Persistence Patterns with Oral Antidiabetes Drug Treatment in Newly Treated Patients-A Population-Based Study

Objective: We assessed persistence patterns with oral antidiabetes drug (OAD) in patients newly dispensed with different OAD classes. Methods: We conducted a population-based cohort study using Quebec Health Insurance Board data. Patients aged 18 years or more newly dispensed an OAD between January 1, 1998 and December 31, 2003 were included in the study (n = 98,940). Persistence was defined as consistently refilling a prescription for the initial OAD within three times the days' supply of the preceding claim. For nonpersistent patients, a second course of therapy was defined as treatment initiation with any OAD after a first discontinuation. Patients were followed from treatment initiation up to December 31, 2004, ineligibility for the drug plan or death, whichever came first, and treatment discontinuation or second course of treatment. Cox regression models were used to compute adjusted hazards ratios (AHR) of persistence and initiation of second courses of therapy. Results: The probability of persisting with the initial OAD over a 12-month period was 65% and 56% for patients initiated on metformin and sylfonylurea, respectively. Compared to metformin, the likelihood of discontinuing the initial OAD over the study period was significantly higher for patients on sulphonylureas (AHR: 1.32; 95% CI 1.29-1.34). Patients started on sulphonylureas were also less likely to start a second course of therapy after a first treatment discontinuation (AHR: 0.91; 95% CI 0.89-0.93). Conclusions: Compared to diabetic patients initiated on metformin, those initiated on sulphonylureas displayed poorer persistence patterns.