Development and validation of a length- and habitus-based method of total body weight estimation for critically ill adults requiring urgent weight-based medical intervention

ABSTRACT Background Erroneous weight estimation during the management of emergency presentations in adults may contribute to patient harm and poor outcomes. Patients can often not be weighed during emergencies and a weight estimation is required to facilitate weight-based therapies. Many existing methods of weight estimation are either unacceptably inaccurate or very difficult to use during the provision of emergency care. Methods The weight estimation system developed in this study was based on and modified from the PAWPER XL-MAC method, a paediatric weight estimation system that uses recumbent length and mid-arm circumference (MAC) to predict total body weight. This model was validated in the 2015 – 2018 National Health and Nutrition Examination Survey (NHANES) datasets. The primary outcome measure was to achieve >95% of estimations within 20% of measured weight (P20>95%). Results The modified PAWPER XL-MAC model achieved a P20 of 96.0% and a P10 of 71.3% in the validation dataset (N=11520). This accuracy (P20>95%) was maintained in both sexes, all ages, all ethnic groups, all lengths and in all habitus-types, except for the subgroup of severely obese individuals. Conclusions The modified PAWPER XL-MAC model proved to be a very accurate method of weight estimation. It is more accurate than most other published reports of existing methods of weight estimation, except for patients’ own estimations. It therefore could have a role in facilitating emergency drug dose calculations, if prospective studies bear out the accuracy found in this study.