Predictors of nonadherence to continuation and maintenance antidepressant medication in patients with remitted recurrent depression

OBJECTIVE: To identify predictors of nonadherence to continuation and maintenance antidepressant medication among patients with remitted recurrent depression.

METHOD: We used data of 91 remitted, recurrently depressed patients (at least 2 major depressive episodes as assessed by the Structured Clinical Interview for DSM-IV Axis I Disorders) treated with continuation and maintenance antidepressant medication in a 2-year prospective study. Patients were recruited at psychiatric centers and through media announcement from February 2000 through September 2000. Adherence was assessed with the Medication Adherence Questionnaire. Nonadherence on this scale indicates that patients missed 20% or more of their antidepressant medication. We determined nonadherence point prevalences at the 7 assessment points. Based upon these 7 assessments, we found nonadherence percentages ranging from 39.7% to 52.7% with a mean of 46.5% over 2 years. We examined a set of potential risk factors (patient-related, disease-related, and treatment-related) measured at baseline.

RESULTS: In univariate analysis using a stringent significance level (p <or= .005), we found no independently related predictors of nonadherence over a 2-year period. In a multivariate analysis with backward elimination, the baseline predictors for nonadherence over a 2-year period were a higher level of personality pathology and a higher level of education.

CONCLUSION: There are no clear predictors of nonadherence to antidepressants in the continuation and maintenance phases in remitted, recurrently depressed patients. Further research should focus on the process of becoming nonadherent to antidepressants in the longest phase of antidepressant use to maximize the potential protective effect of these medications.