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MALNUTRITIONMEASUREMENT APPROACHES

Dr. Veronika Scherbaum, 2008

reflects individual‘s healthas influenced by food intake/utilisation and subsequent levels of nutrients

WHY DO WE NEED TO MEASURE IT?- Provides baseline information- Determines areas of high risk / priority

- Essential for planning nutrition policies

- Useful for evaluating nutrition programmes

NUTRITIONAL STATUS

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HOW DO WE MEASURE the nutritional status?

• Anthropometry• Dietary• Clinical• Biochemical

investigations

ANTHROPOMETRIC ASSESSMENT at individual / family level

• How severely malnourished is this child/adult?

• How fast is this child/adult responding to nutritional rehabilitation (GMP)*?

• How many malnourished people are in one family?

• Affected age group?

•Growth Monitoring Programme

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ANTHROPOMETRIC ASSESSMENT at population level

AT NATIONAL LEVEL- representative results

of all regions- trend assessment- for long term planningDemographic health survey (DHS)

FOR CERTAIN POPULATION GROUPS- under circumstances of food crises- nutrition baseline survey (NGOs)- evaluation of the progress / change as a result of an

intervention (nutritional surveillance)

DEFINITION OF ANTHROPOMETRY

„a technique that uses human body measurementsto draw conclusions about the nutritional status of individuals and populations“

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ANTHROPOMETRIC Assessment

VARIABLES

• Age (months)• Weight (kg)• Length ≤ 85 cm /

Height > 85 cm

• MUAC (cm)

• Sex

INDICES

• Weight-for-age• Length/height-for-age• Weight-for-length/height

• Body-Mass-Index/age

• MUAC-for-age

• Sex – WFA, etc

WIDLY USED NUTRITIONAL INDICES IN CHILDREN (< 5 years)

LENGTH / HEIGHT-FOR-AGE- reflects skeletal growth, past/chronic

malnutrition, stunting

WEIGHT-FOR LENGTH / HEIGHT- indicates acute weight loss, wasting

(useful in emergencies when age is not known)

WEIGHT-FOR-AGE- identifies underweight caused by either

wasting or stunting or a combination of both (useful in clinics and GMPs)

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WEIGHT – FOR – AGE REFERENCE DATA (US-NCHS*)

(* US – National Centre for Health Statistics)

WHO, 2006

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Types of scale used

ENN 29, 2006

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LIMITATIONS:- Clothing not defined

- Scale not at eye level

- Clinical signs of PEM e.g. distended abdomennot recognized

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REASONS FOR EXCLUSION OF CHILDREN < 6 MONTHS

• Thought to be protected by breast feeding

• Anthropometric measurements are influenced by birth weight

• Reference population (NCHS) wasless applicable because reference infants were virtually all bottle-fed

• Survey staff is hesitant to weigh and measure young infants

• Imprecision in measurements is larger as proportion of measurement (+/- 100 g)

Reasons for exclusion of infants < 6 months

a swinga trouser

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A rod

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„Road to health“ Chart

LIMITATIONS OF WEIGHT-FOR-AGE IN EMERGENCIES

• Age of the child is often unknown

• WFA measures chronic and acute malnutrition

• Lack of skilled staff for interpretation of individual weight and follow-up (GMP)

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STUNTING

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WASTING

Age in months

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CALCULATING NUTRITIONAL INDICES

An individual child‘s measurement (e.g. weight)is compared with the expected value of a child of the same age from a reference population and presented as:

• A percentage of the expected measurement (percentage median)

• A standard deviation-score (z-score) in relation to the median

• As percentiles

W/H wasting

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Z-Score is a standardized measure of the distance of an observation from the mean of a distribution

The z-value =observation – mean

divided by SD of the reference population

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Percentage of median = observed value divided byMedian reference value x 100It is popular in clinical settings (e.g. road to health growth chart)because it is straight forward to interpret

