The placebo effect revisited: lessons learned to date

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.

Replication crisis and placebo studies: rebooting the bioethical debate

A growing body of cross-cultural survey research shows high percentages of clinicians report using placebos in clinical settings. One motivation for clinicians using placebos is to help patients by capitalising on the placebo effect's reported health benefits. This is not surprising, given that placebo studies are burgeoning, with increasing calls by researchers to ethically harness placebo effects among patients. These calls propose placebos/placebo effects offer clinically significant benefits to patients. In this paper, we argue many findings in this highly cited and 'hot' field have not been independently replicated. Evaluating the ethicality of placebo use in clinical practice involves first understanding whether placebos are efficacious clinically. Therefore, it is crucial to consider placebo research in the context of the replication crisis and what can be learnt to advance evidence-based knowledge of placebos/placebo effects and their clinical relevance (or lack thereof). In doing so, our goal in this paper is to motivate both increased awareness of replication issues and to help pave the way for advances in scientific research in the field of placebo studies to better inform ethical evidence-based practice. We argue that, only by developing a rigorous evidence base can we better understand how, if at all, placebos/placebo effects can be harnessed ethically in clinical settings.

Efficacy of Perilla frutescens (L.) Britton var. frutescens extract on mild knee joint pain: A randomized controlled trial

Objectives: This study aimed to evaluate the clinical efficacy and safety of PE extracts developed for the purpose of relieving pain and improving knee joint function on semi-healthy people with mild knee joint pain.

Methods: A randomized, double-blind, two-arm, single-center, placebo-controlled clinical trial was conducted. Individuals with knee joint pain and a visual analogue scale (VAS) score < 50 mm were included in the study, and participants with radiological arthritis were excluded. Participants were administered either PFE or a placebo capsule (700 mg, twice a day) orally for eight weeks. The comparisons of the changed VAS score and Western Ontario and McMaster Universities Osteoarthritis (WOMAC) scores between the PFE and placebo groups were primary outcomes, while the five inflammation-related laboratory tests including cartilage oligomeric matrix protein, cyclooxygenase-2, neutrophil and lymphocyte ratio, high sensitive C-reactive protein, and erythrocyte sedimentation rate were secondary outcomes. Also, a safety assessment was done.

Results: Eighty participants (mean age, 38.4 ± 14.0, male: female, 28:52) were enrolled; 75 completed the trial (PFE 36 and placebo 39). After eight weeks, both VAS and WOMAC scores were reduced in the PFE and placebo groups. The changed scores were significantly higher in the PFE group compared to the placebo group: 19.6 ± 10.9 vs. 6.8 ± 10.5; VAS scores (p < 0.001), and 20.5 ± 14.7 vs. 9.3 ± 16.5; total WOMAC scores (p < 0.01) including the sub-scores for pain, stiffness, and functions. No significant changes were reported in the five inflammation-related laboratory parameters. All adverse events were considered minor and unlikely to result from the intervention.

Conclusion: Eight weeks of PFE intake was more effective than placebo in reducing knee joint pain and improving knee joint function in sub-healthy people with mild knee joint pain, and there were no major safety concerns.

Clinical Trial Registration:https://cris.nih.go.kr/cris/search/detailSearch.do?search_lang=E&focus=reset_12&search_page=M&pageSize=10&page=undefined&seq=23101&status=5&seq_group=19745, identifier CRIS: KCT0007219

Association between personality traits and placebo effects: a preregistered systematic review and meta-analysis

ABSTRACT

Placebo effects are ubiquitous yet highly variable between individuals and therefore strongly affect clinical trial outcomes such as pain relief. It is unclear whether dispositional psychological traits influence responsiveness to placebo. This preregistered meta-analysis and systematic review synthesized the literature investigating the association between personality traits and placebo effects. Based on 21 studies with 798 participants, we performed formal meta-analyses for 10 different personality traits, including behavioral inhibition, fun seeking, goal-drive persistence, reward responsiveness, empathic concern, empathic fantasy, perspective-taking, personal distress, optimism, and anxiety. We did not find evidence of associations between any of these traits and magnitude of placebo effects, which was supported by equivalence tests. Furthermore, we did not find evidence for moderating factors such as placebo manipulation type (conditioning or nonconditioning) or condition (pain or nonpain). These findings challenge the notion that personality influences responsiveness to placebos and contradict its utility for identifying placebo "responders" and "nonresponders."

Proportion attributable to contextual effects in general medicine: a meta-epidemiological study based on Cochrane reviews

OBJECTIVES

Our objectives were to examine the magnitude of the proportion attributable to contextual effects (PCE), which shows what proportion of the treatment arm response can be achieved by the placebo arm across various interventions, and to examine PCE variability by outcome type and condition.

DESIGN

We conducted a meta-epidemiological study.

SETTING

We searched the Cochrane Database of Systematic Reviews with the keyword 'placebo' in titles, abstracts and keywords on 1 January 2020.

PARTICIPANTS

We included reviews that showed statistically significant beneficial effects of the intervention over placebo for the first primary outcome.

MAIN OUTCOME MEASURES

We performed a random-effects meta-analysis to calculate PCEs based on the pooled result of each included review, grouped by outcome type and condition. The PCE quantifies how much of the observed treatment response can be achieved by the contextual effects.

PUBLIC AND PATIENT INVOLVEMENT STATEMENT

No patient or member of the public was involved in conducting this research.

RESULTS

We included 328 out of 3175 Cochrane systematic reviews. The results of meta-analyses showed that PCEs varied greatly depending on outcome type (I²=98%) or condition (I²=98%), but mostly lie between 0.40 and 0.95. Overall, the PCEs were 0.65 (95% CI 0.59 to 0.72) on average. Subjective outcomes were 0.50 (95% CI 0.41 to 0.59), which was significantly smaller than those of semiobjective (PCE 0.78; 95% CI 0.72 to 0.85) or objective outcomes (PCE 0.94; 95% CI 0.91 to 0.97).

CONCLUSIONS

The results suggest that much of the observed benefit is not just due to the specific effect of the interventions. The specific effects of interventions may be larger for subjective outcomes than for objective or semiobjective outcomes. However, PCEs were exceptionally variable. When we evaluate the magnitude of PCEs, we should consider each PCE individually, for each condition, intervention and outcome in its context, to assess the importance of an intervention for each specific clinical setting.

Factors Associated With Placebo Treatment Response in Functional Dyspepsia Clinical Trials

INTRODUCTION

Controlling for potential placebo effects is an important aspect of gaining an accurate estimate of how much the therapy alone changes patient symptoms or other end points. When the placebo effect is large, this can lead to only a small fraction of changes seen in the active therapy group being attributed to the therapy itself. This problem has been well studied in some disorders of brain-gut interaction but not in functional dyspepsia where placebo response rates of 40% and higher have been reported. Understanding risk factors for placebo response might lead to changes in trial design that could reduce the magnitude of the problem. This study sought to identify risk factors for the placebo effect in a functional dyspepsia clinical trial with a longer-term aim of suggesting trial design changes that might minimize the problem.

METHODS

A secondary analysis of the clinical trial data was undertaken using 2 arms deemed to involve placebo therapy. Potential predictors were drawn from a wide range of patient characteristics including psychological, clinical, and physiological features.

