Effects of open-label placebos across populations and outcomes: an updated systematic review and meta-analysis of randomized controlled trials
Abstract This work synthesizes and updates findings from previous systematic-reviews and meta-analyses on open-label placebos (OLPs). For the first time, it directly tests whether OLPs differ in effects between clinical and non-clinical samples, and between self-report and objective outcomes. We sea...
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Nature Portfolio
2025-08-01
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| Online Access: | https://doi.org/10.1038/s41598-025-14895-z |
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| author | Johannes C. Fendel Carl Tiersch Paul Sölder Jens Gaab Stefan Schmidt |
| author_facet | Johannes C. Fendel Carl Tiersch Paul Sölder Jens Gaab Stefan Schmidt |
| author_sort | Johannes C. Fendel |
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| description | Abstract This work synthesizes and updates findings from previous systematic-reviews and meta-analyses on open-label placebos (OLPs). For the first time, it directly tests whether OLPs differ in effects between clinical and non-clinical samples, and between self-report and objective outcomes. We searched eight databases up to November 9, 2023, and included 60 randomized controlled trials (RCTs), compromising 63 separate comparisons. OLPs yielded a small positive effect across various health-related outcomes (k = 63, n = 4554, SMD = 0.35, CI 95% = 0.26; 0.44, p < 0.0001, I2 = 53%). The effect differed between clinical (k = 24, n = 1383, SMD = 0.47) and non-clinical samples (k = 39, n = 3171, SMD = 0.29; Q = 4.25, p < 0.05), as well as between self-reported (k = 55, n = 3919, SMD = 0.39) and objective outcomes (k = 17, n = 1250, SMD = 0.09; Q = 7.24, p < 0.01). Neithter the level of suggestiveness nor the type of control moderated the effect. These findings confirm that OLPs are effective for both clinical and non-clinical samples—particularly when effects are assessed via self-reports. |
| format | Article |
| id | doaj-art-5b09d7ad1fc540aeaa4cc73de4b5ebee |
| institution | Kabale University |
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| language | English |
| publishDate | 2025-08-01 |
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| spelling | doaj-art-5b09d7ad1fc540aeaa4cc73de4b5ebee2025-08-20T03:46:08ZengNature PortfolioScientific Reports2045-23222025-08-0115111410.1038/s41598-025-14895-zEffects of open-label placebos across populations and outcomes: an updated systematic review and meta-analysis of randomized controlled trialsJohannes C. Fendel0Carl Tiersch1Paul Sölder2Jens Gaab3Stefan Schmidt4Department of Psychosomatic Medicine and Psychotherapy, Faculty of Medicine, Medical Center - University of Freiburg, University of FreiburgDivision of Clinical Psychology and Psychotherapy, Faculty of Psychology, University of BaselCognition, Action and Sustainability Unit, Department of Psychology, University of FreiburgDivision of Clinical Psychology and Psychotherapy, Faculty of Psychology, University of BaselDepartment of Psychosomatic Medicine and Psychotherapy, Faculty of Medicine, Medical Center - University of Freiburg, University of FreiburgAbstract This work synthesizes and updates findings from previous systematic-reviews and meta-analyses on open-label placebos (OLPs). For the first time, it directly tests whether OLPs differ in effects between clinical and non-clinical samples, and between self-report and objective outcomes. We searched eight databases up to November 9, 2023, and included 60 randomized controlled trials (RCTs), compromising 63 separate comparisons. OLPs yielded a small positive effect across various health-related outcomes (k = 63, n = 4554, SMD = 0.35, CI 95% = 0.26; 0.44, p < 0.0001, I2 = 53%). The effect differed between clinical (k = 24, n = 1383, SMD = 0.47) and non-clinical samples (k = 39, n = 3171, SMD = 0.29; Q = 4.25, p < 0.05), as well as between self-reported (k = 55, n = 3919, SMD = 0.39) and objective outcomes (k = 17, n = 1250, SMD = 0.09; Q = 7.24, p < 0.01). Neithter the level of suggestiveness nor the type of control moderated the effect. These findings confirm that OLPs are effective for both clinical and non-clinical samples—particularly when effects are assessed via self-reports.https://doi.org/10.1038/s41598-025-14895-zOpen-label placeboObjective outcomeMeta-analysisSystematic-review |
| spellingShingle | Johannes C. Fendel Carl Tiersch Paul Sölder Jens Gaab Stefan Schmidt Effects of open-label placebos across populations and outcomes: an updated systematic review and meta-analysis of randomized controlled trials Scientific Reports Open-label placebo Objective outcome Meta-analysis Systematic-review |
| title | Effects of open-label placebos across populations and outcomes: an updated systematic review and meta-analysis of randomized controlled trials |
| title_full | Effects of open-label placebos across populations and outcomes: an updated systematic review and meta-analysis of randomized controlled trials |
| title_fullStr | Effects of open-label placebos across populations and outcomes: an updated systematic review and meta-analysis of randomized controlled trials |
| title_full_unstemmed | Effects of open-label placebos across populations and outcomes: an updated systematic review and meta-analysis of randomized controlled trials |
| title_short | Effects of open-label placebos across populations and outcomes: an updated systematic review and meta-analysis of randomized controlled trials |
| title_sort | effects of open label placebos across populations and outcomes an updated systematic review and meta analysis of randomized controlled trials |
| topic | Open-label placebo Objective outcome Meta-analysis Systematic-review |
| url | https://doi.org/10.1038/s41598-025-14895-z |
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