PMID:
21576145
Authors:
Mora MS, Nestoriuc Y, Rief W.
Title:
Lessons learned from placebo groups in antidepressant trials.
Journal:
Philos Trans R Soc Lond B Biol Sci. 2011 Jun 27;366(1572):1879-88. doi:
Abstract:
This comprehensive review provides an overview about placebo and nocebo phenomena
in antidepressant trials. Improvements in the placebo groups may partly be
explained through methodological issues such as natural course of depression and
regression to the mean, but also fundamentally reflect investigators' and
participants' expectations. A meta-analysis by our group of 96 randomized
placebo-controlled trials showed large placebo responses to antidepressant
medication. Moderator analyses revealed substantially larger placebo responses in
observer ratings compared with self-report. Effect sizes in observer ratings
showed strong increase with publication year while this effect was not found for
patients' self-ratings. This reflects the strong influence of investigators'
expectations. The analysis of 'nocebo effects', e.g. adverse effects in placebo
groups of antidepressant trials also confirms the impact of expectations: nocebo
symptoms reflected the typical side-effect patterns expected in the drug group,
with higher symptoms rates in the placebo groups of tricyclic antidepressant
trials compared with placebo groups of trials testing selective serotonin
reuptake inhibitors. While the placebo response seems to be similar for women and
men, gender differences were found for nocebo rates. In the conclusion, we
discuss potential implications for clinical trial designs and argue for
interventions aimed at optimizing positive expectations of treatment benefit
while minimizing the impact of adverse effects.
This page is constructed based on the NCBI service.