RESULTS

Predictors of a stronger placebo effect on the gastrointestinal symptom rating scale included higher functional dyspepsia symptom burden at baseline (b = -0.101), coexisting irritable bowel syndrome (b = -0.436), and higher scores on the Nepean Dyspepsia Index eat/drink domain (-0.005). Baseline symptom burden and coexisting irritable bowel syndrome were found to be independent placebo predictors, explaining 13% of the variance in change in gastrointestinal symptom rating scale. Anxiety, childhood sexual abuse, sleep amount, and frequent abdominal pain were also found to be predictors of change in individual symptom scores.

DISCUSSION

The findings of this study yield actionable insights into trial methodology that may help to reduce the magnitude of the placebo effect in future functional dyspepsia treatment trials.

Transcranial direct current stimulation of 3 cortical targets is no more effective than placebo as treatment for fibromyalgia: a double-blind sham-controlled clinical trial

ABSTRACT

Transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) and the dorsolateral prefrontal cortex seem to improve pain and other symptoms of fibromyalgia (FM), although the evidence on the effectiveness of tDCS and the optimal stimulation target is not robust enough. Our main objective was to establish the optimal area of stimulation, comparing the 2 classical targets and a novel pain-related area, the operculo-insular cortex, in a sham-controlled trial. Using a double-blind design, we randomly assigned 130 women with FM to 4 treatment groups (M1, dorsolateral prefrontal cortex, operculo-insular cortex, and sham), each receiving fifteen 20-minute sessions of 2 mA anodal tDCS over the left hemisphere. Our primary outcome was pain intensity. The secondary outcomes were the other core symptoms of FM (fatigue, mood, cognitive and sleep disorders, and hyperalgesia measured by the pressure pain threshold). We performed the assessment at 3 time points (before, immediately after treatment, and at 6 months follow-up). The linear mixed-model analysis of variances showed significant treatment effects across time for clinical pain and for fatigue, cognitive and sleep disturbances, and experimental pain, irrespective of the group. In mood, the 3 active tDCS groups showed a significantly larger improvement in anxiety and depression than sham. Our findings provide evidence of a placebo effect, support the use of tDCS for the treatment of affective symptoms, and challenge the effectiveness of tDCS as treatment of FM.

A therapeutic guide on pediatric irritable bowel syndrome and functional abdominal pain-not otherwise specified

Disorders of the gut-brain interaction negatively impact quality of life and carry a substantial socioeconomic burden. Irritable bowel syndrome (IBS) and functional abdominal pain-not otherwise specified (FAP-NOS) are common functional abdominal pain disorders in childhood. The pathophysiology is not fully understood, and high-quality intervention trials and international guidelines are missing. Therefore, the management of these disorders remains challenging. This review aims to provide an up-to-date overview of therapeutic possibilities for pediatric IBS or FAP-NOS and recommends management strategies. To prevent unnecessary referrals and extensive costs, it is fundamental to make a positive diagnosis of IBS or FAP-NOS in children with chronic abdominal pain with only minimal investigations. A tailor-made approach for each patient, based on the accompanying physical and psychological symptoms, is proposed to date.

CONCLUSION

Shared decision-making including non-pharmacological and pharmacological interventions should be considered and discussed with the family.

WHAT IS KNOWN

• Irritable bowel syndrome and functional abdominal pain-not otherwise specified are common in childhood. • Although the number of treatment options has grown recently, managing these disorders can be challenging and unsatisfactory, and no evidence-based international management guidelines are available.

WHAT IS NEW

• We suggest using a stepwise individualized approach to management, where after first-line management, both non-pharmacological and pharmacological interventions should be discussed.

Microcurrent Therapy as a Therapeutic Modality for Musculoskeletal Pain: A Systematic Review Accelerating the Translation From Clinical Trials to Patient Care

Objective

To summarize the level of knowledge regarding the effects of microcurrent therapy (MCT) on musculoskeletal pain in adults.

Data Sources

The PubMed, Physiotherapy Evidence Database, Cumulative Index to Nursing Allied Health Literature, Cochrane Central Register of Controlled Trials, and Igaku Chuo Zasshi database were searched from the time of their inception to December 2020.

Study Selection

Randomized controlled trials (RCTs) investigating the effects of MCT on musculoskeletal pain were included. Additionally, non-RCTs were included to assess the adverse events.

Data Extraction

The primary outcomes were pain and adverse events related to MCT. To assess the reproducibility of MCT, we evaluated the completeness of treatment description using the Template for Intervention Description and Replication (TIDieR) checklist. We also assessed the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

Data Synthesis

A comprehensive assessment of 4 RCTs and 5 non-RCTs that met the inclusion criteria revealed that MCT significantly improved shoulder pain (1 study, 40 patients) and knee pain (1 study, 52 patients) compared with sham MCT without any severe adverse events. MCT has clinically significant benefits for knee pain. This study also revealed a clinically significant placebo response in treating knee pain. This evidence highlights the substantial effect of placebo response in clinical care. These treatment effects on knee pain are further supported by the high quality of evidence in GRADE with high reproducibility in TIDieR.

Conclusions

The findings of this meta-analysis highlight the effect of placebo response in treating knee pain. MCT is a potential, core nonpharmacologic treatment option in clinical care with minimal adverse events and should be further investigated. This study proposes a framework for the future investigation of the effect of MCT on musculoskeletal pain to enhance the study quality and reproducibility.

Meta-analysis comparing placebo responses in clinical trials of painful HIV-associated sensory neuropathy and diabetic polyneuropathy

Background and aims The placebo response has been identified as one factor responsible for the lack of therapeutic trials with positive outcomes in neuropathic pain. Reviews have suggested that certain neuropathic pain conditions, including HIV-associated sensory neuropathy (HIV-SN), exhibit a greater placebo response than other neuropathic aetiologies. If true, such a finding could substantially affect clinical trial design and therapeutic developments for these conditions. This study aimed to identify any difference in placebo response between trials of systemic pharmacological intervention in HIV-SN and a comparable neuropathic condition, diabetic polyneuropathy (DPN) and to identify factors influencing the placebo response. Methods A systematic review search to identify randomised, double-blind studies of systemic pharmacological interventions for painful HIV-SN and DPN published between January 1966 and June 2019 was performed. A meta-analysis of the magnitude of placebo response and the proportion of placebo responders was conducted and compared between the two disease conditions. A meta-regression was used to assess for any study and participant characteristics that were associated with the placebo response. Only studies meeting a methodological quality threshold were included. Results Seventy-five trials were identified. There was no statistically significant difference in the proportion of placebo responders (HIV-SN = 0.35; versus DPN = 0.27, p = 0.129). The difference observed in the magnitude of the placebo response [pain reduction of 1.68 (1.47-1.88) DPN; 2.38 (1.87-2.98) in HIV-SN] was based on only 2 trials of HIV-SN and 35 of DPN. Potential factors influencing the placebo response such as psychological measures, were reported inconsistently. Conclusions We found no statistically significant difference in the placebo response rate between painful HIV-SN and DPN. Too few studies were available that reported the necessary information to clarify potential differences in the magnitude of placebo response or to elucidate parameters that could be contributing such differences. Implications The placebo response is one factor that may contribute to a lack of positive trials in neuropathic pain; some etiologies may display larger responses than others. This meta-analysis found no significant difference in placebo response between trials of HIV-associated sensory neuropathy and painful diabetic polyneuropathy, although limited data were available.

