Introduction: Greater adherence to medications has been broadly demonstrated to be associated with improved clinical outcomes. However, there is limited real-world evidence on adherence to glucagon-like peptide-1 receptor agonist (GLP-1RA) therapy in patients with type 2 diabetes mellitus (T2DM).
Methods: This retrospective cohort study used United States administrative claims data to compare adherence to GLP-1RAs in T2DM patients initiating exenatide once weekly (QW), exenatide twice daily (BID), or once-daily liraglutide (initiated therapy = index therapy). Patients were included if they had T2DM, were GLP-1RA-naïve, initiated a GLP-1RA from 02/01/2012-01/31/2013 (date of initiation = index), were ≥18 years at index, and had continuous enrollment for 12 months before (baseline) to 6 months after index (follow-up). Study outcome was index GLP-1RA adherence (proportion of days covered [PDC] during follow-up, dichotomized at ≥80% vs. <80%, and at ≥90% vs. <90%). Multivariable logistic regressions compared adherence between the GLP-1RAs, adjusting for potential confounders. Sensitivity analyses were performed separating liraglutide by dose (1.2 mg/1.8 mg).
Results: Study sample included 4,041 exenatide QW, 4,586 exenatide BID, and 14,211 liraglutide (6,641 1.2 mg, 7,570 1.8 mg) patients. Median unadjusted PDC values were 0.783 for exenatide QW, 0.500 exenatide BID, 0.722 liraglutide, 0.761 liraglutide 1.2 mg, and 0.683 liraglutide 1.8 mg. Compared with patients treated with either exenatide BID or liraglutide, patients treated with exenatide QW had a statistically significantly greater multivariable-adjusted odds of achieving adherence of ≥80% (odds ratio vs. exenatide QW (OR) = 0.41 for exenatide BID; 0.80, liraglutide; 0.87, liraglutide 1.2 mg; 0.75, liraglutide 1.8 mg) and ≥90% (OR = 0.31 for exenatide BID; 0.60 liraglutide; 0.66 liraglutide 1.2 mg; 0.56 liraglutide 1.8 mg) (all P < 0.001).
Conclusion: Patients initiating exenatide QW had significantly higher adjusted odds of adherence compared with patients initiating other GLP-1RAs. Given differences in adherence across the GLP-1RAs, research correlating these factors with clinical and economic outcomes is warranted.