Restless legs syndrome: Losing sleep over the placebo response

The placebo response is a vexing problem for clinical trial design and drug development. Defined as a clinical improvement that occurs in participants treated with a physiologically inert substance, the placebo response has been largely ascribed to "expectation of clinical improvement and Pavlovian conditioning."1 Other factors certainly play a role, however, including strict application of inclusion and exclusion criteria at study entry with subsequent reversion to the mean; that is, participants and investigators, knowing entry criteria for a trial, may subconsciously (or intentionally) overrate signs and symptoms to get into a trial, and then present at subsequent visits in their more typical state. Though this is not traditionally considered part of the true placebo response, it is likely that this phenomenon contributes to what is measured as the magnitude of the placebo response. Clinical trial design strategies such as central blinded ratings and avoiding the use of primary outcome measure criteria for screening can mitigate this phenomenon, but these are not routinely utilized.
Source: Neurology - Category: Neurology Authors: Tags: Clinical trials Systematic review/meta analysis, Restless legs syndrome EDITORIALS Source Type: research