Effect of the initial combination approach vs initial monotherapy approach on 1-year trajectories of adherence in drug-naive patients with type 2 diabetes

BACKGROUND: The choice of initial pharmacotherapy approach may influence the medication-taking behavior of patients with type 2 diabetes (T2D). However, there remains a notable gap in the literature to assess the longitudinal adherence pattern of 2 treatment approaches, initial combination vs initial monotherapy with as-needed intensification. OBJECTIVE: To assess the impact of the initial combination therapy approach vs the initial monotherapy approach with as-needed intensification on adherence trajectories and factors associated with the trajectories. METHODS: Retrospective study using Merative MarketScan research databases (2017-2019). We have included continuously enrolled drug-naive patients with T2D who received initial monotherapy with as-needed intensification or initial combination therapy. Adherence was measured 12 months after the index date using the proportion of days covered (PDC). Monthly PDC was incorporated into a logistic group-based trajectory model, and patients were categorized into trajectory groups. A multinomial logistic regression model was conducted to examine the association of the diabetes management approach (combination vs initial monotherapy with as-needed intensification) on resultant adherence trajectory, adjusting for baseline characteristics. RESULTS: We identified 116,597 Commercial/Medicare and 18,295 patients with Medicaid insurance. The 4-group and 3-group trajectory models for Commercial/Medicare and Medicaid patients, respectively, were selected. Within 1-year follow-up period, odds of lower adherence trajectories were higher for patients receiving initial combination therapy vs initial monotherapy with as-needed intensification group in both populations (Commercial/Medicare; rapid decline: odds ratio [OR] = 1.73, 95% CI = 1.65-1.8; gradual decline: OR = 1.50, 95% CI = 1.41-1.60; gaps in adherence: OR = 1.40, 95% CI = 1.31-1.45; Medicaid; rapid decline trajectory: OR = 1.32, 95% CI = 1.16-1.50). CONCLUSIONS: Findings highlighted better adherence patterns among patients receiving initial monotherapy with as-needed intensification compared with initial combination therapy during 1-year post-treatment initiation.