Blinded trials taken to the test: an analysis of randomized clinical trials that report tests for the success of blinding

Expectancy Effects in Psychedelic Trials

Clinical trials of psychedelic compounds like psilocybin, lysergic acid diethylamide (LSD), and N,N-dimethyltrptamine (DMT) have forced a reconsideration of how nondrug factors, such as participant expectations, are measured and controlled in mental health research. As doses of these profoundly psychoactive substances increase, so does the difficulty in concealing the treatment condition in the classic double-blind, placebo-controlled trial design. As widespread public enthusiasm for the promise of psychedelic therapy grows, so do questions regarding whether and how much trial results are biased by positive expectancy. First, we review the key concepts related to expectancy and its measurement. Then, we review expectancy effects that have been reported in both micro- and macrodose psychedelic trials from the modern era. Finally, we consider expectancy as a discrete physiological process that can be independent of, or even interact with, the drug effect. Expectancy effects can be harnessed to improve treatment outcomes and can also be actively managed in controlled studies to enhance the rigor and generalizability of future psychedelic trials.

Seeing Through the Blind: Belief About Treatment Randomization and Smoking Cessation Outcome Among People With Current or Past Major Depressive Disorder Who Smoke in a Placebo-Controlled Trial of Varenicline

INTRODUCTION

Blinding participants to randomization is a cornerstone of science. However, participant beliefs about their allocation can influence outcomes. We examined blind integrity, the association between trial arm belief and cessation, and potential mechanisms linking treatment arm and treatment arm belief among people with major depressive disorder (MDD) who smoke receiving varenicline in a placebo-controlled trial.

AIMS AND METHODS

175 participants were asked at the end of treatment (EOT) if they thought they received placebo, varenicline, or were not sure. We assessed the relationship between treatment arm belief and actual treatment allocation, examined the association between treatment arm belief and EOT cessation, and evaluated changes in craving, withdrawal, side effects, depression symptoms, and smoking reward as mediators through which treatment arm was believed.

RESULTS

Treatment arm belief was significantly associated with actual arm assignment (χ2(2) = 13.0, p = .002). Participants in the varenicline arm were >3 times as likely to believe they were taking varenicline, versus "not sure" (RR = 3.05 [1.41-6.60], p = .005). Participants in the placebo arm were just as likely to believe they were taking placebo versus "not sure" (χ2[2] = 0.75, p = .69). Controlling for treatment arm, belief that one received varenicline was significantly associated with an increase in cessation rate (OR = 5.91 [2.06-16.92], p = .001). Change in the rewarding experience of smoking may mediate participant ability to discern getting varenicline (B = 0.077 [0.002-0.192], p < .05).

CONCLUSIONS

Participants receiving varenicline can discern that they received varenicline and this belief is associated with higher cessation rates. Research is needed to continue to examine how participants correctly identify their allocation to varenicline.

TRIAL REGISTRATION

Data come from the trial NCT02378714.

IMPLICATIONS

The present study adds to the sparse literature on blind integrity, particularly in the field of tobacco cessation. Randomized clinical trial participants can discern their assignment to varenicline, and believing that one received varenicline was associated with significantly higher cessation rates. Identifying treatment arm allocation may be associated with changes in the rewarding aspects of smoking that have been well documented with varenicline use. Masking allocation to varenicline is challenging. The effects of this medication in clinical trials may represent both pharmacological effects and participants' abilities to recognize that they are receiving the medication.

Influence of lack of blinding on the estimation of medication-related harms: a retrospective cohort study of randomized controlled trials

BACKGROUND

Empirical evidence suggests that lack of blinding may be associated with biased estimates of treatment benefit in randomized controlled trials, but the influence on medication-related harms is not well-recognized. We aimed to investigate the association between blinding and clinical trial estimates of medication-related harms.

METHODS

We searched PubMed from January 1, 2015, till January 1, 2020, for systematic reviews with meta-analyses of medication-related harms. Eligible meta-analyses must have contained trials both with and without blinding. Potential covariates that may confound effect estimates were addressed by restricting trials within the comparison or by hierarchical analysis of harmonized groups of meta-analyses (therefore harmonizing drug type, control, dosage, and registration status) across eligible meta-analyses. The weighted hierarchical linear regression was then used to estimate the differences in harm estimates (odds ratio, OR) between trials that lacked blinding and those that were blinded. The results were reported as the ratio of OR (ROR) with its 95% confidence interval (CI).

RESULTS

We identified 629 meta-analyses of harms with 10,069 trials. We estimated a weighted average ROR of 0.68 (95% CI: 0.53 to 0.88, P < 0.01) among 82 trials in 20 meta-analyses where blinding of participants was lacking. With regard to lack of blinding of healthcare providers or outcomes assessors, the RORs were 0.68 (95% CI: 0.53 to 0.87, P < 0.01 from 81 trials in 22 meta-analyses) and 1.00 (95% CI: 0.94 to 1.07, P = 0.94 from 858 trials among 155 meta-analyses) respectively. Sensitivity analyses indicate that these findings are applicable to both objective and subjective outcomes.

CONCLUSIONS

Lack of blinding of participants and health care providers in randomized controlled trials may underestimate medication-related harms. Adequate blinding in randomized trials, when feasible, may help safeguard against potential bias in estimating the effects of harms.

The impact of blinding on estimated treatment effects in randomized clinical trials on acupuncture: A meta-epidemiological study

OBJECTIVE

To evaluate the sole impact of blinding patients and outcome assessors in acupuncture randomized controlled trials (RCTs) on treatment effects while considering the type of outcome measures.

METHODS

We searched databases for the meta-analyses on acupuncture with both blinded and non-blinded RCTs. Mixed-effects meta-regression models estimated the average ratio of odds ratios (ROR) and differences in standardized mean differences (dSMD) for non-blinded RCTs versus blinded mixed-effects meta-regression model.

RESULTS

The study included 96 meta-analyses (1012 trials). The average ROR for lack of patient blinding was 1.08 (95% confidence intervals 0.79-1.49) in 18 meta-analyses with binary patient-reported outcomes. The average ROR for lack of outcome assessor blinding was 0.98 (0.77-1.24) in 43 meta-analyses with binary subjective outcomes. The average dSMD was -0.38 (-0.96 to 0.20) in 10 meta-analyses with continuous patient-reported outcomes. The average dSMD was -0.13 (-0.45 to 0.18) in 25 meta-analyses with continuous subjective outcomes. The results of the subgroup analysis were consistent with the primary analysis findings.

