Doctors and nurses estimation of the weight of patients: A preventable source of systematic error.

Background: Although accurate determination of body weight is important in the management of the poisoned patient, many patients have their weight estimated rather than formally measured.

Objective: To determine how good medical staff are at estimating patients*** body weights.

Methods: Medical staff were asked to estimate the weight of six patients on a poisons ward. Estimated and actual patient weights were statistically compared.

Results: Medical staff produced a large range of estimated weights for all patients. Patient weight was incorrectly estimated by greater than 10% in 61% of individual estimations. There was poor statistical correlation between actual and estimated weight.

Conclusions: All patients administered medication based on body weight and those treated following an overdose of any substance should have formal body weight determined as part of their standard management.