Dear Kiros,
You asked me to comment the systematic review:
Utilisation of mid-upper arm circumference versus weight-for-height in nutrition rehabilitation programmes: a systematic review of evidence.
http://www.who.int/nutrition/publications/guidelines/updates_management_SAM_infantandchildren_review1.pdf
The current discussion is whether MUAC alone or MUAC and WFH should be used to select children in need of treatment. I am not sure this is really what is discussed in this WHO working document.
To choose between WFH and MUAC as admission criteria, you have to give preference to the indicator which selects from the community children with the highest risk of death and which are most likely to respond to treatment (currently, RUTF + antibiotics).
This issue was investigated in 6 different community based studies examining ROC curves (sensitivity plotted against specificity for a whole range of cut-off) of MUAC and WFH to predict deaths (Bairagi, 1981) (Alam et al., 1989) (Vella et al., 1994) (Van den Broeck et al., 1996) (Briend et al., 2012) (Mwangome et al., 2012). All of them showed that MUAC had a ROC curve above that of WFH. In several of these studies, a prediction as good as that of WFH could have been obtained by just tossing a coin. A review in 1994 on the relationship between anthropometry and mortality based on studies available at that time concluded that “the most consistent observation is that WFH is the least effective predictor of mortality” (Pelletier, 1994).
Before going to MUAC, one has to check that selected children respond to treatment. The response to treatment of children selected by MUAC compared to those selected by WFH has little been investigated. The WHO working document, however, quotes 4 studies examining this response. None of them suggest that children selected by MUAC respond differently.
So in summary, there is consistent evidence that MUAC better selects high risk children who also respond to treatment. The conclusion is clear: we should go for MUAC.
None of the community studies on anthropometry and mortality is mentioned in the WHO working document, and the association between MUAC and risk of death not highlighted, although this association is behind the current move of programmes towards MUAC, independently of its easiness of use in the community. The only reference to mortality in this WHO working document is based on treated children with an unknown representativity of the examined sample compared to the overall population. Also, there is no mention of the specificity of WFH compared to MUAC, which considerably weakens the conclusion of the analysis. A randomly allocated variable not associated with mortality can predict all deaths in a sample if a very low specificity is accepted.
The WHO working document, and also two recent papers (Isanaka et al., 2015) (Grellety et al., 2015) raise the question of children of the risk of death of children with WFH <-3 and MUAC > 115mm, currently not selected by standard MUAC only programmes. And indirectly advise for possibly using both indicators. I don’t think, however, this is the correct approach to improve the identification process (Briend et al., 2012). ROC curves show that increasing the MUAC cut off is will be more effective and we also know this will be programmatically much easier. So I suggest that instead of continuing this sterile discussion about including children with WFH <-3, we should consider increasing the MUAC cut off. Children with a MUAC of 116 mm are hardly better off than those currently selected and regrettably there is no discussion about the opportunity to treat them as well, although MSF in different programmes used this approach successfully (see: http://files.ennonline.net/attachments/2401/FEX-50-Web-Final.pdf p 108).
This option of increasing the MUAC cut off instead of keeping WFH < -3 is not discussed in the WHO working document.
A frequent objection to increasing the MUAC cut-off is that this will increase dramatically the number of patients admitted for treatment. This is true, there will be an increase of patient numbers, and the decision has to be thought carefully, taking into account treatment capacity. The effect on treatment coverage has to be assessed. However, adding children with WFH <- 3 in a MUAC<115 mm only programme would also increase the number of patients by about 60%. See again the table derived from 522 surveys collected by Mark (with about 500 000 children in total) I mentioned in a previous post on the breakdown of different categories of SAM children:
MUAC < 115 mm and WHZ < -3 23%
MUAC < 115 and WHZ >-3 39%
MUAC > 115 and WHZ < -3 38%
One could easily increase the MUAC to make it more inclusive, increasing the number of high risk children detected, i.e. increasing the sensitivity of screening, without going beyond the patient numbers that you would get by also including all children with WFH < -3.
Ideally, the MUAC cut off for SAM treatment should be based on risk assessment and response to specific SAM treatment. We know that the risk of death no more decreases beyond 125 mm (Myatt et al., 2006). We have no information on a cut off based on response to treatment, however. Even if children with a MUAC 120-125 mm are at a high risk, this does not mean they need a specific treatment with RUTF, they may well respond to a less expensive food supplement or an adequate diet based on local foods, with mineral and vitamin supplements, if needed. More research is needed on this.
The WHO working document also ends up suggesting that analysing current programmes will help to decide if it is relevant to use WFH<-3 as additional admission criteria or if MUAC <115 mm alone is sufficient. This statement has to be qualified, as this is correct only if SAM children treated are representative of SAM children seen in the community, something very difficult to achieve. For this, you have to make sure that different categories of children are referred to treatment in the same way and have the same treatment seeking behaviour. A real challenge. The Grellety et al. study should be an eye opener in this respect as it is based on a sample from which nearly all high risk low MUAC children were excluded and no conclusion relevant to admission criteria can be obtained from it (see my previous post). In addition to that, data from treated children are difficult to interpret. After a few days, there are few deaths and many of them are unrelated to malnutrition if treatment is correctly implemented.
