Patient Safety Authority Department of Health: Final recommendation to ensure accurate patient weights (8 September 2018)

Summary

This document from the Patient Safety Authority outlines final recommendations to acute care facilities in the USA regarding patient weights. The Patient Safety Authority is responsible for submitting recommendations to the Department of Health (Department) in the US for changes in health care practices and procedures which may be instituted for the purpose of reducing the number and severity of serious events and incidents.

Content

Having accurate patient information (for example, age, allergies, laboratory results) helps practitioners select medications, doses and routes of administration. One vital piece of information, the patient's weight, is especially important, because it is used to calculate the appropriate dose of a medication (for example, mg/kg, mcg/kg, mg/m2). A prescribed or dispensed medication dose can differ significantly from the appropriate dose because of missing or inaccurate patient weights.

Patients in oncology treatment, patients with renal insufficiency, or who are elderly, paediatric or neonatal are at greater risk for adverse drug events, because they are more vulnerable to the effects of an error, and their weight may change frequently over short periods of time. Formulas such as the Cockcroft-Gault equation, which is used to calculate creatinine clearance to aid in the dosing of medications, and the Harris-Benedict formula, which is used to calculate basal metabolic rate, rely on knowledge of an accurate patient weight. Also, both height and weight are needed to use nomograms to determine body surface area and body mass index, for example, when calculating doses for chemotherapy.

In the United States, most patients are weighed in pounds. But weighing and documenting patients' weights in pounds introduces the need to convert the weight into kilograms—an error-prone process—to conduct weight-based and other dosing. Another risk when measuring the patient's weight in pounds is failing to convert the weight into kilograms but recording that weight in kilograms (that is, documenting a weight of 200 lbs. as 200 kg instead of 90.9 kg), resulting in more than two-fold dosing errors.

This document recommends a number of procedures to ensure accurate patient weights.

Further reading

Weight-based medication errors: How to tip the scale in the right direction