The nocebo effect : a clinicians guide

Objective: This paper aims to provide an overview on the nocebo effect, focusing on recognition — its phenomenology, at-risk demographic profiles, clinical situations and personality factors, as well as discriminating somatic symptoms in the general population from treatment-related adverse effects. Lastly, the paper addresses available evidence-based strategies for management and minimisation of the nocebo effect.

Method: Data for this paper were identified by searching PubMed using the search terms "nocebo" and “nocebo effect”, augmented by a manual search of the references of the key papers and the related literature.

Results: The nocebo effect refers to non-pharmacodynamic, harmful or undesirable effects occurring after inactive treatment, a phenomenon that also occurs in the context of active therapy. Known drivers include classical conditioning and negative expectations concerning treatment. Recent meta-analyses have reported a considerable prevalence, ranging from 18% in the symptomatic treatment of migraine, to more than 74% in multiple sclerosis. Recognition of the nocebo-driven adverse effects presents a challenge, especially because of its non-specific nature and the similarity to the active medication’s expected profile. Traits such as neuroticism, pessimism and type A personalities may predispose individuals to this phenomenon. Clinical management of the nocebo effect includes awareness and recognition, changing the manner of disclosure of potential drug-related adverse effects, shaping patients’ expectations and enhancing the treatment alliance.

Conclusion: The nocebo effect is a common, clinically significant, yet covert driver of clinical outcomes. Increased awareness of its features, as well as knowledge of strategies on how to manage it, are fundamental so that clinicians can mitigate its impact on clinical practice.

Nocebo effects in the treatment of major depression: results from an individual study participant-level meta-analysis of the placebo arm of duloxetine clinical trials

BACKGROUND: The nocebo effect, when a harmless substance creates harmful effects in a person who takes it, is a clinically salient yet seldom studied phenomenon that may be associated with poorer treatment outcomes, perceived adverse events, and treatment discontinuation. The covert presence of nocebo responders in clinical trials may contribute to outcome variance in both placebo and active treatment arms for important primary and secondary endpoints. Nocebo effects are thought to be driven by expectancy and conditioning. METHOD: This study analyzed pooled clinical trial data in the placebo arms of controlled trials of antidepressant medications to investigate variables associated with the emergence of adverse outcomes in placebo-treated participants (N = 2,457). Specifically, we examined treatment-emergent adverse events (TEAEs) and discontinuation in placebo-treated individuals. Trials were commenced between 1993 and 2010 as studies of duloxetine versus active comparator and/or placebo. RESULTS: TEAEs were reported by 1,569 placebo-treated participants (63.9%), with 115 (4.7%) discontinuing from the studies due to TEAEs and 274 (11.2%) showing worsening of Hamilton Depression Rating Scale total score during placebo treatment. There was specifically no evidence to support the expectancy hypothesis, that reported TEAEs were influenced by adverse effects described in the clinical trials participant information and consent forms, or the conditioning hypothesis, that reported TEAEs would be influenced by adverse effect profiles of previous antidepressant medications used by these study participants. There was some evidence to suggest that people who had previously used complementary medications were more likely to report TEAEs. Variables specific to individual studies were the strongest predictors of TEAEs. DISCUSSION: In this study, TEAEs were very common among placebo-treated clinical trial participants. Unexpectedly, there was no evidence to associate TEAEs with adverse clinical outcomes, nor were the conditioning or expectancy hypotheses supported by these data. CONCLUSIONS: The nocebo effect is a common, covert, and poorly understood driver of clinical outcomes that requires further investigation.