Adherence for members taking oral oncolytic agents undergoing dose modification strategies.

Abstract

e23058 Background: The use of oral oncolytic agents has transformed oncology care. Previous studies have reported that patient, treatment, and health system-related factors may influence adherence rates in patients prescribed oral oncolytic agents. The purpose of this study is to assess adherence rates in members of a large national pharmacy benefit manager taking oral oncolytic agents who experienced a modification to their dosing regimen. Methods: Adult members receiving palbociclib, abemaciclib, ribociclib, axitinib, lenvatinib, or cabozantinib between 01/01/2021 and 12/31/2022 were eligible for the study. Members who did not maintain continuous eligibility for 180 days prior to and 2 years after the first fill in the study period were excluded. Members were stratified by presence of dose modification, defined by a change in daily dose from one prescription to the next. Adherence was assessed via the proportion of days covered (PDC) which is the total days with medication coverage divided by the number of days between the index fill and exhaust of the final fill in the study period. Optimal adherence was defined as PDC ≥ 0.85. Standard statistical tests for continuous and categorical variables were utilized. Logistic regression was performed with the endpoint of optimal adherence. P values < 0.05 are significant. Results: 13,641 members were included in the final analysis, with 7,093 (52%) experiencing a modification to their dosing regimen during the study period. Several significant differences in sociodemographic variables were present in this study with members experiencing a dose modification being older (mean [standard deviation (SD)]: 65.7 [11.9] vs. 64.9 [13.0] yr; p < 0.001), more likely to be male (23.3% vs. 15.0%; p < 0.001), more likely to reside in high socioeconomic status (SES) regions (23.7% vs. 21.5%; p = 0.005) and more likely to receive tyrosine kinase inhibitors (TKIs) (37.6% vs. 23.6%; p < 0.001). Adherence was high overall with 74.6% of members achieving a PDC ≥ 0.85; however, members with dose modifications were less likely to be adherent (69.7% vs. 80.0%; p < 0.001). Holding other confounders constant, having a dose modification was associated with a decreased likelihood of adherence (Odds Ratio [95% Confidence Interval]: 0.6 [0.55-0.65]; p < 0.001). Conclusions: Dose modification was associated with significant decreases in adherence to oral oncolytic medications. Interventions designed to minimize dose modifications or to provide additional member support during a dose modification may optimize oral oncolytic adherence.