Lecture 4: Interpreting Anthropometric Data Flashcards
What are some measurements of body size?
- Weight
- Height
- Elbow breadth
- MUAC
- Head circumference
- Length
What do head circumferences measure?
Brain growth
At age two what do we switch?
From measuring lying down to standing up
What fraction of people in NZ are of a healthy weight?
1/3
What BMI indicates normal weight?
18.5 - 24.9
What BMI indicates you are overweight?
25.0 - 29.9
What BMI indicates mild obesity?
30.0 - 34.9
What BMI indicates moderate obesity?
35.0 - 39.9
What BMI indicates extreme obesity?
> 40.0
What is metabolic syndrome a straight forward term to describe?
Increased BP, glucose, TAG’s, reduced HDL cholesterol
What is sensitivity?
How good a measure/test is at correctly identifying people who have the disease
What is normal waist circumference range?
Men: 94 - 102cm
Women: 80 - 88cm
What is abnormal waist circumference range?
Men: >102cm
Women: >88cm
What are growth indices derived from?
A combination of raw measurements (e.g. “weight-for-height”)
What are growth indices used to compare?
Individuals/groups with a growth chart or reference data
What is occipital frontal circumference (OFC)?
Using flexible, non-stretch tape over the most prominent part on back of head (occiput) and just above the eyebrows (supraorbital ridges)
What measurement does OFC give?
The largest circumference of the head
What can head circumference show in under 2’s?
- Index of chronic protein-energy deficiency
- Brain development
What is wasting?
“acute malnutrition” - because it is believed that episodes of wasting have a short duration
What is stunting?
“chronic malnutrition” - longer duration
What is weight-for-age used to assess?
over- or under-nutrition
What is a limitation of weight-for-age?
- can’t distinguish tall thin children who are underweight from those who are short with adequate weight
What is under-nutrition under-estimated?
If rates of stunting are high but rates of wasting are low
What infants and children can be measured by length?
< 85cm
How is length measured?
Using a calibrated length board - measure without shoes, wearing light underclothing or nappy
What is weight-for-height?
assesses a person’s body weight relative to their height
What does low weight-for-height in low income countries indicate?
“wasting” (failure to gain sufficient weight relative to height)
What does low weight-for-height in high income countries indicate?
Growth faltering and wasting in hospital patients
What are limitations of weight-for-height?
Need to also use height-for-age:
- Could be stunted
- Oedema
What is height-for-age an index of?
Past nutritional status
What is stunting due to?
Extended period of inadequate food supply, poor dietary quality - causes increased morbidity in childhood (2nd or 3rd yr of life)
What is reference data used to do?
- Facilitate international comparisons
- Evaluate trends over time
- Evaluate effectiveness of intervention programmes
How is reference data used in clinical settings?
- Monitor growth
- Identify under- or over- nutrition
- Assess response to treatment
A growth standard is NOT a….
Growth reference
What is a growth reference?
Growth pattern of healthy population
What is a growth standard?
Recommended pattern of growth - specific health outcomes and decreased long term health risks
BF babies grow similarly or faster in the 1st 2-3 months and then…
Grow less rapidly compared to formula fed babies
What is the WHO growth standard for overweight (<5 yrs of age)?
wt-for-ht z-score of over 2
What is the WHO growth standard for obesity (<5 yrs of age)?
wt-for-ht z-score of over 3
Which growth standard is the best?
WHO - choose one method and stick with it
What is reference data used to generate?
- Percentiles
- Z-scores
When should percentiles be used?
in high income countries
When should z-scores be used?
especially in low income countries, but also high income countries
What percentiles indicate individuals at risk?
Below the 3rd/5th percentiles or above the 97th/95th percentiles
When should percentiles not be used?
For individuals/populations from low-income countries if using reference data from high income countries
What does a z-score tell us?
How many standard deviations an individuals measurement is away from the population mean
What does a standard deviation tell us?
About the spread of our data around the mean
The higher spread or variability….
the higher the standard deviation
Z-score equation:
Z-score = (persons measurement - reference mean) / reference SD
What does a z-score of 0 mean?
It is on the mean/median
