Weight-Based Medication Errors and How to Combat Them

June 20, 2023

KG Only Patient Scales

Medication errors occur every day, with an estimated 7 million patients affected annually in the United States. These errors contribute to approximately 7,000 to 9,000 deaths yearly. While hundreds of thousands of patients experience adverse drug reactions, many go unreported. All told, medication errors cost the healthcare industry in excess of $40 billion each year.

Medication administration errors can occur from failures in any of the five rights (right patient, right medication, right time, right dose, and right route). These types of errors make up about 50% of all medication dosing errors. Up to nearly three-quarters of those errors are found by pharmacists or nurses.

While the potential for an adverse drug event (ADE) can result from various sources, including individual staff error, it can also result from system-level failures. These may include understaffing, poor processes, improper storage, insufficient training, or even practitioner distractions.

What Defines a Medication Error?

The National Coordinating Council for Medication Error Reporting and Prevention (NCCMERP) defines a medication error as "any preventable event that may cause or lead to inappropriate medication use or patient harm while the medication is in control of the healthcare professional, patient, or consumer."

Organizations like the NCCMERP have released recommendations to help prevent medication errors relating to administration. These guidelines help ensure patient safety and include measures such as clearly distinguishing look-alike/sound-alike drugs, utilizing barcodes on medications that coordinate with patient I.D. bracelets and charts, and requiring at least two patient identifiers before administering a medication.

High-alert medications, i.e., drugs associated with the highest risk of harm, are another concern for hospitals and regulators. If incorrectly administered, these medications can cause significant patient harm. According to the Patient Safety Network, hospitals should identify their high-alert drugs and take special precautions to help reduce the risk of errors and ensure patient safety during administration. Such drugs may include chemotherapy medications, opioids, and insulin, among others.

Other recommended guidelines include ensuring proper staffing levels so the nursing staff can safely and effectively administer medication at the prescribed timeframes without interruption.

Weight Discrepancy: A Common Culprit in Medication Errors

While implementation of many of the above guidelines and procedures require significant planning and oversight, one common cause of incorrect medication dosing in hospital settings can be easily remedied.

Inaccurate recording of a patient's weight in pounds versus kilograms is often a culprit in weight-based medication-dosing errors. As medication doses are often based on a patient's weight, having the wrong information can result in too small or too large of a dose. This is often due to lack of standardization in the practice of weighing patients, which includes the types of weighing instruments or scales used or relying on estimates or outdated information during emergency situations.

The Centers for Disease Control and Prevention (CDC) has pushed for hospitals to exclusively implement a metric weight measurement system to avoid confusion in medical facilities in the U.S., one of only three countries in the world that still uses the imperial system. This is vital since it is essential to have an accurate metric weight for every patient who needs a medication that is based on body weight.

Four Common Weight-Dosing Errors

Lack of awareness around the incidence and prevalence of weight-dosing errors perpetuates the problem. There are four common errors that contribute to these problems:

  • Failure to weigh a patient
  • Inaccurate documentation due to incorrect or missing unit of measure
  • Incorrect conversion between pounds and kilograms
  • Inaccurate estimation of weight by staff or patient/caregiver

Weight-based dosing errors are a particular problem in certain areas within hospitals and other healthcare facilities, and with certain patient populations. In hospitals, Emergency Departments (EDs) are reported to be the top location where weight-dosing errors occur.

ED staff frequently estimate a patient's weight or rely on a reported weight from the patient or caregiver for chart documentation and calculation purposes due to the patient's condition and need for urgent treatment. This causes the clinician to skip formal weighing. Both of these methods are prone to error.

Patient groups who experience dramatic fluctuations in weight throughout their care are another area where weight-dosing errors are frequent. Oncology patients, in particular, are one sub-group where varied weights can cause errors. According to a study analyzing the Pennsylvania Patient Safety Reporting System, up to 15 percent of dosing errors in cancer patients occurred due to incorrect weight logs.

According to a study of pediatric hospitals, children are also at greater risk of weight-dosing errors during in-patient visits due to the "complicated process of calculating" medication doses based on a wide weight range. Read more about pediatric medication dosing errors here.

Kilogram-Only Patient Scales Aid with Standardization

Consistent and well-documented processes, access to appropriate and accurate weighing equipment, and recording systems that require accurate data, including unit of measure and date, are all essential components of a safe and effective weight-dosing protocol.

But another potential solution is universal metric-system adoption.

The Institute for Safe Medication Practices notes numerous errors in hospitals, with healthcare providers weighing patients in pounds and logging their weights in kilograms. Weighing discrepancies can be avoided by adopting the use of kilogram-only scales. Kilogram-only scales can aid in reducing the number of weight-dosing calculation errors by ensuring all weights are reported in kilograms instead of pounds since all weight-dosed medications are calculated using the metric system. 

In an effort to help facilities ensure standardization of metric weight measurement, AliMed offers a variety of KG Only and KG Locking Patient Scales to help ensure patient weight is properly measured and documented in kilograms. These scales can greatly reduce the risk of calculation and dosing errors. KG Only models record weight in kilograms only, while KG Locking Models utilize Everlock® technology, which allows staff to set and lock weight measurements in kilograms to reduce the chances of accidentally switching the scales to pounds.

Medication dosing errors can pose a significant risk to the patient population. But these errors are preventable. By implementing safe medication practices, which include devices to aid with accurate patient weighing, facilities can minimize medication errors and protect patients from harm.


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