OBJECTIVES : The objective of the study was to compare adherence and persistence among patients with Type 2 Diabetes Mellitus (T2DM) and Chronic Kidney Disease (CKD) treated with Dipeptidyl Peptidase-4 (DPP-4) inhibitor versus pioglitazone.

METHODS : This retrospective cohort study used Truven MarketScan® administrative claims databases from 2009-2015. One-year adherence for patients with T2DM and non-dialysis CKD who initiated therapy with either a DPP-4 inhibitor or pioglitazone was measured by the Proportion of Days Covered (PDC) following an initial dispensing and PDC ≥ 0.80 was coded as adherent. Persistence was calculated as the number of days between the first dispensing and the beginning of a gap of two times the days supply or the end of the last days supply or 365 days, whichever came first. Multivariate logistic regression and cox-proportional hazard models were used to estimate confounder-adjusted differences between the groups for adherence and persistence, respectively.

RESULTS : The final cohort included 9,019 patients (DPP-inhibitor: 7002; pioglitazone: 2017). In the adjusted analysis, DPP-4 inhibitor users demonstrated a 1.41 (95% Confidence Interval (C.I.) 1.25-1.59) higher odds of being adherent compared to pioglitazone users. The adjusted hazard ratio for persistence differed by index year. Relative to 2010, persistence with pioglitazone decreased in 2011/2012 and then increased in 2013/2014. The DPP-4 inhibitors first had lower (2010: 0.78 (95% C.I. 0.70- 0.87), 2011/2012: 0.60 (95% C.I. 0.54- 0.66)), and then similar (2013/2014: 1.03 (95% C.I. 0.88- 1.19)) hazards of non-persistence compared to pioglitazone.

CONCLUSIONS : Among patients with T2DM and non-dialysis CKD, the use of DPP-4 inhibitors was associated with better adherence compared to pioglitazone. Safety warnings in 2011 and approval of generic products in 2012 may have impacted pioglitazone persistence. This inconsistent results for persistence with pioglitazone warrant further investigation.