title: An observational study examining the effect of comorbidity on the rates of persistence and adherence to newly initiated oral anti-hyperglycaemic agents.
abstract: OBJECTIVE
  To examine whether the type of comorbid condition affects medication persistence and adherence in patients initiating oral anti-hyperglycaemic (OAH) therapy.
  
  
  METHODS
  The Irish Health Services Executive pharmacy claims database was used to identify a cohort of incident OAH therapy users (anatomical therapeutic chemical A10B), ≥25 years, between June 2009 and December 2010. Persistence and adherence were examined at 6 and 12 months post-therapy initiation. Comorbidity was ascertained using modified versions of the RxRisk and RxRisk-V indices and classified as either concordant or discordant with diabetes. Adjusted odds ratios (ORs) and 95% confidence intervals (95%CIs) were determined in relation to comorbidity using logistic regression analysis, adjusting for age, gender and type of OAH prescribed.
  
  
  RESULTS
  In the study cohort (n = 21 280), persistence was 74.0% and 62.6% and adherence was 70.0% and 66.7% for all OAHs at 6 and 12 months, respectively. Patients with only concordant comorbidity were significantly more likely to be persistent at 6 (OR 1.45, 95%CI 1.28, 1.65) and 12 months (OR 1.22, 95%CI 1.09, 1.38). Patients with only discordant comorbidity were significantly less likely to be persistent at 6 (OR 0.40, 95%CI 0.35, 0.46) and 12 months (OR 0.43 95%CI 0.38, 0.50) (p < 0.0001). Results were similar for adherence.
  
  
  CONCLUSIONS
  The study suggests that the persistence and adherence of OAH therapy in incident users are affected by the type of comorbidity present; this may help in identifying effective interventions aimed at optimising medication use.
authors.affiliation: Trinity College Dublin, Dublin, Ireland.
authors.forename: Miriam P
authors.initials: MP
authors.lastname: O'Shea
authors.forename: Mary
authors.initials: M
authors.lastname: Teeling
authors.forename: Kathleen
authors.initials: K
authors.lastname: Bennett
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D015897:Comorbidity; D016208:Databases, Factual; D003920:Diabetes Mellitus / Q000188:drug therapy / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D007494:Ireland / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D015995:Prevalence; D012189:Retrospective Studies; D016903:Drug Monitoring
chemical_list: D007004:Hypoglycemic Agents
keywords: adherence; comorbidity; oral anti-hyperglycaemic therapy; persistence; pharmacoepidemiology; type 2 diabetes