Impact of Medication Adherence and Persistence on Clinical and Economic Outcomes in Patients with Type 2 Diabetes Treated with Liraglutide: A Retrospective Cohort Study

INTRODUCTION: Adherence to diabetes medication has been linked to improved glycemic levels and lower costs, but previous research on adherence has typically involved oral antidiabetic medication or insulin. This study examines how adherence and persistence to once-daily liraglutide impact glycemic control and economic outcomes in a real-world population of adult type 2 diabetes (T2D) patients. METHODS: A retrospective cohort study using administrative claims data from July 2009 through September 2013. Patients aged ≥18 years with T2D treated with liraglutide were identified (index date = first liraglutide prescription). Adherence was based on the proportion of days covered (PDC); with PDC ≥0.80 classified as adherent. Non-persistent patients were those with a gap in therapy of >90 days. Lab results for glycated hemoglobin (A1C) were used to identify whether patients achieved target levels of <7.0% and ≤ 6.5%, or experienced a reduction of ≥1.0% in A1C from pre-index (baseline) to post-index (follow-up). Logistic regression was used to estimate the likelihood of achieving the A1C goals, adjusted for baseline characteristics. Diabetes-related medical, pharmacy, and total costs were modeled and estimated for the adherence and persistence cohorts. RESULTS: A total of 1321 patients were identified. The mean PDC was 0.59 and 34% of patients were classified as adherent, while 60% were persistent over 12 months of follow-up. Adherent and persistent patients were more likely to achieve each of the A1C goals than their non-adherent and non-persistent counterparts after adjusting for patient characteristics. Adherence and persistence were associated with higher adjusted diabetes-related pharmacy and total healthcare costs during follow-up; whereas persistent patients had significantly lower diabetes-related medical costs than non-persistent patients. CONCLUSIONS: Adherence and persistence to liraglutide are associated with improved A1C outcomes. Persistent patients showed significantly lower medical costs versus those discontinuing liraglutide. Total healthcare costs were higher for adherent and persistent cohorts driven by higher pharmacy costs.