One in Five Parents Make Major Dosing Errors

Diana Phillips

September 12, 2016

One out of five parents who meted out liquid medication in a randomized controlled trial measured more than twice the directed dose, and nearly all of them measured inaccurately to some degree.

The use of a dosing cup vs a syringe greatly increased the risk for error, as did medication labels that listed dosing instructions in teaspoons rather than milliliters, even when teaspoon measures were clearly marked on the dosing cup or syringe.

H. Shonna Yin, MD, from the department of pediatrics at New York University School of Medicine–Bellevue Hospital, and colleagues report the findings in an article published online September 12 in Pediatrics.

The findings suggest that changing the labeling and dosing tool attributes for children's liquid medication could have a marked influence on error rates. Specifically, the authors say that replacing the dosing cup with an oral syringe, especially for measuring small doses of liquid medications, and avoiding the use of teaspoon alone as a measurement unit on medication labels might help.

Such recommendations go beyond the move to milliliter-exclusive dosing advocated by the American Academy of Pediatrics in a 2015 Policy Statement, as reported previously by Medscape Medical News.

Unit Concordance Not Enough

The current study was designed to identify the specific attributes of medication labels and dosing tools that affect parent errors in dosing liquid medications. "Specifically, we examined the extent to which rates of parent dosing errors are affected by discordance in unit pairing on the label and tool and by dosing tool characteristics," the authors explain. "We hypothesized that unit concordance would be associated with fewer errors and that parents would measure most accurately with syringes."

To test their hypothesis, the researchers randomly assigned 2110 parents of children aged younger than 9 years from three urban pediatric clinics to one of five study groups. English- and Spanish-speaking parents were included in the study population.

Each of the caregivers was given a series of bottle labels and tools and was asked to demonstrate medication dosing. Specifically, each participant was asked to measure three different doses (2.5, 5, and 7.5 mL) using three tools (10-mL syringes with 0.2-mL markings, 10-mL syringes with 0.5-mL markings, and a 30-mL capacity dosing cup) for a total of 9 doses. The labels were printed in English or Spanish, based on caregiver preference, and the order of dosing was random.

The study groups differed by the pairing of units used on the bottle label and tool, as follows:

Group Label Unit(s) Tool Unit(s)
1 mL mL
2 mL and tsp mL and tsp
3 mL and tsp mL and tsp
4 mL mL and tsp
5 tsp mL and tsp

 

Of the study arms, Group 1 was considered the gold standard, "because a move to a milliliter-only system has been recommended by numerous organizations," the authors write.

Overall, 21% of parents made a large dosing error, defined as an amount of medication more than twice the directed dose, and 99.3% measured at least one dose that was not the exact amount stated in the label. Additionally, most of the parents (84.4%) made at least one dosing error, defined as a deviation of more than 20%. On average, parents made mistakes in 25.3% of their nine doses measured (mean [SD] number of errors = 2.3 [2.0]).

Of the errors, 68.0% were overdoses, and more errors were recorded with 2.5- and 7.5-mL dose amounts compared with 5-mL dose amounts (2.5 vs 5 mL adjusted odds ratio [aOR] = 4.2; 95% confidence interval [CI], 3.8 - 4.6; 7.5 vs 5 mL aOR = 1.4; 95% CI, 1.2 - 1.5).

The likelihood of making an error was linked to test order, with fewer errors being made as parents went through the trials.

Compared with the milliliter-only group, use of teaspoon only on the label when paired with an mL and tsp tool was the only group whose error rate differed significantly from the milliliter gold standard.

Across the study arms, dosing cups were associated with more than four times increased odds of all errors compared with syringes, and similar findings were observed for the likelihood of large errors specifically.

The differences in error rates between cups and syringes were greatest for 2.5- and 5-mL doses, suggesting that "it may be beneficial to recommend the use of different tool types depending on the dose amount," the authors write. "Our findings indicate that particularly when smaller doses are prescribed, providers may want to encourage parent use of syringes by providing them with a syringe to take home; cups may be acceptable for larger doses."

The researchers also note that parents were more likely to make dosing errors with dose amounts of 2.5 and 7.5 mL compared with 5 mL, "suggesting that whole numbers may be better understood."

However, the simplification of syringes with fewer markings did not seem to influence error rate differences. "It may be that parents benefit so much from using a syringe over a cup that the added benefit of simplification of markings is not discernible," the authors write.

Although the error rates were not significantly influenced by the types of unit of measurement discordance between labels and tools, the findings do support the avoidance of using teaspoon alone on labels, according to the authors.

Importantly, the significant number of dosing errors, even with syringes, suggests that "more intensive education by physicians, pharmacists, and other staff may be needed," the authors write. "[U]se of strategies such as pictures or drawings, teachback, or showback, and demonstration may be beneficial."

"Because parents may not use tools provided to them, counseling and general education about the importance and proper use of standard dosing tools remain important," the authors conclude.

Pediatrics. Published online September 12, 2016. Full text

This study was supported by the National Institutes of Health (NIH) Eunice Kennedy Shriver National Institute of Child Health and Human Development.

Three of the study coauthors reported having served as consultants to and received grant funding from Merck Sharp & Dohme for work unrelated to this study.

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