The Association between Depression and Medication Nonpersistence in New Users of Antidiabetic Drugs

Objectives To measure the association between depression and nonpersistence with antidiabetic drugs (ADs) among new users of oral ADs and to estimate factors associated with nonpersistence among these new users with depression. Methods We used administrative claims data to identify an adult cohort (≥18 years) of new oral AD users who were free of depression. We followed the patients from AD initiation until either discontinuation, ineligibility for the public drug plan, death, or the end of the study. A proportional hazard Cox regression model with depression as a time-dependent variable was used to compute the adjusted hazard ratio of nonpersistence. A proportional hazard Cox regression model was also used to identify factors associated with nonpersistence in the subcohort of patients with depression. Results We identified 114,366 new oral AD users, of whom 4,808 were diagnosed with depression during the follow-up. A greater proportion (55.4%) of patients with depression (vs. 42.5% without depression) discontinued their treatment during the follow-up. The adjusted hazard ratio of nonpersistence with ADs was 1.52 (95% confidence interval 1.41–1.63). Among patients with depression, independent factors associated with nonpersistence included younger age at oral AD initiation (<45 years) and starting treatment with drugs other than metformin (especially polytherapy with insulin). Conclusions Patients with depression are more likely to discontinue their treatment. Health care professionals should pay attention to patients on AD therapy who also suffer from depression, especially if the patients are young or are using insulin because these patients are at an increased risk of nonpersistence.