Efficacy of an occluding toothpaste on dentinal hypersensitivity over 14 days

OBJECTIVES

To evaluate a 0.454% stannous fluoride/5% sodium tripolyphosphate (STP) toothpaste's ability to provide relief from dentinal hypersensitivity (DH) applied using 'focused brushing.'

MATERIALS AND METHODS

In two randomised, examiner-blind, parallel-group studies, a SnF₂/STP toothpaste was applied by brushing two selected sensitive teeth before 1 min whole-mouth brushing, compared to 1 min whole-mouth brushing only, with a negative control toothpaste. DH was assessed via evaporative (air) (Schiff scale) and tactile (Yeaple probe) stimuli after 7 and 14 d of twice-daily brushing.

RESULTS

In total, 141 (Study 1)/142 (Study 2) participants were randomised. In Study 1, the test treatment significantly reduced DH at 7/14 d versus baseline (7/14 d Schiff difference: -0.74 [-0.84,-0.65]/-1.39 [-1.54,-1.23]; tactile: 6.00 [4.88,7.13]/15.30 [13.34,17.26]); whereas the Control treatment did not (7/14 d Schiff difference -0.03 [-0.13,0.06]/-0.10 [-0.25,0.06]; tactile: 0.77 [-0.36,1.90]/0.77 [-1.20,2.74]). Differences between Test and Control were statistically significant (p < 0.0001 all cases). In Study 2, both treatments reduced DH compared to baseline by both measures, but there were no significant between-treatment differences. Toothpastes were generally well-tolerated.

DISCUSSION AND CONCLUSIONS

Previous studies and Study 1 support SnF₂/5% STP toothpaste efficacy; Study 2 results may have been influenced by placebo/Hawthorne effects. DH study design needs to, where possible, negate such effects.

Pharmacologic Treatment in Functional Abdominal Pain Disorders in Children: A Systematic Review

CONTEXT

Functional abdominal pain disorders (FAPDs) are common in childhood, impacting quality of life and school attendance. There are several compounds available for the treatment of pediatric FAPDs, but their efficacy and safety are unclear because of a lack of head-to-head randomized controlled trials (RCTs).

OBJECTIVE

To systematically review the efficacy and safety of the pharmacologic treatments available for pediatric FAPDs.

DATA SOURCES

Electronic databases were searched from inception to February 2021.

STUDY SELECTION

RCTs or systematic reviews were included if the researchers investigated a study population of children (4-18 years) in whom FAPDs were treated with pharmacologic interventions and compared with placebo, no treatment, or any other agent.

DATA EXTRACTION

Two reviewers independently performed data extraction and assessed their quality. Any interresearcher disagreements in the assessments were resolved by a third investigator.

RESULTS

Seventeen articles representing 1197 children with an FAPD were included. Trials investigating antispasmodics, antidepressants, antibiotics, antihistaminic, antiemetic, histamine-2-receptor antagonist, 5-HT4-receptor agonist, melatonin, and buspirone were included. No studies were found on treatment with laxatives, antidiarrheals, analgesics, antimigraines, and serotonergics.

LIMITATIONS

The overall quality of evidence on the basis of the Grading of Recommendations, Assessment, Development and Evaluations system was very low to low.

CONCLUSIONS

On the basis of current evidence, it is not possible to recommend any specific pharmacologic agent for the treatment of pediatric FAPDs. However, agents such as antispasmodics or antidepressants can be discussed in daily practice because of their favorable treatment outcomes and the lack of important side effects. High-quality RCTs are necessary to provide adequate pharmacologic treatment. For future intervention trials, we recommend using homogenous outcome measures and instruments, a large sample size, and long-term follow-up.

Can insights from placebo and nocebo mechanisms studies improve the randomized controlled trial?

Background and aims The randomized controlled trial (RCT) is currently facing several challenges, one of these being that the placebo response appears to be increasing in RCTs, thereby making it difficult to demonstrate an effect of potentially new treatments over placebo. This problem has primarily been approached by predicting the magnitude of the placebo response via stable factors, such as demographic variables, and/or by developing complex designs aimed at reducing the placebo response in the hope that it will improve the test of the active treatment. Yet, the success of this approach has so far been limited. Methods A new approach toward improving the RCT is put forward based on placebo and nocebo mechanism studies, i.e. studies that investigate the mechanisms underlying placebo analgesia and nocebo hyperalgesia. In a series of meta-analyses the magnitude of placebo and nocebo effects were determined. Experimental studies across nociplastic and neuropathic pain conditions and across pharmacological and acupuncture treatments investigated psychological and neurobiological mechanisms underlying these effects. The obtained results were used to make approximations of expectations to see if that could predict the placebo response in RCTs and function as a new way of tapping into the placebo component of treatment effects. Results The magnitude of placebo and nocebo effects is large and highly variable. Placebo effects exist across chronic pain conditions with varying degrees of known etiology as well as across pharmacological and non-pharmacological treatments. Patients' perception of the treatment, the verbal suggestions given for pain relief, and the patients' expectations toward pain relief contribute to the magnitude of the placebo effect and to pain relief following placebo interventions. Also, unintentional unblinding and patients' perception of a treatment markedly influence the treatment outcome. By making approximations of expectations toward treatment effects it was possible to predict the magnitude of the placebo response in RCTs. Conclusions and implications The new approach of tapping into or directly asking patients about their perception and expectations toward a treatment, along with the account of the natural history of pain, has the potential to improve the information that can be obtained from RCTs. Thus, by interfacing insights from placebo and nocebo mechanism studies, it may be possible to enhance the information that can be obtained from RCTs and to account for a large part of the variability in the placebo component of the overall treatment effect. This approach has the potential to improve the scientific evaluation of treatments, as well as to illustrate how the effect of treatments can be optimized in clinical practice, which is the crux of evidence-based medicine.

Pharmacological interventions for the treatment of insomnia: quantitative comparison of drug efficacy

PURPOSE

Although different forms of pharmacological intervention are often prescribed for insomnia disorder, the comparative efficacies among various drugs remain unclear. We therefore conducted this study to quantitatively compare the efficacy of various pharmacotherapies for insomnia by modeling.

METHODS

We searched PubMed, EMBASE and Cochrane Library databases for randomized placebo-controlled trials of insomnia medications that were conducted within a designated time period (from the inception dates to May 16, 2019). Pharmacodynamic models were established to describe the time course of changes from baseline in selected sleep parameters. Sleep quality and dropout rates were also compared by a single-arm meta-analysis.

RESULTS

In sum, 43 studies covering 44 trials (14,535 patients) were included in the analysis. The drugs evaluated included flurazepam, quazepam, temazepam, triazolam, eszopiclone, zaleplon, zolpidem, extended-release zolpidem, suvorexant, ramelteon and doxepin. The established models revealed eszopiclone had the highest efficacy in terms of sleep latency (SL), total sleep time (TST), and sleep quality, and was also associated with the lowest dropout rates. The effect of suvorexant on the parameter 'wake after sleep onset' (WASO) was significantly higher than that of the other drugs analyzed.

CONCLUSIONS

Each drug has its own characteristics in the treatment of insomnia, and this needs to be taken into consideration to meet individual clinical needs. These results serve as a quantitative supplement for clinical practice by reflecting the difference in efficacy of various drugs in the treatment of insomnia.

