Early and intermediate responses as factors predicting efficiency of antidepressive agents

An important limitation in the treatment of depression is the lack of reliable factors for predicting treatment response. Most of these factors have been related to biological and clinical aspects. A clinical aspect that has proved to reasonably predict long-term efficacy is early response. An adequate early response predicts a good outcome at the long term. The purpose of this study was to quantify the proportion of patients who show no response to a fixed dose of antidepressants after 2,4, and 6 weeks of treatment, and then respond by week 8. Additionally, a subgroup of patients was followed using the same methodology until 12 weeks of treatment. A lack of response by weeks 4 and 6 predicted a final lack of response both at weeks 8 and 12 of treatment. Alternatively, a robust response as early as week 2 predicted a good response by the end of the two treatment periods. These findings should help clinicians revalorate treatment when finding no response after 4 or 6 weeks of treatment.