CONCLUSIONS

Blinding of participants and outcome assessors does not significantly influence acupuncture treatment efficacy. It underscores the practical difficulties of blinding in acupuncture RCTs and the necessity to distinguish between trials with and without successful blinding to understand treatment expectations' effects. Enhancing blinding procedures' quality and assessment in future research is crucial for improving RCTs' internal validity and reliability.

Distinguishing Immunologic and Behavioral Effects of Vaccination

The interpretation of vaccine efficacy estimands is subtle, even in randomized trials designed to quantify the immunologic effects of vaccination. In this article, we introduce terminology to distinguish between different vaccine efficacy estimands and clarify their interpretations. This allows us to explicitly consider the immunologic and behavioral effects of vaccination, and establish that policy-relevant estimands can differ substantially from those commonly reported in vaccine trials. We further show that a conventional vaccine trial allows the identification and estimation of different vaccine estimands under plausible conditions if one additional post-treatment variable is measured. Specifically, we utilize a "belief variable" that indicates the treatment an individual believed they had received. The belief variable is similar to "blinding assessment" variables that are occasionally collected in placebo-controlled trials in other fields. We illustrate the relations between the different estimands, and their practical relevance, in numerical examples based on an influenza vaccine trial.

Sham controls in device trials for chronic pain - tricky in practice-a review article

Background

Chronic pain affects one in four people and this figure is likely to increase further in line with an ageing population. Efforts to evaluate nonpharmacological interventions to support this patient population have become a priority for pain research. For device trials, the use of a sham control can add to the scientific validity and quality of a study. However, only a small proportion of pain trials include a sham control, and many are of poor quality. To facilitate the conduct of high-quality trials there is a need for a comprehensive overview to guide researchers within this area. The objective of this review was to synthesise the published data to address this need.

Methods

We identified studies that considered the evaluation, design, and conduct of sham-controlled trials in chronic pain by searching MEDLINE, CINAHL and Science Direct to November 2022. Studies that included sufficient content to inform the conduct/design of future research were included. An inductive thematic analysis approach was used to identify themes that require consideration when conducting sham-controlled trials. These are presented as a narrative review.

Results

37 articles were included. Identified themes related to the type of sham device, sham design, bias, study population and ethics.

Conclusions

To conduct good quality research the challenges surrounding the use of sham interventions need to be better considered. We highlight salient issues and provide recommendations for the conduct and reporting of sham-controlled device trials in chronic pain.

Success of blinding a procedural intervention in a randomised controlled trial in preterm infants receiving respiratory support

BACKGROUND

Blinding of treatment allocation from treating clinicians in neonatal randomised controlled trials can minimise performance bias, but its effectiveness is rarely assessed.

METHODS

To examine the effectiveness of blinding a procedural intervention from treating clinicians in a multicentre randomised controlled trial of minimally invasive surfactant therapy versus sham treatment in preterm infants of gestation 25-28 weeks with respiratory distress syndrome. The intervention (minimally invasive surfactant therapy or sham) was performed behind a screen within the first 6 h of life by a 'study team' uninvolved in clinical care including decision-making. Procedure duration and the study team's words and actions during the sham treatment mimicked those of the minimally invasive surfactant therapy procedure. Post-intervention, three clinicians completed a questionnaire regarding perceived group allocation, with the responses matched against actual intervention and categorised as correct, incorrect, or unsure. Success of blinding was calculated using validated blinding indices applied to the data overall (James index, successful blinding defined as > 0.50), or to the two treatment allocation groups (Bang index, successful blinding: -0.30 to 0.30). Blinding success was measured within staff role, and the associations between blinding success and procedural duration and oxygenation improvement post-procedure were estimated.

RESULTS

From 1345 questionnaires in relation to a procedural intervention in 485 participants, responses were categorised as correct in 441 (33%), incorrect in 142 (11%), and unsure in 762 (57%), with similar proportions for each of the response categories in the two treatment arms. The James index indicated successful blinding overall 0.67 (95% confidence interval (CI) 0.65-0.70). The Bang index was 0.28 (95% CI 0.23-0.32) in the minimally invasive surfactant therapy group and 0.17 (95% CI 0.12-0.21) in the sham arm. Neonatologists more frequently guessed the correct intervention (47%) than bedside nurses (36%), neonatal trainees (31%), and other nurses (24%). For the minimally invasive surfactant therapy intervention, the Bang index was linearly related to procedural duration and oxygenation improvement post-procedure. No evidence of such relationships was seen in the sham arm.

CONCLUSION

Blinding of a procedural intervention from clinicians is both achievable and measurable in neonatal randomised controlled trials.

Blinding Is Seeing: A Single-Centre Study Into the Viability of Auto-Injectors for Blinded-Drug Administration in Randomised Controlled Trials

Objective The aim of the study was to assess the viability of auto-injector systems (A-INJ) for preserving investigator blinding in randomized controlled trials (RCT). Background Blinding refers to the concealment of group allocation from one or more individuals involved in a clinical research study. In the dosing of subcutaneous (SC) and intramuscular (IM) investigational medicinal products (IMP), specific challenges arise in maintaining investigator blinding. These challenges primarily involve the active injectate's viscosity and visual appearance (colour/translucency) in comparison to the placebo. Existing methods to control these issues are not perfect. Common approaches include using unblinded investigators or applying films or additives to make the active and placebo injectates appear similar. Method A single-centre experimental and descriptive study was carried out to compare the use of an A-INJ (Owen Mumford, Autoject 2) with the use of a conventional syringe (CS) in delivering a 1 ml dose of both placebo and reference IMP. The percentage delivery of the injectate was compared between the A-INJ IMP and placebo groups. Additionally, eight trained research physicians serving as investigators recorded their assessments of safety and effectiveness after performing serial injections with the A-INJ into a human-tissue analogue. Results Overall, a mean of 95.38% of 1ml placebo injectate was released from the A-INJ, compared to 96.00% from the CS. A total of 94.715% of 1 ml IMP injectate was released from the A-INJ, as opposed to 94.74% from the CS. Independent t-test analyses showed no statistical significance between the experimental arms. The mean administration time was 8.5 seconds. Investigators were unable to differentiate between the two solutions when using the A-INJ. There were no recorded concerns about investigators becoming unblinded, which stands in contrast to concerns associated with using the CS. Conclusion In assessing the viability of A-INJ use in RCTs, we noted a marked improvement when blinding was used. A-INJ systems effectively administer both placebo and active injectates, thereby maintaining the benefit of blinding without the need to alter the placebo through the addition of colourants or viscosity additives. While audio cues from the A-INJ and the time required to administer the injectate pose challenges, solutions are suggested. Although our findings are preliminary, they add to the existing literature on the advantages of A-INJs for administering injectable compounds and offer new perspectives on their utility in RCTs.

