Impact of WHO Growth Standards on SAM response to treatment

Summary of published research¹

More younger admissions to therapeutic feeding programmes are one of the implications of moving to the new WHO Growth Standards.

A recent study set out to assess the impact of adopting the World Health Organisation (WHO) growth standards and weight-forheight z-score (WHZ) criterion on the response to treatment of severe acute malnutrition in children compared with the use of the National Centre for Health Statistics (NCHS) growth reference.

The study used data from children aged 6-59 months with acute malnutrition who were admitted to the Medecins sans Frontieres (MSF) nutrition programme in Maradi, Niger, during 2006 (N= 56,216). Differences in weight gain, duration of treatment, recovery from malnutrition, mortality, loss to follow-up and need for inpatient care were compared for severely malnourished children identified according to the NCHS reference and weight-forheight <70% of the median (WHM) criterion versus the WHO standards and the WHZ <-3 criterion.

A total of eight times more children (n=25,754) were classified as severely malnourished according to the WHO standards compared to the NCHS reference (n=2,989). Children included according to the WHO standards had shorter durations of treatment, greater rates of recovery, fewer deaths, and less loss to follow-up or need for inpatient care. Previous estimates of the change in the prevalence of severe acute malnutrition range from increases of 1.5 to 2.5 times and 1.7 to 4.2 times, when applying the same WHZ of <-3 to both the NCHS reference and the WHO standards. Differences among estimates are likely because of the criterion used for comparison and will depend on the age, weight, and height profiles of the population.

The authors concluded that the introduction of the WHO standards with the z-score criterion to identify children for admission into severe acute malnutrition treatment programmes would imply the inclusion of children who are younger but have relatively higher weight for height on admission compared with the NCHS reference. These children have fewer medical complications requiring inpatient care and are more likely to experience shorter durations of treatment and lower mortality rates.

The WHO standards with the z-score criterion might become a useful tool for the early detection of acute malnutrition in children, although additional research on the resource implications of this transition is required. The implications of the introduction of the WHO standards should also be evaluated in the context of new community-based programmes for the management of severe acute malnutrition, because fewer children would require inpatient care according to the WHO standards and z-score criterion compared with the NCHS reference and percent of the median criterion.

¹Isanaka. S et al (2008). Assessing the impact of the introduction of the WHO growth standards and weight for height z-scores criterion on the response to treatment of severe acute malnutrition in children: Secondary data analysis. Accessed at www.pediatrics.org on December 30, 2008. Preliminary findings of this research featured in issue 34 of Field Exchange, Impact of WHO Growth Standards on admissions in Niger. P6. Field Exchange 34. October 2008.