Weight-for-Height Z-score Gain during Inpatient Treatment and Subsequent Linear Growth during Outpatient Treatment of Young Children with Severe Acute Malnutrition: A Prospective Study from Uganda

BACKGROUND: Linear catch-up growth after treatment of severe acute malnutrition (SAM) is low, and little is known about the association between ponderal and subsequent linear growth. OBJECTIVE: The study assessed the association of weight-for-height z-score (WHZ) gain with subsequent linear growth during SAM treatment and examined its modifiers. METHODS: This was a prospective study, nested in a trial (ISRCTN16454889), among 6–59-mo-old children treated for SAM in Uganda. Weight, total length (TL), and knee-heel length (KHL) were measured at admission, weekly during inpatient therapeutic care (ITC), at discharge, and fortnightly during outpatient therapeutic care (OTC) for 8 wk. Linear regression was used to assess the association between WHZ gain during ITC and linear growth during OTC. RESULTS: Of 400 children, 327 were discharged to OTC and 290 were followed up for 8 wk. Mean WHZ gains were 0.45 in ITC and 1.24 in OTC, whereas mean height-for-age z-score (HAZ) declined by 0.41 during ITC and increased by 0.14 during OTC. WHZ gain during ITC was positively associated with HAZ, TL, and KHL gains during OTC [regression coefficients (β) (95% CI): 0.12 (0.09, 0.15) z-score; 3.1 (2.4, 3.8) mm and 0.5 (0.1, 0.7) mm, respectively]. The regression coefficients were highest for the middle tertile of WHZ gain with respect to HAZ and TL. Admission diarrhea and low plasma citrulline reduced the association between WHZ gain during ITC and HAZ and TL gain during OTC (P < 0.001). In contrast, pneumonia (P = 0.051) and elevated plasma C-reactive protein (P < 0.001) increased the association with TL gain, but reduced the association with KHL gain (P < 0.001). CONCLUSIONS: Among children admitted with SAM, considerable WHZ gain during ITC was followed by very modest linear catch-up growth during OTC, with no indication of a WHZ gain threshold, above which linear growth was higher. To optimize linear growth in these children, early treatment of infections and conditions affecting the gut may be necessary.