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MUAC Cutoffs for Adults

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Anonymous 310

Normal user

7 Dec 2009, 13:09

As per the SMART recommendtions, the scale and severity of the nutritional situation is determined by nutritional status of under-five children and Mortality (CMR, U5MR) together with contextual indicators. However, in some communities adults are more vulnerable than children during emergency and crisis as preference of feeding is given to children. Assessing children malnutrition in thesee communities often doesn't give the situation on the ground. This results in selection of in appropriate programs only to discover the consequences after implementation. Therefore, asessing adult malnutrition should be part of the design in such circumstances.

My question for ENN forum is concerning the indicators for assessing adult malnutrition during emergencies. Since BMI is for assessing chronic adult undernutrition, I believe MUAC is a preferable indicator to assess nutrition situation during emergencies as it tells acute under-nutrition. My question here is that unlike BMI, I couldn't get a standard cutoff points for MUAC to classify the degree of the problem as it is there for children (i.e., <11cm MUAC Severe, 11-12.49 MUAC Moderate, etc). Is there any standard cutoff points for MUAC in adults to charcterize the extent of the problem? I have seen few proposed cutoff points by Collins et al, SCN 2000; Ferro Luzi & James, 1995; and local cutoffs for admission to Supplementary and Therapeutic programs.

I am looking forward to hear an expert opinion on this

Thanks, Beka Teshome
Ethiopia

Michael Golden

Normal user

7 Dec 2009, 22:49

There is not a universally accepted cut-off for adults. The Ethiopian National Protocol has defined SAM in adults
as:
MUAC < 170 mm or
MUAC < 180 mm with recent weight loss or underlyingchronic illness or
BMI < 16 with with recent weight loss or
Presence of bilateral pitting oedema (unless there is another clear cut cause).

The addition of "with recent weight loss" comes from the thesis analysis of Dr Carlos Navarro who examined many thousands of SAM adults in Burundi and Congo-Brazzaville.
The use of the term "chronic energy deficiency" is outmoded and should not be used - a low BMI defines degrees of THINNESS without any aetiological pointers - thinness should not be used as a proxy for the deficiency of any particular nutrient or energy. Just as anaemia should not be renamed chronic iron deficiency - or even chronic vitamin B12 deficiency - etc! The name derives from the work of Prakash Shetty studying poor adults in India - where after doing calorimetry he decided that the thin adults were energy deficient - IDECG then took this work and its members coined the phrase Chronic energy deficiency - a complete misnomer for thinness from any cause.

Mark Myatt

Consultant Epideomiologist

Frequent user

10 Dec 2009, 12:48

The situations in which (non-elderly) adults are at greater risk of malnutrition than children is very rare. The 6-59 month age group was selected as a "canary in a coal mine" or "early warning" sub-population because of this. The only time I have been forced to focus on the adult population was in Somalia in the early 1990s when the situation was very "advanced" and huge numbers of children had died and there were (mostly) only adults left to treat. There are programs that are targeted at adults outside of severe emergencies (e.g. SFP for pregnant and lactating women) and surveys assessing need will be useful in this context.

You should concentrate on the global estimate since, unless you have huge sample sizes, you will have poor precision on a low prevalence indicator such as prevalence of SAM.

It is common practice to use women of childbearing age when collecting this data. I suppose you could make arguments about early warning, prevention of low birth weight, targeting at risk households, age-dependence, &c. but there is also a good practicable point that you can get women of childbearing age in a standard nutritional survey (the commonest carer present when you measure the child). You may need to increase sample sizes a little to get enough women,

BMI is problematic since it is affected strongly by body shape, oedema, hydration, water retention, and time of day (height reduces during the day, weight goes up after meals and down after defecation). If you use BMI then you should correct for body shape. BMI is quite difficult to collect in surveys (needs different scales and height boards than for children). It is difficult to collect in the old, the disabled, and the weak. It has no meaning in pregancy.

The standard MUAC thresholds < 210 and < 185 for moderate and severe. These are used as admission criteria for nutritional support programs for pregnant and lactating women, people living with AIDS, and the chronically sick. These thresholds (as with MUAC in children) are based on risk of negative outcomes. The most evidence available is for risk of low birth weight when used in second and third trimesters (I suppose that first trimester pregnancy is not so easy to detect and you get a lot of loss-to-follow-up as mothers move to their home villages and due to miscarriage).

I disagree with Mike. I find the distinction between CED and AED to be useful ways of thinking about malnutrition (akin to wasting and stunting in children but adults can't stunt very much) and there is some epidemiological support for the utility of these concepts from mid-20th century labour and death camps. The two ideas point to, admittedly not well separated, constellations of aetiologies. I have written (with Collins and Duffield) that, just as with stunting and wasting, CED and AED are identified by different indicators (BMI and MUAC) so this should not come as a surprise.

The quoted (i.e. by Mike) thresholds seem to me to be very restrictive. I wonder about the evidence-base used to collect them. Some of these thresholds, following Ferro Luzi & James, were developed by regressing MUAC against BMI and selecting a MUAC threshold that corresponded to a BMI threshold which is believed to be associated with a negative outcome (as long as the subject is not old, an athlete, long-limbed, or drank a lot of milk while they were growing up). The problems with BMI means that such thresholds are unlikley to be universal.

Just my tuppence.

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