Key result
Lusaka formula shows similar accuracy to Broselow tape for pediatric weight estimation.
Why the study?
Accurate weight estimation in children is essential to reduce dosing errors, prompting validation of the locally derived Lusaka formula against commonly used tools.
Does the Lusaka formula accurately estimate weight compared to existing tools in children presenting for surgery in Zambia?
Cross-Sectional (n=330)
No
Does the Lusaka formula accurately estimate weight compared to existing tools in children presenting for surgery in Zambia?
Absolute Event Rate: 48.5% vs 51.6%
The locally derived Lusaka formula provides comparable accuracy to the Broselow tape for weight estimation in Zambian children, covering a wider age range and avoiding the overestimation seen with other age-based tools.
May support Lusaka formula as local alternative for pediatric weight estimation; leaves open prospective validation in diverse settings.
BACKGROUND: In children, the use of actual weight or predicted weight from various estimation methods is essential to reduce harm associated with dosing errors. This study aimed to validate the new locally derived Lusaka formula on an independent cohort of children undergoing surgery at the University Teaching Hospital in Lusaka, Zambia, to compare the Lusaka formula's performance to commonly used weight prediction tools and to assess the nutritional status of this population. METHODS: The Lusaka formula (weight = [age in months/2] + 3.5 if under 1 year; weight = 2×[age in years] + 7 if older than 1 year) was derived from a previously published data set. We aimed to validate this formula in a new data set. Weights, heights, and ages of 330 children up to 14 years were measured before surgery. Accuracy was examined by comparing the (1) mean percentage error and (2) the percentage of actual weights that fell between 10% and 20% of the estimated weight for the Lusaka formula, and for other existing tools. World Health Organization (WHO) growth charts, mid upper arm circumference (MUAC), and body mass index (BMI) were used to assess nutritional status. RESULTS: The Lusaka formula had similar precision to the Broselow tape: 160 (48.5%) vs 158 (51.6%) children were within 10% of the estimated weight, 241 (73.0%) vs 245 (79.5%) children were within 20% of the estimated weight. The Lusaka formula slightly underestimated weight (mean bias, -0.5 kg) in contrast to all other predictive tools, which overestimated on average. Twenty-two percent of children had moderate or severe chronic malnutrition (stunting) and 4.7% of children had moderate or severe acute malnutrition (wasting). CONCLUSIONS: The Lusaka formula is comparable to, or better than, other age-based weight prediction tools in children presenting for surgery at the University Teaching Hospital in Lusaka, Zambia, and has the advantage that it covers a wider age range than tools with comparable accuracy. In this population, commonly used aged-based prediction tools significantly overestimate weights.
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Phiri et al. (2021) conducted a cross-sectional in Children presenting for surgery (n=330). Lusaka formula vs. Broselow tape and other predictive tools was evaluated on Percentage of actual weights within 10% of estimated weight. The Lusaka formula estimated weight within 10% of actual weight in 48.5% of children, compared to 51.6% for the Broselow tape, and slightly underestimated weight with a mean bias of -0.5 kg.
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