Het placebo-effect: Is de wens vader van de gedachte?

The placebo effect remains an interesting topic for research. Recently, a systematic review estimated the percentage of responders after various placebo interventions in studies assessing prophylactic treatment for migraine. The authors report that after oral, pharmacologic placebos, 22% of patients reported an attack frequency reduction of > 50% and that after sham acupuncture, this percentage was 38%. In this commentary the methodological issues of the paper are discussed, and the conclusion is that in research into placebo effects the wish might be father to the thought.