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MUAC cut off point

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Nick

Normal user

28 Apr 2009, 11:32

What things should be mentioned in deciding MUAC cut off point ?
what data are need?

I want to know the admission criteria and discharge criteria for severe and
moderate acute malnourished child in global setting.
Now, in my country, we are using the following criteria for admission on
acute malnourished child.


* admission criteria *

< 11 cm ( MUAC)for severe and between 11cm and 12.5 cm for moderate
Now, our nutrition cluster are going to decide new MUAC cut off point for
admission.


Therefore, I need to know about how to decide MUAC cut off point? And, what
data (ex: compare with WFH or other else) are need to mention in deciding
MUAC cut off point.

Mark Myatt

Consultant Epideomiologist

Frequent user

6 May 2009, 10:36

I think that the cut-points need to be decided by mortaility risk rather than by comparison with W/H since W/H is only weakly associated with mortality and the relationship between W/H and mortality varies between populations. The relationship between MUAC and mortality is pretty stable accross different populations. These review articles:

http://tng.brixtonhealth.com/node/15

and:

http://tng.brixtonhealth.com/node/18

show the relationship between MUAC and mortality in several popualtions. From these reviews. I would used MUAC < 110 mm and 110 mm <= MUAC < 125 mm for severe and moderate cases respectively (which is what you have).

Mark Myatt

Consultant Epideomiologist

Frequent user

6 May 2009, 13:12

I forgot to mention that you may want to use MUAC as a first stage screen for admission into programs using W/H for admission. I would caution against doing this unless the W/H measurements and calculations are done in the field. Referring on MUAC to a W/H program can destroy coverage through the "problem of rejected referrals" (see CTC literature for more on this issue).

The trick to using MUAC in this way is to go for a cut-point that detects (e.g.) W/H < 80% with high sensitivity. The cut-point should not be too high as this will involve you weighing and measuring a great many children which removes the advantage in using a two-stage screen.

The common threshold for this use is 135 mm. If you have data from a nutritional anthropometry survey that collected both MUAC and W/H (yet another reason why you should collect both and SMART / ENA should handle MUAC data) you can fine-tune this threshold. There is a (rather old DOS-based) program available from:

http://www.brixtonhealth.com/Screen100Setup.exe

designed for this purpose. The analysis is not difficult ... (1) apply a case-definition for W/H, (2) set a threshold for a MUAC case-definition at 125 mm, (3) apply the MUAC case-definition, (4) create a 2-by-2 table (MUAC case by W/H case) and calculate sensitivity and specificity, (5) increase MUAC threshold by 1 mm and if < 145 mm repeat from step 3 (above), and (6) select the MUAC threshold with high sensitivity and reasonably specificity.


Tamsin Walters

en-net moderator

Forum moderator

6 May 2009, 13:28

Thank for replying and suggestion


sincerely
Nicholas

Mara Nyawo

Nutrition Specialist / UNICEF

Normal user

10 May 2009, 11:44

I have heard that WHO/UNICEF will recommend that the cut-off point for SAM be increased to MUAC <115mm, and MAM >=115 to <125 for children from 6 months. Would this be to make sure that more children with an increased risk of mortality are identified earlier?

Mark Myatt

Consultant Epideomiologist

Frequent user

10 May 2009, 12:14

In short ... YES. It will approximately double case-numbers (assuming good case-finding). There will be some trade-off of sensitivity in favour of specificity.

Things are not quite as simple as your question seems to suggest. The case-definition can make a large difference to case-finding exhaustivity. This is one of the reasons that MUAC is now preferred over W/H see:

http://tng.brixtonhealth.com/node/15

for a full discussion of this issue.

Case-finding / case-detection is, however, more than having a handy case-definition. We can see this in the coverage proportions achieved by OTP-style programs. Programs that rely on extension workers, periodic screening, and passive case-finding usually achieve coverage proportions of between 15% and 30%. CTC-style programs with well-implemented community mobilisation regularly achieve coverage proportions of between 70% and 80%. The point of this is that if you want to find case you also need to have a well-designed and well-implemented strategy for case-finding.

It is one thing to identify cases and quite another to recruit them. This requires a proximate, responsive, and hospitable program. Effective case-finding is just one element of program coverage.

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