EARLY-ONSET OF ANTIDEPRESSANT ACTION OF VENLAFAXINE - PATTERN-ANALYSIS IN INTENT-TO-TREAT PATIENTS

Pattern analysis has been used to distinguish between the true effect of an antidepressant and a placebo effect. The placebo effect constitu tes clinical improvement that is attributable to the caregiver, treatm ent setting, or placebo substance. Pattern analysis allows identificat ion of patients who have early persistent responses, delayed persisten t responses, or no responses to a drug. In our study, we used this met hod to assess the onset and persistence of antidepressant activity of high daily doses of venlafaxine. Our analysis considered scores on the Global Improvement item of the Clinical Global Impressions scale for intent-to-treat patients in two double-masked, placebo-controlled stud ies of at least 6 weeks' duration. Dosages in both studies were rapidl y titrated upward so patients received at least 200 mg/d within the fi rst week of treatment. Improvement within the first 2 weeks was consid ered early, and improvement not followed by a relapse through the sche duled end of treatment was considered persistent. Significantly greate r percentages of patients in the venlafaxine group (27% and 20% in stu dy 1 and study 2, respectively) than in the placebo group (9% and 2.%, respectively) had a clinically meaningful drug response within the fi rst 2 weeks of treatment. This early response persisted for the durati on of each trial. We concluded that venlafaxine in dosages of at least 200 mg/d demonstrates an early and persistent onset of efficacy compa red with placebo.