The placebo effect and its determinants in fibromyalgia: meta-analysis of randomised controlled trials

Comparative Effectiveness of Noninvasive Brain Stimulation for the Treatment of Pain, Fatigue, and Sleep Quality in Fibromyalgia. A Systematic Review With Network Meta-Analysis

OBJECTIVES

There is tentative evidence to support the analgesic effects of noninvasive brain stimulation (NiBS) in fibromyalgia (FM), but a comprehensive synthesis is lacking. This systematic review with network meta-analysis (NMA) aimed to determine the relative effectiveness of different NiBS techniques, such as transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) in FM, and to identify the optimal stimulation location and intensity/frequency.

METHODS

Four databases were searched until July 9, 2023 for randomized trials (RCTs) comparing NiBS in FM. Pain was the primary outcome, while fatigue and sleep were secondary outcomes. A frequentist NMA calculated standardized-mean-differences (SMDs) for pain, with pairwise meta-analysis for fatigue and sleep. Bias was assessed with the Cochrane-risk-of-bias-tool (RoB-2.0), and evidence certainty through confidence-in-NMA.

RESULTS

Forty-three RCTs with 2120 participants were included. NMA showed that low frequency (LF)-rTMS (SMD: -1.20, 95% CI: -1.82 to -0.58), dual tDCS (SMD: -0.91, 95% CI: -1.82 to -0.58), and high frequency (HF)-rTMS (SMD: -0.58, 95% CI: -1.00 to -0.17) likely results in a reduction in pain intensity at the end of intervention compared with sham stimulation. For stimulation location, right dorsolateral prefrontal cortex (DLPFC)(SMD: -1.42, 95% CI: -2.69 to -0.15), bilateral DLPFC (SMD: -0.94, 95% CI: -1.82 to -0.05), and left primary motor cortex (M1)(SMD: -0.49, 95% CI: -0.85 to -0.14) likely results in reduction in pain intensity at the end of intervention, with DLPFC maintaining effects in short-term. LF-rTMS over DLPFC (SMD: -1.42, 95% CI: -2.69 to -0.15) and HF-rTMS over M1 (SMD: -0.78, 95% CI: -1.39 to -0.18) likely results in the reduction in pain intensity at the end of intervention, with LF-rTMS over right DLPFC maintaining effects in the short term. NiBS appears to be safe and may reduce fatigue and improve sleep quality.

DISCUSSION

Excitatory stimulation like HF-rTMS over M1 and inhibitory like LF-rTMS over DLPFC may yield better results.

Effects of Coenzyme Q10, Tryptophan, and Magnesium Supplementation on Fatigue in Patients with Fibromyalgia - A Randomized Trial

Fibromyalgia (FM) is a prevalent and multifactorial condition requiring pharmacological and non-pharmacological interventions for its management. Coenzyme Q10 (CoQ10), magnesium, and tryptophan are associated with FM symptoms, but their combined effects in this condition are poorly understood. The objective of the study was to assess the effects of CoQ10, tryptophan, and magnesium supplementation in patients with FM. This single-center, randomized, double-blind, placebo-controlled, two-period, two-sequence crossover study included adult patients diagnosed with FM for at least two years. The study comprised two periods of three months each, and a one-month washout period between them. Participants were randomized to receive the dietary supplement or placebo. The primary endpoint was the change in the item fatigue of the combined index of fibromyalgia impact in patients (ICAF). Secondary outcomes included changes in the remaining ICAF factors and items and in the total score. Of 110 enrolled patients, 89 (mean age: 51.0 years; 96.6% women) completed the study. Most participants (94.4%) were on pharmacological treatment for FM. Fatigue improved significantly in the placebo group, with a non-significant reduction in the dietary supplement group. Pain intensity significantly decreased in both groups, while sleep quality and functional impact showed a significant reduction in the dietary supplement group. The ICAF total score improved significantly after 3 months of receiving the dietary supplement. Adverse events (n = 35) were mild and homogenously distributed between groups. The dietary supplement was efficacious in improving physical aspects of FM, including pain, sleep quality, and impact, and showed good tolerability.

A scoping review of placebo and nocebo responses and effects: insights for clinical trials and practice

Placebo and nocebo responses and effects influence treatment outcomes across a variety of conditions. The current scoping review aims to synthesise evidence from systematic reviews and meta-analyses in both clinical and healthy populations, elucidating key determinants of placebo and nocebo responses and effects, including individual, clinical, psychological and contextual factors. Among the 306 publications identified, 83% were meta-analyses and 17% systematic reviews, with a predominance of research in medical specialties (81.7%) such as psychiatry and neurology. Placebo responses were significantly more studied than nocebo responses. Individual determinants (e.g., age), clinical determinants (e.g., baseline symptom severity) and psychological determinants (e.g., expectations) were found to influence placebo and nocebo outcomes. Contextual determinants, including trial design and the method of treatment administration, also played critical roles. Several key underinvestigated areas in the current body of systematic reviews and meta-analyses were also identified. This scoping review highlights valuable insights into the determinants of placebo and nocebo responses and effects on a group level, potentially offering practical implications for optimising clinical trial designs and enhancing patient care strategies in clinical practice. However, to fully leverage these benefits, it is crucial to address the underexplored topics through more rigorous investigations using a person-centred perspective.

Effects of connective tissue massage and kinesiotaping in patients with fibromyalgia

BACKGROUND

Fibromyalgia (FM) is a common soft tissue rheumatic disease. There is no established treatment plan for FM. Current treatments primarily focus on controlling symptoms and improving the quality of life. The aim of our study was to determine how connective tissue massage (CTM) and kinesiotaping (KT) affect pain and depression in patients with fibromyalgia, and to compare their effects on quality of life.

METHODS

Thirty-four patients diagnosed with fibromyalgia were included. Participants divided into two groups. Group 1: CTM (n = 17, mean age = 35.47 ± 6.84 years), Group 2: KT (n = 17, mean age = 34.00 ± 5.46 years). This study was initiated by obtaining sociodemographic information. Pain (Visual Analogue Scale (VAS)), pain characteristics (McGill Pain Questionnaire), disease impact on patients (Fibromyalgia Impact Questionnaire (FIQ)), depression (Beck's Depression Inventory (BDI)), and quality of life (Short Form-36 (SF-36)) were evaluated. All participants received electrotherapy (TENS and infrared treatment) for 25 min, 5 days a week for 4 weeks. CTM was applied 3 days a week, KT was applied 2 days a week for 4 weeks.

RESULTS

A significant improvement with very large effect size was found in VAS, McGill, FIQ, BDI, and SF-36 variables in both groups (p < 0.05). The change after 4 weeks of treatment was similar between groups in terms of all parameters (p > 0.05).

CONCLUSION

Both CTM and KT improved pain, disease effects depression, and quality of life. These two interventions, which are not superior, can be added to the treatment program for patients with fibromyalgia.

Nutraceutical Supplementation as a Potential Non-Drug Treatment for Fibromyalgia: Effects on Lipid Profile, Oxidative Status, and Quality of Life

Fibromyalgia (FM) is a chronic syndrome of unknown etiology, although many studies point to inflammation, oxidative stress, and altered mitochondrial metabolism as some of the cornerstones of this disease. Despite its socioeconomic importance and due to the difficulties in diagnosis, there are no effective treatments. However, the use of non-drug treatments is increasingly becoming a recommended strategy. In this context, the effects of supplementation of FM patients with an olive (poly)phenol, vitamin C, and vitamin B preparation were investigated in this work, analyzing complete blood count, biochemical, lipid, and coagulation profiles, and inflammation and oxidation status in blood samples. To gain a better understanding of the molecular mechanisms and pathways involved in the etiology of FM, a proteomic study was also performed to investigate the mechanisms of action of the supplement. Our results show that the nutraceutical lowers the lipid profile, namely cholesterol, and improves the oxidative status of patients as well as their quality of life, suggesting that this product could be beneficial in the co-treatment of FM. ClinicalTrials.gov (ID: NCT06348537).

