How should undernutrition be diagnosed in Nigerian hospitalised infants aged under six months?

Abstract

It is often assumed that breast fed infants aged under 6 months are at low risk for undernutrition, but where there is non‐exclusivity or underlying medical problems the risk is high. Because of extremely high energy requirements this rapidly impacts on weight gain, causing wasting and weight faltering (WF).Common screening methods for undernutrition have largely not been standardised or validated for very young infants, in particular for skin folds. The WHO growth chart project published standards for subscapular and triceps skin folds in 2007, but only from age 3 months to 5 years.ObjectivesTo assess the prevalence of undernutrition in hospitalised infants aged 0.5–6 months, defined as either WF or low fat stores and then to assess the utility of different screening methods to identify these infants.MethodsNorms for weight gain were established using retrospective weights of 411 healthy infants age < 6 months attending a large well baby clinic in Eunugu, Nigeria; the lower 5th percentile for weight gain conditional on birth weight was defined as WF. Skin folds measured in 195 UK hospitalised infants 0–1 years with very low rates of undernutrition were used to identify the lower 5th percentile for sum of skin folds (10mm) (SSF). A sample of infants age 2 weeks to < 6 months admitted to the teaching hospital in Eunugu were studied. Measures of weight, length, mid‐upper arm circumference (MUAC) and triceps and subscapular skin folds were taken.ResultsOf the 125 hospitalised infants, 86 (69%) were admitted for infectious causes and only 6 (5%) because of undernutrition. Low SSF were found in 41 (33%). Birth weight was known in 105 infants, from these 25 (24%) had WF and a total of 45 (36%) had WF or low SSF, or both. Low MUAC showed high sensitivity to identify WF and/or low fat stores, but at a cost of more children being mislabelled. Low weight for age also showed high sensitivity, particularly for WF, but with a higher positive predictive value (PPV) and thus fewer children being mislabelled. Low WFH showed both low sensitivity and low PPV.ConclusionsIn hospitalised infants under six months a MUAC <11 cm is a reasonably effective screening threshold for identification of undernutrition, but low weight is more specific, while low WFH would miss over half the undernourished infants.Support or Funding InformationIfeyinwa Ezeofor was supported by a Ford Foundation Scholarship Sensitivity and positive predictive value of different screening measures to predict undernutrition, as defined by WF and/or low fat or measure or low fat or WF individually. Screening Measure To predict WF and/or low fat Low fat (SSF) Low CWG (WF) Prevalence Sensitivity PPV Sensitivity PPV Sensitivity PPV MUAC <11cm 36% (45) 73% 73% 73% 67% 80% 51% WFHZ <‐2 25% (30) 49% 67% 46% 57% 65% 51% WAZ <‐2SD 29% (36) 69% 86% 66% 75% 92% 77%