Efficacy of an anhydrous stannous fluoride toothpaste for relief of dentine hypersensitivity: A randomized clinical study

Aim

To compare efficacy of an anhydrous 0.454% w/w stannous fluoride/sodium fluoride toothpaste (Test) versus a sodium monofluorophosphate toothpaste (Negative control) and a stannous chloride/sodium fluoride toothpaste (Positive control) for dentine hypersensitivity relief after 8 weeks’ twice‐daily use.

Materials and Methods

In this randomized, examiner‐blind, stratified, parallel study, primary and secondary efficacy variables were mean changes in Schiff score (evaporative [air] sensitivity) and tactile threshold (Yeaple probe), respectively, from baseline to Week 8 between Test (n = 62) and Negative control (n = 62). Test and Positive control (n = 61) comparisons were exploratory objectives.

Results

All groups significantly improved from baseline on both dentine hypersensitivity measures (p < .0001). Difference between adjusted mean changes from baseline in Schiff sensitivity scores at Week 8 for Test versus Negative control groups was 0.19 (95% CI 0.002, 0.374), in favour of the Negative control (p = .0476; 12.57% difference). Difference in tactile threshold was −7.20 g (95% CI −16.376, 1.975), and this was not statistically significant (p = .3715; −21.83% difference). Test group showed no significant difference versus Positive control for either measure. Toothpastes were generally well tolerated.

Conclusion

While twice‐daily use of Test toothpaste significantly reduced dentine hypersensitivity from baseline, there was no significant advantage over negative or positive controls. Study registration: Clinicaltrials.gov; NCT03310268.

Three randomized studies of dentine hypersensitivity reduction after short-term SnF2 toothpaste use

Aim

To evaluate effects of a 0.454% stannous fluoride test toothpaste on dentine hypersensitivity (DH) applied by fingertip, then 3 days’ brushing, versus a sodium monofluorophosphate‐based control.

Materials and Methods

In three randomized clinical studies, DH was assessed using evaporative (Schiff scale) and tactile (Yeaple probe) stimuli. Participants applied toothpaste to two sensitive teeth by fingertip (60 s each); DH was re‐assessed, prior to brushing. Test treatment participants brushed their sensitive teeth, with all participants then brushing all teeth for ≥60 s, twice daily for 3 days. DH was re‐assessed. Data were analysed by study and then pooled.

Results

In two studies, test treatment significantly reduced DH versus control treatment after fingertip application and 3 days’ brushing (both measures). In one study, both treatments significantly reduced DH without between‐treatment differences. Mean Schiff differences (95% confidence intervals) for fingertip/3d were as follows: Study 1: −0.09 (−0.280, 0.092)/ −0.18 (−0.442, 0.072); Study 2: −0.72 (−0.839, −0.610)/ −1.02 (−1.150, −0.882); and Study 3: −0.26 (−0.387, −0.123)/ −0.92 (−1.055, −0.793). Pooled analysis indicated test treatment significantly reduced DH versus control (both timepoints, both measures). Toothpastes were generally well‐tolerated.

Conclusion

Studies indicated that single, fingertip application of a SnF₂ toothpaste reduced DH versus a control. DH relief increased over 3 days.

Pain, placebo, and test of treatment efficacy: a narrative review

Over the past decade, the mechanisms underlying placebo effects have begun to be identified. At the same time, the placebo response appears to have increased in pharmacological trials and marked placebo effects are found in neurostimulation and surgical trials, thereby posing the question whether non-pharmacological interventions should be placebo-controlled to a greater extent. In this narrative review we discuss how the knowledge of placebo mechanisms may help to improve placebo control in pharmacological and non-pharmacological trials. We review the psychological, neurobiological, and genetic mechanisms underlying placebo analgesia and outline the current problems and potential solutions to the challenges with placebo control in trials on pharmacological, neurostimulation, and surgical interventions. We particularly focus on how patients' perception of the therapeutic intervention, and their expectations towards treatment efficacy may help develop more precise placebo controls and blinding procedures and account for the contribution of placebo factors to the efficacy of active treatments. Finally, we discuss how systematic investigations into placebo mechanisms across various pain conditions and types of treatment are needed in order to 'personalise' the placebo control to the specific pathophysiology and interventions, which may ultimately lead to identification of more effective treatment for pain patients. In conclusion this review shows that it is important to understand how patients' perception and expectations influence the efficacy of active and placebo treatments in order to improve the test of new treatments. Importantly, this applies not only to assessment of drug efficacy but also to non-pharmacological trials on surgeries and stimulation procedures.

The impact of valence framing on response expectancies of side effects and subsequent experiences: a randomised controlled trial

Objective: Pre-treatment side effect expectancies often influence subsequent experiences; however, expectancy-based reduction strategies are lacking. We explored whether framing information about adverse responses (in positive or negative formats) altered expectancies and experiences of a cold pressor task. We further investigated associations between expectancies and experiences, to inform potential interventions. Design: Healthy volunteers (N = 134), randomised to receive positively- or negatively-framed pre-cold pressor task information, self-rated 12 expectancies for cold pressor experiences, emotional state and coping style. Main Outcome Measures: Self-reports of the same 12-experiences (recorded during and after the experiment) were assessed. Results: Framing had minimal impact on expectancies and experiences; however, discomfort threshold (p = .08, d = 0.22) showed a trend in the expected direction. Hierarchical regressions revealed expectancies uniquely, significantly predicted 6-23% of the variance for 11 subsequent experiences. Following a popular charity event (Ice Bucket Challenge), all participants showed higher 'discomfort thresholds' (p = .001, d = 0.59), and those in the negative frame reported more overall 'discomfort' (p = .01, d = 0.60) than participants in the positive condition. Conclusion: Expectancies uniquely influenced subsequent cold pressor experiences. Framing had minimal impact in this 'analogue' medical setting, only influencing 'discomfort threshold'. 'Discomfort threshold' and overall 'discomfort' were also impacted by a social media challenge, highlighting a potential area for intervention.

How May Placebo Mechanisms Influence Orofacial Neuropathic Pain?

The conceptualization of placebo has changed from inactive pills to a detailed understanding of how patients' perception of receiving a treatment influences pain processing and overall treatment outcome. Large placebo effects were recently demonstrated in chronic neuropathic pain, thereby opening the question of whether placebo effects also apply to orofacial neuropathic pain. In this article, we review the new definitions, magnitude, and social, psychological, neurobiologic, and genetic mechanisms of placebo effects in pain, especially neuropathic pain, to illustrate that placebo effects are not simply response bias but psychoneurobiological phenomena that can be measured at many levels of the neuroaxis. We use this knowledge to carefully illustrate how patients' perceptions of the treatment, the relationship with the health care provider, and the expectations and emotions toward a treatment can influence test and treatment outcome and potentially skew the results if they are not taken into consideration. Orofacial neuropathic pain is a new research area, and we review the status on definition, diagnosis, mechanisms, and pharmacologic treatment of neuropathic pain after trigeminal nerve injury, as this condition may be especially influenced by placebo factors. Finally, we have a detailed discussion of how knowledge of placebo mechanisms may help improve the understanding, diagnosis, and treatment of orofacial neuropathic pain, and we illustrate pitfalls and opportunities of applying this knowledge to the test of dental treatments.

Placebo analgesia effects across central nervous system diseases: what do we know and where do we need to go?

