Evaluation of medication compliance in patients on antidepressants at an outpatient tertiary cancer center setting.

Objective: The purpose is to evaluate antidepressant compliance in a cancer population at a tertiary cancer center and to determine if there are covariates of importance in predicting the level of compliance in the study population.

Methods: Patients who received at least three prescriptions covering parts of each month for a continuous 6-month period with at least one of the months being in 2006 from a tertiary cancer center were identified as the prevalent population of interest for this retrospective study. Data collected included demographics, cancer and co-morbid diagnoses, and compliance to antidepressant medication using medication possession ratio (MPR) by patient, medication class, and individual agents. Analysis was conducted using descriptive statistics, analysis of variance, and logistic regression (using MPR ≥ 80 as cutoff).

Results: The study population included 297 patients with demographics showing 69% female, 71% Caucasian, a mean age of 52.94 (SD: 12.42), and an average 403 days of follow-up. The MPR for the total study population was 0.87 with 78% of the population having an MPR of ≥ 80% and 22% having an MPR of less than 80%. While there was no significant difference in MPR by different pharmaceutical classes, there were significant differences in the MPR by specific agents (p = 0.02), with nortriptyline having the lowest MPR of 0.79 and doxepin, fluoxetine, mirtazapine, and venlafaxine all having MPR over 0.90. There was also a trend toward a difference in MPR between Caucasians versus non-Caucasians, p = 0.055.

Conclusion: There appears to be relatively good compliance to antidepressant medications in the study population.