Effect of prebiotic and probiotic supplementation on reduced pain in patients with fibromyalgia syndrome: a double-blind, placebo-controlled randomized clinical trial

It has recently been observed that microorganisms in the gut can regulate brain processes through the gut microbiota-brain axis, affecting pain, depression, and sleep quality. Consequently, prebiotics and probiotics may potentially improve physical, psychological, and cognitive states in those with fibromyalgia syndrome (FMS) who have an altered microbiota balance. In a randomised, double-blind, placebo-controlled clinical trial to determine the effects of probiotic and prebiotic treatments on pain, sleep, quality of life, and psychological distress (depression and anxiety) in FMS, 53 female participants with FMS were randomised to receive either: 1) 4 × 1010 CFUs per day for the 18 patients in the probiotics group; 2) 10 g dose inulin per day for the 17 patients in the prebiotic group; or 3) a placebo for 8 weeks for the 18 patients in this group. The mean ages of the groups were similar and there was no significant difference between the groups. The impact of FMS on pain, sleep quality, quality of life, anxiety, and depressive symptoms were measured at baseline, 4 weeks, and 8 weeks post-intervention. Probiotic supplementation significantly decreased the Beck Depression Index (BDI), Beck Anxiety Index (BAI), and Pittsburgh Sleep Quality Index (PSQI) scores compared to baseline, while prebiotic supplementation only significantly decreased PSQI scores. Moreover, participants who received probiotic treatment presented a significantly reduced Visual Analogue Scale (VAS) score compared with those who received placebo treatment, after the interventions. Probiotic supplementation significantly improved sleep quality, depression, anxiety, and pain scores compared to those at baseline in FMS patients, while prebiotic supplementation significantly improved pain scores and sleep quality. The potential benefits of using probiotics for treatment management in FMS patients is supported by the results of the current study and might provide an important strategy to combat FMS-associated diseases.

Contextual effects: how to, and how not to, quantify them

The importance of contextual effects and their roles in clinical care controversial. A Cochrane review published in 2010 concluded that placebo interventions lack important clinical effects overall, but that placebo interventions can influence patient-reported outcomes such as pain and nausea. However, systematic reviews published after 2010 estimated greater contextual effects than the Cochrane review, which stems from the inappropriate methods employed to quantify contextual effects. The effects of medical interventions (i.e., the total treatment effect) can be divided into three components: specific, contextual, and non-specific. We propose that the most effective method for quantifying the magnitude of contextual effects is to calculate the difference in outcome measures between a group treated with placebo and a non-treated control group. Here, we show that other methods, such as solely using the placebo control arm or calculation of a 'proportional contextual effect,' are limited and should not be applied. The aim of this study is to provide clear guidance on best practices for estimating contextual effects in clinical research.

Electroacupuncture Reduces Fibromyalgia Pain via Neuronal/Microglial Inactivation and Toll-like Receptor 4 in the Mouse Brain: Precise Interpretation of Chemogenetics

Fibromyalgia (FM) is a complex, chronic, widespread pain syndrome that can cause significant health and economic burden. Emerging evidence has shown that neuroinflammation is an underlying pathological mechanism in FM. Toll-like receptors (TLRs) are key mediators of the immune system. TLR4 is expressed primarily in microglia and regulates downstream signaling pathways, such as MyD88/NF-κB and TRIF/IRF3. It remains unknown whether electroacupuncture (EA) has therapeutic benefit in attenuating FM pain and what role the TLR4 pathway may play in this effect. We compared EA with sham EA to eliminate the placebo effect due to acupuncture. We demonstrated that intermittent cold stress significantly induced an increase in mechanical and thermal FM pain in mice (mechanical: 2.48 ± 0.53 g; thermal: 5.64 ± 0.32 s). EA but not sham EA has an analgesic effect on FM mice. TLR4 and inflammatory mediator-related molecules were increased in the thalamus, medial prefrontal cortex, somatosensory cortex (SSC), and amygdala of FM mice, indicating neuroinflammation and microglial activation. These molecules were reduced by EA but not sham EA. Furthermore, a new chemogenetics method was used to precisely inhibit SSC activity that displayed an anti-nociceptive effect through the TLR4 pathway. Our results imply that the analgesic effect of EA is associated with TLR4 downregulation. We provide novel evidence that EA modulates the TLR4 signaling pathway, revealing potential therapeutic targets for FM pain.

Betting on Non-Invasive Brain Stimulation to Treat Gambling Disorder: A Systematic Review and Meta-Analysis

Gambling disorder (GD) is a behavioral addiction that severely impacts individuals' functioning, leading to high socioeconomic costs. Non-invasive brain stimulation (NiBS) has received attention for treating psychiatric and neurological conditions in recent decades, but there is no recommendation for its use for GD. Therefore, this study aimed to systematically review and analyze the available literature to determine the effectiveness of NiBS in treating GD. Following the PRISMA guidelines, we screened four electronic databases up to July 2022 and selected relevant English-written original articles. We included ten papers in the systematic review and seven in the meta-analysis. As only two studies employed a sham-controlled design, the pre-post standardized mean change (SMCC) was computed as effect size only for real stimulation. The results showed a significant effect of NiBS in reducing craving scores (SMCC = -0.69; 95% CI = [-1.2, -0.2], p = 0.010). Moreover, considering the GD's frequent comorbidity with mood disorders, we ran an exploratory analysis of the effects of NiBS on depressive symptoms, which showed significant decreases in post-treatment scores (SMCC = -0.71; 95% CI = [-1.1, -0.3], p < 0.001). These results provide initial evidence for developing NiBS as a feasible therapy for GD symptoms but further comprehensive research is needed to validate these findings. The limitations of the available literature are critically discussed.

Clinical Trials in Chronic Arthritic Diseases with Underestimated Impact of Placebo Effects on Study Size Calculation

Whether and to which extent placebo treatment in double-blinded randomized controlled clinical trials is effective in chronic arthritic diseases has not been studied before. Therefore, a systematic literature search was undertaken to detect eligible trials. Demographic data of the placebo groups as well as concomitant and previous disease outcomes were collected. Analyses of significant bivariate correlations and linear regression between clinical endpoints and characteristics of the placebo groups were performed. A total of 152 double-blinded randomized controlled studies, including 21,616 participants in the placebo groups, was analyzed. The results of bivariate correlations and linear regressions revealed significant positive associations between responses in the placebo groups and the following factors: (i) naïvety of previous treatment and (ii) early stage of disease. In addition to the clinical relevance, the results support the importance of the placebo effect on study size calculations, and will allow an optimized calculation of patients' numbers for early placebo-controlled trials conducted in patients with chronic arthritic diseases.

Nocebo vs Placebo Effects: Their Clinical Relevance

The placebo effect can be defined as any improvement of illnesses or reduction of subjective symptoms that result from interventions possessing no known physical effects. By contrast, the nocebo effect refers to undesirable symptoms or illnesses that follow interventions also lacking known physical effects. It may also play a role in chronic illnesses that lack objective confirmation. Both placebo and nocebo effects can be potent and must be understood by both practitioners and researchers for proper application in clinical medicine. Individual caregivers can apply these principles to modify results in the daily care of patients.

