Expectations: How and when do they contribute to placebo analgesia?

Do cognitive bias and heuristics influence improvement in knee pain in patients with knee osteoarthritis treated with open label placebo? The CHIPS study - An exploratory study using questionnaire and group concept mapping

Objective

This study explored if the patient-experience and the affect heuristic influenced improvements in painful symptoms, in response to open label placebo injections in patients with knee OA. It furthermore explored if other cognitive biases or heuristics were involved in the response to open-label placebo.

Method

A mixed method study in a pre-specified knee OA cohort. The influence of patient-experience, and the affect heuristic, on change in painful symptoms in response to an open-label placebo injection, were assessed using a questionnaire and multivariate linear regression. The group concept mapping method was used to characterise the expectations and hopes regarding the effect of an open-label placebo injection in non-responders and responders, defined as the lower- and upper quartile of the ΔVAS pain scores.

Results

103 participants received the questionnaire, and 60 finalised questionnaires were included in the analysis showing that the reduction in pain was associated with the patient-experience and that the affect heuristic acted as an effect modifier. Three workshops were held for non-responders (n ​= ​13) and responders (n ​= ​15) each generating respectively 113 and 119 statements. It was found that the two groups reported different expectations and hopes for the open label placebo injections.

Conclusions

The patient-experience influenced the response to an open label placebo injection in patients with knee OA, and this influence was moderated by the strength of the affect heuristic. Furthermore, non-responders and responders reported different hopes and expectation towards the open label placebo injection indicating the presence of the optimism bias in the responder group.

Summary of the 2024 Professionals in Nutrition for Exercise and Sport "10 Questions/10 Experts" Session-Hot Topics for the Paris Olympic Games

This article provides a recap of the 10 Questions/10 Experts session at the 2024 American College of Sports Medicine Annual Meeting. Each of the speakers considered the validity of common "myths," while providing evidence-based opinions to support, or, bust, myths addressing the following questions: (1) Would 100 g/hr of carbohydrate be advisable for the Olympic Cycling Road race? (2) Is there an advantage in the marathon of ingesting bicarbonate as a hydrogel product? (3) Can genotyping be used to individualize caffeine supplementation in football? (4) Should low fluid consumers drink more to improve 1,500-m track performance? (5) Do urinary markers of dehydration predict poor basketball performance? (6) Do placebo effects influence 10-km track performance? (7) Should combat athletes make weight using glucagon-like peptide-1 receptor agonists? (8) Would crushed ice ingestion help tennis umpires make better decisions in the heat? (9) Are collagen supplements useful to reduce tendon and ligament injuries in volleyball? and (10) Should female athletes plan their training and diet according to their menstrual cycle? This article describes the content of each of the presentations including the most important outcomes and conclusions drawn by the presenters.

Virtual Reality to Improve Sleep Quality in Patients Suffering from Painful Diabetic Polyneuropathy: A Proof of Concept Study

Background/Objectives: Sleep disturbance is often observed in the context of chronic pain. We hypothesize that, by providing an immersive Virtual Reality (VR) experience with a serious game to chronic pain patients an hour before bedtime, attention can be diverted from the pain condition, consequently leading to improved sleep quality. The aim is to evaluate the efficacy of VR compared to usual care in reducing the number of awakenings during the night and increasing sleep efficiency in patients suffering from painful diabetic polyneuropathy (PDPN). Methods: Eight patients with PDPN were randomized to either two weeks of VR or two weeks of usual care, followed by a cross-over. The primary outcome measurements were sleep efficiency and number of awakenings during the night. As secondary outcomes, self-reported sleep quality, insomnia, pain catastrophizing, anxiety, depression, pain intensity, side effects and impression of change were evaluated. Results: Data of seven patients were analysed. Actigraphy data, self-reported sleep quality, insomnia, pain catastrophizing, anxiety, depression and pain intensity scores did not differ between usual care and VR. As for impression of change, more patients improved after VR compared to usual care (V = 21, p = 0.03). Conclusions: A 2-week period of pain neuroscience education through VR did not result in increased sleep efficiency or fewer awakenings compared to usual care in patients with PDPN. These pilot results indicate that patients subjectively experience an improvement, yet this is not substantiated by either self-reported or objective measurements.

Women show a positive response to platelet-rich plasma despite presenting more painful knee osteoarthritis than men

PURPOSE

The purpose of this study was to evaluate the impact of gender on the efficacy of platelet-rich plasma (PRP) in patients with knee osteoarthritis (KOA), comparing their short-term response between men and women.

