Lecture 4 - Interpreting Anthropometric Data Flashcards
what are the measurements of body size
- weight
- height
- elbow breadth
- mid upper arm circumference
- head circumference
- length
what is a normal BMI
18.5-24.9
what is overweight BMI
25.0-29.9
what is obese BMI
> 30
what is obese extreme BMI
> 40
what is sensitivity
how good a measure / test is at correctly identifying people who have the disease
what are growth indices derived from
from a combination of raw measurements
growth indices are essential for
essential for interpretation of measurements
growth indices are used to
compare individuals / groups with a growth chart or reference data
what does OFC stand for
“occipital frontal circumference”
what should be used to measure head circumference
flexible, non stretch tape (fiberglass or steel)
how should head circumference be measured
over the most prominent part of the back of head (occiput) and just above the eyebrows (supraorbital ridges) = this is the largest circumference of head
head circumference for age is an index of
chronic protein energy deficiency (<2 years)
low head circumference for age (<2 years) shows
decreased brain development
what is wasting referred to as
sometimes referred to as “acute malnutrition” because it is believed that episodes of wasting have a short duration
in contrast to wasting what is stunting regarded as
regarded as indicating chronic malnutrition
what does a wasted child look like
thinner than normal
what does a stunted child look like
shorter than normal
what does a wasted and stunted child look like
thinner and shorter than normal
weight for age is used to assess
over or under nutrition
what is a limitation of weight for age
- cant distinguish tall thin children who are underweight from those who are short with adequate weight
when talking about weight for age, if rates of stunting are high but rates of wasting are low what occurs
under nutrition under estimation
the measurement of length is for infants and children that are
younger than 2 years and <85cm
what is used to measure length
a calibrated length board
how is length measured
measure infant without shoes and wearing light underclothing or nappy
what is said if weight for height is high in children
overweight
in low income countries if weight for height is low in children it is considered
wasting = failure to gain sufficient weight relative to height
in low income countries weight for height is used to identify
children likely to benefit from feeding programme
in high income countries what is more likely to be identified using weight for age growth index
growth faltering in infants and children
in high income countries weight for height is used clinically to
identify wasting in hospital patients, especially elderly
what are limitations for weight for height (stunted)
weight may be appropriate for height > may be classified as normal > need to also use height for age
what are limitations for weight for height (oedema)
weight may appear normal for height > need to also use height for age
height for age is an index of
past nutritional status
stunting is due to
extended period of inadequate food supply, poor dietary quality, increased morbidity in childhood
stunting can result in shorter stature in adulthood and therefore
reduced work capacity, poor reproductive outcomes
what is a limitation to height for age
cant identify wasted children so also need to use weight for height
reference data is used to
- facilitate international comparisons of anthropometric indices across populations
- evaluate trends overtime (surveillance studies)
- evaluate the effectiveness of intervention programs
reference data in clinical settings is used to
- monitor growth
- identify those with under or over nutrition
- asses the response to treatment
is a growth standard and growth reference the same
NO
what is a growth reference
growth pattern of a healthy population
what is a growth standard
recommended pattern of growth > specific health outcomes and decreased long term health risks
the WHO growth standard, how was the population defined
multiple countries
- no known health or environmental constraint on growth
- mothers do not smoke
- singleton birth at term
- no significant morbidity
how long was the WHO growth standard study and were the children breastfed and when was complementary feeding introduced
- exclusively breastfed to 4 months and continue breast feeding to 12 months
- complementary feeding introduced at 6 months
why was it important that babies were breastfed in the growth standard study
breastfeeding is ideal method of feeding for infant, exclusively breastfed infants grow differently from formula fed babies
how do breastfed babies grow differently to formula fed babies
grow similarly or faster in 1st 2-3 months and then grow less rapidly
in high income countries, reference data is used to generate
percentiles
especially in low income countries but also in high income countries, reference data is used to generate
z-scores
what is a percentile show
position of the measured value in relation to all the measurements for the reference population
what are individuals at risk in percentiles
below the 3rd/5th percentiles or above the 97th/95th percentiles
when should percentiles not be used
not be used for individuals/populations from low income countries if using reference data from high income countries
what is a z-score
a z-score tells us how many standard deviations an individual measurement is away from the population mean
what does standard deviation tell us
tells us about the spread of our data around the mean
the higher the standard deviation means
the higher the spread or the variability
what is the equation for a z-score
(persons measurement - reference mean) / reference standard deviation
what does it mean if a z-score is 0
it is on the mean / median
if a z-score is +1 it is ..
one standard deviation above the mean
if a z-score is +2 it is ..
2 standard deviations above the mean
if a z-score is -1 it is ..
1 standard deviation below the mean
in low income countries what should be used to measure wasted children
weight for height
in low income countries what should be used to measure weight change
weight for height
in low income countries what should be used to measure stunted children
height for age