Association of low-dose naltrexone and transcranial direct current stimulation in fibromyalgia: a randomized, double-blinded, parallel clinical trial

INTRODUCTION

Fibromyalgia is a complex, generalized, and diffuse chronic musculoskeletal pain. Pharmacological approaches are widely used to relieve pain and increase quality of life. Low-Dose Naltrexone (LDN) was shown to increase the nociceptive threshold in patients with fibromyalgia. Transcranial Direct Current Stimulation (tDCS) is effective for pain management.

OBJECTIVE

The purpose of this study was to evaluate the analgesic and neuromodulatory effects of a combination of LDN and tDCS in patients with fibromyalgia.

METHODS

This was a randomized, double-blinded, parallel, placebo/sham-controlled trial (NCT04502251; RBR-7HK8N) in which 86 women with fibromyalgia were included, and written informed consent was obtained from them. The patients were allocated into four groups: LDN + tDCS (n = 21), LDN + tDCS Sham (n = 22), placebo + tDCS (n = 22), and placebo+tDCS Sham (n = 21). The LDN or placebo (p.o.) intervention lasted 26 days; in the last five sessions, tDCS was applied (sham or active, 20 min, 2 mA). The following categories were assessed: sociodemographic, Visual Analog Pain Scale (VAS), Pain Catastrophizing Scale (PCS), State-Trait Anxiety Inventory (STAI), Fibromyalgia Impact Questionnaire (FIQ), Beck Depression Inventory (BDI-II), Profile of Chronic Pain Scale (PCP:S), Pain Pressure Threshold (PPT), and Conditioned Pain Modulation (CPM). Blood samples were collected to analyze BDNF serum levels.

RESULTS

At baseline, no significant difference was found regarding all measurements. VAS pain was significantly reduced in the LDN + tDCS (p = 0.010), LDN + tDCS Sham (p = 0.001), and placebo+tDCS Sham (p = 0.009) groups. In the PCP:S, the LDN+tDCS group showed reduced pain frequency and intensity (p = 0.001), effect of pain on activities (p = 0.014) and emotions (p = 0.008). Depressive symptoms reduced after all active interventions (p > 0.001).

CONCLUSION

Combined LDN+tDCS has possible benefits in reducing pain frequency and intensity; however, a placebo effect was observed in pain using VAS, and further studies should be performed to analyze the possible association.

Placebo: a brief updated review

Our aims were to provide updated information on placebo/nocebo effect and the potential use of placebo in clinical practice. This article can only provide a rough overview on the placebo and nocebo effect and is intended to serve as a starting point for the reader to go deeper into the corresponding literature. The placebo effect has been observed in multiple medical conditions, after oral administration, with manual therapies as well as with surgery and invasive procedures. The use of placebo in clinical trials is fundamental, although the ethics of its use is under discussion. The placebo may behave like a drug from the pharmacokinetic and pharmacodynamic point of view and can also be associated with adverse events (nocebo effect). Placebo can modify treatment by increasing or decreasing the effects of drugs. The factors associated with the occurrence of placebo effect are multiple, but in addition to those that depend on the placebo itself, the doctor-patient relationship would be the most important. As a result of findings that were published in the last two decades, the psycho-neurobiological basis of placebo is becoming better understood, although further studies are needed. In conclusion, the placebo effect in the clinic exhibits weak to moderate intensity. Placebo, in addition to its use in the clinical trial, should be considered another therapeutic remedy either as stand alone or in association with treatment, and could be useful in certain circumstances. The use of placebo should be regulated by the European health authorities through a guide in clinical practice that will improve patient care.

Placebo administration for dry eye disease: a level I evidence based systematic review and meta-analysis

Background

The efficacy of various common treatment options for dry eye disease (DED) has been investigated against placebo. However, the potential beneficial effect of placebo in the management of DED is still unclear.

Aim

This meta-analysis investigated the impact of placebo administration in DED in Ocular Surface Disease Index (OSDI), Schirmer I test (SIT), tear breakup time (TBUT), corneal staining, and complications.

Method

This meta-analysis and systematic review was conducted according to the 2020 PRISMA guidelines. In March 2022, Pubmed, Web of Science, Google Scholar, and Embase were accessed. All the randomised clinical trials which investigated any active treatment against a placebo control group were considered. The following data were extracted at baseline and at last follow-up: Ocular Surface Disease Index (OSDI), tear breakup time test (TBUT), Schirmer I test (SIT), corneal staining.

Results

Data from 56 studies (12,205 patients) were retrieved. Placebo administration is not effective in improving TBUT (P = 0.3), OSDI (P = 0.2), SIT (P = 0.1) and corneal staining (P = 0.1) from baseline to last follow-up. Active treatment led to a higher TBUT and SIT compared to placebo administration (P < 0.0001). The active treatment resulted in a lower OSDI compared to placebo administration (P = 0.0005). Five studies reported data on the corneal staining. No difference was found between placebo administration and active treatment (P = 0.8).

Conclusion

Placebo administration does not impact symptoms of DED and can be successfully employed to evaluate the efficacy of active treatments.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11096-022-01439-y.

Research in Mindfulness Interventions for Patients With Fibromyalgia: A Critical Review

Fibromyalgia is one of the most common causes of widespread chronic pain. It has a huge impact on the quality of life, namely because it appears earlier in life than most of the chronic pain conditions. Furthermore, emotional-cognitive distress factors, such as depression and anxiety, are a common feature in patients with fibromyalgia. The neurobiological mechanisms underlying fibromyalgia remain mostly unknown. Among non-pharmacological treatments, cognitive-behavioral therapy has been used during the last decade, namely with the enrolment of patients in programs of mindfulness-based stress reduction (MBSR) and in mindfulness-based interventions (MBI). We critically analyzed the literature to search for scientific evidence for the use of MBI in fibromyalgia. The studies were evaluated as to several outcomes of fibromyalgia improvement along with aspects of the study design which are currently considered relevant for research in mindfulness. We conclude that despite the sparsity of well-structured longitudinal studies, there are some promising results showing that the MBI are effective in reducing the negative aspects of the disease. Future design of studies using MBI in fibromyalgia management should be critically discussed. The importance of active controls, evaluation of sustained effects along with investigation of the subserving neurobiological mechanisms and detailed reports of possible adverse effects should be considered.

Pregabalin administration in patients with fibromyalgia: a Bayesian network meta-analysis

Several studies investigated the effectiveness and the safety of different doses of pregabalin in fibromyalgia. However, the optimal protocol remains controversial. A Bayesian network meta-analysis comparing 300, 450, and 600 mg/daily of pregabalin for fibromyalgia was conducted. The literature search was conducted in January 2022. All the double-blind randomised clinical trials comparing two or more dose protocols of pregabalin for fibromyalgia were accessed. Studies enrolling less than 50 patients were not eligible, nor were those with a length of follow-up shorter than eight weeks. The outcomes of interests were: Fibromyalgia Impact Questionnaire (FIQ), sleep quality, and adverse events. The network meta-analyses were performed using the routine for Bayesian hierarchical random-effects model analysis, with log odd ratio (LOR) and standardized mean difference (SMD) effect measure. Data from 4693 patients (mean age 48.5 years) were retrieved. 93.1% (4370 of 4693 patients) were women. The median follow-up was 14.8 weeks. Pregabalin 450 mg/daily resulted in greater reduction in Fibromyalgia Impact Questionnaire (SMD - 1.83). Pregabalin 600 demonstrated the greatest sleep quality (SMD 0.15). Pregabalin 300 mg/daily evidenced the lowest rate of adverse events (LOR 0.12). The dose of pregabalin must be customised according to patients' characteristics and main symptoms.

