Medication adherence and persistence in the treatment of Canadian ulcerative colitis patients: analyses with the RAMQ database

BACKGROUND Although high non-adherence to medication has been noticed for ulcerative colitis (UC), little is known about adherence to mesalamine treatments and determinants that can predict adherence. The objective of this study was to assess adherence and persistence to mesalamine treatments and their potential determinants in mild to moderate UC patients in a real-life setting in Quebec, Canada. METHODS A retrospective prescription and medical claims analysis was conducted using a random sample of mesalamine users with UC. For inclusion, patients were required to initiate an oral mesalamine treatment between January 2005 and December 2009. Patients with a diagnosis of Crohn's disease were excluded. Treatment adherence (medication possession ratio [MPR]) and persistence were evaluated over a 1-year period after the index prescription using the Kaplan-Meier method with log-rank test and stepwise regression to identify potential determinants. RESULTS A sample of 1,681 of the new oral mesalamine users (mean age = 55.3) patients was obtained. Overall, the percentage of patients with a MPR of 80% or greater at 12 months was 27.7%, while persistence was 45.5%. Among patients treated with mesalamine delayed/extended-release tablets (Mezavant®), adherence and persistence were 40.9% and 71.9%, respectively. Predictors of high adherence included, male gender (OR=1.3; 95% confidence interval [CI]=1.1-1.6), older age (>60 years; OR=1.6; 95% CI=1.3-2.0) and current use of corticosteroids (OR=1.4; 95% CI=1.1-1.8). Predictors of high persistence included male sex (OR=1.4; 95% CI=1.1-1.7), current use of corticosteroids (OR=1.4; 95% CI=1.1-1.7) and presence of hypertension or respiratory diseases (OR=1.2; 95% CI=1.01-1.55). CONCLUSIONS The majority of patients with UC exhibited low adherence and persistence to mesalamine treatments. Various determinants of improved adherence and persistence were identified.