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Teaspoon, tablespoon units linked to higher odds for dosage error
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Parents who used teaspoon or tablespoon units to measure their child’s medication had higher odds for dosage error than those who used milliliter-only units, according to study findings in Pediatrics.
H. Shonna Yin, MD, MS, of New York University School of Medicine and Bellevue Hospital Center in New York, and colleagues assessed provider communication and medication errors among 287 parents whose children were prescribed liquid medications. Parents were English or Spanish speakers. Medication error was defined as error in knowledge of prescribed dose, error in observed dose measurement (compared with intended or prescribed dose), with a deviation threshold for error greater than 20%.
H. Shonna Yin
Overall, 31.7% of parents made an error in knowledge of prescribed dose and approximately 40% made an error in measurement. One in six parents (16.7%) used a kitchen spoon rather than a standard instrument; 38% used an oral syringe; 16% used a dropper; 13.9% used a dosing cup; 13.6% used a dosing spoon; and 1.7% used a measuring spoon.
Nearly 37% of the time, medication labels and prescriptions did not contain the same units. Of prescriptions using only milliliters, 41.7% had milliliter-only; 50% had teaspoon-only; and the remainder added teaspoon to the milliliter unit. It was common for parents not to use units listed in the prescription. When a prescription used milliliters, 45% of parents did not use milliliters. When a prescription used teaspoon, 36.7% of parents did not use teaspoon.
Units used by parents was associated with both types of measurement error. Parents who used teaspoon or tablespoon were more likely to make errors in their intended (adjusted OR=2.3; 95% CI, 1.2-4.4) and prescribed (adjusted OR=1.9; 95% CI, 1.03-3.5) dose.
Errors regarding teaspoon and tablespoon measurements for intended dose were found among parents with low health literacy. This observation was not found among parents with adequate health literacy.
Parents who reported using teaspoon or tablespoon units were more likely to use a nonstandard instrument than those who used milliliter-only. Further, parents who used a nonstandard instrument were at least two times more likely to make an error in measurement compared with their intended (adjusted OR=2.4; 95% CI, 1.1-5) and prescribed (adjusted OR=2.6; 95% CI, 1.2-5.5) doses.
“Our findings provide evidence in support of a growing national initiative to move to a milliliter-only standard and may allay fears about the elimination of teaspoon and tablespoon terms. A move to a milliliter-only standard may promote safe use of pediatric liquid medications among groups at particular risk for misunderstanding medication instructions, such as those with low [health literacy] and non-English speakers,” the researchers concluded.
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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Edward A. Bell, PharmD, BCPS
It is well known that the most common medication-related error in pediatrics is related to drug dosing. Errors in drug dosing and administration can result from many facets of the dosing process, including mathematical errors, confusion over mg/kg/day vs. mg/kg/dose errors, and dose expression, among others. In this study, Yin and colleagues have shown that the units of dose measurement and expression can be an additional source of error.
Pediatric health care professionals who prescribe liquid medications may not give much thought as to how, what may seem like relatively simple dosing instructions, prescribed doses are administered by parents. “One teaspoonful twice daily” can be a common source of error, as demonstrated by the study results. While “one teaspoonful” instructions may seem to be clear and easy to understand, the amount of liquid medication measured, and how it is measured, can be easily confused by some parents.
Yin evaluated children who were prescribed liquid medications, mostly antibiotics, in two hospital emergency departments, and how accurately the children’s parents administered these medications. Over 30% made an error in knowledge of the prescribed dose, and 40% made an error in dose measurement. Confusion over doses expressed as “mL” or “teaspoonful” and errors in choice of dose-measurement device contributed to these errors. Parents who used teaspoon or tablespoon dose measurement units were significantly more likely to make an error, as compared to parents using millimeter units. Studies such as Yin’s are useful reminders that a few minutes of explanation on dosing and dose measurement when prescribing and dispensing liquid medications can be important. It may be time to eliminate use of “teaspoonful” and “tablespoonful” dosing measurement units.
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