Short-Term Magnesium Therapy Alleviates Moderate Stress in Patients with Fibromyalgia: A Randomized Double-Blind Clinical Trial

Patients suffering from fibromyalgia often report stress and pain, with both often refractory to usual drug treatment. Magnesium supplementation seems to improve fibromyalgia symptoms, but the level of evidence is still poor. This study is a randomized, controlled, double-blind trial in fibromyalgia patients that compared once a day oral magnesium 100 mg (Chronomag®, magnesium chloride technology formula) to placebo, for 1 month. The primary endpoint was the level of stress on the DASS-42 scale, and secondary endpoints were pain, sleep, quality of life, fatigue, catastrophism, social vulnerability, and magnesium blood concentrations. After 1 month of treatment, the DASS-42 score decreased in the magnesium and placebo groups but not significantly (21.8 ± 9.6 vs. 21.6 ± 10.8, respectively, p = 0.930). Magnesium supplementation significantly reduced the mild/moderate stress subgroup (DASS-42 stress score: 22.1 ± 2.8 to 12.3 ± 7.0 in magnesium vs. 21.9 ± 11.9 to 22.9 ± 11.9 in placebo, p = 0.003). Pain severity diminished significantly (p = 0.029) with magnesium while the other parameters were not significantly different between both groups. These findings show, for the first time, that magnesium improves mild/moderate stress and reduces the pain experience in fibromyalgia patients. This suggests that daily magnesium could be a useful treatment to improve the burden of disease of fibromyalgia patients and calls for a larger clinical trial.

The neglect of sex: A call to action for including sex as a biological variable in placebo and nocebo research

Sex differences exist in the prevalence, progression and treatment efficacy of a wide array of medical conditions. While the placebo and nocebo effects have become increasingly relevant in the clinical arena, little is known about the influence of biological sex on placebo and nocebo effects. This paper discusses the existing, relatively limited and sometimes conflicting evidence about how sex impacts the occurrence and magnitude of the placebo and nocebo effects, mainly focusing on pain studies. We present recent evidence that when compared to men, women suffering from chronic orofacial pain may derive greater benefit from the placebo effect for analgesia. Nonetheless, we broadly argue that the field is not currently positioned to draw definitive conclusions and propose several important factors that may explain the inconsistency in the literature and that should be taken into account in future research. These include the specific target symptom of the placebo or nocebo manipulation and whether or not the target is related to the medical condition, the placebo or nocebo induction method, the sex of the experimenter or physician, and so forth. Future research should intentionally include sex a biological variable to favor translation of placebo and nocebo mechanisms into clinical applications.

Pharmacological management of fibromyalgia: a Bayesian network meta-analysis

INTRODUCTION

The identification of the most effective therapy for patients with fibromyalgia (FM) remains controversial. Thus, we conducted a Bayesian network meta-analysis to compare several drugs employed as pharmacological management for FM.

AREAS COVERED

The following databases were accessed in October 2021: PubMed, Google Scholar, Embase, and Scopus. All the randomized clinical trials (RCTs) that compare two or more pharmacological management for fibromyalgia were accessed. Only studies involving a minimum of 10 patients with a length of follow-up longer than 4 weeks were included. The data from the fibromyalgia impact questionnaire (FIQ) and the physical and mental subscales short form 36 (SF36) were extracted at last follow-up. Additionally, the number of adverse events leading to the study of discontinuation was extracted. The compounds of interests were duloxetine, pregabalin, fluoxetine, gabapentin, milnacipran, trazodone, placebo, nortriptyline, IGF-I, amitriptyline, and the combination of fluoxetine and amitriptyline, pregabalin, and trazodone.

EXPERT OPINION

According to published evidence, pregabalin, and duloxetine evidenced the greatest improvement of the FIQ and SF36 Physical and Mental subscales, along with the lowest rate of adverse events leading to study discontinuation. The results must be interpreted in light of possible adverse events associated with the use of these drugs.

Differential Brain Perfusion Changes Following Two Mind–Body Interventions for Fibromyalgia Patients: an Arterial Spin Labelling fMRI Study

Objectives

Further mechanistic insight on mind–body techniques for fibromyalgia (FMS) is needed. Arterial spin labelling (ASL) imaging can capture changes in regional cerebral blood flow (rCBF) that relate to spontaneous pain.

Methods

We recruited FMS patients undergoing either mindfulness-based stress reduction training (MBSR, n = 14) or a psychoeducational programme (FibroQoL, n = 18), and a control FMS group with no add-on treatment (n = 14). We acquired whole-brain rCBF maps and self-report measures at baseline and following treatment and explored interaction effects in brain perfusion between the treatment group and session with a focus on the amygdala, the insula and the anterior cingulate cortex (ACC).

Results

We identified a significant interaction effect in the amygdala, which corresponded with rCBF decreases following FibroQoL specifically. At baseline, rCBF in the amygdala for the FibroQoL group correlated with pain catastrophizing and anxiety scores, but not after treatment, suggesting a decoupling between activity in the amygdala and negative emotional symptoms of FMS as a consequence of treatment. Baseline rCBF correlated positively with pain symptoms in the ACC and the anterior insula across all patients; moreover, the correlation between rCBF changes post intervention in the insula and pain improvement was negative for both treatments and significantly different from the control group. We suggest that there is disruption of the typical relationship between clinical pain and activity as a product of these two nonpharmacological therapies.

Conclusions

We have demonstrated that different mind-to-body treatments correspond to differential changes in clinical symptoms and brain activity patterns, which encourages future research investigating predictors of treatment response.

Trial Registration

 NCT02561416.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12671-021-01806-2.

Placebo Responses and Their Clinical Implications in Fibromyalgia: A Meta-Analysis Using SSRI and SNRI Trials

Background: Fibromyalgia (FM) is a chronic primary pain condition, associated with widespread musculoskeletal pain, disturbed sleep, fatigue, cognitive dysfunction, and a range of comorbid conditions such as irritable bowel syndrome, and depression. Despite its high prevalence of 2% in the general population, FM continues to pose scientific and clinical challenges in definition, etiology, and day-to-day management. In terms of treatment, FM can be treated with selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs). Objective: Patients with FM and other chronic primary pain syndromes are known to experience substantial and clinically relevant placebo effects. An update of the placebo responses for various outcomes in the FM population and especially a discussion about clinical implications is therefore needed. Methods: We used data from a large data pool that includes randomized controlled trials (RCTs) examining within-placebo mean change scores of baseline vs. follow-up assessments in FM trials of SSRIs and SNRIs. The primary outcomes were pain, functional disability, and depression and using different scales. We assessed heterogeneity of included trials. Results: A total of 29 RCTs with N = 8,453 patients suffering from FM were included in our analysis. Within-placebo mean change scores of baseline vs. follow-up assessments were large for pain (mean change = 2.31, 95% CI: 0.42-4.21, p = 0.017), functional disability (mean change = 3.31, 95% CI: 2.37-4.26, p < 0.000), and depression (mean change = 1.55, 95% CI: 0.92-2.18, p < 0.000). Heterogeneity was found to be large for all outcomes. Impact: Our results provide preliminary evidence that placebo responses, which also consist of non-specific effects, might play a role in the treatment of FM. Furthermore, we highlight limitations of our analyses and make suggestions for future studies.

