Using Anthropometry to Optimize Nutrition Programs for Management of Acute Malnutrition

Millions of children under 5 years of age suffer from severe acute malnutrition (SAM), worldwide, at any given time contributing to 1 million deaths per year, if not more. Anthropometric measurements including weight, height, and mid-upper arm circumference (MUAC) are used to measure nutritional status of children. Growth references/standards have been created to show expected growth in children who are living in conditions favorable for growth and are often displayed in tables showing weight-for-height (WFH) as percentage of the median or in the form of Zscores such as weight-for-height Z-scores (WHZ). The references/standards are used to determine the degree of malnutrition that children are experiencing and thus whether they meet the admission criteria for treatment programs. They are also used to determine the prevalence of malnutrition in a population present at a given time. MUAC differs from growth references/standards as it assesses risk of mortality rather than expectation of growth. The community-based management of acute malnutrition (CMAM) model is commonly used for children with SAM between the ages of 6 and 59 months. This involves both outpatient care in outpatient therapeutic programs (OTP) for SAM cases without complication and/or inpatient care in stabilization centres (SC), for SAM cases with complications. The main priority of treatment programs for SAM is to minimize mortality. There are many factors involved in the process of counting, predicting, identifying, and selecting children in need of treatment in nutrition programs as well as determining criteria for discharge from programs. This PhD consisted of five studies which explored how to use anthropometric indices in nutritional programs. The first study involved examining an alternative method for estimating the prevalence of acute malnutrition, specifically the PROBIT method, which is based on properties of the normal distribution. A simulation of 1.26 million virtual surveys generated from 560 real nutrition surveys from 31 different countries was used to compare bias and precision of this approach with the standard method. The results of this study showed that the PROBIT method can estimate prevalence of global acute malnutrition (GAM) and moderate acute malnutrition (MAM) using WHZ or MUAC. The study shows, however, that the PROBIT method is inferior to the classical method for estimating the prevalence for SAM by WHZ or MUAC at sample sizes n >150. It does seem suitable for small sample sizes and thus perhaps could be useful for surveillance. The second study involved determining an incidence conversion factor (J) empirically that could be used to estimate annual incidence of SAM based on prevalence data taken from nutrition surveys. This estimate is useful in predicting the expected number of children to be admitted into therapeutic nutrition programs and subsequent resources required. Organizations often include an incidence conversion factor (J = 1.6) in the formula to calculate expected yearly case load into programs. The estimation of J was done by correlating expected number of children to be treated, based on prevalence surveys and population estimates, with the number of children actually treated in CMAM programs. Twenty-four data sets from six different countries were used that included prevalence surveys and program admission data for 5 months following the survey. The results showed a significant relationship between the number of SAM cases admitted to CMAM programs and the estimated burden of SAM from prevalence surveys. The value for J extrapolated from our results was found to be higher than the one currently used by organizations. The value also may vary between regions. The third study was done to determine, if WFH is used, which growth standard or reference is best to identify children most at risk of death and thus ensure inclusion into the nutrition program. Data from 54,661 children treated in a nutrition program in Maradi, Niger were analyzed. Difference in classification of children as either moderate or severely malnourished as per the National Centre for Health Statistics (NCHS) growth reference and the WHO growth standards was investigated as well as risk of mortality based on different growth reference/standards. Results showed that 40% of the total children in the program which were classified as moderately malnourished as per NCHS standards would have been classified as severely malnourished if they had been assessed by the WHO standards. Almost half the deaths in the program were in this group and the children had three times the risk of dying during the program than the children classified as moderately wasted by both standards. The results of this study showed that the subgroup who would be reclassified is vulnerable to mortality and thus would benefit from being classified using the WHO growth standards to ensure admission into a nutritional program. The last two studies evaluated the use of MUAC in nutrition programs as an independent anthropometric measurement for malnutrition and examined the response of MUAC to treatment and the outcomes of children after being discharged from a nutrition program with a MUAC-based protocol. Both studies compared length of stay and percent weight gain of children in relation to nutritional status on admission as well as response to treatment based on height at admission. In addition, the fifth study evaluated the outcomes of children 3 months after discharge from the treatment program to determine the safety of using MUAC-based protocol. The data from study four was from a nutrition program in Gedaref, North Sudan consisting of 753 children. The data from study five was from a nutrition program in Malawi consisting of 257 children and 155 children for follow-up after discharge. The results of these studies showed that with these MUAC-based protocols, the duration of treatment and percent of weight gain are higher in the most malnourished children, regardless of their height. The results of study five also showed MUAC ≥ 125 mm as a safe discharge criterion with an acceptable level of negative outcomes at three months’ post discharge in the context of Malawian Ministry of Health outpatient care facilities. In conclusion, the classical method of counting individual cases of malnutrition in surveys is preferred to over the PROBIT method for estimating acute malnutrition prevalence from large sample surveys. The PROBIT method may be useful in sentinel-site surveillance systems with small sample sizes. The estimation of expected cases of malnutrition from prevalence surveys may require revision of the currently used incidence conversion factor (J). If using WFH in treatment programs, it is highly recommended to use the WHO growth standards instead of the NCHS reference to ensure inclusion of children with high mortality risk into the program. Lastly, if using MUAC-based protocol in treatment programs it is recommended to use MUAC for both admission and discharge criteria to ensure the most effective and safe treatment is delivered to the children most at risk of mortality.