Severely malnourished children with a low weight-for-height have similar mortality to those with a low mid-upper-arm-circumference: II. Systematic literature review and meta-analysis

Abstract

Background: The WHO recommended criteria for diagnosis of sever acute malnutrition (SAM) are weight-for-height/length Z-score (WHZ) of <- 3Z of the WHO₂₀₀₆ standards, a mid-upper-arm circumference (MUAC) of < 115 mm, nutritional oedema or any combination of these parameters. A move to eliminate WHZ as a diagnostic criterion has been made on the assertion that children with a low WHZ are healthy, that MUAC is a "superior" prognostic indicator of mortality and that adding WHZ to the assessment does not improve the prediction of death. Our objective was to examine the literature comparing the risk of death of SAM children admitted by WHZ or MUAC criteria.

Methods: We conducted a systematic search for reports which examined the relationship of WHZ and MUAC to mortality for children less than 60 months. The WHZ, MUAC, outcome and programmatic variables were abstracted from the reports and examined. Individual study's case fatality rates were compared by chi-squared analysis and random effects meta-analyses for combined data.

Results: Twenty-one datasets were reviewed. All the patient studies had an ascertainment bias. Most were inadequate because they had insufficient deaths, used obsolete standards, combined oedematous and non-oedematous subjects, did not report the proportion of children with both deficits or the deaths occurred remotely after anthropometry. The meta-analyses showed that the mortality risks for children who have SAM by MUAC < 115 mm only and those with SAM by WHZ < -3Z only are not different.

Conclusions: As the diagnostic criteria identify different children, this analysis does not support the abandonment of WHZ as an important independent diagnostic criterion for the diagnosis of SAM. Failure to identify such children will result in their being denied treatment and unnecessary deaths from SAM.

Keywords: Acute malnutrition; Case fatality rate; Child; Diagnosis; Human; Kwashiorkor; MUAC; Meta-analysis; Mid-upper-arm circumference; Mortality; Nutrition; Oedema; SAM; Severe acute malnutrition; Simpson’s paradox; Systematic review; WHZ; Wasting; Weight-for-height.

Fig. 1

Flow of study selection

Fig. 2

Forest plot of the RR in children diagnosed by WHZ-only relative to MUAC-only with and without oedema. Legend: IND India; NER Niger; SDN South Sudan; UGA Uganda; MWI Malawi; COD Democratic Republic of the Congo; SEN Senegal; KEN Kenya; CMR Cameroun; Ln RR natural log of relative risk; CI confidence intervals. In each of the forest plots “favours WHZ” indicates that the Relative Risk for death is higher in children with WHZ < − 3Z than with a MUAC of < 115 mm; “favours MUAC” indicates that the Relative Risk for death of children with a MUAC < 115 mm is higher than those with WHZ < − 3Z

Fig. 3

The cut-off weights for heights that define SAM by the different references in use in the studies reviewed. Legend: WHO World Health Organisation, 2006 standards; NCHS National Center for Health Statistics (USA) 1977; CDC2000 Center for Disease control and Prevention, Atlanta, USA, 2000 reference

Fig. 4

Forest plot of the RR in children diagnosed by WHZ relative to MUAC grouped by the standards used. Legend: WHO/115 WHO criteria and MUAC< 115 mm; NCHS/115 NCHS criteria and MUAC< 115 mm; CDC2000/110 CDC2000 criteria and MUAC< 110 mm; IND India; NER Niger; SDN South Sudan; UGA Uganda; SEN Senegal; CMR Cameroun; KEN Kenya; COD Democratic Republic of the Congo; ETH Ethiopia; MWI Malawi; BFA Burkina Faso; RR relative risk; CI confidence intervals

Fig. 5

Relative Risk of mortality in children diagnosed by WHZ relative to MUAC by mode of treatment. Legend: IPF In-patient Facility (Hospital. Therapeutic Feeding Center); OTP Out-patient treatment program (Home treatment); Com community study; IND India; NER Niger; SDN South Sudan; UGA Uganda; SEN Senegal; CMR Cameroun; KEN Kenya; COD Democratic Republic of the Congo; ETH Ethiopia; MWI Malawi; BFA Burkina Faso; RR relative risk; CI confidence intervals

Fig. 6

Relative Risk of mortality in children diagnosed by WHZ relative to MUAC omitting the duplicate data. Legend: S-whz WHZ below cut off point with MUAC above cut-off point as defined in the paper; S-muac MUAC below cut off point with WHZ above cut-off point as defined in the paper; All-whz WHZ below the cut-off point, with MUAC either above or below the cut-off point as defined in the paper; All-muac MUAC below the cut-off point, WHZ either above or below the cut-off as defined in the paper; IND India; NER Niger; SDN South Sudan; UGA Uganda; SEN Senegal; CMR Cameroun; KEN Kenya; COD Democratic Republic of the Congo; ETH Ethiopia; MWI Malawi; BFA Burkina Faso; RR relative risk; CI confidence intervals