Parent Preferences and Perceptions of Milliliters and Teaspoons: Role of Health Literacy and Experience

Background and objectives: A recent American Academy of Pediatrics policy statement recommends milliliter-exclusive dosing for pediatric liquid medications. Little is known about parent preferences regarding units, perceptions about moving to milliliters only, and the role of health literacy and prior milliliter-dosing experience.

Methods: Cross-sectional analysis of data collected as part of a randomized controlled study in 3 urban pediatric clinics (SAFE Rx for Kids study). English- and Spanish-speaking parents (n = 493) of children aged ≤8 years were randomized to 1 of 4 study arms and given labels and dosing tools which varied in label instruction format (text plus pictogram, text only) and units (milliliter only ["mL"], milliliter/teaspoon ["mL"/"tsp"]). Outcomes included teaspoon preference in dosing instructions and perceived difficulty with milliliter-only dosing. The predictor variable was health literacy (Newest Vital Sign; low [0-1], marginal [2-3], adequate [4-6]). The mediating variable was prior milliliter-dosing experience.

Results: Over two-thirds of parents had low or marginal health literacy. The majority (>70%) preferred to use milliliters, perceived milliliter-only dosing to be easy, and had prior milliliter-dosing experience; 11.5% had a teaspoon preference, 18.1% perceived milliliter-only dosing will be difficult, and 17.7% had no prior milliliter-dosing experience. Parents with lower health literacy had a higher odds of having a teaspoon preference (low vs adequate: adjusted odds ratio [AOR] = 2.9 [95% confidence interval [CI] 1.3-6.2]), and greater odds of perceiving difficulty with milliliter-only dosing (low vs adequate: AOR = 13.9 [95% CI 4.8-40.6], marginal vs adequate: AOR = 7.1 [95% CI 2.5-20.4]). Lack of experience with milliliter dosing partially mediated the impact of health literacy.

Conclusions: Most parents were comfortable with milliliter-only dosing. Parents with low health literacy were more likely to perceive milliliter-only dosing to be difficult; educational efforts will need to target this group to ensure safe medication use.