The Probiotic VSL#3® Does Not Seem to Be Efficacious for the Treatment of Gastrointestinal Symptomatology of Patients with Fibromyalgia: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Gastrointestinal symptomatology is frequent among patients with fibromyalgia, which increases disease burden and lacks specific treatment, either pharmacological or non-pharmacological. We aimed to evaluate the efficacy and tolerability of a multi-strain probiotic, VSL#3^®, for the treatment of fibromyalgia-associated gastrointestinal manifestations. This randomized, placebo-controlled trial included 12 weeks of probiotic or placebo treatment followed by 12 weeks of follow up. The primary outcome variable was the mean change from the baseline to the endpoint in the composite severity score of the three main gastrointestinal symptoms reported by patients with fibromyalgia (abdominal pain, abdominal bloating and meteorism). Secondary outcome variables were the severity of additional gastrointestinal symptoms, fibromyalgia severity, depression, sleep disturbance, health-related quality of life and patients' overall impression of improvement. No differences were found between VSL#3^® (n = 54) and the placebo (n = 56) in the primary outcome (estimated treatment difference: 1.1; 95% confidence interval [CI]: -2.1, 4.2; p = 0.501), or in any of the secondary outcomes. However, responders to VSL#3 were more likely to maintain any improvement during the follow-up period compared to responders in the placebo arm. Overall, VSL#3 tolerability was good. Our data could not demonstrate any beneficial effects of VSL#3^® either on the composite score of severity of abdominal pain, bloating and meteorism or in any of the secondary outcome variables. More research is needed to elucidate specific factors that may predict a favourable response to treatment in patients with fibromyalgia.

Placebo effect in pharmacological management of fibromyalgia: a meta-analysis

INTRODUCTION

The management of fibromyalgia involves a combination of pharmacological and non-pharmacological treatments.

SOURCE OF DATA

Recently published literature in PubMed, Google Scholar and Embase databases.

AREAS OF AGREEMENT

Several pharmacological and non-pharmacological strategies have been proposed for the management of fibromyalgia. However, the management of fibromyalgia remains controversial. The administration of placebo has proved to be more effective than no treatment in many clinical settings and evidence supports the 'therapeutic' effects of placebo on a wide range of symptoms.

AREAS OF CONTROVERSY

The placebo effect is believed to impact the clinical outcomes, but its actual magnitude is controversial.

GROWING POINTS

A meta-analysis comparing pharmacological management versus placebo administration for fibromyalgia was conducted.

AREAS TIMELY FOR DEVELOPING RESEARCH

Drug treatment resulted to be more effective than placebo administration for the management of fibromyalgia. Nevertheless, placebo showed a beneficial effect in patients with fibromyalgia. Treatment-related adverse events occurred more frequently in the drug treatment.

LEVEL OF EVIDENCE

I, Bayesian network meta-analysis of double-blind randomized clinical trials.

Attempting to Separate Placebo Effects from Exercise in Chronic Pain: A Systematic Review and Meta-analysis

BACKGROUND

Pain is the most disabling characteristic of musculoskeletal disorders, and while exercise is promoted as an important treatment modality for chronic musculoskeletal conditions, the relative contribution of the specific effects of exercise training, placebo effects and non-specific effects such as natural history are not clear. The aim of this systematic review and meta-analysis was to determine the relative contribution of these factors to better understand the true effect of exercise training for reducing pain in chronic primary musculoskeletal pain conditions.

DESIGN

Systematic review with meta-analysis DATA SOURCES: MEDLINE, CINAHL, SPORTDiscus, EMBASE and CENTRAL from inception to February 2021. Reference lists of prior systematic reviews.

ELIGIBILITY CRITERIA

Randomised controlled trials of interventions that used exercise training compared to placebo, true control or usual care in adults with chronic primary musculoskeletal pain. The review was registered prospectively with PROSPERO (CRD42019141096).

RESULTS

We identified 79 eligible trials for quantitative analysis. Pairwise meta-analysis showed very low-quality evidence (GRADE criteria) that exercise training was not more effective than placebo (g [95% CI]: 0.94 [- 0.17, 2.06], P = 0.098, I² = 92.46%, studies: n = 4). Exercise training was more effective than true, no intervention controls (g [95% CI]: 0.99 [0.66, 1.32], P < 0.001, I² = 92.43%, studies: n = 42), usual care controls (g [95% CI]: 0.64 [0.44, 0.83], P < 0.001, I² = 76.52%, studies: n = 33), and when all controls combined (g [95% CI]: 0.84 [0.64, 1.04], P < 0.001, I² = 90.02%, studies: n = 79).

CONCLUSIONS

There is very low-quality evidence that exercise training is not more effective than non-exercise placebo treatments in chronic pain. Exercise training and the associated clinical encounter are more effective than true control or standard medical care for reductions in pain for adults with chronic musculoskeletal pain, with very low quality of evidence based on GRADE criteria.

Effects of Wearable Transcutaneous Electrical Nerve Stimulation on Fibromyalgia: A Randomized Controlled Trial

Purpose

Fibromyalgia is a chronic condition characterized by widespread pain and interference with daily activities. The aim of this study is to assess the benefit of transcutaneous electrical nerve stimulation (TENS) for persons diagnosed with fibromyalgia.

Patients and Methods

Adults meeting diagnostic criteria for fibromyalgia were randomized in a double-blind trial to receive either an active (n=62) or sham (n=57) wearable TENS device for 3-months. Subjects were classified as having lower or higher pain sensitivity by Quantitative Sensory Testing (QST). Patient Global Impression of Change (PGIC, primary outcome) and secondary efficacy measures including Fibromyalgia Impact Questionnaire (FIQR), Brief Pain Inventory (BPI) and painDETECT questionnaire (PDQ) were assessed at baseline, 6-weeks and 3-months. Treatment effects were determined by a mixed model for repeated measures (MMRM) analysis of the intention-to-treat (ITT) population (N=119). A pre-specified subgroup analysis of pain sensitivity was conducted using an interaction term in the model.

Results

No differences were found between active and sham treatment on PGIC scores at 3-months (0.34, 95% CI [−0.37, 1.04], p=0.351) in the ITT population. However, in subjects with higher pain sensitivity (n=60), PGIC was significantly greater for active treatment compared to sham (1.19, 95% CI [0.24, 2.13], p=0.014). FIQR total score (−7.47, 95% CI [−12.46, −2.48], p=0.003), FIQR pain item (−0.62, 95% CI [−1.17, −0.06], p=0.029), BPI Interference (−0.70, 95% CI [−1.30, −0.11], p=0.021) and PDQ (−1.69, 95% CI [−3.20, −0.18], p=0.028) exhibited significant improvements for active treatment compared to sham in the ITT population. Analgesics use was stable and comparable in both groups.

Conclusion

This study demonstrated modest treatment effects of reduced disease impact, pain and functional impairment from wearable TENS in individuals with fibromyalgia. Subjects with higher pain sensitivity exhibited larger treatment effects than those with lower pain sensitivity. Wearable TENS may be a safe treatment option for people with fibromyalgia.

Clinicaltrials.gov Registration

NCT03714425.

Higher Pain Sensitivity Predicts Efficacy of a Wearable Transcutaneous Electrical Nerve Stimulation Device for Persons With Fibromyalgia: A Randomized Double-Blind Sham-Controlled Trial

OBJECTIVES

This study investigated the efficacy of a transcutaneous electrical nerve stimulation (TENS) device (Quell®) for persons with symptoms due to fibromyalgia (FM).

MATERIALS AND METHODS

One hundred nineteen (N = 119) subjects were randomly assigned to use an active (N = 62) or sham (N = 57) TENS for three months. All subjects completed baseline questionnaires and were administered quantitative sensory testing (QST). Subjects completed the Patients' Global Impression of Change (PGIC, primary outcome measure) and other mailed questionnaires (secondary outcome measures) at six weeks and three months.

