Nocebo as a potential confounding factor in clinical trials for Parkinson's disease treatment: a meta‐analysis

Abstract

Our analysis indicates a significant dropout rate related to nocebo in trials for PD treatment. Adherence and efficacy may be adversely affected with additional implications for clinical practice.

Neuro-Bio-Behavioral Mechanisms of Placebo and Nocebo Responses: Implications for Clinical Trials and Clinical Practice

“…Many patients discontinue drug intake because of unwanted side effects, although being in the placebo arm, or because the reported adverse effects are in discordance with the pharmacokinetic of the drug (Rief et al, 2006(Rief et al, , 2009ade la Cruz et al, 2010;Stathis et al, 2013).…”

Nocebo in Alzheimer's disease; meta-analysis of placebo-controlled clinical trials

“…Nocebo has been studied in RCTs for several neurological conditions, including multiple sclerosis [9], headache [10,11], neuropathic pain [12], fibromyalgia [1], diabetic peripheral neuropathy [13], Parkinson's disease [14] and depression [2,15]. In these studies dropouts because of AEs in placebo treated patients varied from 2% (in multiple sclerosis) to almost 10% (in Parksinson's disease and fibromyalgia).…”

Nocebo phenomenon

“…Volunteers in the placebo-arm of trials often report adverse effects to the sham treatment. In studies of neurological disorders, the percentage of reported adverse effects in the placebo-arm has been as high as 64-74% (Mitsikostas, 2012;Stathis, Smpiliris, Konitsiotis & Mitsikostas, 2013). Furthermore, Mitsikostas, Mantonakis, and Chalarakis (2011) noted that the rates of the nocebo effect seen in clinical trials may be underestimated, as patients who are reluctant to receive novel medical treatments due to anxiety or mistrust, so more susceptible to nocebo response, might avoid participation in a clinical trial.…”