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Nocebo in fibromyalgia: Meta-analysis of placebo-controlled clinical trials and implications for practice
European Journal of Neurology, 10/06/2011
Exclusive author commentary
Clinical Article
Mitsikostas DD et al. – Nocebo is remarkably prevalent in fibromyalgia(FM) patients participating in randomized clinical trials(RCTs). Because nocebo contributes to drug intolerance and treatment failure in clinical practice, identification of predisposing factors and efforts to prevent nocebo by educating these patients appropriately may be important for FM outcome.
Methods- Following a systematic Medline search for RCTs for FM pharmacologic treatment published between 2001 and 2010, the authors assessed percentages of placebo-treated patients reporting at least one adverse effect(AE) or discontinuing because of placebo intolerance and searched for factors influencing nocebo’s extent
- Percentages were compared with those revealed by similar meta-analyses of RCTs for multiple sclerosis and primary headaches
- Data were extracted from 16 RCTs fulfilling search criteria
- Of 2026 placebo-treated patients, 67.2% (95%CI: 51.0–81.5%) reported at least one AE, and 9.5% (95%CI: 8.3–10.9%) discontinued placebo treatment because of intolerance
- AEs in placebo arms corresponded quantitatively and qualitatively to those in active drug arms (ρ> 0.88, P< 0.0001)
- Younger age and larger placebo arm size were associated with increased dropout rates.
- Patients with depression were more likely to withdraw from trials
- Nocebo dropouts in FM trials were fourfold and twofold higher than in RCTs for multiple sclerosis treatment and migraine preventive treatment
D. D. Mitsikostas (10/07/2011) comments:
This study provides evidence for a powerful nocebo effect in patients suffering from fibromyalgia, that limits current treatment efficacy significantly. Apart from daily clinical practice implications, trial designers should also aware that nocebo decreases study population of RCTs for fibromyalgia up to 20%. It is essential therefore to pay more attention on nocebo and to further explore influencing factors.
