Prevalence and outcome of partial remission in depression

The goal of treatment of major depression should be full remission. Many patients, however, fail to achieve or maintain symptom-free status. Residual depressive symptoms are common, even where there has been a robust response to antidepressant therapy. In clinical studies, approximately one-third of patients achieve a full remission, one-third experience a response and one-third are nonresponders. Partial remission is characterized by the presence of poorly defined residual symptoms. These symptoms typically include depressed mood, psychic anxiety, sleep disturbance, fatigue and diminished interest or pleasure. It is currently unclear which factors predict partial remission. However, it is clear that residual symptoms are powerful predictors of relapse, with relapse rates 3-6 times higher in patients with residual symptoms than in those who experience full remission. Residual symptoms are also associated with more medical and psychiatric visits, increased public assistance, disability benefits, thoughts of and attempts at suicide and chronicity. The risk of stroke and coronary events is also higher in patients with residual depressive symptoms. The substantial proportion of patients who achieve only partial remission has traditionally been neglected in antidepressant trials. Given that residual symptoms may relate, in part, to an incompatibility between patient and treatment, further research is needed to predict a better match. These symptoms are a clinically relevant state of illness, and the correct choice of initial antidepressant treatment should offer the greatest chance of achieving full remission.