Group-Based Trajectory Modeling to Identify Longitudinal Patterns of Adherence to Oral Antidiabetic Medication in Older Adults on Concomitant Triple Therapy (Oral Antidiabetics, RAS Antagonists, Statins)

OBJECTIVES: Diabetes, hypertension, and hyperlipidemia frequently occur together in older adults, and the coexistence of these conditions significantly increases the risk of cardiovascular outcomes. Medication adherence is instrumental in decreasing these risks but becomes more challenging given the increased regimen complexity with concomitant triple therapy. Compared to single estimates of the proportion of days covered (PDC), group-based trajectory modeling (GBTM) can graphically display the dynamic nature of adherence and depict patient adherence behavior patterns. The objective of this study was to evaluate adherence to oral antidiabetics (OADs) using GBTMs among elderly patients on concomitant triple therapy.

METHODS: Patients on concurrent triple therapy were identified using a Texas Medicare Advantage dataset from July 2016 to December 2016 with continuous enrollment. Patients had to have an overlap of 30 days of triple therapy as per the STAR metrics, including renin-angiotensin system antagonists (antihypertensives), oral antidiabetics, and statins, a second prescription of each component of triple therapy within the identification period, and a 12 month follow up after the triple therapy. Monthly OAD adherence was measured using PDC during the 1-year follow-up period. Patients were defined as adherent if they had ≥80% (24 out of the 30 days) covered for any OADs. The monthly PDC of OADs medication was incorporated into a logistic GBTM to provide distinct patterns of adherence. Two-five adherence groups were estimated using the second-order polynomial function of time.

RESULTS: A total of 10,201 concurrent triple therapy users were identified. Based on Bayesian information criteria, clinical relevance, and 5% minimum membership criteria the model with 4 distinct trajectories of adherence was selected. The 3-groups included gradual decline (12.3%), adherent (34.6%), and near perfectly adherent (53.1%).

CONCLUSIONS: Identifying adherence patterns to OADs in concomitant triple therapy patients can provide insight into adherence behavior and guide the development of tailored interventions.