Objective: Sodium-glucose co-transporter 2 inhibitors were first approved in the US in 2013; therefore, real-world (RW) studies describing outcomes are limited. This retrospective study evaluated adherence and persistence among patients initiating canagliflozin (CANA), dapagliflozin (DAPA), GLP-1 agonists (GLP-1s), and DPP-4 inhibitors (DPP-4s) over a 12-month follow-up from a US managed care perspective.
Methods: Patients newly initiating CANA, DAPA, GLP-1s, or DPP-4s from February 1, 2014-June 30, 2014 were identified from the QuintilesIMS PharMetrics Plus Database. The first fill defined the index date/drug. Patients were required to have a T2DM diagnosis (ICD-9-CM 250.x[0,2]) and ≥12 months of continuous enrollment pre- and post-index (follow-up). Main outcome measures were adherence (proportion of days covered, PDC; medication possession ratio, MPR) and persistence on index therapy. PDC or MPR ≥0.80 was considered adherent. Patients were considered persistent until evidence of discontinuation (gap ≥90 days between two subsequent index therapy prescriptions). Kaplan-Meier (KM) analysis assessed time to discontinuation, while a Cox proportional hazards model (PHM) evaluated risk of discontinuation. Logistic regression models evaluated the likelihood of non-adherence.
Results: The final sample consisted of 23,702 patients (6,546 CANA, 3,087 DAPA, 6,273 GLP-1s, and 7,796 DPP-4s; 56% male, and mean [SD] age = 55 [9.1] years). Mean PDC ranged from 0.56 (GLP-1), to 0.71 (CANA), with 33-56% adherent, respectively; MPR results were similar. Fifty-two per cent (GLP-1) to 68% (CANA) were persistent over the follow-up. CANA patients had the longest time to discontinuation. In regression analyses, compared to CANA 100 mg, DAPA, DPP-4, and GLP-1 patients had a significantly higher likelihood of non-adherence and a significantly higher risk of discontinuation. CANA 300 mg patients had a significantly lower likelihood of non-adherence and a significantly lower risk of discontinuation compared to CANA 100 mg.
Conclusions: Adherence and persistence were significantly better with CANA (100 mg and 300 mg) compared to DAPA, GLP-1s, and DPP-4s in the RW setting.
Keywords: Diabetes mellitus; canagliflozin; dapagliflozin; medication adherence; persistence; retrospective studies; sodium-glucose transporter 2 inhibitors; type 2.