It's Not Just the Placebo Effect We Have to Worry About: Introducing Lessebo

Michael S. Okun, MD

Changes on the motor section of the Unified Parkinson's Disease Rating Scale were greater in active-comparator than in placebo-comparator studies, a meta-analysis shows.

When a clinical trial setting involves use of a placebo, patients' expectation of a negative outcome caused by the potential for receiving the placebo is referred to as the “lessebo effect.” To study this effect, researchers conducted a meta-analysis of double-blind, randomized, controlled trials of dopamine agonists for Parkinson disease (PD). They compared changes on the motor section of the Unified Parkinson's Disease Rating Scale (mUPDRS) between trials with active-treatment control arms and those with placebo control arms.

A total of 28 study arms (3277 patients) used an active comparator, and 42 study arms (4554 patients) used placebo controls. The mean mUPDRS score change from baseline to treatment end was 1.6 units greater in the active-controlled study arms than in the placebo-controlled study arms. The difference was larger in the early-PD group (3.3 mUPDRS units) and in studies of ≤12 weeks' duration.

Citation(s):

Mestre TA et al. Another face of placebo: The lessebo effect in Parkinson disease — meta-analyses. Neurology 2014 Mar 21; [e-pub ahead of print].