Placebo effects are well established in healthy participants experiencing experimental or acute pain. Yet, little is known about the mechanisms of placebo analgesia effects in patients with chronic pain and even less is known in patients suffering from central nervous system (CNS) diseases where pain is prevalent, difficult to manage, and often undertreated. This article briefly reviews the current knowledge of placebo analgesia effects in healthy participants with the aim of discussing how the mechanisms in placebo analgesia differ between healthy participants and patients. The focus will be on placebo analgesia effects in chronic pain conditions as well as in 2 CNS diseases: Alzheimer disease and Parkinson disease. Finally, strengths and weaknesses of the current knowledge will be discussed and it will be demonstrated how insights from the placebo literature may point to new ways of improving treatments among patients experiencing pain in relation to CNS diseases.

A Direct Comparison of Placebo and Nocebo Effects on Visuospatial Attention: An Eye-Tracking Experiment

Background: Placebo and nocebo effects on visual attention are still poorly understood. This eye-tracking study directly compared effects of sham transcranial magnetic stimulation (sTMS) that was administered along with the verbal suggestion that the treatment would either increase (placebo) or decrease (nocebo) left-sided visual attention. Method: Twenty women who had reported decreased attention (nocebo responders) and 20 women who had reported increased attention (placebo responders) following sTMS completed a visual search task with three visual load levels. The task was conducted once with and once without the placebo or the nocebo (sTMS). Left-sided fixations and reaction times for left-sided targets (in comparison with right-sided targets) were analyzed. Results: Contrary to the verbal suggestion, the nocebo responders showed more left-sided fixations in the nocebo condition (compared with the control condition) and responded faster to left-sided targets in the high-load condition. The placebo had no effect on fixations and reaction times. Conclusion: These results indicate a more beneficial effect of a nocebo compared with a placebo for the first time. Limits and possibilities of placebo and nocebo interventions are discussed.

The psychological effects of physical exercise: A controlled study of the placebo effect

The research on well-being and physical exercise point to the possibility of a placebo effect. This study analyzes the effect of expectancy manipulation on psychological (well-being and self-esteem) and physical (agility and cardiorespiratory fitness) outcomes after a seven-week program of aerobic training. 114 undergraduate students (age M = 19.81, SD = 1.75; 86.1% women) were randomized into G1 - No Exercise (n = 13), G2 - Exercise only (n = 15), G3 - Exercise + Manipulation of expectations: No psychological effect (n = 17) and G4 - Exercise + Manipulation of expectations: Psychological effect (n = 21). Outcome measures were the Rosenberg Self-Esteem Scale, the Well-Being subscale of the Subjective Exercise Experiences Scale, the Agility T-test and the 20-meter Shuttle Run Test. Paired t-tests showed significant improvements from baseline in self-esteem, agility, and cardiovascular fitness for the exercise groups. G4 also showed a significant improvement in well-being. ANCOVA with adjustments for the baseline measures was used to test between-group differences at the end of the program. The only significant differences at posttest were between G1 and the exercise groups. The data do not support a differential effect of elevated expectations of psychological benefits on the participants' self-esteem or psychological well-being after an aerobic training program. Future research should analyze whether reinforcing expectations more frequently throughout the program might show a more robust influence.

Psychedelics and the essential importance of context

Psychedelic drugs are making waves as modern trials support their therapeutic potential and various media continue to pique public interest. In this opinion piece, we draw attention to a long-recognised component of the psychedelic treatment model, namely ‘set’ and ‘setting’ – subsumed here under the umbrella term ‘context’. We highlight: (a) the pharmacological mechanisms of classic psychedelics (5-HT2A receptor agonism and associated plasticity) that we believe render their effects exceptionally sensitive to context, (b) a study design for testing assumptions regarding positive interactions between psychedelics and context, and (c) new findings from our group regarding contextual determinants of the quality of a psychedelic experience and how acute experience predicts subsequent long-term mental health outcomes. We hope that this article can: (a) inform on good practice in psychedelic research, (b) provide a roadmap for optimising treatment models, and (c) help tackle unhelpful stigma still surrounding these compounds, while developing an evidence base for long-held assumptions about the critical importance of context in relation to psychedelic use that can help minimise harms and maximise potential benefits.

The Management of Paediatric Functional Abdominal Pain Disorders: Latest Evidence

Recurrent abdominal pain (RAP) is one of the most common health complaints in both children and adults. Although RAP is considered a functional disorder rather than an organic disease, affected children and their families can still experience anxiety and concerns that can interfere with school, sports, and regular daily activities and lead to frequent attendances at pediatric emergency departments or pediatric gastroenterology clinics. Our review shows experts do not agree on a universally proven management that will work on every child presenting with functional abdominal pain (FAP). Treatment strategies include both non-pharmacological and pharmacological options. Non-pharmacological treatments are usually very well accepted by both children and their parents and are free from medication side effects. Nevertheless, they may be as effective as the pharmacological interventions; therefore, according to many experts and based on the majority of current evidence, a non-pharmacological approach should be the first intervention attempt in children with RAP. In particular, the importance of the bio-psychosocial approach is highlighted, as a majority of children will improve with counselling and reassurance that no serious organic pathologies are suspected, especially when the physician establishes a trustful relationship with both the child and their family. Placebo and pharmacological interventions could be attempted when the bio-psychosocial approach is not applicable or not efficacious. In some difficult cases, finding an effective treatment for FAP can be a challenge, and a number of strategies may need to be tried before symptoms are controlled. In these cases, a multidisciplinary team, comprising a pediatric gastroenterologist, dietician, psychologist, and psychotherapist, is likely to be successful.

Functional abdominal pain disorders in children

Chronic abdominal pain is a common problem in pediatric practice. The majority of cases fulfill the Rome IV criteria for functional abdominal pain disorders (FAPDs). At times, these disorders may lead to rather serious repercussions. Area covered: We have attempted to cover current knowledge on epidemiology, pathophysiology, risk factors related to pathophysiology, clinical evaluation and management of children with FAPDs. Expert commentary: FAPDs are a worldwide problem with a pooled prevalence of 13.5%. There are a number of predisposing factors and pathophysiological mechanisms including stressful events, child maltreatment, visceral hypersensitivity, altered gastrointestinal motility and change in intestinal microbiota. It is possible that the environmental risk factors intricately interact with genes through epigenetic mechanisms to contribute to the pathophysiology. The diagnosis mainly depends on clinical evaluation. Commonly used pharmacological interventions do not play a major role in relieving symptoms. Centrally directed, nonpharmacological interventions such as hypnotherapy and cognitive behavioral therapy have shown both short and long term efficacy in relieving pain in children with FAPDs. However, these interventions are time consuming and need specially trained staff and therefore, not currently available at grass root level. Clinicians and researchers should join hands in searching for more pragmatic and effective therapeutic modalities to improve overall care of children with FAPDs.

What Is Minimally Required to Elicit Placebo Effects?

Placebo effects have often been attributed to cognitive processes described as "learning" and/or "expectancy," yet the role of conscious awareness is unclear. Furthermore, little is known about the placebo effects in patients with limited cognitive abilities, such as intellectual disability. Here, recent data on placebo mechanisms in patients with impaired cognitive function will be discussed, as well as experimental studies investigating how implicit cognitive processes may shape placebo effects. Together these studies comment on the minimum requirements in order to elicit placebo effects, both from the view of conscious awareness and from the perspective of Intelligence Quotient and basic brain function. Together with recent conceptualizations of placebo effects in terms of predictive coding, there is evidence to suggest that placebo effects are fundamental responses of the brain that have developed to promote survival.

