Blister packaging to support warfarin adherence in paediatric patients: A pilot retrospective study.

Introduction: Warfarin continues to be used in children for specific indications. Children must test their blood regularly and adherence to the medication routine can be highly challenging. Warfarin nonadherence has the potential for significant complications. Blister packaging (BP) is not commonly applied to warfarin therapy due to frequent dose titrations however BP may be useful in improving adherence.

Objective: To evaluate the efficacy of BP warfarin to determine its impact on outpatient management.

Methods: Retrospective chart review of children aged from 18 months to 18 years with suboptimal adherence transitioned to BP between 2021 and 2023. Data collected included international normalized ratio (INR) reminders, missed doses, bleeding or thrombotic events, and INRs for 6 months pre-/post-BP. Time in therapeutic range (TTR) analysis as a measure of safety and efficacy was used.

Results: Eleven charts were reviewed. Mean and median age were 11 and 9 years, respectively (4 to 17 range), nine female and two male. International normalized ratio reminders required decreased 30% pre-/post-BP initiation 84 (mean 7.6, range 0 to 18/child) and 59 (mean 5.4; range 1 to 15/child), respectively. Missed doses decreased by 20% pre-/post-BP 35 (mean 3.2; range 0 to 10) and 29 (mean 2.6; range 0 to 10), respectively. The TTR increased by a median of 11.61% from pre to post. This difference was not statistically significant (P-value from Wilcoxon signed rank test: 0.1602).

Conclusion: This study demonstrates that BP is a viable option that supports warfarin management. Caregivers described BP as beneficial with a trend to increased TTR and a decrease in healthcare provider workload.