The difference between 'placebo group' and 'placebo control': a case study in psychedelic microdosing

In medical trials, 'blinding' ensures the equal distribution of expectancy effects between treatment arms in theory; however, blinding often fails in practice. We use computational modelling to show how weak blinding, combined with positive treatment expectancy, can lead to an uneven distribution of expectancy effects. We call this 'activated expectancy bias' (AEB) and show that AEB can inflate estimates of treatment effects and create false positive findings. To counteract AEB, we introduce the Correct Guess Rate Curve (CGRC), a statistical tool that can estimate the outcome of a perfectly blinded trial based on data from an imperfectly blinded trial. To demonstrate the impact of AEB and the utility of the CGRC on empirical data, we re-analyzed the 'self-blinding psychedelic microdose trial' dataset. Results suggest that observed placebo-microdose differences are susceptible to AEB and are at risk of being false positive findings, hence, we argue that microdosing can be understood as active placebo. These results highlight the important difference between 'trials with a placebo-control group', i.e., when a placebo control group is formally present, and 'placebo-controlled trials', where patients are genuinely blind. We also present a new blinding integrity assessment tool that is compatible with CGRC and recommend its adoption.

Assessment of patient perception of treatment assignment and patient-reported outcomes in a cannabis use disorder trial

Background: Blinding is a cornerstone of trial methodology. Prior work indicates participant-perceived assignment may be associated with trial outcomes. Less is known about how perception changes over time and if this is associated with outcomes.Objectives: To evaluate if participants change their perception of assignment over time in a blinded trial, and if perception is associated with different types of patient-reported outcomes (PROs).Methods: This was a secondary analysis of data from the Achieving Cannabis Cessation-Evaluating N-Acetylcysteine Treatment (ACCENT) trial, which evaluated the efficacy of N-acetylcysteine (NAC) relative to placebo for treating cannabis use disorder. Participants (N = 234; 164 men, 70 women) were asked at weeks 5 and 9 what treatment (placebo or NAC) they believed they were receiving. We included PROs proximal (cannabis-associated problems, craving) and distal (anxiety) to the intervention. Analysis was by multiple linear regression and mixed models.Results: Approximately 20% of participants in both arms changed their perception over time. Relative to participants who consistently perceived assignment to placebo, participants who consistently perceived assignment to NAC did not always have comparatively better average scores (coefficient -3.3 [95% CI: -7.0, 0.5]). In some analyses, participants who switched to guessing NAC from placebo had comparatively better average scores (coefficient -3.0 [95% CI: -9.3, 3.4]), but this was inconsistent across outcomes or strata defined by actual assignment or guess accuracy.Conclusion: The study suggests that the proportion of individuals who switch their perception over time is modest. However, this group may influence the estimates of intervention effects on some PROs.

Expectation effects in working memory training

There is a growing body of research focused on developing and evaluating behavioral training paradigms meant to induce enhancements in cognitive function. It has recently been proposed that one mechanism through which such performance gains could be induced involves participants' expectations of improvement. However, no work to date has evaluated whether it is possible to cause changes in cognitive function in a long-term behavioral training study by manipulating expectations. In this study, positive or negative expectations about cognitive training were both explicitly and associatively induced before either a working memory training intervention or a control intervention. Consistent with previous work, a main effect of the training condition was found, with individuals trained on the working memory task showing larger gains in cognitive function than those trained on the control task. Interestingly, a main effect of expectation was also found, with individuals given positive expectations showing larger cognitive gains than those who were given negative expectations (regardless of training condition). No interaction effect between training and expectations was found. Exploratory analyses suggest that certain individual characteristics (e.g., personality, motivation) moderate the size of the expectation effect. These results highlight aspects of methodology that can inform future behavioral interventions and suggest that participant expectations could be capitalized on to maximize training outcomes.

Efficacy of sodium bicarbonate ingestion strategies for protecting blinding

Sodium bicarbonate (NaHCO₃) is a widely researched ergogenic aid, but the optimal blinding strategy during randomised placebo-controlled trials is unknown. In this multi-study project, we aimed to determine the most efficacious ingestion strategy for blinding NaHCO₃ research. During study one, 16 physically active adults tasted 0.3 g kg^-1 body mass NaHCO₃ or 0.03 g kg^-1 body mass sodium chloride placebo treatments given in different flavour (orange, blackcurrant) and temperature (chilled, room temperature) solutions. They were required to guess which treatment they had received. During study two, 12 recreational athletes performed time-to-exhaustion (TTE) cycling trials (familiarisation, four experimental). Using a randomised, double-blind design, participants consumed 0.3 g kg^-1 body mass NaHCO₃ or a placebo in 5 mL kg^-1 body mass chilled orange squash/water solutions or capsules and indicated what they believed they had received immediately after consumption, pre-TTE and post-TTE. In study one, NaHCO₃ prepared in chilled orange squash resulted in the most unsure ratings (44%). In study two, giving NaHCO₃ in capsules resulted in more unsure ratings than in solution after consumption (92 vs 33%), pre-TTE (67 vs. 17%) and post-TTE (50 vs. 17%). Administering NaHCO₃ in capsules was the most efficacious blinding strategy which provides important implications for researchers conducting randomised placebo-controlled trials.

Transcranial Direct Current Stimulation vs Sham for the Treatment of Inattention in Adults With Attention-Deficit/Hyperactivity Disorder: The TUNED Randomized Clinical Trial

IMPORTANCE

Transcranial direct current stimulation (tDCS) may improve symptoms of inattention in adults with attention-deficit/hyperactivity disorder (ADHD). However, previous trials are characterized by small sample sizes, heterogeneous methodologies, and short treatment periods using clinic-based tDCS.

OBJECTIVE

To determine the efficacy and safety of home-based tDCS in treating inattention symptoms in adult patients with ADHD.

