Milliliters Could Reduce Pediatric Medication Errors

A new study finds that parents who used teaspoon or tablespoon units to measure medication were twice as likely to make an error as those who used milliliters.

Although many Americans are unfamiliar with the metric system, the results of a recent study suggest that establishing the milliliter as the standard unit of measurement for pediatric medications could reduce the number of dosing errors made by parents.

The Centers for Disease Control and Prevention, the FDA, the Institute for Safe Medication Practices, and the American Academy of Pediatrics have all suggested that using the milliliter as the standard unit of measurement for pediatric liquid medications could reduce the confusion of dosing instructions for parents. Other stakeholders, however, have expressed concerns that eliminating the familiar teaspoon and tablespoon will only add to the confusion. The current study, published online on July 14, 2014, in Pediatrics, found the opposite to be true.

Researchers of the study analyzed the association between the unit parents used to measure their child’s liquid medication and the number of medication errors they made. English- or Spanish-speaking parents whose children had been prescribed liquid medications in 2 emergency departments were interviewed by phone and in an in-person follow-up appointment about their child’s medication, the dosing unit, and which instrument they used to administer the medication.

The results of the study indicated that medication errors were common. Overall, 31.7% made in an error in knowledge of the prescribed dose. In addition, the unit of measurement indicated on the prescription did not match the unit listed on the medication label 36.7% of the time. Parents also often used a different unit than the one listed on the prescription or the label. When a prescription used milliliters, 45% of parents did not use milliliters, and when a prescription used teaspoons, 36.7% did not use a teaspoon. Moreover, 16.7% grabbed a kitchen spoon to measure the medication rather than a standard instrument.

The unit used by the parent was significantly associated with medication errors. Compared with parents who only used milliliters to measure the medication, those who used the teaspoon or tablespoon measure were twice as likely to make an error in the amount of medication they intended to give their child, and the amount indicated by the prescription. These associations were stronger among parents with low health literacy (HL) and those who spoke Spanish. Among parents who used teaspoon and tablespoon units, 30.7% used a nonstandard instrument to measure the prescription, compared with just 1% of those who used milliliters.

“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,” the authors of the study write. “A move to a milliliter-only standard may promote the safe use of pediatric liquid medications among groups at particular risk for misunderstanding medication instructions, such as those with low HL and non—English speakers.”

The researchers suggest that the consistent use of milliliter units between prescriptions and labels should be promoted to pharmacists and other health care professionals.