RESULTS

The subjects averaged 50.4 ± 13.5 years of age, 93.3% were female, and 79.8% were Caucasian. Most showed benefit from using the TENS, but no differences between groups were found on the primary outcome measure after three months (active 3.87 ± 1.85, sham 3.73 ± 1.80, 95% confidence interval [CI] [-0.60, 0.88], p = 0.707). Those with more hypersensitivity showed most improvement on the PGIC at six weeks (0.22, 95% CI [0.01, 0.43], p = 0.042) and three months (0.20, 95% CI [0.00, 0.41], p = 0.049) and among those with higher sensitivity based on QST, the active TENS group showed the most benefit with TENS compared with the sham treatment (1.20, 95% CI [0.22, 2.18], p = 0.017). No TENS-related serious adverse events were reported. Subjects in the sham group correctly identified their treatment 87.5% of the time, while, surprisingly, subjects in the active group correctly identified their treatment only 17.4% of the time.

CONCLUSION

This study found no differences between those who were exposed to maximal-frequency active stimulation or minimal-frequency sham stimulation from a wearable TENS in reducing FM-related symptoms. However, those with greater hypersensitivity showed most benefit from TENS. Additional studies to help determine the role individual differences play in the use of TENS in managing FM-related symptoms are needed.

Repeated Intravenous Lidocaine Infusions for Patients with Fibromyalgia: Higher Doses of Lidocaine Have a Stronger and Longer-Lasting Effect on Pain Reduction

OBJECTIVES

To determine the effect of escalating doses of lidocaine infusion with or without added magnesium on pain levels and the duration of pain relief in patients with fibromyalgia (FM).

METHODS

A retrospective chart review of 74 patients diagnosed with FM who underwent at least three escalating doses of intravenous (IV) lidocaine infusions (5 mg/kg of body weight, 7.5 mg/kg, and 7.5 mg/kg of lidocaine + 2.5 g of magnesium sulfate) was conducted. Each patient's subjective impression of change in pain intensity and duration of pain relief after each treatment was recorded, along with an 11-point numeric rating scale (NRS) for pain intensity, immediately before and after each infusion.

RESULTS

Short-term lidocaine analgesia was evaluated by the reduction in NRS pain score according to the patients reported pre- (immediately before treatment) and post-treatment (immediately after treatment) values. There was a statistical difference in the NRS score reduction between doses 5 mg/kg and 7.5 mg/kg of lidocaine (P = 0.009). Long-term analgesia was evaluated at follow-up visits by the patient's subjective impression of change in pain intensity and duration of pain relief. There was a statistical difference in the percentage of pain relief and the mean duration of pain relief between the treatments with 5 mg/kg and 7.5 mg/kg of lidocaine (P = 0.007 and P = 0.003). Although there was a trend of greater response to magnesium sulfate as a beneficial adjunct to the lidocaine infusion, we were unable to find a statistically significant difference for any of the variables studied.

CONCLUSIONS

This study demonstrated that escalating doses of IV lidocaine to 7.5 mg/kg safely and effectively reduced the pain with prolonged effect in a significant number of patients diagnosed with fibromyalgia. Larger, prospective clinical studies are required to confirm this finding.

Ganoderma lucidum Effects on Mood and Health-Related Quality of Life in Women with Fibromyalgia

Fibromyalgia syndrome is a chronic rheumatic disorder characterized by generalized and widespread musculoskeletal pain. It is associated with several secondary symptoms such as psychological and pain-specific distress, which can directly impact daily functioning and quality of life, like anxiety and depression. The Ganoderma lucidum (GL) mushroom seems to be able to improve fibromyalgia symptoms, including depression and pain. The purpose of the study is to evaluate the effects of GL on happiness, depression, satisfaction with life, and health-related quality of life in women with fibromyalgia. A double-blind, randomized placebo pilot trial was carried out, with one group taking 6 g/day of micro-milled GL carpophores for 6 weeks, during which the second group took a placebo. Our results did not show any statistically significant between-group differences, although a distinct trend of improved levels of happiness and satisfaction with life and reduced depression were evident at the end of treatment compared to the baseline in the GL group. However, due to the limitations of the study protocol, additional studies are necessary to confirm these findings.

Age, sex, disease severity, and disease duration difference in placebo response: implications from a meta-analysis of diabetes mellitus

BACKGROUND

The placebo response in patients with diabetes mellitus is very common. A systematic evaluation needs to be updated with the current evidence about the placebo response in diabetes mellitus and the associated factors in clinical trials of anti-diabetic medicine.

METHODS

Literature research was conducted in Medline, Embase, the Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov for studies published between the date of inception and June 2019. Randomized placebo-controlled trials conducted in type 1and type 2 diabetes mellitus (T1DM/T2DM) were included. Random-effects model and meta-regression analysis were accordingly used. This meta-analysis was registered in PROSPERO as CRD42014009373.

RESULTS

Significantly weight elevation (effect size (ES) = 0.33 kg, 95% CI, 0.03 to 0.61 kg) was observed in patients with placebo treatments in T1DM subgroup while significantly HbA1c reduction (ES = - 0.12%, 95% CI, - 0.16 to - 0.07%) and weight reduction (ES = - 0.40 kg, 95% CI, - 0.50 to - 0.29 kg) were observed in patients with placebo treatments in T2DM subgroup. Greater HbA1c reduction was observed in patients with injectable placebo treatments (ES = - 0.22%, 95% CI, - 0.32 to - 0.11%) versus oral types (ES = - 0.09%, 95% CI, - 0.14 to - 0.04%) in T2DM (P = 0.03). Older age (β = - 0.01, 95% CI, - 0.02 to - 0.01, P < 0.01) and longer diabetes duration (β = - 0.02, 95% CI, - 0.03 to - 0.21 × 10^-2, P = 0.03) was significantly associated with more HbA1c reduction by placebo in T1DM. However, younger age (β = 0.02, 95% CI, 0.01 to 0.03, P = 0.01), lower male percentage (β = 0.01, 95% CI, 0.22 × 10^-2, 0.01, P < 0.01), higher baseline BMI (β = - 0.02, 95% CI, - 0.04 to - 0.26 × 10^-2, P = 0.02), and higher baseline HbA1c (β = - 0.09, 95% CI, - 0.16 to - 0.01, P = 0.02) were significantly associated with more HbA1c reduction by placebo in T2DM. Shorter diabetes duration (β = 0.06, 95% CI, 0.06 to 0.10, P < 0.01) was significantly associated with more weight reduction by placebo in T2DM. However, the associations between baseline BMI, baseline HbA1c, and placebo response were insignificant after the adjusted analyses.

CONCLUSION

The placebo response in diabetes mellitus was systematically outlined. Age, sex, disease severity (indirectly reflected by baseline BMI and baseline HbA1c), and disease duration were associated with placebo response in diabetes mellitus. The association between baseline BMI, baseline HbA1c, and placebo response may be the result of regression to the mean.

Comparison of two tDCS protocols on pain and EEG alpha-2 oscillations in women with fibromyalgia

Transcranial Direct Current Stimulation (tDCS) has been used as an alternative treatment for pain reduction in fibromyalgia. In this study, in addition to behavioral measures, we analyzed oscillations in alpha 2 frequency band in the frontal, occipital, and parietal regions, in response to the application of two neuromodulation protocols in fibromyalgia. The study was a randomized, double-blind, placebo-controlled clinical trial with 31 women diagnosed with fibromyalgia. The participants were allocated to three groups with the anodic stimulation applied on the left motor cortex: Group 1, for five consecutive days; Group 2, for 10 consecutive days; and Group 3, sham stimulation for five consecutive days. Statistical analysis showed a reduction in pain intensity after treatment for groups in general [F (1.28) = 8.02; p = 0.008; η2 = 0.223], in addition to a reduction in alpha 2 in the frontal (p = 0.039; d = 0.384) and parietal (p = 0.021; d = 0.520) regions after the treatment on five consecutive days. We conclude that neuromodulation protocols produced similar effects on pain reduction, but differed with respect to the changes in the alpha 2 frequency band in the frontal and parietal regions.

