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Accuracy of weight estimation methods in adults, adolescents and children: a prospective study
  1. Giles N Cattermole1,2,
  2. Appolinaire Manirafasha1,3
  1. 1Department of Anaesthesia, Critical Care and Emergency Medicine, University of Rwanda College of Medicine and Health Sciences, Kigali, Rwanda
  2. 2Emergency Department, Princess Royal University Hospital, Orpington, UK
  3. 3Emergency Department, King Faisal Hospital, Kigali, Rwanda
  1. Correspondence to Dr Giles N Cattermole, Emergency Department, Princess Royal University Hospital, Orpington, BR6 8ND, UK; giles{at}


Introduction Weight estimation of both adult and paediatric patients is often necessary in emergency or low-resource settings when it is not possible to weigh the patient. There are many methods for paediatric weight estimation, but no standard methods for adults. PAWPER and Mercy tapes are used in children, but have not been assessed in adults. The primary aim of this study was to assess weight estimation methods in patients of all ages.

Methods Patients were prospectively recruited from emergency and outpatient departments in Kigali, Rwanda. Participants (or guardians) were asked to estimate weight. Investigators collected weight, height, mid-arm circumference (MAC) and humeral-length data. In all participants, estimates of weight were calculated from height and MAC (PAWPER methods), MAC and humeral length (Mercy method). In children, Broselow measurements and age-based formulae were also used. The primary outcome measure was the proportion of estimates within 20% of actual weight (p20).

Results We recruited 947 participants: 307 children, 309 adolescents and 331 adults. For p20, the best methods were: in children, guardian estimate (90.2%) and PAWPER XL-MAC (89.3%); in adolescents, PAWPER XL-MAC (91.3%) and guardian estimate (90.9%); in adults, participant estimate (98.5%) and PAWPER XL-MAC (83.7%). In all age groups, there was a trend of decreasing weight estimation with increasing actual weight.

Conclusion This prospective study of weight estimation methods across all age groups is the first adult study of PAWPER and Mercy methods. In children, age-based rules performed poorly. In patients of all ages, the PAWPER XL-MAC and guardian/participant estimates of weight were the most reliable and we would recommend their use in this setting.

  • global health
  • paediatrics
  • resuscitation

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  • Handling editor Lara Nicole Goldstein

  • Twitter @gilesmole

  • Presented at These results were presented as a poster at the Royal College of Emergency Medicine annual scientific conference, October 2017.

  • Contributors Both authors meet the requirements for authorship. GNC and AM devised the study and wrote the protocol. AM oversaw the running of the study. GNC analysed the data and wrote the manuscript draft. GNC and AM reviewed and revised the paper.

  • Funding This authors received grant of £1381 from the Royal College of Emergency Medicine Research Grants for Low Income Countries Award Scheme, part of which funded this study.

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Patient consent for publication Not required.

  • Ethics approval Ethical approval was obtained from the Institutional Review Board, College of Medicine and Health Sciences, University of Rwanda (reference 406/CMHS IRB/2016) and from the Ethics Committee, CHUK (reference EC/CHUK/214/2016). Written consent in Kinyarwanda was obtained from patients or guardians as appropriate.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available on reasonable request. Deidentified Excel/Medcalc datasets are available on request from the author (ORCID ID 0000-0002-8910-2307).