<60% <7

5%

<60%

100%

<75%

<90%

Height

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www.fantaproject.org, 2006

WASTING: ACUTE MALNUTRITION

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Severe

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PREVALENCE (%) OF STUNTING, UNDERWEIGHT AND WASTING

children < 5 years, 1995-2003

05

101520253035404550

Africa South Asia Latin Am All DC

Stunting Underw

Wasting

Seasonality of acute malnutrition of children (0-59 mo) in Bangladesh

HKI, 1999

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-2

-1.5

-1

-0.5

0

0.5

0 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59

Africa Latin America and Caribbean Asia

Global weight-for-age Z-scores (underweight)W

AZ-

scor

es

Age

Source: Shrimpton, R. et al, 2001. http://www.pediatrics.org/cgi/content/full/107/5/e75

0 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59

Global height-for-age Z-scores (stunting)

HA

Z-sc

ores

Age

-2.5

-2

-1.5

-1

-0.5

0

0.5

Africa Latin America and Caribbean Asia

Source: Shrimpton, R. et al, 2001. http://www.pediatrics.org/cgi/content/full/107/5/e75

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60 million wasted

The timing of growth failure

130 million underweight150 million stunted

Window of opportunity

R. Shrimpton (data from 39 studies)

Prevalence of stunting, under-weight, and wasting (<-2 SD) in children in Latin America and the

Caribbean

05

101520253035404550

Bolivia

BrazilColombia

Dominican Rep

Ecuador

HaitiEl Salvador

Guatemala

Mexico

Nicaragua

Peru

Prev

alan

cia

22

00

1010

2020

3030

4040

5050

0 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35

VULNERABLEAGE

VULNERABLEAGE

PercentPercent

Note: Stunting reflects chronic malnutrition; wasting reflects acute malnutrition;underweight reflects chronic or acute malnutrition, or a combination of both. Plotted values aresmoothed by a five month moving average.

Note: Stunting reflects chronic malnutrition; wasting reflects acute malnutrition;underweight reflects chronic or acute malnutrition, or a combination of both. Plotted values aresmoothed by a five month moving average.

Source: Demographic Health SurveysSource: Demographic Health Surveys

Age (Months)Age (Months)

Stunting, Underweight and Wastingin Bolivia

Low height / ageLow height / age

Low weight / ageLow weight / age

Low weight-for-heightLow weight-for-height

S Fishman et al., CQHR, Vol 1, WHO 2004

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WHO Global database on Child growth and Malnutrition, 2002

Prevalence of stunted children indeveloping countries

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MID-UPPER-ARM CIRCUMFERENCE

Development of MUAC for age growth reference data

Bull World Health Org 1997, 75: 11-18

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Observed relationship

between MUAC and child

mortality in five studies

Food and Nutrition Bulletin, Vol 27, 3 (suppl), 2006

To find midpoint between tip of shoulder and elbow

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MUAC – SCREENING in children

• To identify potentially malnourished children

• Children with a MUAC <12.5 cm are referred to further measurementsand may be eligible for supplementary (WFH<80%, <-2 z-score) or therapeutic feeding(WFH<70%, <-3 z-score)

MUAC-based selection methods

Food and Nutrition Bulletin, Vol 27, 3 (suppl), 2006

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MID-UPPER-ARM CIRCUMFERENCE

ADVANTAGES- Rapid screening

- Less equipment required

- MUAC-FOR-AGE

DISADVANTAGES- Measurement errors- Deciding if a child is

between e.g. 1 and 5 years old

- Variable cut-off points are usede.g. <12.5cm, <11.5cm<11cm for severe malnutrition

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MUAC SCREENING in ADULTS

MUAC (cm) FEMALELeft arm≥ 23 normal21-23 moderate< 21 severe

malnourished

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BODY-MASS-INDEX (BMI) ASSESSMENTWeight (kg) / height2 (m2)

To be used between 20-65 yearsBMI / AGE during adolescence

BMI <16 Severe malnutrition16.0-16.9 Moderate malnutrition17.0-18.5 Mild malnutrition18.6-19.9 Possibly malnourished20.0-24.9 Healthy25.0-29.9 Overweight30.0-34.9 Pre-obese≥ 35 Obese

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SEVERITY INDEX BASED ON BMI

BMI < 18.5 NUTRITIONAL SITUATION

5 – 9.9% low risk → monitoring10 – 19.9% moderate risk → attention20 – 39.9% serious situation → action≥ 40% very critical situation

→ immediate relief action