Effect of Normal Saline Injections on Lateral Epicondylitis Symptoms: A Systematic Review and Meta-analysis of Randomized Clinical Trials

BACKGROUND

Lateral epicondylitis, or tennis elbow, is a painful degenerative disorder that commonly occurs in adults between 40 and 60 years of age. Normal saline (NS) injections have been used as placebo through a large number of randomized controlled trials (RCTs) focused on the treatment of lateral epicondylitis.

PURPOSE

This meta-analysis of RCTs aimed to assess the therapeutic effect of NS injections on lateral epicondylitis symptoms and compare results with established minimal clinically important difference criteria.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

MEDLINE, Embase, Web of Science, and Scopus databases were searched for clinical trials reporting pain and joint function with the visual analog scale, Patient-Rated Tennis Elbow Evaluation, and Disabilities of the Arm, Shoulder and Hand in patients with lateral epicondylitis. The meta-analysis was conducted with a random effects model and generic inverse variance method. Heterogeneity was tested with the I² statistic index.

RESULTS

A total of 15 RCTs included in this meta-analysis revealed a significant improvement in pain (mean difference, 3.61 cm [95% CI, 2.29-4.92 cm]; P < .00001; I² = 88%; visual analog scale) and function (mean difference, 25.65 [95% CI, 13.30-37.99]; P < .0001; I² = 82%; Patient-Rated Tennis Elbow Evaluation / Disabilities of the Arm, Shoulder and Hand) after NS injection (≥6 months).

CONCLUSION

NS injections yielded a statistically significant and clinically meaningful improvement in pain and functional outcomes in patients with lateral epicondylitis. New research should focus on better methods to diminish the potential confounders that could lead to this effect because NS injections could mask the real effect of an active therapeutic intervention in RCT.

REGISTRATION

CRD42019127547 (PROSPERO).

Placebo Responses and Placebo Effects in Functional Gastrointestinal Disorders

Much has been written about the placebo effects in functional gastrointestinal disorders (FGD), especially in irritable bowel syndrome (IBS), driven by the early hypothesis that in randomized controlled trials (RCTs) of IBS, the placebo effect might be specifically high and thus, corrupts the efficacy of novel drugs developed for this condition. This narrative review is based on a specific search method, a database (www.jips.online) developed since 2004 containing more than 4,500 papers (data papers, meta-analyses, systematic reviews, reviews) pertinent to the topic placebo effects/placebo response. Three central questions-deducted from the body of current literature-are addressed to explore the evidence behind this hypothesis: What is the size placebo effect in FGD, especially in IBS, and is it different from the placebo effect seen in other gastrointestinal disorders? Is the placebo effect in FGD different from other functional, non-intestinal disorders, e.g. in other pain syndromes? Is the placebo effect in FGD related to placebo effects seen in psychiatry, e.g. in depression, anxiety disorders, and alike? Following this discussion, a fourth question is raised as the result of the three: What are the consequences of this for future drug trials in FGD? In summary it is concluded that, contrary to common belief and discussion, the placebo effect seen in RCT in FGD is not specifically high and extraordinary as compared to other comparable (i.e. functional) disorders. It shares less than expected commonalities with the placebo effect in psychiatry, and very few predictors have yet been identified that determine its effect size, especially some that are driven by design features of the studies. Current practice of RCT in IBS seems to limit and control the placebo effect quite well, and future trial practice, e.g. head-to-head trial, still offers options to maintain this control, even in the absence of placebos used.

Placebos in chronic pain: evidence, theory, ethics, and use in clinical practice

Despite their ubiquitous presence, placebos and placebo effects retain an ambiguous and unsettling presence in biomedicine. Specifically focused on chronic pain, this review examines the effect of placebo treatment under three distinct frameworks: double blind, deception, and open label honestly prescribed. These specific conditions do not necessarily differentially modify placebo outcomes. Psychological, clinical, and neurological theories of placebo effects are scrutinized. In chronic pain, conscious expectation does not reliably predict placebo effects. A supportive patient-physician relationship may enhance placebo effects. This review highlights "predictive coding" and "bayesian brain" as emerging models derived from computational neurobiology that offer a unified framework to explain the heterogeneous evidence on placebos. These models invert the dogma of the brain as a stimulus driven organ to one in which perception relies heavily on learnt, top down, cortical predictions to infer the source of incoming sensory data. In predictive coding/bayesian brain, both chronic pain (significantly modulated by central sensitization) and its alleviation with placebo treatment are explicated as centrally encoded, mostly non-conscious, bayesian biases. The review then evaluates seven ways in which placebos are used in clinical practice and research and their bioethical implications. In this way, it shows that placebo effects are evidence based, clinically relevant, and potentially ethical tools for relieving chronic pain.

Electromagnetic Field Therapy: A Rehabilitative Perspective in the Management of Musculoskeletal Pain - A Systematic Review

Electromagnetic fields (EMFs) provide a non-invasive, safe, and easy method to treat pain with respect to musculoskeletal diseases. The purpose of this systematic review was to describe the use of electromagnetic therapy in the rehabilitation field by investigating the efficacy in acute and chronic pain in the musculoskeletal disorders. A database search was conducted using the following resources: PubMed, Cochrane, PEDro, SCOPUS, and WoS. The following MESH terms were used: [Electromagnetic field AND/OR Rehabilitation], [Electromagnetic field AND/OR Pain], [Pulsed Magnetic field AND/OR Rehabilitation] and [Pulsed Magnetic field AND/OR Pain], [Pulsed Electromagnetic field AND/OR Rehabilitation] and [Pulsed Electromagnetic field AND/OR Pain], per the guidelines of the PRISMA statement. Articles published between January 1, 2009 and December 31, 2018 were included as assessment of musculoskeletal pain conditions, randomized clinical trial including crossover and prospective design studies, full English text available, population age > 18 years; instead were excluded neurological randomized clinical trials, transcranial magnetic stimulation application, neuropathic pain, animal/in vitro studies, and articles without English abstract or English full text. Three independent investigators (AMC, NG, and LP) retrieved all the information. Twenty-one RTC (N=21) were considered for the inclusion and exclusion criteria. The results showed as pulsed magnetic fields at low intensity and frequency (from 1 Hz up to 100 Hz) are commonly used with efficacy in resolving musculoskeletal pain. EMFs therapy is a well tolerated, effective with no negative side effects, which can be integrated with rehabilitation for the treatment of chronic and acute pain in musculoskeletal diseases, but further studies are needed to examine the use of more standardized protocols.

The placebo response in myasthenia gravis assessed by quantitative myasthenia gravis score: A meta-analysis

INTRODUCTION

This meta-analysis investigates the placebo response in generalized myasthenia gravis (MG) trials by means of Quantitative Myasthenia Gravis (QMG) scores.

METHODS

PubMed, Scopus, Web of Science, Cochrane Controlled Trial Register, and EMBASE were searched. QMG score, dropouts rate, adverse events (AEs), and AEs responsible for dropouts were examined, together with treatment moderators.

RESULTS

The magnitude of placebo response showed an effect size of 0.24, which was significantly lower than 0.67 of the drug response (P = 0.019). Furthermore, the forest plot revealed that, overall, active treatments showed a significantly higher impact on QMG scores than placebos.

CONCLUSIONS

Placebo and drug responses in MG trials are small and moderate, respectively. The lack of MG trials with a pure placebo arm or a no-treatment control arm made it impossible to disentangle improvements due to the placebo psychological effect from other effects such as natural history and/or regression to the mean. Muscle Nerve 59:671-678, 2019.