DESIGN, SETTING, AND PARTICIPANTS

Randomized, double-blind, parallel, sham-controlled clinical trial (tDCS for the Treatment of Inattention Symptoms in Adult Patients With ADHD [TUNED]), conducted from July 2019 through July 2021 in a single-center outpatient academic setting. Of 277 potential participants screened by phone, 150 were assessed for eligibility on site, and 64 were included. Participants were adults with ADHD, inattentive or combined subtype. Exclusion criteria included current stimulant drug treatment, current moderate to severe symptoms of depression or anxiety, diagnosis of bipolar disorder with a manic or depressive episode in the last year, diagnosis of schizophrenia or another psychotic disorder, and diagnosis of autism spectrum disorder; 55 of participants completed follow-up after 4 weeks.

INTERVENTIONS

Thirty-minute daily sessions of home-based tDCS for 4 weeks, 2 mA anodal-right and cathodal-left prefrontal stimulation with 35-cm2 carbon electrodes.

MAIN OUTCOMES AND MEASURES

Inattentive scores in the clinician-administered version of the Adult ADHD Self-report Scale version 1.1 (CASRS-I).

RESULTS

Included in this trial were 64 participants with ADHD (31 [48%] inattentive presentation and 33 [52%] combined presentation), with a mean (SD) age of 38.3 (9.6) years. Thirty participants (47%) were women and 34 (53%) were men. Fifty-five finished the trial. At week 4, the mean (SD) inattention score, as measured with CASRS-I, was 18.88 (5.79) in the active tDCS group and 23.63 (3.97) in the sham tDCS group. Linear mixed-effects models revealed a statistically significant treatment by time interaction for CASRS-I (βinteraction = -3.18; 95% CI, -4.60 to -1.75; P < .001), showing decreased symptoms of inattention in the active tDCS group over the 3 assessments compared to the sham tDCS group. Mild adverse events were more frequent in the active tDCS group, particularly skin redness, headache, and scalp burn.

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial, daily treatment with a home-based tDCS device over 4 weeks improved attention in adult patients with ADHD who were not taking stimulant medication. Home-based tDCS could be a nonpharmacological alternative for patients with ADHD.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04003740.

Oral Health Coaches at Well-Baby Clinics to Promote Oral Health in Preschool Children From the First Erupted Tooth: Protocol for a Multisite, Pragmatic Randomized Controlled Trial

Background

Early childhood caries is considered one of the most prevalent diseases in childhood, affecting almost half of preschool-age children globally. In the Netherlands, approximately one-third of children aged 5 years already have dental caries, and dental care providers experience problems reaching out to these children.

Objective

Within the proposed trial, we aim to test the hypothesis that, compared to children who receive usual care, children who receive the Toddler Oral Health Intervention as add-on care will have a reduced cumulative caries incidence and caries incidence density at the age of 48 months.

Methods

This pragmatic, 2-arm, individually randomized controlled trial is being conducted in the Netherlands and has been approved by the Medical Ethics Research Board of University Medical Center Utrecht. Parents with children aged 6 to 12 months attending 1 of the 9 selected well-baby clinics are invited to participate. Only healthy children (ie, not requiring any form of specialized health care) with parents that have sufficient command of the Dutch language and have no plans to move outside the well-baby clinic region are eligible. Both groups receive conventional oral health education in well-baby clinics during regular well-baby clinic visits between the ages of 6 to 48 months. After concealed random allocation of interventions, the intervention group also receives the Toddler Oral Health Intervention from an oral health coach. The Toddler Oral Health Intervention combines behavioral interventions of proven effectiveness in caries prevention. Data are collected at baseline, at 24 months, and at 48 months. The primary study endpoint is cumulative caries incidence for children aged 48 months, and will be analyzed according to the intention-to-treat principle. For children aged 48 months, the balance between costs and effects of the Toddler Oral Health Intervention will be evaluated, and for children aged 24 months, the effects of the Toddler Oral Health Intervention on behavioral determinants, alongside cumulative caries incidence, will be compared.

Results

The first parent-child dyads were enrolled in June 2017, and recruitment was finished in June 2019. We enrolled 402 parent-child dyads.

Conclusions

All follow-up interventions and data collection will be completed by the end of 2022, and the trial results are expected soon thereafter. Results will be shared at international conferences and via peer-reviewed publication.

Trial Registration

Netherlands Trial Register NL8737; https://trialsearch.who.int/Trial2.aspx?TrialID=NL8737

International Registered Report Identifier (IRRID)

DERR1-10.2196/39683

Assessment of blinding in randomized controlled trials of antidepressants for depressive disorders 2000-2020: A systematic review and meta-analysis

BACKGROUND

In double-blind randomized controlled trials (RCTs) of antidepressants, blinding can be broken due to the apparent side effects, and unsuccessful blinding can lead to overestimation of effect sizes. New generation antidepressants with less severe side effects may be less susceptible to broken blinding. However, successfulness of blinding in new generation antidepressant trials and its influence on trial effect size estimates remain unclear.

METHODS

Extending a previous systematic review assessing blinding successfulness in psychiatric trials (2000-2010), we searched PubMed/Medline for double-blinded antidepressant RCTs (2010-2020) for trials assessing blinding success. Our primary outcome was the degree of blinding successfulness, measured as kappa statistics between guesses and true allocations. We used random-effects meta-analysis to synthesize studies. We used meta-regression and Pearson's r to examine the relationship between blinding success and effect sizes. This study is registered with PROSPERO (CRD42021249973).

FINDINGS

Among 154 eligible studies, 11 (7·1%) contained information on blinding assessment between 2010 and 2020. Five studies were added from the previous review, and altogether nine of the 16 studies provided usable data. Agreement in individual studies ranged from κ=-0·14 to 0·38. The summary agreement between guesses and the truth was 0·21 (95% CI: 0·14 to 0·28) among patients and 0·17 (95% CI: 0·05 to 0·30) among assessors. Blinding success was not associated with effect size (patients: r = 0·37, p = 0·32; assessors: r = 0·28; p = 0·72). Meta-regression also failed to find a significant relationship between blinding success and depression effect sizes (β=0·06, p = 0·09).

INTERPRETATION

Less than 10% of the antidepressant RCTs reported blinding assessment. The results in new generation antidepressant trials indicated that patients and assessors were unlikely to be able to judge treatment allocation. There was little evidence that the extent of unblinding biased the effect size estimates of new generation antidepressants.

