The possibility of receiving a placebo during a clinical trial might influence some participants to report worsening of symptoms — even if they actually remained on the active drug — according to a study that involved patients with depression.
Bret R. Rutherford, MD, of the Columbia University Center for Psychoanalytic Training and Research, new York, and colleagues reanalyzed data from two studies involving discontinuation of the antidepressant fluoxetine. They looked at 673 patients with major depressive disorder who responded to 12 weeks of open treatment with the drugs, who were than randomized to continue with fluoxetine or placebo.
The researchers used mixed effects longitudinal models to see if possible randomization to placebo at 12 weeks resulted in significant depressive symptom worsening.
Participants continuing to receive fluoxetine and those switched to placebo had significantly higher mean Hamilton Depression Rating Scale (HDRS) scores immediately after randomization compared to the final weeks of open treatment (P < .001 for both fluoxetine- and placebo-treated patients), the researchers reported in the Journal of Clinical Psychiatry.
In addition, the decline in depression scores (greater levels of depression) was associated with the level of improvement patients experienced in the first few weeks of open treatment.
“These results suggest that treatment changes influence patients’ expectations of improvement, which, in turn, affect their depressive symptoms,” the researchers concluded.
The objective of the study is to determine whether patient expectancy plays a role in observed placebo and nocebo effects in two clinical trials.
Data were reanalyzed from 2 fluoxetine-discontinuation studies conducted from March 1990 to September 1992 and from May 1997 to December 2002. The 673 outpatients included were aged 18–65 years with DSM-III-R major depressive disorder, responded to 12-week duration open treatment, and were randomized to continued fluoxetine or placebo for an additional year. Mixed effects longitudinal models determined whether the possible randomization to placebo at 12 weeks resulted in significant depressive symptom worsening across treatments.