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A comparison of placebo effects in clinical analgesic trials versus studies of placebo analgesia
Abstract
A previous meta-analysis of clinical analgesic trial studies showed generally low magnitudes of placebo analgesia (N. Engl. J. Med. 344 (2001) 1594). However, as studies included in their analysis used only placebo as a control condition, we conducted two meta-analyses, one in which 23 studies used only placebo as a control condition, and one in which 14 studies investigated placebo analgesic mechanisms. Magnitudes of placebo analgesic effects were much higher in the latter (mean effect size=0.95) as compared to the former (mean effect size=0.15) and were significantly different (P=0.003). This difference as well as differences in effect sizes within studies of placebo mechanisms may be parsimoniously explained by differences in expected pain levels produced by placebo suggestions and by conditioning. Furthermore, some of the studies of placebo analgesic mechanisms indicate that the magnitude of placebo analgesia is higher when the placebo analgesic effect is induced via suggestion combined with conditioning than via suggestion alone or conditioning alone. Based on these findings, we suggest that placebo analgesic effects are most optimally conceptualized in terms of perception of the placebo agent, and therefore a new definition of placebo response is proposed.
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“However, in some cases cue effects can persist even after reinforcement ceases, resisting extinction and sometimes even growing over time (34–37).”
From Social information creates self-fulfilling prophecies in judgments of pain, vicarious pain, and cognitive effort (2026) · cites this paper as [36]
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“Still, the induction of positive expectations regarding an intervention's outcome using verbal suggestions have frequently been shown to affect numerous health outcomes previously (Colloca & Miller, 2011), for example, in (placebo) pain research (Peerdeman et al., 2016; Vase et al., 2002).”
From Mindfulness Effects on Anxiety: Disentangling the Role of Decentering and Treatment Expectations (2024) · cites this paper as Vase et al., 2002
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Metadata
- Authors
- Vase, L., Riley, J. L., & Price, D. D.
- Affiliations
- Aarhus University (DK)
- University of Florida Health (US)
- Corresponding author
- Price, Donald D.
- Venue
- Pain
- Published
- 2002-10
- Volume
- 99
- Issue
- 3
- Pages
- 443-452
- ISSN
- 0304-3959 (ISSN-L)
- OpenAlex
- W1966127473
- Cited by
- 434
- References
- 60
- Citations by year
- 2026: 5 · 2025: 18 · 2024: 13 · 2023: 13 · 2022: 16 · 2021: 18 · 2020: 18 · 2019: 22 · 2018: 19 · 2017: 14 · 2016: 22 · 2015: 15 · 2014: 28 · 2013: 21 · 2012: 14
- FWCI
- 6.85
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Pain (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Life Sciences › Neuroscience › Cognitive Neuroscience › Pain Management and Placebo Effect
- Health Sciences › Medicine › Physiology (medical) › Pain Mechanisms and Treatments
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
- Keywords
- placebo analgesia, placebo response
- MeSH terms
- Analgesia, Clinical Trials as Topic, Humans, Pain Measurement, Placebo Effect
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