The placebo mystique: Implications for clinical trial methodology

Abstract

The World Medical Association Declaration of Helsinki states that the use of a placebo in a clinical trial can only be justified ethically when no proven active treatment is available as a comparison. Despite this, placebos remain a popular choice as controls in clinical trials. Recent literature reviews have suggested that reliance on placebos may, in part, be because of methodological misconceptions about the need for placebos to control for the 'placebo effect'. This study aimed to assess doctors' understanding of the requirements for placebo use in clinical trials. Two hundred doctors working in tertiary hospitals in Melbourne, Australia were surveyed in regards to their understanding of the role of the placebo and placebo effects in clinical trials. There was a 72% response rate. Doctors were specifically asked if a placebo was required in a randomised clinical trial, in preference to another form of control, to control for the 'placebo effect'. The majority of respondents (62%) incorrectly believed that placebos are essential to control for the 'placebo effect' in a randomised clinical trial. Misconceptions about the methodological requirement for placebos in randomised controlled trials may influence researcher decisions to use placebo controls in unethical situations.