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Chronic malnutrition rate interpretation

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Anonymous 106

Normal user

20 May 2010, 11:53

What is the latest in terms of interpreting chronic malnutrition rates? I am particularly interested in conditions where acute malnutrition is less than 5% but chronic malnutrition rates range in the 30 to upper 40 percentiles for under 5 year olds. Can chronic malnutrition rates be used in conjunction with acute malnutrition rates to help assess food security of a community? Thank you.

Mark Myatt

Consultant Epideomiologist

Frequent user

20 May 2010, 13:33

I don't know about the "latest" in interpreting chronic malnutrition "rates". I am also not sure about assessing "food security" using a combined indicator since the term "food security" tends to have quite a broad definition. Having said that ...

I think you might be looking for something like the "composite index of anthropometric failure" (CIAF) which uses W/H, H/A, and W/A to create a composite indicator. The index is quite simple to calculate:

(1) Do your survey (SMART, 30-by-30, &c.).

(2) Calculate and add W/H, H/A, and W/A indices (z-scores)

(3) Apply the usual case-definitions for each indicator (i.e. WHZ < -2, HAZ < -2, WAZ < -2) so you have three YES/NO variable indicating wasting, stunting, and underweight for each child.

(4) Apply grouping case-definitions:

(A) wasting = NO, stunting = NO, underweight = NO
(B) wasting = YES, stunting = NO, underweight = NO
(C) wasting = YES, stunting = NO, underweight = YES
(D) wasting = YES, stunting = YES, underweight = YES
(E) wasting = NO, stunting = YES underweight = YES
(F) wasting = NO, stunting = YES, underweight = NO
(Y) wasting = NO, stunting = NO, underweight = YES

(5) Count the number in each group.

(6) Calculate the CIAF as [(B + C + D + E + F + Y) / N] * 100 where "N" is the total number of children (i.e. A + B + C + D + E + F + Y). This simplifies to [(N - A) / N] * 100.

See http://tinyurl.com/2unqmq7 for a fuller discussion of the CIAF.

I think that the CIAF is an interesting attempt at a composite index. The use of W/H instead of MUAC is problematic as W/H is biased by body-shape. You could replace W/H with MUAC. This would make a better indicator. Also you'll need to be careful about what you do with oedema as this will upwardly bias both W/H and W/A. You could include oedema in your case-definition of wasting but (C), (D), (E), and (Y) will be biased downward. This might be a problem in setting where oedema is common (e.g. Malawi, DRC, &c.). You also have to be aware that the H/A and W/A indices can be very prone to error when age data is not accurate.

The key reference is "Svedberg P (2000), Poverty and Undernutrition: Theory, Measurement, and Policy. Oxford: OUP" which you can read online at: http://tinyurl.com/38xywn5

More on the CIAF (i.e. examples of its use and some test cases) can be found at:

http://tinyurl.com/3252s6q

http://tinyurl.com/36uu57n

http://tinyurl.com/3yjdfc9

http://tinyurl.com/3xx7vfg

http://tinyurl.com/3x478e4

http://tinyurl.com/366ndd8

I hope this helps.

Chris Hillbruner

DCOP - FEWS NET

Normal user

8 Oct 2015, 15:27

This is another interesting example of using CIAF, in this this case to explore the relationship between mortality risk and the presence of multiple anthropometric deficits.

http://ajcn.nutrition.org/content/97/4/896.full

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