Fibromyalgia: placebo has moderate effect size

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  • A meta-analysis has found a moderate effect size for placebo across 124 randomized controlled trials (RCTs).
Why this matters
  • Because of the paucity of effective treatments for fibromyalgia, clinicians can harness the placebo effect in their clinical practice.
Study design
  • Meta-analysis was conducted on 124 RCTs (n=15,633).
  • The placebo effect was calculated by comparing changes with placebo vs no-treatment control groups.
  • Funding: Arthritis Research UK.
Key results
  • Placebo patients had significantly better improvements in pain, fatigue, sleep quality, physical function, and other outcomes relative to no treatment.
  • The magnitude of the effect size (ES) for pain relief was 0.52.
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