Placebo response and its determinants in children with ADHD across multiple observers and settings: A randomized clinical trial

This study aims to quantify placebo response (PR) in children with attention deficit hyperactivity disorder (ADHD) as assessed by parents and teachers and to explore some of its determinants. Five hundred and forty children with ADHD (ages 6-12) were recruited to a randomized, double-blind, placebo-controlled crossover trial with methylphenidate. The main outcome variable was Conners' Global Index (CGI), based on assessment of behaviour by parents (CGI-P) and teacher (CGI-T). PR was calculated as the difference between CGI-P/T scores at baseline and placebo week. There was a highly significant PR as assessed by the parents' and teachers' (p < 0.001). The magnitude of PR as assessed by parents was greater (10.57 points) compared to that assessed by teachers (3.93 points). The determinants of PR were different between parents and teachers. For parents, income, marital status, education, maternal smoking during pregnancy, and prior psychostimulant exposure (PPE) showed a significant effect on PR. For teachers, only ethnicity and PPE had an effect. The pattern of PR revealed two distinct profiles that may shed some light on the mechanisms involved in PR. PR in children with ADHD varies depending on the setting of the observations and the evaluator. Several psychosocial factors have been identified as modulators of PR. This is relevant for the design and interpretation of clinical trials and for clinical practice.

Treatment expectations but not preference affect outcome in a trial of CBT and exercise for pain

Background: Patients' beliefs and attitudes toward a treatment can affect treatment response. In unblinded trials this can affect outcomes. Aims: The aim of this analysis was to examine the association between treatment preference and expectation and outcome in a trial of pain treatments. Methods: In a randomized trial (ISRCTN67013851) of four treatments for chronic widespread pain, participants were asked which they would prefer and what improvement they expect from each. The proportion of participants reporting positive health outcomes at three time points after treatment were compared between those matched or unmatched with their preference and between those with and without expectation for improvement. Odds ratios were calculated adjusted for baseline characteristics associated with preference and expectation. Results: Four hundred forty-two participants were recruited to the trial (69.5% female). The proportion reporting positive outcomes among participants matched to their preference compared to those unmatched was 33.3% vs. 34.4% at the end of treatment (adjusted odds ratio [aOR] = 0.80, 95% confidence interval [CI], 0.44-1.46), 34.4% vs. 29.0% at 3 months (aOR = 1.23, 95% CI, 0.67-2.26), and 34.8% vs. 30.3% at 2 years (aOR = 1.31, 95% CI, 0.70-2.46). The proportion of participants reporting positive outcomes among those expecting improvement compared to those not expecting improvement was 36.6% vs. 15.0% at the end of treatment (aOR = 2.03, 95% CI, 1.07-3.85), 34.1% vs. 13.2% at 3 months (aOR = 2.31, 95% CI, 1.22-4.38), and 32.8% vs. 19.1% at 2 years (aOR = 1.16, 95% CI, 0.67-2.36). Conclusions: Treatment preference had no clear effect on outcomes, but expectation did. These results could inform future approaches to management, and researchers assessing treatments should take into account this expectation effect.

The Placebo Response in Pediatric Abdominal Pain-Related Functional Gastrointestinal Disorders: A Systematic Review and Meta-Analysis

OBJECTIVE

To investigate the magnitude and determinants of the placebo response in studies with pediatric abdominal pain-related functional gastrointestinal disorders.

STUDY DESIGN

The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and CINAHL were searched for systematic reviews and randomized placebo-controlled trials concerning children 4-18 years of age with an abdominal pain-related functional gastrointestinal disorder. The primary outcome was the pooled proportion of subjects assigned to placebo with improvement as defined by the authors. The effect of trial characteristics on the magnitude of the placebo response was investigated using univariate meta-regression analysis.

RESULTS

Twenty-one trials were identified. The pooled proportion of subjects with improvement was 41% (95% CI, 34%-49%; 17 studies) and with no pain was 17% (95% CI, 8%-32%; 7 studies). The pooled standardized mean difference on the Faces Pain Scales compared with baseline was -0.73 (95% CI, -1.04 to -0.42; 8 studies). There was significant heterogeneity across studies with respect to both outcomes. Lower dosing frequency (P = .04), positive study (P = .03), longer duration of treatment (P < .001), and higher placebo dropout (P < .001) were associated with higher report of no pain. Response on Faces Pain Scales was greater in studies conducted in the Middle East (P = .002), in studies that did not report the randomization schedule (P = .02), and in studies with a higher percentage of females (P = .04).

CONCLUSIONS

Approximately 41% of children with abdominal pain-related functional gastrointestinal disorders improve on placebo. Several trial characteristics are correlated significantly with the proportion of patients with no pain on placebo and with the magnitude of the placebo response on Faces Pain Scales. These data could be valuable for the design of future studies.

Does the model of additive effect in placebo research still hold true? A narrative review

Personalised and contextualised care has been turned into a major demand by people involved in healthcare suggesting to move toward person-centred medicine. The assessment of person-centred medicine can be most effectively achieved if treatments are investigated using ‘with versus without’ person-centredness or integrative study designs. However, this assumes that the components of an integrative or person-centred intervention have an additive relationship to produce the total effect. Beecher’s model of additivity assumes an additive relation between placebo and drug effects and is thus presenting an arithmetic summation. So far, no review has been carried out assessing the validity of the additive model, which is to be questioned and more closely investigated in this review.

Initial searches for primary studies were undertaken in July 2016 using Pubmed and Google Scholar. In order to find matching publications of similar magnitude for the comparison part of this review, corresponding matches for all included reviews were sought.

A total of 22 reviews and 3 clinical and experimental studies fulfilled the inclusion criteria. The results pointed to the following factors actively questioning the additive model: interactions of various effects, trial design, conditioning, context effects and factors, neurobiological factors, mechanism of action, statistical factors, intervention-specific factors (alcohol, caffeine), side-effects and type of intervention.

All but one of the closely assessed publications was questioning the additive model. A closer examination of study design is necessary. An attempt in a more systematic approach geared towards solutions could be a suggestion for future research in this field.

Common Factors in Pediatric Psychiatry: A Review of Essential and Adjunctive Mechanisms of Treatment Outcome

OBJECTIVE

The purpose of this article is to review the literature on hypothesized behavioral correlates of pharmacotherapy treatment response. A particular focus is placed on what have been referred to as "common factors" across mental health treatments, including medication adherence, therapeutic alliance, motivation for behavior change, and expectancies for positive treatment outcomes. These understudied factors may provide unique explanations for mechanisms of symptom change, patient risk as a result of protocol deviation, and attenuated treatment outcomes.

METHOD

A literature search was conducted to evaluate the relationship between treatment processes in pediatric psychiatry and medication adherence, therapeutic alliance, motivation for behavior change, and expectancies for positive treatment outcomes.

RESULTS

Substantial variability and room for improvement was identified for each common factor. Behavioral protocols have already been developed to address many aspects of common factors in pediatric psychiatric treatment, but are not yet a part of many practice parameters.

