Adherence and discontinuation of prescription cannabidiol for the management of seizure disorders at an integrated care center

Abstract

Objective: Evaluate adherence, discontinuation rates, and reasons for non-adherence and discontinuation of prescription CBD during the 12-months post-initiation period at an integrated care center.

Methods: This was a prospective study of patients prescribed CBD by a neurology clinic provider with initial prescription fulfillment through the center's specialty pharmacy from January 2019 through April 2020. Baseline demographics and reasons for non-adherence and/or discontinuation were collected from the electronic health record and pharmacy claims history was used to calculate adherence using proportion of days covered (PDC). Patients were included in the PDC analysis if they had at least 3 fills during the study period. Non-adherence was defined as a PDC < 0.8. Descriptive statistics were used to summarize data with categorical variables represented as frequencies and percentages and continuous variables as medians and interquartile ranges (IQRs).

Results: We included 136 patients with a median age of 14 years (IQR 9 - 21). Most patients were white (n = 115, 85%), with a diagnosis of intractable epilepsy (n = 100, 74%). Among the 128 patients with 3 or more fills, the median PDC was 0.99 (IQR 0.95 - 1.00) with non-adherence seen in 6% (n = 8) of patients. The most common reason for non-adherence was side effects (n = 2, 25%). Prescription CBD was discontinued by 23% (n = 31) of patients with a median time to discontinuation of 117 days (IQR 68 - 216). The most common reason for discontinuation was major side effects (n = 12, 39%). The most common side effects leading to discontinuation were agitation/irritability (n = 4), mood changes (n = 4), aggressive behavior (n = 3), and increased seizure frequency (n = 3).

Conclusion: Adherence to prescription CBD at an integrated care center was high with approximately 94% of patients considered adherent. Providers and pharmacists may improve adherence and discontinuation rates by educating patients on the timeline of response, potential side effects, and potential for dose adjustments.

Keywords: ASM; Drug resistant epilepsy; Epidiolex; Epilepsy; Medication adherence; Persistence.