Background & Aims

Although placebo effects have proven effective in relieving acute and chronic pain in both research and clinical treatments, the implementation of dedicated strategies aimed at evoking such effects remains difficult because of ethical concerns [1]. As such, this study investigated the opinions of patients with fibromyalgia, a chronic musculoskeletal pain disease, and healthy controls regarding the underlying learning mechanisms of placebo effects and their practical application with placebo-based strategies.

Methods

158 age- and sex-matched adult patients and controls (79 per group) completed an online survey. Participants were asked to rate the perceived influence of various learning mechanisms on placebo effects (e.g., verbal suggestions, classical conditioning, and social learning) as well as acceptability and perceived effectiveness of placebo-based strategies (i.e., open-label and closed-label strategies, dose-extending strategies and treatment-enhancing strategies). Respondents’ knowledge about placebo effects was obtained through a 7-item quiz.

Results

The perceived influence of learning mechanisms on placebo effects did not differ between both groups (p ? 0.05), yet healthy controls considered placebo-based strategies more acceptable and effective than patients (p < 0.001 for both). When the results were interpreted across groups, closed-label strategies were considered significantly less acceptable than any other strategy (all p < 0.001). Higher acceptability of the strategies was related to higher perceived effectiveness ratings (p < .0001). Furthermore, more knowledge on placebo effects was predictive of higher acceptability (p = 0.005) and perceived effectiveness (p < 0.001) towards placebo-based strategies.

Conclusions

The obtained results from the survey show that the medical history of a patient marginally determines acceptability and perceived effectiveness of placebo-based strategies. Furthermore, the open character of a strategy, its assumed effectiveness, or its conjuncture with existing medical treatments make it more acceptable, and someone’s knowledge about placebo effects crucially relates to these determining factors. Keeping these factors in mind seems essential for clinical implementation of placebo-based strategies in practice.

References

1.Gold, A. and P. Lichtenberg, The moral case for the clinical placebo. J Med Ethics, 2014. 40(4): p. 219-24.
2.Benedetti, F., I. Rainero, and A. Pollo, New insights into placebo analgesia. Curr Opin Anaesthesiol, 2003. 16(5): p. 515-9.
3.Klinger, R., et al., Placebo analgesia: clinical applications. Pain, 2014. 155(6): p. 1055-8.
4.Evers, A.W.M., et al., Implications of Placebo and Nocebo Effects for Clinical Practice: Expert Consensus. Psychotherapy and psychosomatics, 2018. 87(4): p. 204-210.

Presenting Author

Hans van Lennep

Poster Authors

Hans van Lennep

Master of Science

Leiden University

Lead Author

E-mail

Simone Meijer

Msc.

Leiden University

Lead Author

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Merve Karacaoglu

Msc.

Leiden University

Lead Author

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Ralph Rippe

PhD

Leiden University

Lead Author

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Kaya Peerdeman

Leiden University

Lead Author

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Henriët van Middendorp

PhD

Leiden University

Lead Author

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Andrea Prof. dr. Evers

Health, Medical, and Neuropsychology unit at Leiden University’s Institute of Psychology

Lead Author

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Topics

  • Placebo