An additional limitation of the data analysis of current programmes is that most of them are not adapted to analysing the alternative and more attractive option of increasing the MUAC cut off. Current programme do not screen these children and all children who have a MUAC > 115mm and WFH <-3 are censored.
I let you appreciate the relevance of this WHO document in light of these comments. Of note, I fully support Mark’s statement that well known WFH uncritical supporters are overrepresented among the authors of this WHO working document. The lead author himself has even just published an article highlighting that MUAC < 115 mm does not identify correctly children with WFH <-3 (déjà vu hundreds of times !!!; just wondering how this can still be published) and rejects the use of MUAC on this basis (Roberfroid et al., 2015). Of course, MUAC and WFH do not select the same children, else these two indices would be just as good to assess the risk of dying, whereas MUAC is better. Interestingly, the only reference to mortality in this paper is based on the Grellety study, used to claim that WFH <-3 is much better to detect children who are going to die, but failing to mention that the selection process eliminated virtually all high risk children with a MUAC < 115 mm. No mention either of community based studies.
A personal note to end up. My first papers on MUAC and mortality were published in 1986 (Briend and Zimicki, 1986) (Briend et al., 1986), nearly 30 years ago now. Since then, it has been confirmed many times that MUAC is very good to identify high risk children, much better for that than WFH and easy to implement at the community level, even by mothers (Blackwell et al., 2015). I have enough of the ongoing discussion, I think we should stop saying we have not enough evidence for moving to MUAC. I am rather depressed to see this repeated at the end of this WHO working document which fails to mention the evidence in favour MUAC being a better predictor of the risk of death. I am also upset to see this repeated uncritically in this forum, including by the moderator, neglecting the evidence. Those who want more evidence should read the relevant literature, and avoid relying on poor documents censoring the evidence. Else, they should describe the type of additional study they need to be convinced, if ever, it is just too easy to say there is not enough evidence beyond limits. As shown by the data of the Grellety study, a dogmatic attitude in favour of low WFH children eliminates from treatment many high risk children and results in many unnecessary deaths (by the way, the authors of the Grellety study examined data from an ongoing programme, they did not design it as far as I know and should not be held responsible for the selection process which denied treatment to those most at risk and for the excess of deaths which resulted from this). I am afraid the ongoing debate on whether or not to include children with MUAC > 115 mm and WFH <-3 is counterproductive and diverts our attention from the important reconsideration of current MUAC cut-off in relation to response to treatment. And also diverts on attention from the broader and even far more important issue of access to treatment and current low programme coverage. All this leads to more preventable deaths still occurring among high risk children who remain untreated. No wonder quite a few of us have difficulty in keeping calm in this debate which has been going on for too long.
I hope this helps,
André
References
Alam, N., Wojtyniak, B., Rahaman, M.M., 1989. Anthropometric indicators and risk of death. Am. J. Clin. Nutr. 49, 884–888.
Bairagi, R., 1981. On validity of some anthropometric indicators as predictors of mortality. Am. J. Clin. Nutr. 34, 2592–2594.
Blackwell, N., Myatt, M., Allafort-Duverger, T., Balogoun, A., Ibrahim, A., Briend, A., 2015. Mothers Understand And Can do it (MUAC): a comparison of mothers and community health workers determining mid-upper arm circumference in 103 children aged from 6 months to 5 years. Arch. Public Health Arch. Belg. Santé Publique 73, 26. doi:10.1186/s13690-015-0074-z
Briend, A., Dykewicz, C., Graven, K., Mazumder, R.N., Wojtyniak, B., Bennish, M., 1986. Usefulness of nutritional indices and classifications in predicting death of malnourished children. Br. Med. J. Clin. Res. Ed 293, 373–375.
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Grellety, E., Krause, L.K., Shams Eldin, M., Porten, K., Isanaka, S., 2015. Comparison of weight-for-height and mid-upper arm circumference (MUAC) in a therapeutic feeding programme in South Sudan: is MUAC alone a sufficient criterion for admission of children at high risk of mortality? Public Health Nutr. 18, 2575–2581. doi:10.1017/S1368980015000737
Isanaka, S., Guesdon, B., Labar, A.S., Hanson, K., Langendorf, C., Grais, R.F., 2015. Comparison of Clinical Characteristics and Treatment Outcomes of Children Selected for Treatment of Severe Acute Malnutrition Using Mid Upper Arm Circumference and/or Weight-for-Height Z-Score. PloS One 10, e0137606. doi:10.1371/journal.pone.0137606
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