(B-094) Group-Based Trajectory Modeling to Assess Adherence to Chronic Urate-Lowering Therapies Among Commercially Insured US Adults with Gout

Background: The benefits of urate-lowering therapies (ULTs), such as allopurinol and febuxostat, for managing gout are well established, but suboptimal adherence remains a challenge. Given conflicting evidence regarding factors associated with ULT adherence, it is important to understand longitudinal adherence trajectories and identify factors associated with these trajectories in order to inform interventions aimed at improving adherence.

Objectives: To identify distinct ULT adherence trajectories in a US commercially-insured population and to determine demographic and clinical factors associated with each trajectory.

Methods: This retrospective cohort study used a 25% random sample from the IQVIA PharMetrics® Plus for Academics database. We identified individuals with a first index ULT prescription from 2017-2020. Inclusion criteria were a gout diagnosis in at least one inpatient or two outpatient visits in the year prior to the index ULT and continuous medical and prescription coverage one year before and after the index ULT. Proportion of days covered measured adherence in each of the 12 months post-index ULT. Group-based trajectory modeling identified the number of distinct trajectories that best fit the data. The best model minimized the Bayesian information criterion, had posterior probabilities >0.7 and group size >5%. Multinomial logistic regression identified factors associated with trajectory membership. Adjusted odds ratios (aOR) measured strength of association, and 95% confidence intervals (CI) determined statistical significance.

Results: We categorized 9,404 individuals into four ULT adherence trajectories: early decline (14.97%), high-then-low (7.95%), consistently moderate (16.57%), and continuously high (60.51%). The early decline trajectory was less likely to be >61 years-old relative to the continuously high trajectory (aOR: 0.50[0.41-0.61] 61-75 years and aOR: 0.62[0.47-0.82] 75+ years). The high-then-low and the consistently moderate trajectories were also less likely to be >61 years-old relative to the continuously high trajectory, with similar aORs and 95% CIs. Females were more likely to be in the early decline (aOR: 1.26[1.07-1.48]) and high-then-low (aOR: 1.27[1.04-1.57]) trajectories. Baseline use of gout flare medications was more likely in the early decline (aOR: 1.28[1.11-1.47] colchicine; aOR: 1.62[1.42-1.84] NSAIDs; aOR: 1.27[1.11-1.44] oral glucocorticoids), high-then-low (aOR: 1.48[1.24-1.77] colchicine; aOR: 1.25[1.06-1.47] NSAIDs), and consistently moderate trajectories (aOR: 1.24[1.08-1.42] colchicine; aOR: 1.24[1.10-1.40] NSAIDs).

Conclusions: Younger age, female sex, and users of gout flare medications could benefit from targeted ULT adherence-improving interventions.