CONCLUSION

Interventions to improve common factors can be used immediately in tandem with psychopharmacological interventions to provide increased symptom relief and reduce patient risk. Furthermore, incorporating instruction in common factors interventions can positively affect training of future providers and enhance understanding of the mechanisms of effect of medications. An increased focus on common factors, with a particular emphasis on quantifying the magnitude and mechanisms of their effects on psychopharmacological interventions stand to benefit child patients, their families, treatment providers, training facilities, and pharmaceutical manufacturers.

Developing an Unguided Internet-Delivered Intervention for Emotional Distress in Primary Care Patients: Applying Common Factor and Person-Based Approaches

BACKGROUND

Developing effective, unguided Internet interventions for mental health represents a challenge. Without structured human guidance, engagement with these interventions is often limited and the effectiveness reduced. If their effectiveness can be increased, they have great potential for broad, low-cost dissemination. Improving unguided Internet interventions for mental health requires a renewed focus on the proposed underlying mechanisms of symptom improvement and the involvement of target users from the outset.

OBJECTIVE

The aim of our study was to develop an unguided e-mental health intervention for distress in primary care patients, drawing on meta-theory of psychotherapeutic change and utilizing the person-based approach (PBA) to guide iterative qualitative piloting with patients.

METHODS

Common factors meta-theory informed the selection and structure of therapeutic content, enabling flexibility whilst retaining the proposed necessary ingredients for effectiveness. A logic model was designed outlining intervention components and proposed mechanisms underlying improvement. The PBA provided a framework for systematically incorporating target-user perspective into the intervention development. Primary care patients (N=20) who had consulted with emotional distress in the last 12 months took part in exploratory qualitative interviews, and a subsample (n=13) undertook think-aloud interviews with a prototype of the intervention.

RESULTS

A flexible intervention was developed, to be used as and when patients need, diverting from a more traditional, linear approach. Based on the in-depth qualitative findings, disorder terms such as "depression" were avoided, and discussions of psychological symptoms were placed in the context of stressful life events. Think-aloud interviews showed that patients were positive about the design and structure of the intervention. On the basis of patient feedback, modifications were made to increase immediate access to all therapeutic techniques.

CONCLUSIONS

Detailing theoretical assumptions underlying Internet interventions for mental health, and integrating this approach with systematic in-depth qualitative research with target patients is important. These strategies may provide novel ways for addressing the challenges of unguided delivery. The resulting intervention, Healthy Paths, will be evaluated in primary care-based randomized controlled trials, and deployed as a massive open online intervention (MOOI).

The power and value of placebo and nocebo in painful osteoarthritis

This paper reviews some recent advances in our understanding of the effects of sham or dummy interventions on pain and other symptoms in osteoarthritis (OA), and outlines two new approaches to the investigation of placebo and nocebo effects. We argue that the placebo effect provides us with a valuable way of investigating the nature of conditions like OA. For example, by examining which symptoms, biochemical markers or imaging features do or do not respond to placebo, we might learn more about the relationships between pathology and symptoms in OA. Placebo and nocebo effects are positive or negative outcomes resulting from the human interactions and contexts in which healthcare consultations take place. Subtle changes in behaviours and the environments in which consultations take place can have major effects on pain and other symptoms being experienced by people with OA. Nocebo effects are particularly powerful, leading to many health-care professionals (HCPs) causing unintended harm to their clients. Based on our own research, we conclude that beneficial outcomes are most likely to occur when both the (HCP) and the client feel safe and relaxed, and when the experiences of the client are validated by the (HCP). These findings have important implications for clinical practice. We believe that research in this field needs to be 'trans-disciplinary', escaping from the constraints of the purely biomedical, deterministic, positivist paradigm of most medical research. We provide the example of our own work which combines performance studies and scholarship, with psychology and medicine.

Placebo, nocebo, and neuropathic pain

Over the last decade, the apparent increase in placebo responses in randomized controlled trials (RCTs) of neuropathic pain have complicated and potentially limited development and availability of new effective pain medication. Placebo analgesia and nocebo hyperalgesia effects are well described in nociceptive and idiopathic pain conditions, but less is known about the magnitude and mechanisms of placebo and nocebo effects in neuropathic pain. In neuropathic pain, placebo treatments have primarily been used as control conditions for active agents under investigation in RCTs and these placebo responses are typically not controlled for the natural history of pain and other confounding factors. Recently, mechanistic studies that control for the natural history of pain have investigated placebo and nocebo effects in neuropathic pain in their own right. Large placebo analgesia but no nocebo hyperalgesic effects have been found, and the underlying mechanisms are beginning to be elucidated. Here we review placebo and nocebo effects and the underlying mechanisms in neuropathic pain and compare them with those of nociceptive and idiopathic pain. This allows for a novel discussion on how knowledge of psychological, neurobiological, and genetic factors underlying well-controlled placebo effects may help improve the information that can be obtained from and potentially restore the utility of RCTs.

Krill Oil Improves Mild Knee Joint Pain: A Randomized Control Trial

Background

Krill oil is an edible oil extracted from krill, a small red-colored crustacean found in the Antarctic Ocean. The administration of krill oil is reported to mitigate inflammation in patients with cardiac disease, rheumatoid arthritis, or osteoarthritis. However, the effect of krill oil on mild knee pain has not yet been determined.

Objective

To assess the effect of krill oil on mild knee pain.

Design

A randomized, double-blind, parallel-group, placebo-controlled trial of fifty adults (38–85 years old) with mild knee pain attending the Fukushima Orthopedic Clinic (Tochigi, Japan) between September 2014 and March 2015.

Interventions

Participants were randomized to receive 2 g per day of either krill oil or an identical placebo for 30 days.

Outcomes

The primary outcome was improvement in subjective symptoms of knee pain as assessed by the Japanese Knee Osteoarthritis Measure (JKOM) and Japanese Orthopaedic Association score (JOA). Secondary outcomes included blood and urine biochemical parameters.

Results

Both the placebo and krill oil groups showed significant improvements in the questions in the JKOM and JOA questionnaires after administration. After the intervention, krill oil group showed more improvements than placebo group in two questions regarding the pain and stiffness in knees in JKOM. Controlling for age, sex, weight, and smoking and drinking habits, krill oil significantly mitigated knee pain in sleeping (P < 0.001), standing (P < 0.001) and the range of motion of both right and left knees (both P = 0.011) compared to placebo. Krill oil administration raised plasma EPA (P = 0.048) and EPA/AA ratio (P = 0.003).

Conclusion

This study indicates that krill oil administration (2 g/day, 30 days) improved the subjective symptoms of knee pain in adults with mild knee pain.

Trial registration

UMIN-CTR; ID UMIN000014413

The Psychological Dimensions of Placebo-Studies

Abstract. The placebo effect involves a complex network of psychological variables that are often disregarded by studies enquiring into this effect. It is hence little surprising that these psychological variables confound study outcomes and that experiments investigating the placebo effect often yield radically different results. The current article identifies three categories of psychological and methodological factors that are not systematically considered in placebo research: psychological confounds (Hawthorne effects and demand effects); methodological and data-analysis issues; and clinicians’ expectancy effects. These factors are not necessarily to be seen as mere artifacts, however, because they may constitute favorable components of the placebo effect. A set of benchmark criteria is therefore proposed to allow researchers to capitalize on these components during placebo research rather than have their results confounded by them; and to allow for a more reliable interpretation of study outcomes.

