Performance of the allometric power model in scaling from adult to paediatric antiretroviral dose in children at a Referral Hospital in Windhoek, Namibia

Background: World Health Organization (WHO) advocates use of weight bands in antiretroviral therapy (ART) guidelines. Allometric scaling could be a more reliable method because it uses a non-linear approach in relating dose to body weight. This study evaluates performance of the allometric 3/4 power model in comparison to WHO weight band method in children receiving ART. Methods: Records of children receiving (ABC/3TC) + DTG were reviewed. Paediatric ABC/3TC dose was calculated from the adult dose using the allometric 3/4 power model and compared to WHO weight band dose. Results: WHO weight band strategy grouped 50.6% of the children in the 25 kg category and therefore received the adult dose of ABC/3TC (600 mg/300 mg); only 1.1% received this dose with allometric scaling. Mean dose (3.8 tablets) for the WHO weight band dosing method was found to be significantly higher (p<0.0001) than for allometric scaling (1.5 tablets). Conclusions: WHO weight bands may result in the 25 kg weight category receiving a much higher dose leading to ADRs. Using allometric scaling, we recommend a weight band strategy that could improve paediatric ABC/3TC dosing.