Liquid Medication Errors and Dosing Tools: A Randomized Controlled Experiment

Abstract

Background and objectives: Poorly designed labels and packaging are key contributors to medication errors. To identify attributes of labels and dosing tools that could be improved, we examined the extent to which dosing error rates are affected by tool characteristics (ie, type, marking complexity) and discordance between units of measurement on labels and dosing tools; along with differences by health literacy and language.

Methods: Randomized controlled experiment in 3 urban pediatric clinics. English- or Spanish-speaking parents (n = 2110) of children ≤8 years old were randomly assigned to 1 of 5 study arms and given labels and dosing tools that varied in unit pairings. Each parent measured 9 doses of medication (3 amounts [2.5, 5, and 7.5 mL] and 3 tools [1 cup, 2 syringes (0.2- and 0.5-mL increments)]), in random order. Outcome assessed was dosing error (>20% deviation; large error defined as > 2 times the dose).

Results: A total of 84.4% of parents made ≥1 dosing error (21.0% ≥1 large error). More errors were seen with cups than syringes (adjusted odds ratio = 4.6; 95% confidence interval, 4.2-5.1) across health literacy and language groups (P < .001 for interactions), especially for smaller doses. No differences in error rates were seen between the 2 syringe types. Use of a teaspoon-only label (with a milliliter and teaspoon tool) was associated with more errors than when milliliter-only labels and tools were used (adjusted odds ratio = 1.2; 95% confidence interval, 1.01-1.4).

Conclusions: Recommending oral syringes over cups, particularly for smaller doses, should be part of a comprehensive pediatric labeling and dosing strategy to reduce medication errors.

Trial registration: ClinicalTrials.gov NCT01854151.

FIGURE 1

Medication labels and dosing tools tested. A, Comparison of randomization group characteristics. Unit label and dosing tool pairings were chosen because they represent the most common current standard practices used to display dose amounts on medication labels and dosing tools. The combination of units on labels and dosing tools applied to 3 different dosing tools given to each person (2 oral syringes [1 0.2-mL increment and 1 0.5-mL increment] and 1 cup); each subject measured 3 doses with the 3 tools, for a total of 9 doses. ^aExample of group 2 medication label is shown in Fig 1B. Teaspoon units on English-language medication labels were translated into Spanish, consistent with recommended pharmacy practices. The abbreviation tsp was displayed as cdta on Spanish-language medication bottle labels, and teaspoon was displayed as cucharadita on the Spanish-language medication bottle labels. ^bDosing tools had units marked in English only, as is standard practice in the United States. For dosing tools, mL and tsp tools are most commonly used and were therefore included for the majority of groups. See Fig 1C. ^cThe milliliter-only system is endorsed by the AAP, the Centers for Disease Control and Prevention, and other national organizations. B, Example of group 2 medication label (English). C, Dosing tools tested.

FIGURE 2

Study enrollment flowchart. ^aRan out of time after signing consent.

FIGURE 3

Dosing errors by tool type across the 3 doses tested.