Subject Expectations of Treatment Effectiveness and Outcome of Treatment with an Experimental Antidepressant

Objective: To evaluate the association between treatment expectations and response in a 9-week, single-blind experimental antidepressant treatment study.

Method: Twenty-five adult subjects meeting DSM-IV criteria for major depressive disorder with Hamilton Rating Scale for Depression (HAM-D) scores of >/= 17 completed a treatment trial using the experimental antidepressant reboxetine. Following a 1-week placebo lead-in, subjects received single-blind treatment for 8 weeks with reboxetine 8 to 10 mg/day. During the screening visit, subjects were asked to self-rate their expectations of the effectiveness of the study medication. Forced-choice responses were "not at all effective," "somewhat effective," or "very effective." Response to treatment was defined as a final HAM-D score of </= 10 at the end of the 9-week trial. Data were collected from October 1999 to July 2001.

Results: Subjects with a higher pretreatment expectation of medication effectiveness had a greater likelihood of response. Of the subjects who reported an expectation that the medication would be very effective, 90.0% (N = 9) responded to treatment, while only 33.3% (N = 5) of those who reported expecting medication to be somewhat effective responded to treatment (chi(2) = 7.819, p <.005). There was no association between the level of depression severity, duration of current episode, number of prior episodes, or basic demographic factors and treatment outcome.

Conclusions: These findings indicate that individuals with high baseline expectations of improvement demonstrate a significantly higher level of response to reboxetine than those with lower expectations of improvement with treatment. The data in this study suggest that a subject's expectation of efficacy is associated with the outcome of experimental antidepressant treatment.