FUNDING

None.

Adequacy of an Altitude Fitness Program (Living and Training) plus Intermittent Exposure to Hypoxia for Improving Hematological Biomarkers and Sports Performance of Elite Athletes: A Single-Blind Randomized Clinical Trial

Athletes incorporate altitude training programs into their conventional training to improve their performance. The purpose of this study was to determine the effects of an 8-week altitude training program that was supplemented with intermittent hypoxic training (IHE) on the blood biomarkers, sports performance, and safety profiles of elite athletes. In a single-blind randomized clinical trial that followed the CONSORT recommendations, 24 male athletes were randomized to an IHE group (HA, n = 12) or an intermittent normoxia group (NA, n = 12). The IHE consisted of 5-min cycles of hypoxia−normoxia with an FIO2 of between 10−13% for 90 min every day for 8 weeks. Hematological (red blood cells, hemoglobin, hematocrit, hematocrit, reticulated hemoglobin, reticulocytes, and erythropoietin), immunological (leukocytes, monocytes, and lymphocytes), and renal (urea, creatinine, glomerular filtrate, and total protein) biomarkers were assessed at the baseline (T1), day 28 (T2), and day 56 (T3). Sports performance was evaluated at T1 and T3 by measuring quadriceps strength and using three-time trials over the distances of 60, 400, and 1000 m on an athletics track. Statistically significant increases (p < 0.05) in erythropoietin, reticulocytes, hemoglobin, and reticulocyte hemoglobin were observed in the HA group at T3 with respect to T1 and the NA group. In addition, statistically significant improvements (p < 0.05) were achieved in all performance tests. No variations were observed in the immunological or renal biomarkers. The athletes who were living and training at 1065 m and were supplemented with IHE produced significant improvements in their hematological behavior and sports performance with optimal safety profiles.

Importance of blinding and expectations in opioid-induced constipation: evidence from a randomized controlled trial

OBJECTIVES

Previous studies have found little association between objective measures and the subjective experience of opioid-induced constipation. The subjective experience of opioid-induced constipation may be influenced by treatment expectations. While most trials control for treatment expectations through blinding, success rate is generally low. This study aimed to explore the association between objective measures and the subjective experience of opioid-induced constipation, while considering blinding success and treatment expectations, and other psychological factors.

METHODS

Data from a randomized, double-blinded, placebo-controlled crossover trial including 21 healthy male participants was analyzed. Participants received either placebo, tapentadol, or oxycodone (in equipotent doses) for 14 days. They were assessed on objective and subjective measures of opioid-induced constipation (gastrointestinal transit time and the Patient Assessment of Constipation-Symptoms questionnaire, respectively), treatment guesses to indicate blinding success, and psychological factors.

RESULTS

There was a strong association between objective and subjective measures of opioid-induced constipation when participants were treated with oxycodone (r=0.676, p=0.006). Furthermore, participants were able to guess that they received active treatment when treated with oxycodone (p<0.001), suggesting that treatment expectations may have influenced the subjective experience of symptoms. Finally, patterns of moderate associations between opioid-induced constipation and other psychological factors emerged, although none reached significance (p>0.05).

CONCLUSIONS

Results indicate that treatment expectations could play an important role in the subjective experience of opioid-induced constipation, and support the importance of assessing blinding success in study trials. Besides expectations, other psychological factors may be associated with opioid-induced constipation.

Effectiveness of a WHO self-help psychological intervention for preventing mental disorders among Syrian refugees in Turkey: a randomized controlled trial

Refugees are at high risk of developing mental disorders. There is no evidence from randomized controlled trials (RCTs) that psychological interventions can prevent the onset of mental disorders in this group. We assessed the effectiveness of a self-help psychological intervention developed by the World Health Organization, called Self-Help Plus, in preventing the development of mental disorders among Syrian refugees experiencing psychological distress in Turkey. A two-arm, assessor-masked RCT was conducted in two Turkish areas. Eligible participants were adult Syrian refugees experiencing psychological distress (General Health Questionnaire ≥3), but without a diagnosis of mental disorder. They were randomly assigned either to the Self-Help Plus arm (consisting of Self-Help Plus combined with Enhanced Care as Usual, ECAU) or to ECAU only in a 1:1 ratio. Self-Help Plus was delivered in a group format by two facilitators over five sessions. The primary outcome measure was the presence of any mental disorder assessed by the Mini International Neuropsychiatric Interview at six-month follow-up. Secondary outcome measures were the presence of mental disorders at post-intervention, and psychological distress, symptoms of post-traumatic stress disorder and depression, personally identified psychological outcomes, functional impairment, subjective well-being, and quality of life at post-intervention and six-month follow-up. Between October 1, 2018 and November 30, 2019, 1,186 refugees were assessed for inclusion. Five hundred forty-four people were ineligible, and 642 participants were enrolled and randomly assigned to either Self-Help Plus (N=322) or ECAU (N=320). Self-Help Plus participants were significantly less likely to have any mental disorders at six-month follow-up compared to the ECAU group (21.69% vs. 40.73%; Cramer's V = 0.205, p<0.001, risk ratio: 0.533, 95% CI: 0.408-0.696). Analysis of secondary outcomes suggested that Self-Help Plus was not effective immediately post-intervention, but was associated with beneficial effects at six-month follow-up in terms of symptoms of depression, personally identified psychological outcomes, and quality of life. This is the first prevention RCT ever conducted among refugees experiencing psychological distress but without a mental disorder. Self-Help Plus was found to be an effective strategy for preventing the onset of mental disorders. Based on these findings, this low-intensity self-help psychological intervention could be scaled up as a public health strategy to prevent mental disorders in refugee populations exposed to ongoing adversities.

