Menu ENN Search

MUAC and weight-for-height in identifying high risk children

Summary of research1

The World Health Organisation (WHO) and UNICEF propose to use two independent criteria for diagnosing non-oedematous severe acute malnutrition (SAM) in children aged 6–60 months: mid-upper arm circumference (MUAC) less than 115 mm and weight-for-height z-score (WHZ) less than -3 (based on WHO growth standard). WHZ has been used for years in clinical settings for diagnosing SAM, but the use of MUAC was introduced more recently with the development of community-based management of SAM. In practice, large-scale programmes increasingly use MUAC as single diagnostic criteria as it is closely related to the risk of dying and is easy to implement at the community level after minimum training by health workers or even by volunteers. MUAC and WHZ, however, do not identify the same set of children as having malnutrition, and using only one of the diagnostic criteria proposed by WHO may potentially leave some high-risk children untreated.

A newly published study used an old data set from Senegal to examine the risk of dying of children having either a low MUAC or a low WHZ or a combination of both in the absence of treatment. The specific objective was to test whether combining both MUAC less than 115 mm and WHZ less than -3 would improve the identification of high-risk children.

The original study, which was conducted in 1983 and 1984, followed an open cohort of about 5000 children, comprising all children under 5 living in 30 villages. The team visited the children four times at sixmonth intervals in May and November of 1983 and 1984. At each visit, comprehensive anthropometric measurements were taken (weight, height, head circumference, arm circumference, triceps skin fold and subscapular skin fold).

For this analysis, the data from all children aged 6–59 months at the time of anthropometric assessment were used. WHZ was calculated using the WHO growth standards. Receiver operating characteristic (ROC) curves (sensitivity vs. 1-specificity) were calculated for WHZ and for MUAC using death within six months as outcome. Only the part of the curve with a percentage of false positive less than 5% was explored, as these indicators are always used in a context of limited treatment capacity and a high specificity is required. The anthropometric index with the highest ROC was considered as more adapted to identify high-risk children.

Specificity and sensitivity of ‘MUAC less than 115 mm AND WHZ less than -3’ and also for ‘MUAC less than 115 mm OR WHZ less than -3’ were also estimated and positioned in relation to the ROC curve of MUAC and WHZ.

In total, 12,638 measures were made on 5,751 children, and 303 deaths occurred within six months of the nutritional assessment. The criteria ‘WHZ less than -3 AND MUAC less than 115’ had a specificity of 99.0% and a sensitivity of 5.9%. For ‘MUAC less than 115 mm OR WHZ less than -3’, the specificity was 96.9% and the sensitivity was 13.2%. Both points combining WHZ less than -3 and MUAC less than 115 mm were positioned above the WHZ ROC curve but below the MUAC curve.

For a MUAC, the threshold of 112 mm had a specificity of 99.1, comparable with the specificity observed for ‘MUAC less than 115 AND WHZ less than -3’. However, the sensitivity of MUAC 112 mm was 6.0%, slightly higher than for these two indices combined. For a MUAC of 119 mm, the specificity was 96.9%, comparable with the specificity of ‘WHZ less than -3 OR MUAC less than 115 mm’. However, the sensitivity was higher at 14.9%.

This study confirms that MUAC has a better ability than WHZ to assess the risk of dying. This is consistent with a previous analysis of the same data set, which showed that MUAC was superior to weight for- height (percentage of the National Centre for Health Statistics median) to identify high-risk children. This is also consistent with other reports from the literature.

In addition to confirming previous findings, this study also shows that using WHZ equal to or <-3 and MUAC equal to or <115 mm together did not improve the identification of high-risk children. The position of two possible combinations of WHZ equal to or <-3 and/or MUAC equal to or <115 mm compared with the MUAC ROC curve suggests that using the two indices together may lead to poorer results than using MUAC alone. Arguably, using WHZ equal to or <-3 AND MUAC equal to or <115 mm increases the specificity, but this can be obtained by using a lower MUAC cut-off (112 mm) with a greater sensitivity. Conversely, using WHZ equal to or <-3 OR MUAC equal to or <115 mm increases sensitivity, but it also decreases the specificity. Using a MUAC cut-off of 119 mm, with the same specificity as WHZ equal to or <-3 OR MUAC equal to or <115 mm, will result in a higher sensitivity.

Several explanations have been given to explain the apparent superiority of MUAC to assess the risk of dying. A first hypothesis is that MUAC, which grows continuously with age, selects younger children with a higher risk of dying when used with a cut-off not adjusted for age. Another explanation might be that MUAC is closely related to muscle mass. A close association between MUAC and muscle mass has been suggested by corresponding measures of body composition by Dual energy X-ray absorptiometry. The underappreciated metabolic role of muscle both in health and disease may explain its association with survival.

Finally, it has been shown that WHZ differences are largely influenced by leg length, unrelated to the nutritional status of the child, which may also decrease its ability to identify high risk children.

This study was based on MUAC data carefully collected by skilled investigators. Its findings may not be extrapolated to other settings where these conditions are not met. Appropriate training of field workers and standardisation of measures are probably needed to use MUAC successfully in field conditions to identify highrisk children. The use of colour banded MUAC straps could also help to minimise measurement errors.

