Suboptimal response to antidepressant therapy: definition and clinical implications

Introduction: Insufficient responses to antidepressant drugs can be an important problem, with negative clinical and psychosocial consequences. Materials and methods: On the basis of an extensive analysis of the existing literature, the authors provide a possible operational definition of suboptimal treatment response and review the available data on the frequency of this phenomenon and its implications. Results: A suboptimal response to antidepressant therapy is defined as a partial response or one that includes residual sub-threshold symptoms. These responses are associated with an increased risk for recurrence/relapses, shorter times to recurrence/relapse, higher risks of disease chronicity and suicidal tendencies, reduced functioning, and increases in the costs of care. Suboptimal responses are observed in approximately 70% of all patients after the first cycle of treatment, but with repeated attempts at treatment, this rate drops to approximately one third of cases. Conclusions: Given their frequency and negative consequences, suboptimal responses to antidepressant therapy can be a challenge for clinicians, and complex strategies (e.g., augmentation, add-on, or switching) are often needed to overcome the limitations of the treatment.