Nocebo effects on informed consent within medical and psychological settings: A scoping review

ABSTRACT

Warning research participants and patients about potential risks associated with participation/treatment is a fundamental part of consent. However, such risk warnings might cause negative expectations and subsequent nocebo effects (i.e., negative expectations cause negative outcomes) in participants. Because no existing review documents how past research has quantitatively examined nocebo effects – and negative expectations – arising from consent risk warnings, we conducted a pre-registered scoping review (N = 9). We identified several methodological issues across these studies, which in addition to mixed findings, limit conclusions about whether risk warnings cause nocebo effects.

KEYWORDS:

• Informed consent
• nocebo effects
• negative expectations
• ethics

DATA AVAILABILITY STATEMENT

Due to the nature of this scoping review, all data is available within the manuscript (e.g., all included papers, reason for exclusion, number of duplicates). Our pre-registered scoping review protocol is, however, available on the Open Science Framework (https://osf.io/6ekdr/).

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).

SUPPLEMENTARY MATERIAL

Supplemental data for this article can be accessed online at https://doi.org/10.1080/10508422.2022.2081853

Notes

¹ Due to resource constraints, we deviated from our registered protocol and used EndNote 20 rather than EndNote X9.

² We focus on statistical significance because several studies did not report effect size and/or we calculated effect sizes reported here ourselves. We report effect size(s) where possible.

³ Fleming (1997) did not report specific side-effects, only “side-effects” generally.