Relationship between baseline severity of depression and antidepressant treatment outcome.

INTRODUCTION: Assessment of depression severity is of key importance, since several clinical guidelines recommend choice of treatment dependent on the depression severity grade. Using different tools to assess baseline severity may result in different outcomes. METHODS: This paper describes the results of a multicentre, naturalistic study investigating the relationship between depression symptom severity (using 4 different measures of symptom severity) and clinical outcome among patients hospitalised for depression (N=1 014). Moreover, the impact of differences between methods of measuring depression severity has been investigated. Statistical analyses (univariate measurements, logistic regression models) were conducted to detect coherences and differences between the various methods of severity categorisation. RESULTS: Results revealed different associations between outcome and classification methods. Response or remission rates varied if baseline severity was assessed by different instruments. Moreover, the number of responders increased with higher baseline severity grades of depression, whereas the number of remitters decreased. Additional analyses dependent on outcome criteria using continuous instead of categorical data revealed similar results. DISCUSSION: Baseline severity may be only one of many other important clinical variables that mediate clinical outcome, but it is surely an important one deserving further research and consideration.