Lecture 4 Flashcards

interpreting anthropometric data

1
Q

Determined the sensitivity and specificity of BMI, waist circumference, WHR in relation to:

A

-Insulin resistance
-Insulin sensitivity
-Metabolic syndrome

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2
Q

Sensitivity

A

How good a measure/test is at correctly identifying people who have the disease

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3
Q

which BMI cutoff for obesity is better at picking up increased risk of insulin resistance, poor insulin sensitivity, and increased risk of metabolic syndrome in Maori?

A

The cut off at 30 is going to be better and identifying risks

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4
Q

If you have a higher wasit circumference then you have

A

an increased risk

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5
Q

Growth indices

A

Derived from a combination of raw measurements (e.g weight-for-height)

Essential for interpretation of measurements

Used to compare individuals/groups

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6
Q

Head circumference: what is it called

A

Occipital frontal circumference

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7
Q

Head circumference: how to measure

A
  • Flexible, non stretch tape (fiberglass or steel)
    -over the most prominent part on back of head (occiput) and just above the eyebrows (supraorbital ridges)-> lagest circumference of head
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8
Q

Head circumference for age: what happens if its low

A

-Index of chronic protein energy deficiency (<2y)

-Low = decrease brain development

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9
Q

Wasting

A

Wasting is sometimes referred to as “acute malnutrition” because it is believed that episodes of wasting have a short duration

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10
Q

Stunting

A

Which is regarded as indicating chronic malnutrition

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11
Q

wasted
stunted
wasted and stunted

A

Thinner than normal
Shorter than normal
Thinner and shorter than normal

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12
Q

Weight for age: used for

A

Used to assess over or under nutrition

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13
Q

weight for age limitation

A

Cant distinguish tall thin children who are underweight from those who are short with adequate weight (stunting)

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14
Q

If rates of stunting are high but rates of wasting are low

A

Under nutrition under estimated

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15
Q

Length

A

-For infants and children <85cm
-Calibrated length board
-Measure infant without shoes and wearing light underclothing or nappy

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16
Q

weight for height: Low income countries

A

-Low (in children)= wasting (failure to gain sufficient weight relative to height)
-Used to identify children likely to benefit from feeding programme

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17
Q

Weight for height: High income countries

A

-Growth faltering in infants and children more likely to be identified using weight for age
-Weight for height used clinically to identify wasting in hospital patients- especially elderly

18
Q

Weight for height: Limitation

A

Stunted -> weight may be appropriate for height ->may be classified as normal-> need to also use height for age

Oedema-. weight may appear normal for height-. need to also use height for age

19
Q

height for age:Stunting

A

Due to extended period of inadequate food supply poor dietary quality, increased morbility in childhood (2nd or 3rd year of life

Can result in shorter stature in adulthood-> reduces capacity, poor reproductive outcomes

20
Q

Height for age: Limitation

A

Cant identify wasted children so also need to use weight for height

21
Q

Selection of growth indices: low income countries

A

weight for height is a good option

Height for age is not as good as an option

22
Q

Reference data is used to

A
  • Facilitate international comparisons of anthropometric indices across populations
  • Evaluate trends over time (surveillance studies)
    -Evaluate the effectiveness of intervention programmes
23
Q

Reference data used in clinical settings

A

-Monitor growth
-Identify those with under or over nutrition
-Assess the response to treatment

24
Q

WHO growth standard international reference data:

Growth standard not growth reference

A

-Growth Reference- Growth pattern of healthy population
-Growth standard - Recommended pattern of growth -> specific health outcomes and decreased long term health risks

25
Q

Why? old NCHS/WHO growth reference

A

Growth in infancy not well characterised
-Measurements only every 3 months
-Middle class caucasian
-Formula fed

26
Q

WHO growth standard -How population was defined

Multiple countries

A

No known health or environmental contraint or growth
-Mothers do not smoke
-Singleton birth at term
-No significant morbidity

27
Q

WHO growth standard -How population was defined

0 to 24 mths- Longitudinal

A

-Predominantly BF birth to 4 mths and continue to BF to 12 mths
-CF introduced by 6 mnths

28
Q

WHO growth standard -How population was defined

18 to 71 months -Cross sectional

A

some BF for at least 3 years

29
Q

WHO Growth standard -why important? I

A

-BF is ideal method of feeding for an infant
-Exclusively BF grow differently formula fed babies

BUT: BF babies grow similarly or faster in 1st 2-3 months and then grow less rapidly
-Concern misinterpretation -> reduce mother’ confidence ->stop BF

30
Q

WHO Growth standard - why important? II

A

-at risk of overweight= 85th to 95th centile
-Overweight = >95th centile

31
Q

WHO Growth standard - why important? II

Related to 18 year old BMI of

A

25 (overweight) and 30 (obese)

32
Q

WHO Growth standard (>5 yrs of age)

A

Overweight= wt-for-ht z-score >+2
Obesity = wt-for-ht z-score > +3

33
Q

Evaluation of growth indices

Percentiles ….
Z-scores …..

A

Percentiles used in high income countries

Z-scores used especially in low income countries, but also high income countries

34
Q

Percentiles

A

Position of the measure value in relation to all the measurements for the reference population

35
Q

Percentiles : Individuals at risk

A

Individuals at risk- below the 3rd/fth percentiles or above the 97th/95th percentiles

36
Q

Percentiles; used for

A

Used for evaluation of well nourished populations from high income countries

37
Q

Percentiles: should not be used for

A

Individuals/populations from ow-income countries if using reference data from high income countries

38
Q

Z-scores definition

A

A z-score tells us how many standard deviations an individual measurement is away from the population mean

39
Q

Standard deviation tells us

A

about the spread of our data around the mean

The higher the spread or variability the higher the standard deviation

40
Q

Z-score=

A

(persons measurement- reference mean)/ reference SD

41
Q

If a z-score is 0 it is
If a z-score is +1 it is
If a z-score is +2 it is
If a z-score is -1 it is
If a z-score is -2 it is

A

The mean/median

One standard deviation above the mean

2 standard deviations above the mean

one standard deviation below the mean

2 standard deviations below the mean

42
Q

Interpretation of BMI-for age cut offs

A

NOTES