Magnitude of the placebo effect in randomized trials of antiepileptic agents

Jorge G. Burneo, Victor M. Montori, Edward Faught

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Placebo-controlled randomized trials ideally produce unbiased estimates of the treatment effect after accounting for nonpharmacological effects (regression to the mean, Hawthorne, and placebo effects). Recognizing that the magnitude of these effects may help understand why investigators need to control for them, we sought to measure this magnitude. We reviewed published meta-analyses of randomized, placebo-controlled add-on trials of antiepileptic medications versus placebo, included in the Cochrane Library. In randomized trials of antiepileptic agents for epilepsy, 9.3-16.6% of patients in the placebo arm had a >50% reduction in seizure frequency. This effect represents 20-50% of the effect observed with active agents. Because patients with epilepsy in the placebo arm of randomized trials experience a large clinical benefit due to non pharmacological effects, randomized controlled trials are necessary to gauge the true magnitude of the treatment effect of new antiepileptic agents.

Original languageEnglish (US)
Pages (from-to)532-534
Number of pages3
JournalEpilepsy and Behavior
Issue number6
StatePublished - Dec 2002


  • Antiepileptic agents
  • Epilepsy
  • Placebo
  • Randomized trials

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Behavioral Neuroscience


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