Behavioural Interventions in People with Oropharyngeal Dysphagia: A Systematic Review and Meta-Analysis of Randomised Clinical Trials

Objective: To determine the effects of behavioural interventions in people with oropharyngeal dysphagia. Methods: Systematic literature searches were conducted to retrieve randomized controlled trials in four different databases (CINAHL, Embase, PsycINFO, and PubMed). The methodological quality of eligible articles was assessed using the Revised Cochrane risk-of-bias tool for randomised trials (RoB 2), after which meta-analyses were performed using a random-effects model. Results: A total of 37 studies were included. Overall, a significant, large pre-post interventions effect size was found. To compare different types of interventions, all behavioural interventions and conventional dysphagia treatment comparison groups were categorised into compensatory, rehabilitative, and combined compensatory and rehabilitative interventions. Overall, significant treatment effects were identified favouring behavioural interventions. In particular, large effect sizes were found when comparing rehabilitative interventions with no dysphagia treatment, and combined interventions with compensatory conventional dysphagia treatment. When comparing selected interventions versus conventional dysphagia treatment, significant, large effect sizes were found in favour of Shaker exercise, chin tuck against resistance exercise, and expiratory muscle strength training. Conclusions: Behavioural interventions show promising effects in people with oropharyngeal dysphagia. However, due to high heterogeneity between studies, generalisations of meta-analyses need to be interpreted with care.

A systematic review and meta-analysis of the success of blinding in antidepressant RCTs

Successful blinding in double-blind RCTs is crucial for minimizing bias, however studies rarely report information about blinding. Among RCTs for depression, the rates of testing and success of blinding is unknown. We conducted a systematic review and meta-analysis of the rates of testing, predictors, and success of blinding in RCTs of antidepressants for depression. Following systematic search, further information about blinding assessment was requested from corresponding authors of the included studies. We reported the frequency of blinding assessment across all RCTs, and conducted logistic regression analyses to assess predictors of blinding reporting. Participant and/or investigator guesses about treatment allocation were used to calculate Bang's Blinding Index (BI). The BI between RCT arms was compared using meta-analysis. Across the 295 included trials, only 4.7% of studies assessed blinding. Pharmaceutical company sponsorship predicted blinding assessment; unsponsored trials were more likely to assess blinding. Meta-analysis suggested that blinding was unsuccessful among participants and investigators. Results suggest that blinding is rarely assessed, and often fails, among RCTs of antidepressants. This is concerning considering controversy around the efficacy of antidepressant medication. Blinding should be routinely assessed and reported in RCTs of antidepressants, and trial outcomes should be considered in light of blinding success or failure.

A novel blinding protocol to test participant and therapist blinding during dry needling: a randomised controlled experiment

OBJECTIVES

Dry needling is widely used in physiotherapy. Lack of blinding in clinical trials means that dry needling effects and mechanisms remain unclear, with blinding issues accepted as an unavoidable barrier to better evidence. The authors aimed to overcome this barrier by designing a protocol to double-blind dry needling trials.

DESIGN

A prospectively registered randomised experiment tested a novel blinding protocol for blinding effectiveness.

SETTING

University physiotherapy clinic.

PARTICIPANTS

Therapists (n=15) and asymptomatic volunteers ('recipients') (n=45) were randomly allocated to real and/or sham interventions.

INTERVENTIONS

The protocol involved custom-made needles and cognitive and multisensory blinding techniques.

MAIN OUTCOME MEASURES

The primary outcome was guesses about allocation. The a priori criterion for successful blinding was ≤50% correct guesses (random chance). Secondary analyses explored blinding patterns using blinding indices.

RESULTS

Correct guesses were not different from 50% for therapists [41% (95%CI 30 to 50), n=120 guesses] or recipients [49% (95%CI 38 to 60), n=90 guesses]. Blinding indices supported the primary result but revealed that recipients were better at detecting real dry needling than sham.

CONCLUSION

Both therapists and recipients were successfully blinded, which contrasts with the widely held assumption that double-blinding is impossible for needling interventions. The authors recommend that any future trials can, and therefore should, blind therapists. However, secondary analyses revealed that recipients receiving real dry needling were less blinded than sham recipients, which may still create bias in clinical trials and suggests further work is needed to improve recipient blinding. Nonetheless, the current findings offer an opportunity to gain better evidence concerning the effects and mechanisms of dry needling.

STUDY REGISTRATION

https://osf.io/rkzeb/.

Blinding and expectancy confounds in psychedelic randomized controlled trials

Introduction: There is increasing interest in the potential for psychedelic drugs such as psilocybin, LSD and ketamine to treat several mental health disorders, with a growing number of randomized controlled trials (RCTs) being conducted to investigate the therapeutic effectiveness of psychedelics.Areas covered: We review previous literature on expectancy effects and blinding in the context of psychedelic RCTs - literature which strongly suggest that psychedelic RCTs might be confounded by de-blinding and expectancy. We conduct systematic reviews of psychedelic RCTs using Medline, PsychInfo and EMBASE (Jan 1990 - Nov 2020) and show that currently reported psychedelic RCTs have generally not reported pre-trial expectancy, nor the success of blinding procedures.Expert opinion: While psychedelic RCTs have generally shown promising results, with large effect sizes reported, we argue that treatment effect sizes in psychedelic RCTs are likely over-estimated due to de-blinding of participants and high levels of response expectancy. We suggest that psychedelic RCTs should routinely measure de-blinding and expectancy. Careful attention should be paid to clinical trial design and the instructions given to participants to allow these confounds to be reduced, estimated and removed from effect size estimates. We urge caution in interpreting effect size estimates from extant psychedelic RCTs.

Overall Reporting Descriptions of Acupuncture for Chronic Pain in Randomized Controlled Trials in English Journals

Background

Whether the clinical effect of acupuncture in chronic pain is effective has always been a hot topic of research, which has a great relationship with the overall reporting descriptions of acupuncture, especially the sham acupuncture intervention. To confirm the effectiveness of acupuncture, more clinical studies are often required. Therefore, it is necessary to report high-quality and complete descriptions of acupuncture in clinical trials. This study aims to assess the overall reporting quality of acupuncture for chronic pain in randomized controlled trials (RCTs).

Methods

Three databases from inception to March 2020 were searched, to assess the quality of acupuncture reports included the RCTs based on the pain-specific supplement to Consolidated Standards for Reporting Trials (CONSORT) and Standards for Reporting Interventions in Controlled Trials of Acupuncture (STRICTA) guidelines. The quality of sham acupuncture descriptions was evaluated based on the Template for Intervention Description and Replication (TIDieR)-placebo checklist. Descriptive statistics and analysis of the results were carried out according to the percentage of each item.

