Ease of Use of Two Reusable, Half-Unit Increment Dosing Insulin Pens by Adult Caregivers of Children with Type 1 Diabetes: A Randomized, Crossover Comparison

Abstract

Insulin pens deliver accurate doses, which are important for children who require low doses and are at risk for hypoglycemia.1 Reusable insulin pens that deliver insulin in half-unit (U) increments include HumaPen® Luxura™ HD (Eli Lilly and Company, Indianapolis, IN; insulin lispro injection, 0.5 to 30 units; Pen A) and NovoPen® Junior (Novo Nordisk A/S, Bagsvaerd, Denmark; insulin aspart injection, 1 to 35 U; Pen B). The purpose of this randomized, 2-period, crossover, open-label, simulated injection study was to compare the functional usability and preference of these pens in 65 adult caregivers of children aged 3–12 years with type 1 diabetes. The caregivers’ pen preferences were assessed for overall ease of use as the primary end point and for ease of changing the insulin cartridge and ease of correcting the insulin dose as the secondary end points. All caregivers, who had no experience with reusable pens, watched a video showing the pen usability tasks and had user manuals available for reference. Each caregiver changed a cartridge, dialed and corrected a dose, injected into an injection pad at a high dose (10 U corrected to 6.5 U) and a low dose (5 U corrected to 2.5 U), and, after each dose, completed a 9-item questionnaire derived from the cognitively debriefed Insulin Device Assessment Battery.2 Each item was answered on a 7-point scale (1 = strongly disagree to 7 = strongly agree), giving a total score for the low and high doses (minimum score of 2 up to a maximum score of 14). Proportions of caregivers with a pen preference (different total scores) were used to assess the primary and secondary end points. Caregivers with no preference (equal total scores) were excluded from the main frequentist analyses but were included in the total scores and the exploratory Bayesian Multinomial-Dirichlet model, which accounts for participants with no preference and informs on the relevance of the observed differences.3 The overall mean ages (± standard deviation) of the caregivers and children were 38.8 ± 7.9 years and 8.6 ± 2.9 years, respectively. Caregivers had previously administered insulin to children with a vial/syringe more often (56.9%) than with a prefilled delivery device (43.1%). Among caregivers with a preference (Table 1), the majority chose Pen A over Pen B for the three end points. Results were confirmed with the Bayesian analysis and in the total scores for all 65 caregivers (Table 1). In a final preference question, 80% of all 65 caregivers chose Pen A over Pen B. Table 1 Analyses of the Proportions of Caregivers Preferring Pen A/B or Having No Preference These results were consistent with findings of other studies with the same or similar reusable pens.4–6 Pen A and Pen B use different technologies for correcting a dose and changing an insulin cartridge, which may have contributed to overall ease of use. Differences in the functionality of these pens may have been difficult to discern because some caregivers had no pen preference. Study strengths include the randomized crossover design, subjects who were naive to reusable pens, and three analysis methods that confirmed the results. Study limitations included use of a nonvalidated questionnaire and simulated injections. In conclusion, Pen A is the reusable insulin pen preferred by adult caregivers over Pen B for injecting insulin in children with type 1 diabetes.