Does Sex/Gender Play a Role in Placebo and Nocebo Effects? Conflicting Evidence From Clinical Trials and Experimental Studies

Sex has been speculated to be a predictor of the placebo and nocebo effect for many years, but whether this holds true or not has rarely been investigated. We utilized a placebo literature database on various aspects of the genuine placebo/nocebo response. In 2015, we had extracted 75 systematic reviews, meta-analyses, and meta-regressions performed in major medical areas (neurology, psychiatry, internal medicine). These meta-analyses were screened for whether sex/gender differences had been noted to contribute to the placebo/nocebo effect: in only 3 such analyses female sex was associated with a higher placebo effect, indicating poor evidence for a contribution of sex to it in RCTs. This was updated with another set of meta-analyses for the current review, but did not change the overall conclusion. The same holds true for 18 meta-analyses investigating adverse event (nocebo) reporting in RCT in the placebo arm of trials. We also screened our database for papers referring to sex/gender and the placebo effect in experimental studies, and identified 28 papers reporting 29 experiments. Their results can be summarized as follows: (a) Despite higher sensitivity of pain in females, placebo analgesia is easier to elicit in males; (b) It appears that conditioning is effective specifically eliciting nocebo effects; (c) Conditioning works specifically well to elicit placebo and nocebo effects in females and with nausea; (d) Verbal suggestions are not sufficient to induce analgesia in women, but work in men. These results will be discussed with respect to the question why nausea and pain may be prone to be responsive to sex/gender differences, while other symptoms are less. Lastly, we will discuss the apparent discrepancy between RCT with low relevance of sex, and higher relevance of sex in specific experimental settings. We argue that the placebo response is predominantly the result of a conditioning (learning) response in females, while in males it predominantly may be generated via (verbal) manipulating of expectancies. In RCT therefore, the net outcome of the intervention may be the same despite different mechanisms generating the placebo effect between the sexes, while in experimental work when both pathways are separated and explicitly explored, such differences may surface.

Brain and psychological determinants of placebo pill response in chronic pain patients

The placebo response is universally observed in clinical trials of pain treatments, yet the individual characteristics rendering a patient a ‘placebo responder’ remain unclear. Here, in chronic back pain patients, we demonstrate using MRI and fMRI that the response to placebo ‘analgesic’ pills depends on brain structure and function. Subcortical limbic volume asymmetry, sensorimotor cortical thickness, and functional coupling of prefrontal regions, anterior cingulate, and periaqueductal gray were predictive of response. These neural traits were present before exposure to the pill and most remained stable across treatment and washout periods. Further, psychological traits, including interoceptive awareness and openness, were also predictive of the magnitude of response. These results shed light on psychological, neuroanatomical, and neurophysiological principles determining placebo response in RCTs in chronic pain patients, and they suggest that the long-term beneficial effects of placebo, as observed in clinical settings, are partially predictable.

People vary in the extent to which they feel better after taking an inert, placebo, treatment, but the basis for individual placebo response is unclear. Here, the authors show how brain structural and functional variables, as well as personality traits, predict placebo response in those with chronic back pain.

A Pilot Randomized Controlled Trial to Explore Cognitive and Emotional Effects of Probiotics in Fibromyalgia

It has recently been found that microbes in the gut may regulate brain processes through the gut microbiota–brain axis, which modulates affection, motivation and higher cognitive functions. According to this finding, the use of probiotics may be a potential treatment to improve physical, psychological and cognitive status in clinical populations with altered microbiota balance such as those with fibromyalgia (FMS). Thus, the aim of the present pilot study with a double-blind, placebo-controlled, randomised design was to test whether a multispecies probiotic may improve cognition, emotional symptoms and functional state in a sample of patients diagnosed with FMS. Pain, impact of FMS, quality of life, anxiety and depressive symptoms were measured during the pre- and post-intervention phases; participants also completed two computerised cognitive tasks to assess impulsive choice and decision-making. Finally, urinary cortisol concentration was determined. To our knowledge, this is the first study that explore the effect of a multispecies probiotic in FMS patients. Our results indicated that probiotics improved impulsivity and decision-making in these patients. However, more research is needed to further explore the potential effects of probiotics on other cognitive functions affected in FMS as well as in other clinical populations.

Fibromyalgia Syndrome: A Case Report on Controlled Remission of Symptoms by a Dietary Strategy

A 34-year-old woman suffered from significant chronic pain, depression, non-restorative sleep, chronic fatigue, severe morning stiffness, leg cramps, irritable bowel syndrome, hypersensitivity to cold, concentration difficulties, and forgetfulness. Blood tests were negative for rheumatic disorders. The patient was diagnosed with Fibromyalgia syndrome (FMS). Due to the lack of effectiveness of pharmacological therapies in FMS, she approached a novel metabolic proposal for the symptomatic remission. Its core idea is supporting serotonin synthesis by allowing a proper absorption of tryptophan assumed with food, while avoiding, or at least minimizing the presence of interfering non-absorbed molecules, such as fructose and sorbitol. Such a strategy resulted in a rapid improvement of symptoms after only few days on diet, up to the remission of most symptoms in 2 months. Depression, widespread chronic pain, chronic fatigue, non-restorative sleep, morning stiffness, and the majority of the comorbidities remitted. Energy and vitality were recovered by the patient as prior to the onset of the disease, reverting the occupational and social disabilities. The patient episodically challenged herself breaking the dietary protocol leading to its negative test and to the evaluation of its benefit. These breaks correlated with the recurrence of the symptoms, supporting the correctness of the biochemical hypothesis underlying the diet design toward remission of symptoms, but not as a final cure. We propose this as a low risk and accessible therapeutic protocol for the symptomatic remission in FMS with virtually no costs other than those related to vitamin and mineral salt supplements in case of deficiencies. A pilot study is required to further ground this metabolic approach, and to finally evaluate its inclusion in the guidelines for clinical management of FMS.

Clinical relevance of contextual factors as triggers of placebo and nocebo effects in musculoskeletal pain

Placebo and nocebo effects are embodied psycho-neurobiological responses capable of modulating pain and producing changes at different neurobiological, body at perceptual and cognitive levels. These modifications are triggered by different contextual factors (CFs) presented in the therapeutic encounter between patient and healthcare providers, such as healing rituals and signs. The CFs directly impact on the quality of the therapeutic outcome: a positive context, that is a context characterized by the presence of positive CFs, can reduce pain by producing placebo effects, while a negative context, characterized by the presence of negative CFs, can aggravate pain by creating nocebo effects. Despite the increasing interest about this topic; the detailed study of CFs as triggers of placebo and nocebo effects is still lacked in the management of musculoskeletal pain.

Increasing evidence suggest a relevant role of CFs in musculoskeletal pain management. CFs are a complex sets of internal, external or relational elements encompassing: patient’s expectation, history, baseline characteristics; clinician’s behavior, belief, verbal suggestions and therapeutic touch; positive therapeutic encounter, patient-centered approach and social learning; overt therapy, posology of intervention, modality of treatment administration; marketing features of treatment and health care setting. Different explanatory models such as classical conditioning and expectancy can explain how CFs trigger placebo and nocebo effects. CFs act through specific neural networks and neurotransmitters that were described as mediators of placebo and nocebo effects.

Available findings suggest a relevant clinical role and impact of CFs. They should be integrated in the clinical reasoning to increase the number of treatment solutions, boosts their efficacy and improve the quality of the decision-making. From a clinical perspective, the mindful manipulation of CFs represents a useful opportunity to enrich a well-established therapy in therapeutic setting within the ethical border. From a translational perspective, there is a strong need of research studies on CFs close to routine and real-world clinical practice in order to underline the uncertainty of therapy action and help clinicians to implement knowledge in daily practice.