Efficacy of continuation drug therapy of depression and anxiety: issues and methodologies.

Continuation treatment is the continued administration of a drug after disappearance of acute symptoms for the purpose of maintaining control over the episode. This critical phase of treatment constitutes a neglected area of research concerned with depression and anxiety disorders. Most therapeutic studies focus on the treatment of acute symptoms, using designs of only 4-8 weeks' duration. These studies provide little information on the effectiveness and use of continuation treatment for the duration of an episode, which may extend for months following control of acute symptoms. Furthermore, the relatively few continuation drug therapy studies deal primarily with depressive disorders, leaving anxiety disorders almost two decades behind depressive disorders in terms of published research in this critical area of treatment. This report reviews the current status of continuation drug treatment for anxiety and depression and examines research needs, issues, and problems. It also presents a design model for evaluating the need for and duration of continuation treatment for both depressive and anxiety disorders.