Patients with similar adherence at the end of a time period may exhibit different adherence patterns over time. Group-based trajectory modeling (GBTM) can provide detailed information about longitudinal adherence patterns.
To identify clusters of patients with multiple sclerosis (MS) covered by commercial or Medicare Advantage with Part D (MAPD) insurance with similar patterns of adherence to once- or twice-daily oral disease-modifying drugs (DMDs) over time.
This retrospective study used administrative claims and merged sociodemographic and data from commercial and MAPD enrollees in the Optum database. Eligibility criteria were: ≥1 once-/twice-daily oral DMD claim between January 1, 2014–July 31, 2018 (index); ≥3 MS-related (ICD-9 CM code 340.xx and ICD-10 CM code G35) ambulatory visits, inpatient stays, or DMD claims during a 12-month period; continuous 12-month eligibility with commercial/MAPD insurance before/after index; no baseline oral DMD; and age ≥18 years. Individuals following similar longitudinal progressions of adherence (proportion of days covered [PDC]) were “clustered” together using GBTM. The optimal number of groups best representing the heterogeneity in trajectories was selected considering Extract Log-Likelihood, Akaike information criterion, Bayesian information criterion, and visual assessment of the resulting trajectory groups.
A total of 3683 patients met eligibility criteria (mean [SD] age: 48.8 [11.8] years; female: 74.8%; commercial insurance: 69.6%; MAPD: 30.4%). Mean PDC was 0.71 for commercial and 0.70 for MAPD. GBTM revealed 3 distinct adherence groups: ‘Immediately Non-Adherent’ (mean PDC <0.3 by Month 3), ‘Gradually Non-Adherent’ (mean PDC=0.8 at Month 3 but ≤0.4 by Month 8), and ‘Adherent’ (mean PDC ≥0.8 through the 12-month post-index period), comprising 18.7%, 18.3%, and 62.9% of patients, respectively. Statistically significant differences in patient pre-index characteristics observed across the 3 adherence groups included sex, household income, net worth, comorbid conditions, number of relapses, non-oral DMD utilization, and number of office and ER visits.
This trajectory analysis in patients with MS receiving once- or twice-daily oral DMDs revealed three distinct longitudinal patterns of adherence associated with specific patient characteristics and healthcare resource utilization. Different groups may warrant different clinical interventions to address nonadherence.