Comorbidities and factors related to discontinuation of pharmacotherapy among outpatients with major depressive disorder

Objective: Although many studies have researched adherence to pharmacotherapy among patients with major depressive disorder (MDD), the effects of chronic depression, anxiety comorbidities, migraine, and other factors on adherence have rarely been studied. This study investigated which comorbidities and factors independently predicted discontinuation of pharmacotherapy among psychiatric outpatients with MDD. Methods: One hundred thirty-five subjects (34 men, 101 women) with MDD were enrolled. MDD and anxiety comorbidities were diagnosed using the Structured Clinical Interview for DSM-IV-TR (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision), migraine was diagnosed based on the International Classification of Headache Disorders, 2nd Edition, and depression severity was evaluated using the Hamilton Depression Rating Scale. Six months later, subjects' reasons for discontinuation were investigated, and Cox proportional hazards regression and logistic regression were used to investigate the independent factors predicting discontinuation. Results: Subjects with chronic depression, migraine, panic/agoraphobia, or posttraumatic stress disorder attended follow-up for longer before discontinuation than those without. Chronic depression and greater age independently predicted a longer follow-up before discontinuation. Concern about and intolerance of the side effects of antidepressants and lack of insight into MDD independently predicted discontinuation within 2 months. "Self-reported recovery" was the most common reason for discontinuation; however, 53.8% of the subjects who cited this reason did not reach full remission. Conclusions: The impact of the duration of depression (chronic depression) on adherence may be more important than the severity of depression, anxiety comorbidities, and migraine. Education of MDD patients and society in general to improve understanding of MDD and antidepressants is needed to enhance adherence to pharmacotherapy.