Context Effects in Western Herbal Medicine: Fundamental to Effectiveness?

Western herbal medicine (WHM) is a complex healthcare system that uses traditional plant-based medicines in patient care. Typical preparations are individualized polyherbal formulae that, unlike herbal pills, retain the odor and taste of whole herbs. Qualitative studies in WHM show patient-practitioner relationships to be collaborative. Health narratives are co-constructed, leading to assessments, and treatments with personal significance for participants. It is hypothesized that the distinct characteristics of traditional herbal preparations and patient-herbalist interactions, in conjunction with the WHM physical healthcare environment, evoke context (placebo) effects that are fundamental to the overall effectiveness of herbal treatment. These context effects may need to be minimized to demonstrate pharmacological efficacy of herbal formulae in randomized, placebo-controlled trials, optimized to demonstrate effectiveness of WHM in pragmatic trials, and consciously harnessed to enhance outcomes in clinical practice.

Placebo effects and their determinants in gastrointestinal disorders

Placebo effects in clinical trials have sparked an interest in the placebo phenomenon, both in randomized controlled trials (RCTs) and in experimental gastroenterology. RCTs have demonstrated similar short-term and long-term placebo response rates in gastrointestinal compared to other medical diagnoses. Most mediators and moderators of placebo effects in gastrointestinal diseases are also of similar type and size to other medical diagnoses and not specific for gastrointestinal diagnoses. Other characteristics such as an increase in the placebo response over time and the placebo-enhancing effects of unbalanced randomization were not seen, at least in IBS. Experimental placebo and nocebo studies underscore the 'power' of expectancies and conditioning processes in shaping gastrointestinal symptoms not only at the level of self-reports, but also within the brain and along the brain-gut axis. Brain imaging studies have redressed earlier criticism that placebo effects might merely reflect a response bias. These findings raise hope that sophisticated trials and experiments designed to boost positive expectations and minimize negative expectations could pave the way for a practical and ethically sound use of placebo knowledge in daily practice. Rather than focusing on a 'personalized' choice of drugs based on biomarkers or genes, it might be the doctor-patient communication that needs to be tailored.

Why Ineffective Psychotherapies Appear to Work: A Taxonomy of Causes of Spurious Therapeutic Effectiveness

The past 40 years have generated numerous insights regarding errors in human reasoning. Arguably, clinical practice is the domain of applied psychology in which acknowledging and mitigating these errors is most crucial. We address one such set of errors here, namely, the tendency of some psychologists and other mental health professionals to assume that they can rely on informal clinical observations to infer whether treatments are effective. We delineate four broad, underlying cognitive impediments to accurately evaluating improvement in psychotherapy-naive realism, confirmation bias, illusory causation, and the illusion of control. We then describe 26 causes of spurious therapeutic effectiveness (CSTEs), organized into a taxonomy of three overarching categories: (a) the perception of client change in its actual absence, (b) misinterpretations of actual client change stemming from extratherapeutic factors, and (c) misinterpretations of actual client change stemming from nonspecific treatment factors. These inferential errors can lead clinicians, clients, and researchers to misperceive useless or even harmful psychotherapies as effective. We (a) examine how methodological safeguards help to control for different CSTEs, (b) delineate fruitful directions for research on CSTEs, and (c) consider the implications of CSTEs for everyday clinical practice. An enhanced appreciation of the inferential problems posed by CSTEs may narrow the science-practice gap and foster a heightened appreciation of the need for the methodological safeguards afforded by evidence-based practice.

Who responds to placebos? Considering the "placebo personality" via a transactional model

The placebo effect is now recognised as a genuine psychobiological phenomenon; however, the question of how it can be systematically harnessed to improve health outcomes is not yet clear. One issue that remains unresolved is why some respond to placebos and others do not. A number of traits have been linked to responding, but findings are scattered. In extending prior work, this paper offers three considerations. First, attempts to describe the placebo responder via a single personality trait may be limiting. A synthesis of findings to date suggests placebo responsiveness may reflect a two-faceted construct, with "inward" and "outward" orientation representing the different but related facets of placebo responsiveness. Second, the lack of theoretically driven research may be hindering progress. Personality measures rather than personality theory appear to be driving research and higher order traits are descriptive tools with limited use in predicting behaviour. A biologically based stimulus-response model of personality that considers how individuals respond to certain environmental cues may be more appropriate. Third, a transactional model of placebo responding in which dispositional characteristics interact with environmental contingencies is presented. Responsiveness may manifest in placebo environments where there is a match between an individual's biological trait-like response systems and environmental contingencies. This type of model may be useful in both research and clinical settings. Systematic consideration of how different individuals might respond to different placebo environments might facilitate identification of stable individual characteristics predictive of responding. The ability to determine who is responsive to placebo treatments, and in what context, may enable the matching of individual to treatment, thereby maximising the effectiveness of treatment and minimising possible iatrogenic harm. In the increasingly overtaxed modern health care industry, non-pharmacological treatment alternatives are of critical importance.

Randomised controlled trials may underestimate drug effects: balanced placebo trial design

Background

It is an inherent assumption in randomised controlled trials that the drug effect can be estimated by subtracting the response during placebo from the response during active drug treatment.

Objective

To test the assumption of additivity. The primary hypothesis was that the total treatment effect is smaller than the sum of the drug effect and the placebo effect. The secondary hypothesis was that non-additivity was most pronounced in participants with large placebo effects.

Methods

We used a within-subject randomised blinded balanced placebo design and included 48 healthy volunteers (50% males), mean (SD) age 23.4 (6.2) years. Experimental pain was induced by injections of hypertonic saline into the masseter muscle. Participants received four injections with hypertonic saline along with lidocaine or matching placebo in randomised order: A: received hypertonic saline/told hypertonic saline; B: received hypertonic saline+lidocaine/told hypertonic saline; C: received hypertonic saline+placebo/told hypertonic saline+pain killer; D: received hypertonic saline+lidocaine/told hypertonic saline+pain killer. The primary outcome measure was the area under the curve (AUC, mm²) of pain intensity during injections.

Results

There was a significant difference between the sum of the drug effect and the placebo effect (mean AUC 6279 mm² (95% CI, 4936–7622)) and the total treatment effect (mean AUC 5455 mm² (95% CI, 4585–6324)) (P = 0.049). This difference was larger for participants with large versus small placebo effects (P = 0.015), and the difference correlated significantly with the size of the placebo effect (r = 0.65, P = 0.006).

Conclusion

Although this study examined placebo effects and not the whole placebo response as in randomised controlled trials, it does suggest that the additivity assumption may be incorrect, and that the estimated drug effects in randomised controlled trials may be underestimated, particularly in studies reporting large placebo responses. The implications for randomised controlled trials and systematic reviews need to be discussed.

Causal diagrams, the placebo effect, and the expectation effect

Using causal diagrams, a formal research methodology, we analyzed several definitions of placebo and the placebo effect. We conclude that placebo is an ambiguous, redundant term and that the so-called placebo effect conceals far more interesting effects that are attributed to the patient’s expectation. Biomedical research will benefit from abandoning the term placebo effect and focusing instead on a deeper understanding of the expectation variable, including its causes, effects, and effect modifiers. This avenue of research should be pursued by observational cohorts that are nested within clinical trials.