Early improvement as a predictor of eventual antidepressant treatment response in severely depressed inpatients

Rationale: Traditionally, the therapeutic effect of antidepressants is thought to take several weeks. However, several studies found evidence of early drug response occurring within the first 2 weeks of antidepressant treatment and that this early onset response may predict eventual treatment outcome. Objective: This study aims to investigate the predictive value of early improvement in the course of treatment with imipramine or venlafaxine in an inpatient population with severe major depression. Method: A post hoc analysis was conducted after pooling data from two almost identical trials. The study included 149 patients with DSM-IV diagnosis major depression and a baseline score ≥17 on the 17-item Hamilton Rating Scale for Depression (HAM-D). Patients were randomized for double-blind treatment with either antidepressant. Early improvement (≥25 % reduction on HAM-D score) was evaluated after 2 weeks and response (≥50 % reduction on HAM-D score) after 6 weeks of acute treatment. Results: Of 64 patients achieving early improvement, 38 (59 %) became responders, whereas of 85 patients not achieving early improvement, only 23 (27 %) became responders. There was a significant difference in time to response between patients achieving early improvement and patients not achieving early improvement. Early improvement is a modest sensitive predictor for eventual response. Conclusion: In the present study, although the sensitivity of early improvement was modest, based on the severity of clinical symptoms, a clinician treating a patient with severe major depression may seriously consider changing the treatment at an earlier stage than is presently customary.

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