title: Retrospective analysis of long-term adherence to and persistence with DPP-4 inhibitors in US adults with type 2 diabetes mellitus.
abstract: BACKGROUND
  Patients with type 2 diabetes mellitus (T2DM) must remain adherent and persistent on antidiabetic medications to optimize clinical benefits. This analysis compared adherence and persistence among adults initiating dipeptidyl peptidase-4 inhibitors (DPP-4is), sulfonylureas (SUs), and thiazolidinediones (TZDs) and between patients initiating saxagliptin or sitagliptin, two DPP-4is.
  
  
  METHODS
  This retrospective cohort study utilized the US MarketScan(®) (Truven Health Analytics, Ann Arbor, MI, USA) Commercial and Medicare Supplemental health insurance claims databases. Adults aged ≥18 years with T2DM who initiated a DPP-4i, SU, or TZD from January 1, 2009 to January 31, 2012 were included. Patients must have been continuously enrolled for ≥1 year prior to and ≥1 year following initiation. Adherence was measured using proportion of days covered (PDC), with PDC ≥ 0.80 considered adherent. Persistence was measured as time to discontinuation, defined as last day with drug prior to a 60+ days gap in therapy. Multivariable logistic regression and Cox proportional hazards models compared the outcomes between cohorts, controlling for baseline differences.
  
  
  RESULTS
  The sample included 238,372 patients (61,399 DPP-4i, 134,961 SU, 42,012 TZD). During 1-year follow-up, 47.3% of DPP-4i initiators, 41.2% of SU initiators, and 36.7% of TZD initiators were adherent. Adjusted odds of adherence were significantly greater among DPP-4i initiators than SU (adjusted odds ratio [AOR] = 1.678, P < 0.001) and TZD initiators (AOR = 1.605, P < 0.001). During 1-year follow-up, 55.0% of DPP-4i initiators, 47.8% of SU initiators, and 42.9% of TZD initiators did not discontinue therapy. Adjusted hazards of discontinuation were significantly greater for SU (adjusted hazard ratio [AHR] = 1.390, P < 0.001) and TZD initiators (AHR = 1.402, P < 0.001) compared with DPP-4i initiators. Saxagliptin initiators had significantly better adherence (AOR = 1.213, P < 0.001) compared with sitagliptin initiators, and sitagliptin initiators had significantly greater hazard of discontinuation (AHR = 1.159, P < 0.001). Results were similar over a 2-year follow-up.
  
  
  CONCLUSIONS
  US adults with T2DM who initiated DPP-4i therapy, particularly saxagliptin, had significantly better adherence and persistence compared with patients who initiated SUs or TZDs.
authors.affiliation: Truven Health Analytics, 7700 Old Georgetown Road, 6th Floor, Bethesda, MD, 20814, USA, amanda.farr@truvenhealth.com.
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Farr
authors.forename: John J
authors.initials: JJ
authors.lastname: Sheehan
authors.forename: Suellen M
authors.initials: SM
authors.lastname: Curkendall
authors.forename: David M
authors.initials: DM
authors.lastname: Smith
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Johnston
authors.forename: Iftekhar
authors.initials: I
authors.lastname: Kalsekar
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000453:epidemiology; D004151:Dipeptides / Q000627:therapeutic use*; D054873:Dipeptidyl-Peptidase IV Inhibitors / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D016015:Logistic Models; D008134:Long-Term Care / Q000706:statistics & numerical data; D008297:Male; D006278:Medicare / Q000706:statistics & numerical data; D008875:Middle Aged; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D000068900:Sitagliptin Phosphate / Q000627:therapeutic use*; D013453:Sulfonylurea Compounds / Q000627:therapeutic use*; D014481:United States / Q000453:epidemiology; D016903:Drug Monitoring
chemical_list: D004151:Dipeptides; D054873:Dipeptidyl-Peptidase IV Inhibitors; D007004:Hypoglycemic Agents; D013453:Sulfonylurea Compounds; C502994:saxagliptin; D000218:Adamantane; D000068900:Sitagliptin Phosphate