Results

A total of 74 RCTs were included which met the inclusion criteria. Based on the pain-specific CONSORT, the reporting rates of “Statistical methods”, “Participant flow”, and “Blinding” were “52.70%”, “70.27%”, and “77.03%”, respectively. The weakest reported items in STRICTA were related to the depth of insertion (Item 2c, 54.05%) and the setting and context of treatment (Item 4b, 0.00%). Based on the TIDieR-placebo checklist, the reporting rates of “Item 12”, “Item 11”, “Item 13”, “Item 3”, and “Item 4” were “8.11%”, “10.81%”, “29.73%”, “ 44.59% ”, and “47.30%”, respectively.

Conclusion

At present, the overall report quality of acupuncture treatment for chronic pain in English journals is acceptable, but the report rate in some aspects is still low. In the future, researchers should report RCTs of acupuncture following cleaner checklists and guidelines.

Measuring the success of blinding in placebo-controlled trials: Should we be so quick to dismiss it?

'Blinding' involves concealing knowledge of which trial participants received the interventions from participants themselves and other trial personnel throughout the trial. Blinding reduces bias arising from the beliefs and expectations of these groups. It is agreed that where possible, blinding should be attempted, for example by ensuring that experimental and control treatments look the same. However, there is a debate about if we should measure whether blinding has been successful, this manuscript will discuss this controversy, including the benefits and risks of measuring blinding within the randomised controlled trial.

Blinding in Clinical Trials: Seeing the Big Picture

Blinding mitigates several sources of bias which, if left unchecked, can quantitively affect study outcomes. Blinding remains under-utilized, particularly in non-pharmaceutical clinical trials, but is often highly feasible through simple measures. Although blinding is generally viewed as an effective method by which to eliminate bias, blinding does also pose some inherent limitations, and it behooves clinicians and researchers to be aware of such caveats. This article will review general principles for blinding in clinical trials, including examples of useful blinding techniques for both pharmaceutical and non-pharmaceutical trials, while also highlighting the limitations and potential consequences of blinding. Appropriate reporting on blinding in trial protocols and manuscripts, as well as future directions for blinding research, will also be discussed.

Developing Placebos for Clinical Research in Traditional Chinese Medicine: Assessing Organoleptic Properties of Three Dosage Forms (Oral Liquid, Capsule and Granule)

Background: The successful application of randomized, double-blind placebo-controlled studies requires maximum blinding. Organoleptic properties of the placebo should be similar to the drug, making it difficult to distinguish between the two. The uniqueness of traditional Chinese medicine (TCM) preparations makes it challenging to prepare placebo. Evaluation of the TCM placebo simulation effect can determine whether the preparation of placebo can be genuinely blind in clinical trials. There is still a lack of well-established methods to evaluate TCM placebos. Hence, this study aimed to explore the evaluation methodology of TCM placebo simulation. Methods: An independent evaluation method and three comparative evaluation methods were proposed, and three dosage forms (oral liquid, capsule, and granule) were tested. The independent evaluation, in which each person was given an experimental drug or a placebo, gave an overall assessment of organoleptic properties in a blind state. We comparatively evaluated the similarity in organoleptic properties between the experimental drug and placebo. According to different distribution methods, we divided comparative evaluation methods into three. In method 1, the evaluator was given the experimental drug and placebo and was told that there must be a placebo among them. In method 2, each evaluator was randomly assigned to the combination group or two investigational drugs group. In method 3, the evaluator was assigned to a set of three coded samples, numbered by random three-digit numbers, each different, two of which were identical, and the two samples were equally frequent. Results: In the independent evaluation, there was no difference between TCM placebo and experimental drugs in a blind state at the level of p = 0.05. Even though the comparative evaluation methods enabled identification of potential differences between the two samples, methods 2 and 3 were better than method 1 in eliminating psychological factors. Also, in method 3, the completely random method combined with the blind method eliminated the subjectivity and objectivity bias and improved the experiment's credibility compared with the previous two methods. Conclusion: Regardless of the methods that could evaluate the placebo's simulated effect in actual clinical trials, we suggest that independent evaluation and comparative evaluation (method 3) should be combined to reflect better whether the placebo is truly blind.

Blinding, sham, and treatment effects in randomized controlled trials for back pain in 2000-2019: A review and meta-analytic approach

BACKGROUND

Blinding aims to minimize biases from what participants and investigators know or believe. Randomized controlled trials, despite being the gold standard to evaluate treatment effect, do not generally assess the success of blinding. We investigated the extent of blinding in back pain trials and the associations between participant guesses and treatment effects.

METHODS

We did a review with PubMed/OvidMedline, 2000-2019. Eligibility criteria were back pain trials with data available on treatment effect and participants' guess of treatment. For blinding, blinding index was used as chance-corrected measure of excessive correct guess (0 for random guess). For treatment effects, within- or between-arm effect sizes were used. Analyses of investigators' guess/blinding or by treatment modality were performed exploratorily.

RESULTS

Forty trials (3899 participants) were included. Active and sham treatment groups had mean blinding index of 0.26 (95% confidence interval: 0.12, 0.41) and 0.01 (-0.11, 0.14), respectively, meaning 26% of participants in active treatment believed they received active treatment, whereas only 1% in sham believed they received sham treatment, beyond chance, that is, random guess. A greater belief of receiving active treatment was associated with a larger within-arm effect size in both arms, and ideal blinding (namely, "random guess," and "wishful thinking" that signifies both groups believing they received active treatment) showed smaller effect sizes, with correlation of effect size and summary blinding indexes of 0.35 (p = 0.028) for between-arm comparison. We observed uniformly large sham treatment effects for all modalities, and larger correlation for investigator's (un)blinding, 0.53 (p = 0.046).

CONCLUSION

Participants in active treatments in back pain trials guessed treatment identity more correctly, while those in sham treatments tended to display successful blinding. Excessive correct guesses (that could reflect weaker blinding and/or noticeable effects) by participants and investigators demonstrated larger effect sizes. Blinding and sham treatment effects on back pain need due consideration in individual trials and meta-analyses.

Pharmacological treatment trials of agitation in Alzheimer's disease: A systematic review of ClinicalTrials.gov registered trials

INTRODUCTION

There is increasing emphasis on the importance of optimizing and standardizing clinical trials of agitation in Alzheimer's disease (AD), but the risks of bias arising from published trials and the number and design of unpublished studies are poorly understood.

METHODS

Using the ClinicalTrials.gov database, we systematically reviewed all registered investigational clinical trials for agitation in AD to describe the landscape of agitation drug treatment trials and to assess their quality and generalizability.

