The introductory placebo washout: a retrospective evaluation.
We examined the effects of the "introductory placebo washout" technique by reanalyzing the results of a recent trial of an experimental antidepressant. At the beginning, all patients were placed on placebo in a single-blind design. Patients who were rated as placebo responders with the physician-administered Hamilton Rating Scale for Depression (HRSD) were excluded from the trial. In spite of this technique, an alternative measure of depression indicated that many patients with a positive response to placebo had been entered in the trial. In the reanalysis, elimination of these "hidden placebo responders" did not lower the final placebo response rate and actually diminished the differences observed at the end of the study between the active treatment and placebo groups. These data suggest that the introductory placebo washout may have unpredictable, possibly confounding effects on patient samples in trials of antidepressant agents.
Reimherr
F W
FW
Department of Psychiatry, University of Utah Medical Center, Salt Lake City 84132.
Ward
M F
MF
Byerley
W F
WF
D002986:Clinical Trials as Topic; D003866:Depressive Disorder / Q000188:drug therapy* / Q000523:psychology; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005473:Fluoxetine / Q000627:therapeutic use*; D006801:Humans; D007099:Imipramine / Q000627:therapeutic use*; D015990:Placebo Effect; D011569:Psychiatric Status Rating Scales
D005473:Fluoxetine; D007099:Imipramine