Who should be estimating a patient's weight in the emergency department?

Medical personnel often need to estimate a patient's weight rapidly and accurately to administer pharmacologic agents whose dosages are based on weight. Inaccurate estimates of weight may result in administration of either subtherapeutic or, in other cases, toxic doses of medications. The hypothesis of this study was that the patient is a more accurate estimator of his or her own weight than the physician or nurse caring for him or her.

This was a prospective study in which adult patients presenting to an urban emergency department (ED) were examined for study eligibility. Patients unable to stand were excluded. The patient, physician, and nurse caring for the patients were independently asked to estimate the patients' weights. The patients were then weighed.

A convenience sample of 458 patients were enrolled during a four-week period. The median measured (actual) weight was 172.5 lb. The best estimate of a patient's weight was made by the patient himself or herself: the median difference between patient estimates and actual weights was 0 lb (interquartile range [IQR] = -5 to 5). The physicians and nurses had larger underestimates: -5 lb (IQR = -22 to 12) and -6 lb (IQR = -22 to 10), respectively. Weight was estimated within 10% of actual weight by 90.6% of the patients, 50.4% of the physicians, and 49.6% of the nurses.

When a patient is unable to be weighed, the patient's own weight estimate should be used. If neither is possible, the physician or nurse should estimate the patient's weight.