Replication crisis and placebo studies: rebooting the bioethical debate

Risk factors associated with nocebo effects: A review of reviews

Objective

This meta-review aims to identify and categorize the risk factors that are associated with nocebo effects. The nocebo effect can exert a negative impact on treatment outcomes and have detrimental outcomes on health. Learning more about its potential predictors and risk factors is a crucial step to mitigating it.

Methods

Literature review studies about the risk factors for nocebo effects were searched through five databases (PubMed, Scopus, The Cochrane Library, PsycINFO, and Embase) and through grey literature. Methodological validity and risk of bias were assessed. We conducted a thematic analysis of the results of the forty-three included reviews.

Results

We identified nine categories of risk factors: prior expectations and learning; socio-demographic characteristics; personality and individual differences; neurodegenerative conditions; inflammatory conditions; communication of information and patient-physician relationship; drug characteristics; setting; and self-awareness. We also highlighted the main biochemical and neurophysiological mechanisms underlying nocebo effects.

Conclusions

Nocebo effects arise from expectations of adverse symptoms, particularly when triggered by previous negative experiences. A trusting relationship with the treating physician and clear, tailored treatment instructions can act as protective factors against a nocebo effect. Clinical implications are discussed.

The downside to choice: instrumental control increases conditioned nocebo hyperalgesia

ABSTRACT

Nocebo hyperalgesia is a pervasive problem in which the treatment context triggers negative expectations that exacerbate pain. Thus, developing ethical strategies to mitigate nocebo hyperalgesia is crucial. Emerging research suggests that choice has the capacity to reduce nocebo side effects, but choice effects on nocebo hyperalgesia have not been explored. This study investigated the impact of choice on conditioned nocebo hyperalgesia using a well-established electrocutaneous pain paradigm where increases in noxious stimulation were surreptitiously paired with the activation of a sham device. In study 1, healthy volunteers (N = 104) were randomised to choice over (nocebo) treatment administration, nocebo administration without choice, or a natural history control group. Nocebo hyperalgesia was greater for those with choice than no choice, suggesting that choice increased rather than diminished nocebo hyperalgesia. Study 2 tested whether providing positive information about the benefits of choice in coping with pain could counteract heightened nocebo hyperalgesia caused by choice. A different sample of healthy adults (N = 137) were randomised to receive nocebo treatment with choice and positive choice information, choice only, or no choice. The positive choice information failed to attenuate the effect of choice on nocebo hyperalgesia. The current results suggest that, rather than decreasing nocebo hyperalgesia, treatment choice may exacerbate pain outcomes when a painful procedure is repeatedly administered. As such, using choice as a strategy to mitigate nocebo outcomes should be treated with caution.

If only they knew! A non-inferiority randomized controlled trial comparing deceptive and open-label placebo in healthy individuals

BACKGROUND

Placebo use is widespread in clinical practice. However, they are most often administered deceptively rather than openly. It is often suggested that open-label placebos (OLP) are less effective than deceptive placebos (DP). This study aimed to compare the use of DP and OLP treatments to reduce pain in healthy volunteers.

METHODS

We conducted a non-inferiority, parallel, randomized, controlled trial, which also included a nested cross-over no-treatment condition. This study was conducted at a university clinic in France.

RESULTS

We included 60 subjects and the main result shows that the OLP was not inferior to the DP by a margin of 10 mm. The mean difference between both groups regarding intensity of pain was 0.7 mm with a 95% compatibility interval (95% CI) of ]-∞; 5.4], and 97.5% CI of ]-∞; 6.3]. Secondary outcomes require cautious interpretation of the effect of placebo versus no treatment due to a time-treatment interaction.

CONCLUSION

The study indicates that OLP may perform just as well as DP and could provide support for the use of OLP as an ethical alternative to DP when they are to be used in a clinical setting. If only patients knew about the placebo nature of some treatments they are receiving, unnecessary lies could be avoided while maintaining similar placebo effects.

SIGNIFICANCE

This study is the first to show non-inferiority of placebos administered honestly, also called OLP, compared to DP in reducing pain. This suggests that OLP could be as effective as their deceptive counterparts while having the ethical advantage of not being required to lie. If deception is not a necessary condition for efficacy, OLP should be preferred over DP.

Learning pain from others: a systematic review and meta-analysis of studies on placebo hypoalgesia and nocebo hyperalgesia induced by observational learning

ABSTRACT

Observing someone experience pain relief or exacerbation after an intervention may induce placebo hypoalgesia or nocebo hyperalgesia. Understanding the factors that contribute to these effects could help in the development of strategies for optimizing treatment of chronic pain conditions. We systematically reviewed and meta-analyzed the literature on placebo hypoalgesia and nocebo hyperalgesia induced by observational learning (OL). A systematic literature search was conducted in the databases PubMed, PsycINFO, Web of Science, ScienceDirect, PsycARTICLES, Scopus, and Academic Search Ultimate. Twenty-one studies were included in the systematic review, 17 of which were suitable for meta-analysis (18 experiments; n = 764 healthy individuals). The primary end point was the standardized mean difference (SMD) for pain following placebo cues associated during OL with low vs high pain. Observational learning had a small-to-medium effect on pain ratings (SMD 0.44; 95% confidence interval [CI] 0.21-0.68; P < 0.01) and a large effect on pain expectancy (SMD 1.11; 95% CI 0.49-2.04; P < 0.01). The type of observation (in-person vs videotaped) modulated the magnitude of placebo hypoalgesia/nocebo hyperalgesia ( P < 0.01), whereas placebo type did not ( P = 0.23). Finally, OL was more effective when observers' empathic concern (but no other empathy-related factors) was higher ( r = 0.14; 95% CI 0.01-0.27; P = 0.03). Overall, the meta-analysis demonstrates that OL can shape placebo hypoalgesia and nocebo hyperalgesia. More research is needed to identify predictors of these effects and to study them in clinical populations. In the future, OL could be an important tool to help maximize placebo hypoalgesia in clinical settings.