In conclusion, this study shows that there is no benefit for programmes in using both MUAC equal to or <115 mm and/or WHZ equal to or <-3 to identify high-risk children. If a higher sensitivity is required for programmatic reasons, for instance to take into account a poor food security, it seems preferable to increase the MUAC cut-off rather than combine it with WHZ. In the same way, if a higher specificity is required, in case of limited treatment capacity, lowering the MUAC cut-off should be preferable.

Show footnotes

1Briend. A et al (2011). Mid-upper arm circumference and weight-for-height to identify high-risk malnourished under-five children. Maternal and Child Nutrition 2011

More like this

FEX: Using MUAC to predict and avoid negative outcomes in CMAM programmes: Work inspired by en-net

View this article as a pdf By Odei Obeng Amoako Adobea Gloria, Franck Alé, Paul Binns, Kevin Phelan, Jose Luis Álvarez Moran, Casie Tesfai and Mark Myatt. Odei...

FEX: MUAC Versus Weight-for-Height in Assessing Severe Malnutrition

Summary of published paper1 An infant having MUAC measured during the study in Kenya Current WHO guidelines for the management of severe malnutrition in children recommend...

FEX: MUAC vs WHZ in predicting mortality in hospitalised children under five years of age

Summary of research1 This research contributes to the evidence base regarding which anthropometric indicators identify malnourished sick children most at risk of death. Low...

en-net: Variance in number of children admitted to OTP using MUAC < 11.cm and WHZ <-3SD

Since 2008, we have been screening and admitting children to outpatient therapeutic program using MUAC 11.0; in June 2009 we adopted MUAC< 11.5 as per the new WHO guidelines....

en-net: Only MUAC for admission and discharge?

There has been a discussion about the use of ONLY MUAC as an admission and discharge criteria (http://www.en-net.org/question/468.aspx). Although I understand the challenge in...

en-net: Key questions regarding MUAC only programming - towards a research agenda

I have started this thread in the hope that we can come together there to work out what we need to do to move forward with an informed debate on issues around MUAC-only...

en-net: WFH versus MUAC

I would like experts input in this regard. I wish Mark Myatt to be one of the respondent of my question. Much has been said about the discrepancy of MUAC and WFH in some...

en-net: MUAC cutoff to screen SAM

Looking at the WHO growth standard for MUAC, one can understand the change of MUAC with age. So my concern is, is it feasible to use the same MUAC cutoff (<11.5CM) for...

FEX: Is MUAC alone a sufficient criterion for admission of children at high risk of mortality in South Sudan?

Summary of research 1 Location: South Sudan What we know: The operational implications of using MUAC as the sole anthropometric admission criterion to therapeutic feeding...

en-net: Borderline MUAC and Z-score measurements

What is the most appropriete practical decision should one make when confronted with cases of borderline MUACs and Z-scores of 11.5cm and <2 SD respectively in nutrition...

FEX: Finding the right MUAC cut-off to improve screening efficiency

Author Koert Ritmeijer, MSF Holland In Hlaing Thayer township, Yangon, Burma, ORWs were spending a considerable amount of time doing weight and height measurements on all...

FEX: MUAC alone admission to SAM treatment in Bangladesh

Summary of research1 Location: Bangladesh What we know: MUAC and weight-for-height z score (WHZ) are common anthropometric criteria to diagnose severe acute malnutrition...

en-net: CMAM admission by MUAC gender biased?

I am currently analysing OTP patient cards from Concern's CMAM pilot in Bardiya, Nepal and found the following: In total I have 1469 new admissions registered. According to...

en-net: Using MUAC or WFH in survey: who do you catch?

Dear field I am sure my following question will be easy to answer for many of you, but I forgot how it exactly was. So therefore I approach you. I see a survey (6-59 months) in...

en-net: SENSTIVITY OF MUAC TO MALNUTRITION

how reliable is muac in identifying early cases of malnutrition especially in children above 3 years who use the same cutoffs as younger children Yes. You will need to do this...

en-net: MUAC cut off point

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...

FEX: Impact of WHO Growth Standards on programme admissions in Niger

Summary of research1 Severely malnourished children managed in the MSF-run Centre de Récupération Nutritionnelle Intensive (CRENI) in Maradi, Niger A recent study by...

en-net: Low mid-upper arm circumference identifies children with a high risk of death who should be the priority target for treatment

BMC Nutrition just published a comment that we wrote about a paper published a few months ago by Grellety and Golden.

The link to the original article:

FEX: Can height-adjusted cut-offs improve MUAC’s utility as an assessment tool?

By Michel Van Herp, An Verwulgen, Bérengère Leurquin, and Pascale Delchevalerie Michael Ven Herp, Bérengère Leurquin, An Verwulgen & Pascale Delchevalerie Michael Ven Herp is...

en-net: Highest SAM rate

I've just got the report of a nutrition survey. Severe acute malnutrition figure is extremely high (above 20%, OMS2006) and I was wondering whether this is a plausible result...

Close

Reference this page

MUAC and weight-for-height in identifying high risk children. Field Exchange 42, January 2012. p16. www.ennonline.net/fex/42/weight

(ENN_4243)

Close

Download to a citation manager

The below files can be imported into your preferred reference management tool, most tools will allow you to manually import the RIS file. Endnote may required a specific filter file to be used.