Open-label placebos - a systematic review and meta-analysis of experimental studies with non-clinical samples

Abstract: The use of open-label placebos (OLPs) has shown to be effective in clinical trials. We conducted a systematic review and meta-analysis to examine whether OLPs are effective in experimental studies with non-clinical populations. We searched five databases on April 15, 2021. We conducted separate analyses for self-reported and objective outcomes and examined whether the level of suggestiveness of the instructions influenced the efficacy of OLPs. Of the 3573 identified records, 20 studies comprising 1201 participants were included, of which 17 studies were eligible for meta-analysis. The studies investigated the effect of OLPs on well-being, pain, stress, arousal, wound healing, sadness, itchiness, test anxiety, and physiological recovery. We found a significant effect of OLPs for self-reported outcomes (k = 13; standardized mean difference (SMD) = 0.43; 95% CI = 0.28, 0.58; I2 = 7.2%), but not for objective outcomes (k = 8; SMD =  − 0.02; 95% CI =  − 0.25, 0.21; I2 = 43.6%). The level of suggestiveness of the instructions influenced the efficacy of OLPs for objective outcomes (p = 0.02), but not for self-reported outcomes. The risk of bias was moderate for most studies, and the overall quality of the evidence was rated low to very low. In conclusion, OLPs appear to be effective when examined in experimental studies. However, further research is needed to better understand the mechanisms underlying OLPs

Location
Deutsche Nationalbibliothek Frankfurt am Main
Extent
Online-Ressource
Language
Englisch
Notes
Scientific reports. - 13, 1 (2023) , 3640, ISSN: 2045-2322

Event
Veröffentlichung
(where)
Freiburg
(who)
Universität
(when)
2023
Creator
Spille, Lukas
Fendel, Johannes
Seuling, Patrik D.
Göritz, Anja
Schmidt, Stefan

DOI
10.1038/s41598-023-30362-z
URN
urn:nbn:de:bsz:25-freidok-2348430
Rights
Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
Last update
14.08.2025, 10:46 AM CEST

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Associated

Time of origin

  • 2023

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