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

Abstract

ABSTRACTObjectiveAccurate drug dosing in obese patients requires an estimation of ideal body weight (IBW) or lean body weight (LBW) for dosing hydrophilic medications. Erroneous weight estimates during the management of critically ill adults may contribute to poor outcomes. Existing methods of IBW and LBW estimation or measurement are very difficult to use during emergency care. A new point-of-care model is needed to provide rapid estimates of IBW and LBW for this purpose.MethodsA model was derived based on the PAWPER XL-MAC tape, a paediatric weight estimation system, which uses recumbent length and mid-arm circumference to estimate IBW and LBW. The model was used to generate weight estimations in a derivation sample (n=33155) and a validation sample (n=5926) from National Health and Nutrition Examination Survey (NHANES) datasets. The outcome measure was to achieve >95% of IBW and LBW estimations within 20% of recognised reference standards (P20>95%) and >70% of estimations within 10% of these standards (P10>70%).Main ResultsThe new model achieved a P20 of 100% and a P10 of 99.9% for IBW and a P20 of 98.3% and a P10 of 78.3% for LBW. This accuracy was maintained in both sexes, all ages, all ethnic groups, all lengths and in all habitus-types, except for the morbidly obese female subgroup.ConclusionsThe modified PAWPER XL-MAC model proved to be an accurate method of IBW and LBW estimation. It could, therefore, have an important role in facilitating emergency drug dose calculations in acutely or critically ill obese adult patients.Article summary1)Why is this topic important?Errors in weight estimation, or the use of an inappropriate weight scalar, can translate into medication errors and potential patient harm. The ability to easily estimate TBW, IBW and LBW would enhance patient safety and make correct drug dosing more accessible during the provision of emergency and critical care.2)What does this study attempt to show?This study describes the derivation and validation of a point of care model to provide estimates of IBW and LBW for the purposes of weight based dosing. The model is an adult version of a well-studied paediatric weight estimation system.3)What are the key findings?The model was able to provide accurate estimations of IBW and LBW in a wide range of patient-types. It was the first study to have evaluated such a system. It established that this system would be useful to test in clinical trials.4)How is patient care impacted?The PAWPER XL-MAC system could provide quick and easy estimations of IBW and LBW which can be used in obese patients for appropriate drug dose calculations. This would improve the accuracy of dosing with a potential reduction in medication errors and patient harm.