METHODS

Four hundred-eighteen patients (529 knees) were included. Patients were treated with three injections of PRP on a weekly basis. Blood and PRP samples were randomly tested. Patients were asked to complete the knee injury and osteoarthritis outcome score (KOOS) and 12-item short form survey (SF-12), at baseline and 6 months. Success rates were calculated according to a reduction in the pain score of at least 9.3 points [minimal clinically important improvement (MCII)]. Comparative tests and multivariate regression were performed.

RESULTS

The PRP had a platelet concentration factor of 2.0X compared to blood levels, with no leucocytes or erythrocytes. KOOS scores showed an increase from baseline to 6 months (p < 0.0001). There was an increase in the physical component summary (PCS) (p < 0.0001) and mental component summary (MCS) (p < 0.01) of the SF-12. The number of knees of women with MCII was 156 out of 262 (59.6%), whereas the number of knees of men was 136 out of 267 (50.9%) (p = 0.0468). Women had worse baseline scores on pain (p = 0.009), PCS (p < 0.0001) and MCS (p < 0.0001).

CONCLUSION

Although the symptomatology generated by KOA was worse in women when compared to men, treatment with repeated injections of PRP was effective, ultimately achieving a higher improvement in women providing comparable final follow-up outcomes between men and women.

LEVEL OF EVIDENCE

Level IV.

Placebo effects in osteoarthritis: implications for treatment and drug development

Osteoarthritis (OA) is the most common form of arthritis worldwide, affecting ~500 million people, yet there are no effective treatments to halt its progression. Without any structure-modifying agents, management of OA focuses on ameliorating pain and improving function. Treatment approaches typically have modest efficacy, and many patients have contraindications to recommended pharmacological treatments. Drug development for OA is hindered by the gradual and progressive nature of the disease and the targeting of established disease in clinical trials. Additionally, new medications for OA cannot receive regulatory approval without demonstrating improvements in both structure (pathological features of OA) and symptoms (reduced pain and/or improved function). In clinical trials, people with OA show high 'placebo responses', which hamper the ability to identify new effective treatments. Placebo responses refer to the individual variability in response to placebos given in the context of clinical trials and other settings. Placebo effects refer specifically to short-lasting improvements in symptoms that occur because of physiological changes. To mitigate the effects of the placebo phenomenon, we must first understand what it is, how it manifests, how to identify placebo responders in OA trials and how these insights can be used to improve clinical trials in OA. Leveraging placebo responses and effects in clinical practice might provide additional avenues to augment symptom management of OA.

The Biology of Placebo and Nocebo Effects on Experimental and Chronic Pain: State of the Art

(1) Background: In recent years, placebo and nocebo effects have been extensively documented in different medical conditions, including pain. The scientific literature has provided strong evidence of how the psychosocial context accompanying the treatment administration can influence the therapeutic outcome positively (placebo effects) or negatively (nocebo effects). (2) Methods: This state-of-the-art paper aims to provide an updated overview of placebo and nocebo effects on pain. (3) Results: The most common study designs, the psychological mechanisms, and neurobiological/genetic determinants of these phenomena are discussed, focusing on the differences between positive and negative context effects on pain in experimental settings on healthy volunteers and in clinical settings on chronic pain patients. Finally, the last section describes the implications for clinical and research practice to maximize the medical and scientific routine and correctly interpret the results of research studies on placebo and nocebo effects. (4) Conclusions: While studies on healthy participants seem consistent and provide a clear picture of how the brain reacts to the context, there are no unique results of the occurrence and magnitude of placebo and nocebo effects in chronic pain patients, mainly due to the heterogeneity of pain. This opens up the need for future studies on the topic.

Case Report: "I got my brain back" A patient's experience with music-induced analgesia for chronic pain

Listening to music has progressively been proposed as a complementary alternative for chronic pain; understanding its properties and its neurobiological bases is urgent. We show a phenomenological investigation of a woman who has lived 20  years with chronic pain. The inquiry involved her experience of the context in which she listens to music, the intensity and quality of pain, body mapping, memories, emotions, and cognition. The participant listens to music for different reasons, such as pain and anxiety relief, motivation to exercise, and quality of sleep, but all seem to revolve around different strategies for pain management. Experiences in physiological and cognitive aspects included perceived restorative sleep that may have improved the participant's general wellbeing and improved cognitive and motor performance as well as communication skills. The music enabled the participant not only to relieve pain but also withdrawal effects after discontinuing her opioid-based treatment. These effects may encompass endogenous opioid and dopamine mechanisms involving natural analgesia associated with pleasurable experiences. Future studies could consider phenomenological case studies and therapeutic accompaniment to reorient subjective properties of pain and expand quantitative and qualitative knowledge for more comprehensive reports on music and analgesia.