Open-Label Placebo Treatment: Outcome Expectations and General Acceptance in the Lay Population

Julia W Haas,Winfried Rief,Bettina K Doering

doi:10.1007/s12529-020-09933-1

Abstract

BackgroundMost physicians sometimes apply therapies without specific active ingredients. Although patients seem to judge such placebo treatments as acceptable under certain circumstances, deception is still an ethical problem. Open-label placebos (OLPs) might be a promising approach to solve this dilemma. This study compared general acceptance and outcome expectations of OLPs and deceptive placebos (DPs).MethodsIn an experimental online study, 814 participants read a case vignette of a person with insomnia receiving a pill. The participants were then randomly allocated into two groups, where the second part of the vignette described the pill as either a deceptive placebo (DP group) or as an open-label placebo (OLP group). The Credibility/Expectancy Questionnaire (CEQ) assessed outcome expectations after the first (pre-assessment) and the second (post-assessment) parts of the vignette. Treatment acceptance was measured at post-assessment. Data from 798 participants were analyzed by a mixed multivariate analysis of variance (MANOVA), t-tests, and post-hoc mediation analyses.ResultsThe MANOVA revealed a significant group main effect and a significant time × group interaction effect. At post-assessment, outcome expectations were higher in the DP group than in the OLP group. Acceptance of the placebo treatment was also higher in the DP group than in the OLP group. Mediation analyses confirmed that higher acceptance in the DP group was mediated by higher expectations.ConclusionsWhen laypersons read about placebo treatment, their outcome expectations toward DPs were higher than toward OLPs. Surprisingly, the application of DPs was rated as more acceptable than OLPs. This result might be explained by indirect effects of treatment expectations.

Highlights

According to systematic reviews, placebo application is quite common in clinical practice
It was hypothesized that outcome expectancy would be higher in participants who read the deceptive placebos (DPs) treatment vignette, whereas treatment acceptance would be higher in participants who read the Open-label placebos (OLPs) treatment vignette
Since the results concerning treatment acceptance were contrary to our hypothesis, we further investigated, via two mediation analyses, whether the effect of group on treatment acceptance was mediated by outcome expectations (CEQ credibility and Credibility/Expectancy Questionnaire (CEQ) expectancy as mediation variables)

Summary

Introduction

Placebo application is quite common in clinical practice. While OLP application was first investigated in an uncontrolled pilot study by Park and Covi in 1965 [8], the first trial on OLP including a no-treatment control group was implemented by Kaptchuk and colleagues [9, 10] The information they provided to patients, a practice which was often adopted in later OLP studies, included information about the positive effects of placebos on different symptoms, a brief explanation of classical conditioning as a potential placebo mechanism, and the indication that a positive attitude toward the intervention might be beneficial but not necessary. It was hypothesized that outcome expectancy would be higher in participants who read the DP treatment vignette, whereas treatment acceptance would be higher in participants who read the OLP treatment vignette

Participants and Study Procedure

Results

Discussion