Background: Tailoring interventions to patient subgroups can improve intervention outcomes for various conditions. However, it is unclear how much of this improvement is due to the pharmacological personalisation versus the non-specific effects of the contextual factors involved in the tailoring process, such as the therapeutic interaction. Here, we tested whether presenting a (placebo) analgesia machine as personalised would improve its effectiveness.
Methods: We recruited 102 adults in two samples (N1=17, N2=85) to receive painful heat stimulations on their forearm. During half of the stimulations, a machine purportedly delivered an electric current to reduce their pain. The participants were either told that the machine was personalised to their genetics and physiology, or that it was effective in reducing pain generally.
Results: Participants told that the machine was personalised reported more relief in pain intensity than the control group in both the feasibility study (standardised β=-0.50 [-1.08, 0.08]) and the pre-registered double-blind confirmatory study (β=-0.20 [-0.36, -0.04]). We found similar effects on pain unpleasantness, and several personality traits moderated the results.
Conclusions: We present some of the first evidence that framing a sham treatment as personalised increases its effectiveness. Our findings could potentially improve the methodology of precision medicine research and inform practice.
Funding: This study was funded by the Social Science and Humanities Research Council (93188) and Genome Québec (95747).
Keywords: contextual factors; expectation; human; medicine; neuroscience; pain; personalised medicine; placebo; precision medicine.
Precision treatments are therapies that are tailored to a patient’s individual biology with the aim of making them more effective. Some cancer drugs, for example, work better for people with specific genes, leading to improved outcomes when compared to their ‘generic’ versions. However, it is unclear how much of this increased effectiveness is due to tailoring the drug’s chemical components versus the contextual factors involved in the personalisation process. Contextual factors like patient beliefs can boost a treatment’s outcomes via the ‘placebo effect’ – making the intervention work better simply because the patient believes it to. Personalised treatments typically combine more of these factors by being more expensive, elaborate, and invasive – potentially boosting the placebo effect. Sandra et al. tested whether simply describing a placebo machine – which has no therapeutic value – as personalised would increase its effectiveness at reducing pain for healthy volunteers. Study participants completed several sham physiological and genetic tests. Those in the experimental group were told that their test results helped tailor the machine to increase its effectiveness at reducing pain whereas those in the control group were told that the tests screened for study eligibility. All volunteers were then exposed to a series of painful stimuli and used the machine to reduce the pain for half of the exposures. Participants that believed the machine was personalised reported greater pain relief. Those with a stronger desire to be seen as different from others – based on the results of a personality questionnaire – experienced the largest benefits, but only when told that the machine was personalised. This is the first study to show that simply believing a sham treatment is personalised can increase its effectiveness in healthy volunteers. If these results are also seen in clinical settings, it would suggest that at least some of the benefit of personalised medicine could be due to the contextual factors surrounding the tailoring process. Future work could inform doctors of how to harness the placebo effect to benefit patients undergoing precision treatments.
© 2023, Sandra et al.