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Weight-Based Medication Errors: How to Tip the Scale in the Right Direction



What if I told you that the United States, Liberia, and Myanmar (that’s Burma) have one thing in common that contributes to serious medication errors? What if I told you that every other country in the world does not have this problem? What if I told you there is a fix? ​

Would you, the CEO, require it​?​
​​Would you, the patient, expect it?

​​​​​Th​e United States is one of only three countries in the world that does not use the metric system. Yet, every single medication prescribed today is based on it. In addition to dosages based on the metric system, some doses are also very dependent on patient weight. These include blood thinners, certain antibiotics, chemotherapy agents, and many pediatric doses. The very young, very old, and people with certain medical conditions are at the highest risk of experiencing harm because their bodies are more sensitive to the effects of an error.​

Calculations made with incorrect weights can have devastating, if not fatal, consequences.

Imagine for a minute that you work in a retail business: Every inventory purchase you make is in U.S. dollars, every bill you pay is in U.S. dollars, and every price tag you place on your merchandise is in U.S. dollars, but every time a customer comes to the cash register they pay in euros. You are lucky because the cash register in your department will do the conversion for you. The register in the sporting goods department will also do the conversion if the cashier remembers to select the currency converter—but that is still better than working in the shoe department. The shoe department cashier is required to do the conversion on paper or in their head. Sometimes the accounting department gets the daily closing figures in euros and sometimes in dollars, it just depends on which register is being used and which cashier was on duty.

​Sound like a hot mess? Well, that is exactly what goes on when prescribing and administering medications to patients.​​

​​The patient safety industry has been calling for standardization of weights for years; the Patient Safety Authority (PSA), the Centers for Disease Control, ECRI, the Institute for Safe Medication Practices, the American Academy of Pediatrics, the Emergency Nurses Association, the National Coordinating Council for Medication Error Reporting and Prevention are all in agreement that this is a problem that can be remedied. ​

We keep saying it, yet many healthcare institutions still aren’t doing it.​

In September 2018 PSA issued recommendations​ to Pennsylvania hospitals that very basically said two things: weigh your patients and do it in kilograms. These recommendations were issued because an analysis of PSA data showed that the most common medication error was related to overdose/underdose, 23% of all weight-based medication events mentioned a mix-up between pounds and kilograms, and almost 40% mentioned the patient’s actual weight being higher or lower than their documented weight1—which, although not specified, could be caused by estimation (or not actually weighing the patient). 

More than two years later, in a recent survey of those same facilities, 34% reported they don’t have a policy in place to weigh patients upon admission and more than half (53%) reported that they don’t have a policy to weigh patients in kilograms. 

Before sitting down to write this post I did a quick Google search of the phrase “medication errors caused by weight.” One of the first sites that popped up was a malpractice attorney’s site. It mentioned a 2013 Maryland case of a 2-year-old’s weight entered into the electronic health record as 35 kilograms (the equivalent of 77 pounds) rather than their actual weight of 35 pounds. Thankfully, the child survived a significant overdose of the prescribed medication, but not without losing consciousness and needing to be readmitted to a hospital. 

The website goes on to state, “Avoidable errors like the ones described above are unacceptable and it is understandable that the victims of such errors would feel anger over the harm that a health care provider’s mistake can cause.”I agree.​

So many problems in patient safety are difficult to fix—this does not need to be one of them.​

About this blog

Regina Hoffman serves as the  executive director of Pennsylvania’s Patient Safety Authority and editor-in-chief of Patient Safety, its award-winning journal.  Ms. Hoffman was recognized by Becker’s Hospital Review as one of the top 50 experts leading patient safety in both 2018 and 2020. This blog serves as a source for her to share her insights in patient safety and leadership with Pennsylvania’s healthcare leaders.



1. Bailey, BR, Gaunt, MJ, Grissinger, M. Update on Medication Errors Associated With Incorrect Patient Weights. Pennsylvania Patient Safety Advisory, 2016;13(2):50–57. http://patientsafety.pa.gov/ADVISORIES/Pages/201606_50.aspx 

2. Chihak & Martel. Confusion Over Metric Measurements Leads to Medication Errors. Firm website. Accessed January 26, 2012. https://www.chihaklaw.com/articles/confusion-over-metric-measurements-leads-to-medication-errors/. ​

***​ The views and opinions expressed at or through this blog are the opinions of the author alone and may not reflect the opinions or positions of the Patient Safety Authority or the Commonwealth of Pennsylvania, nor do these views represent in any way medical or legal advice. ​ 

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