Adherence and Persistence with DPP-4 Inhibitors Versus Pioglitazone in Type 2 Diabetes Patients with Chronic Kidney Disease: A Retrospective Claims Database Analysis

Abstract

BACKGROUND: Adherence and persistence with diabetes medication play an important role in glycemic control and may differ by medication class. However, there is a lack of research comparing diabetes medications in patients with renal impairment, despite the challenges and higher burden associated with managing this population. OBJECTIVE: To compare adherence and persistence among patients with type 2 diabetes mellitus (T2DM) and nondialysis chronic kidney disease (CKD) treated with dipeptidyl peptidase-4 (DPP-4) inhibitors versus pioglitazone. METHODS: This retrospective cohort study used Truven MarketScan administrative claims databases from 2009 to 2015. One-year adherence for patients with T2DM and nondialysis CKD who initiated therapy with either a DPP-4 inhibitor or pioglitazone was measured by proportion of days covered (PDC) following an initial dispensing, and PDC ≥ 0.80 was coded as adherent. Persistence was calculated as the days between the index date and last day with the index medication on hand, based on the end of the last days supply or the end of follow-up (i.e., 365 days), whichever occurred first. Multivariate logistic regression and Cox proportional hazards models were used to estimate confounder-adjusted differences between the groups for adherence and persistence. RESULTS: The final cohort included 9,019 patients (DPP-4 inhibitors: 7,002; pioglitazone: 2,017). In the adjusted analysis, DPP-4 inhibitor users demonstrated a 1.41 (95% CI = 1.25-1.59) higher odds of being adherent compared with pioglitazone users. Overall adjusted HR for persistence was 0.74 (95% CI = 0.69-0.79), which favored DPP-4 inhibitors compared with pioglitazone. Relative to 2010, persistence with pioglitazone decreased in 2011-2012 and then increased in 2013-2014. In the subgroup analysis, DPP-4 inhibitors first had lower (2010: OR = 0.78, 95% CI = 0.70-0.87; 2011-2012: OR = 0.60, 95% CI = 0.54-0.66) and then similar (2013-2014: OR = 1.03, 95% CI = 0.88-1.19) hazards of nonpersistence compared with pioglitazone. CONCLUSIONS: Among patients with T2DM and nondialysis CKD, the use of DPP-4 inhibitors was associated with better adherence compared with pioglitazone. However, following the approval of generic pioglitazone and associated lower cost sharing after 2012, the magnitude of difference in adherence between the medication classes reduced. Similarly, safety warnings in 2011 and approval of generic products in 2012 may have affected pioglitazone persistence, leading to first higher and then similar hazards for nonpersistence with pioglitazone as compared with DPP-4 inhibitors. These shifts in the results for pioglitazone warrant further investigation and close monitoring of the population initiating this medication. DISCLOSURES: No funding was received for this study. The authors have no conflicts of interest to disclose. An abstract for this study was presented as a podium presentation at the International Society of Pharmacoeconomics and Outcomes Research (ISPOR) 2019 Annual Meeting; May 18-22, 2019; New Orleans, LA.