Quetelet Index, is a measure of acute nutritional status. It is based on the Fogarty Metropolitan Life tables of ideal weight for height.

These indicators could be presented based on the IR file or the PR file.  Using the PR file would result in a slightly larger sample size, but the IR file is chosen for consistency with other women’s indicators, and as some of the women’s characteristics used in presenting the results are only available for women with completed interviews.

Changes over Time

In phases of the DHS survey before DHS-IV, either only interviewed women or mothers of children under 5 years (or the cutoff for the health section of the individual questionnaire) were weighed and measured. In some surveys, only a subsample of these women were selected for anthropometry. All comparisons between surveys, either over time or between countries, should take into account the possible differences in the defined population base. While pregnant women and women two months postpartum are weighed and measured, they are excluded from the report tabulations because of weight gain during pregnancy.

References

James, W. P., T.A. Ferro-Luzzi, and J.C. Waterlow, 1988. “Definition of chronic energy deficiency in adults: Report of a working party of the International Dietary Energy Consultative Group.” European Journal of Clinical Nutrition, 42: 969–981. https://www.researchgate.net/publication/20006752_Definition_of_chronic_energy_deficiency_in_adults_Report_of_a_working_party_of_the_International_Dietary_Energy_Consultative_Group

NCD Risk Factor Collaboration. 2017. “Worldwide Trends in Body-Mass Index, Underweight, Overweight, and Obesity from 1975 to 2016: A Pooled Analysis of 2416 Population-Based Measurement Studies in 128.9 Million Children, Adolescents, and Adults. Lancet 390: 2627–42. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)32129-3/fulltext

Nestel, P., and S. Rutstein 2002. “Defining nutritional status of women in developing countries.” Public Health Nutrition, 5 (1): 17–27. https://pdfs.semanticscholar.org/6e92/a38ce0272be6f6804b48a47fa7909d467de3.pdf

Metropolitan Life Insurance Company. 1942. “Ideal weights for women”. New York Statistical Bulletin, 23 (6).

WHO. 2017. Global Nutrition Monitoring Framework: Operational Guidance for Tracking Progress in Meeting Targets for 2025. http://www.who.int/nutrition/publications/operational-guidance-GNMF-indicators/en/

Resources

DHS-7 Tabulation plan: Table 11.12.1

API Indicator IDs:

AN_NUTS_W_SHT, AN_NUTS_W_NRM, AN_NUTS_W_THN, AN_NUTS_W_TH1, AN_NUTS_W_TH2, AN_NUTS_W_OWT, AN_NUTS_W_OVW, AN_NUTS_W_OBS, AN_NUTS_W_BMI

(API link, STATcompiler link)

GNMF Indicator 10: Proportion of overweight and obese women 18+ years of age (body mass index ≥25 kg/m2)

Percentage of men by nutritional status

Definition

1)     Percentage of men age 15–49 by nutritional status based on specific body mass index (BMI) levels.

2)     Mean body mass index (BMI) for men age 15–49.

Coverage:

Population base: All men age 15-49 (MR file, PR file)

Time period: Current status at time of survey

Numerators:

1)     Number of men age 15-49 with a body mass index (BMI) with the following values:

a)      Normal: 18.5 to 24.9 (hb40 in 1850:2499)

b)     Total thin: less than 18.5 (hb40 in 1200:1849)

c)      Mildly thin: 17.0 to 18.4 (hb40 in 1700:1849)

d)     Moderately and severely thin: less than 17.0 (hb40 in 1200:1699)

e)     Total overweight or obese (>= 25.0) (hb40 in 2500:6000)

f)       Overweight: 25.0 to 29.9 (hb40 in 2500:2999)

g)      Obese: 30.0 or more (hb40 in 3000:6000)

2)     Mean BMI: Sum of BMI for men age 15–49 who were weighed and measured (∑ hb40/100, if hb40 in 1200:6000)

Denominator: Number of men age 15–49 with a valid BMI (hb40 in 1200:6000)

Variables: MR file, PR file.

Calculation

To calculate the nutritional status for men, it is first necessary to merge the anthropometric variables from the household members recode (PR file) to the men’s recode (MR file) using the cluster, household and line numbers (see Matching and Merging Datasets in Chapter 1).

The body mass index is calculated as weight in kilograms divided by the square of height in meters.

The percentages of men, by category, are equal to the category numerators divided by the denominator and multiplied by 100.

The mean BMI is equal to the numerator divided by the denominator.

Handling of Missing Values

Men who were not weighed and measured and women whose values for weight and height were not recorded are excluded from both the denominator and the numerators. Men whose calculated BMI is below 12.0 or above 60.0 are flagged as out of range and are excluded from both the denominator and the numerators.

Notes and Considerations

BMI, also known as the Quetelet Index, is a measure of acute nutritional status. It is based on the Fogarty Metropolitan Life tables of ideal weight for height.

These indicators could be presented based on the MR file or the PR file.  Using the PR file would result in a slightly larger sample size, but the MR file is chosen for consistency with other men’s indicators, and as some of the men’s characteristics used in presenting the results are only available for men with completed interviews.

Changes over Time

In some surveys, only a subsample of men were selected for anthropometry. All comparisons between surveys, either over time or between countries, should take into account the possible differences in the defined population base.

References

See References for Percentage of women by nutritional status.

Resources

DHS-7 Tabulation plan: Table 11.12.2

API Indicator IDs:

AN_NUTS_M_NRM, AN_NUTS_M_THN, AN_NUTS_M_TH1, AN_NUTS_M_TH2, AN_NUTS_M_OWT, AN_NUTS_M_OVW, AN_NUTS_M_OBS, AN_NUTS_M_BMI

(API link, STATcompiler link)

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