Lene Vase
Professor, Department of Psychology and Behavioural Sciences, School of Business and Social Sciences, Aarhus University

Can knowledge of placebo and nocebo mechanisms help improve the RCT?

The RCT is currently facing several challenges. One of these challenges is that the placebo response appears to be increasing in RCTs, thereby making it difficult to prove a putative effect of new treatments over placebo. This problem has primarily been approached by using stable factors to predict the magnitude of the placebo response and by developing complex designs aimed at reducing the placebo response, in the hope that it would improve the test of the active treatment. Still, the success of this approach has so far been limited.
Based on placebo mechanism studies, a new approach is proposed. The magnitude of placebo effects is large and highly variable. Pharmacological and non-pharmacological treatments, patients’ perception of the treatment, verbal suggestions given for pain relief, as well as patients’ expectations towards pain relief contribute, across different types of chronic pain, to the magnitude of the placebo effect. A recent study has shown that it is possible to make approximations of patients’ expectations towards the treatment and hence predict the magnitude of the placebo response in RCTs. Also, by directly asking patients, in future studies about their perceptions and expectations towards the treatment it may be possible to account for the contribution of the placebo component to the overall treatment.
Thus, by interfacing insights from placebo and nocebo mechanism studies, it may be possible to enhance the information that can be obtained from RCTs and to account for the variability in the placebo component of the overall treatment effect in ethically appropriate ways. This approach has the potential to improve the scientific test of treatments as well as to illustrate how the effect of treatments can be optimized in clinical practice.


Lene Vase received her PhD in experimental psychology in 2006 and she currently holds a position as professor at the Department of Psychology and Behavioural Sciences, School of Business and Social Sciences, Aarhus University, Aarhus, Denmark. Her research focuses on how psychological interventions or dispositions may enhance or decrease the experience of pain with a special focus on placebo analgesia and nocebo hyperalgesia effects. Recently, she has investigated how knowledge of placebo and nocebo mechanisms may improve the test of new treatments in Randomized Controlled Trials. She has published more than 60 papers and book chapters and has given several presentations at conferences world-wide. She has numerous international collaborations, and she was awarded the EU Innovative Medicines Initiative grant EUROPAIN together with leading pain laboratories in Europe. She is currently Associate Editor on PAIN and member of the steering committee for the Society for Interdisciplinary Placebo Studies.