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The placebo effect and its determinants in fibromyalgia: meta-analysis of randomized controlled trials

Chen, Xi; Zou, Kun; Abdullah, Natasya; Whiteside, Nicola; Sarmanova, Aliya; Doherty, Michael; Zhang, Weiya

Authors

Xi Chen

Kun Zou

Natasya Abdullah

Nicola Whiteside

Aliya Sarmanova

Michael Doherty

Weiya Zhang



Abstract

The aims of this study were to determine whether placebo treatment in randomised controlled trials (RCTs) is effective for fibromyalgia and to identify possible determinants of the magnitude of any such placebo effect. A systematic literature search was undertaken for RCTs in people with fibromyalgia that included a placebo and/or a no-treatment (observation only or waiting list) control group. Placebo effect size (ES) for pain and other outcomes was measured as the improvement of each outcome from baseline divided by the standard deviation of the change from baseline. This effect was compared with changes in the no-treatment control groups. Meta-analysis was undertaken to combine data from different studies. Subgroup analysis was conducted to identify possible determinants of the placebo ES. A total of 3912 studies were identified from the literature search. After scrutiny, 229 trials met the inclusion criteria. Participants who received placebo in the RCTs experienced significantly better improvements in pain, fatigue, sleep quality, physical function, and other main outcomes than those receiving no treatment. The ES of placebo for pain relief was clinically moderate (0.53, 95%CI 0.48 to 0.57). The ES increased with increasing strength of the active treatment, increasing participant age and higher baseline pain severity, but decreased in RCTS with more women and with longer duration of fibromyalgia. In addition, placebo treatment in RCTs is effective in fibromyalgia. A number of factors (expected strength of treatment, age, gender, disease duration) appear to influence the magnitude of the placebo effect in this condition.

Journal Article Type Article
Journal Clinical Rheumatology
Print ISSN 0770-3198
Electronic ISSN 1434-9949
Publisher Springer Verlag
Peer Reviewed Peer Reviewed
APA6 Citation Chen, X., Zou, K., Abdullah, N., Whiteside, N., Sarmanova, A., Doherty, M., & Zhang, W. (in press). The placebo effect and its determinants in fibromyalgia: meta-analysis of randomized controlled trials. Clinical Rheumatology, https://doi.org/10.1007/s10067-017-3595-8
DOI https://doi.org/10.1007/s10067-017-3595-8
Keywords Fibromyalgia, Meta-analysis, Pain management, Placebo effect, Rheumatic diseases, Systematic reviews and methodology
Publisher URL https://link.springer.com/article/10.1007%2Fs10067-017-3595-8
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0





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