The Effect of Patient and Investigator Expectation on the Efficacy of Escitalopram in the Treatment of Patients With Major Depressive Disorder.

This study is designed to determined if trial design, in the form of the frequency of patient contact (assessment visit numbers) has an effect on the efficacy outcome after 8-week treatment with escitalopram.

The placebo response is a major issue in clinical trials for psychiatric disorders-and especially in the management of depression. Possible contributing factors to this problem include diagnostic misclassification, issues concerning inclusion/exclusion criteria, outcome measures' lack of sensitivity to change, measurement errors, poor quality of data entry and verification, waxing and waning of the natural course of depression, regression toward the mean phenomenon, patient and clinician expectations about the trial, study design issues, non-specific therapeutic effects, and high attrition.

Over the past few decades, researchers have attempted to reduce the placebo effect in a variety of ways. Unfortunately, approaches with very little or no benefit have included restricting enrollment to selected populations, rater training, requirement of same rater, and placebo lead-in phases. Some benefits, although often marginal, have been derived from standardizing diagnostic procedures, managing clinicians' overestimation of change, simplification of study visits and assessments, minimizing nonspecific, therapeutic effects, extending trial duration, reducing number of sites, increasing the sensitivity of outcome measures, and reducing the number of treatment arms.

Thus far, there has been no attempt to develop new study designs aimed at reducing the placebo effect.

We are proposing a novel study design, suitable for doubleblind, trials in mood disorders. This design is aimed at characterizing and identifying both the overall placebo response rate and the sample size required for such