Assessment of outcome in depression

Valid and reliable methods of assessing outcome in depression are crucial to antidepressant efficacy studies but are also important for all studies that relate response to other variables. In this paper we review basic issues of reliability and validity associated with outcome measurement. We distinguish between scales or inventories designed for screening or diagnosis and those intended for outcome assessment. We note historical changes in patient selection (e.g. outpatients instead of inpatients, differentiating psychotic and non-psychotic) and how these changes affect commonly used scales such as the Hamilton Depression Rating Scale. We examine whether antidepressants with different mechanisms of action are best assessed with similar or different symptoms. And we review studies that have identified 'core' symptoms of depression and compare these findings to the magnitude of individual symptom change we found in five studies of selective serotonergic or nonadrenergic antidepressants.