RESULTS

We included 52 clinical studies registered over the past 25 years. Within published randomized controlled trials (RCTs), there was a high rate of participant dropout, poor reporting of randomization procedures, and inconsistent definitions of the sample included for analysis. There was also evidence of publication and funder bias.

DISCUSSION

We discuss factors that limit the internal and external validity of published RCTs and make additional recommendations for the conduct and reporting of future clinical trials of agitation in AD.

Virtual controls as an alternative to randomized controlled trials for assessing efficacy of interventions

Randomized controlled trials are ubiquitously spoken of as the "gold standard" for testing interventions and establishing causal relations. This article presents evidence for two premises. First: there are often major problems with randomized designs; it is by no means true that the only good design is a randomized design. Second: the method of virtual controls in some circumstances can and should replace randomized designs.Randomized trials can present problems with external validity or generalizability; they can be unethical; they typically involve much time, effort, and expense; their assignments to treatment conditions often can be maintained only for limited time periods; examination of their track record reveals problems with reproducibility on the one hand, and lack of overwhelming superiority to observational methods on the other hand.The method of virtual controls involves ongoing efforts to refine statistical models for prediction of outcomes from measurable variables, under conditions of no treatment or current standard of care. Research participants then join a single-arm study of a new intervention. Each participant's data, together with the formulas previously generated, predict that participant's outcome without the new intervention. These outcomes are the "virtual controls." The actual outcomes with intervention are compared with the virtual control outcomes to estimate effect sizes. Part of the research product is the prediction equations themselves, so that in clinical practice, individual treatment decisions may be aided by quantitative answers to the questions, "What is estimated to happen to this particular patient with and without this treatment?"The method of virtual controls is especially indicated when rapid results are of high priority, when withholding intervention is likely harmful, when adequate data exist for prediction of untreated or standard of care outcomes, when we want to let people choose the treatment they prefer, when tailoring treatment decisions to individuals is desirable, and when real-world clinical information can be harnessed for analysis.

Blinding and bias in a hypnotic clinical trial

OBJECTIVES

Information is lacking regarding how commonly unblinding of treatment assignment occurs in hypnotic randomized clinic trials (RCTs). We now report the "best guesses" of clinical trial participants, versus study coordinators, versus study physicians in the study Reducing Suicidal Ideation Through Insomnia Treatment (REST-IT).

METHODS

REST-IT, a, 8-week double-blind RCT, compared zolpidem extended-release (ER) versus placebo at bedtime in 103 adults with major depressive disorder with insomnia and suicidal ideation, and who received open label selective serotonin reuptake inhibitors. At the conclusion of study participation, 89 of the participants in this study, the study coordinators, and the study physicians each independently recorded their "best guess" of the treatment assigned.

RESULTS

Patients guessed correctly 58.4% of the time, coordinators 53.9% of the time, and physicians 49.4% of the time, and none were different from chance alone. Agreement between patient/coordinator, patient/doctor, and coordinator/doctor dyads were 75%-78% with no significant differences in agreement between the dyads.

CONCLUSIONS

"Best guesses" of all parties were not different from chance, suggesting that the blind was maintained and that assessment bias was minimized in this RCT of zolpidem ER versus placebo. Our results may not apply to other hypnotics or other RCT designs.

A virtual experimenter does not increase placebo hypoalgesia when delivering an interactive expectancy manipulation

Lack of standardization and unblinding threaten the research of mechanisms involved in expectancy effects on pain. We evaluated a computer-controlled virtual experimenter (VEx) to avoid these issues. Fifty-four subjects underwent a baseline-retest heat pain protocol. Between sessions, they received an expectancy manipulation (placebo or no-treatment) delivered by VEx or text-only control condition. The VEx provided standardized "social" interaction with the subjects. Pain ratings and psychological state/trait measures were recorded. We found an interaction of expectancy and delivery on pain improvement following the intervention. In the text conditions, placebo was followed by lower pain, whereas in the VEx conditions, placebo and no-treatment were followed by a comparable pain decrease. Secondary analyses indicated that this interaction was mirrored by decreases of negative mood and anxiety. Furthermore, changes in continuous pain were moderated by expectation of pain relief. However, retrospective pain ratings show an effect of expectancy but not of delivery. We conclude that we successfully applied an automated protocol for inducing expectancy effects on pain. The effect of the VEx regardless of treatment may be due to interactions of attention allocation and locus of control. This points to the diversity of expectancy mechanisms, and has implications for research and computer-based treatment applications.

Effectiveness of Kinaesthetic Exercise program on Position Sense, Pain, and Disability in Chronic Neck Pain Patients with Cervical Spondylosis – A Randomized Comparative Trial

Background Chronic neck pain (CNP) is a significant health problem with only a few evidence-based treatment options. There is growing evidence for the effectiveness of kinaesthetic rehabilitation in musculoskeletal disorders. This study aims to assess kinaesthetic exercise programs' efficacy on cervical position sense, pain, and disability in subjects with cervical spondylosis (CS).

Methods CNP subjects (>3 months) with a diagnosis of CS were randomly assigned to either a study group (n=125) who received kinesthetic exercises or to a comparative group (n=125) who received isometric neck exercises and deep cervical flexor (DCF) strengthening exercises. Both group subjects participated in the individualized training program for 24 sessions in 6 weeks. The outcome measures were cervical joint position errors (JPE’s) in flexion, extension, rotation left and right, pain intensity, and neck disability.

Results All outcomes were improved significantly from baseline to post 24 sessions of intervention. When compared between groups, there was a significant reduction in JPE’s in flexion (mean difference [MD]= 071, CI=0.22–1.20, p=0.001), extension (MD=1.26, CI=0.70–1.81, p< 0.001) and right rotation (MD=1.08, CI=0.58–1.58, p<0.001), pain intensity (MD=1.58, CI=1.09–2.08, p<0.001), and neck disability (MD=10.27, CI=7.42–13.12, p<0.001) after 24 sessions of intervention favoring the study group.

Conclusion Study group subjects who received kinesthetic rehabilitation showed more significant improvements in terms of improved proprioception, decreased pain intensity and disability following 24 sessions of interventions compared with the comparative group.

Sample size, study length, and inadequate controls were the most common self-acknowledged limitations in manual therapy trials: A methodological review

OBJECTIVES

The aim of this study was to quantify and analyze the presence and type of self-acknowledged limitations (SALs) in a sample of manual therapy (MT) randomized controlled trials.

STUDY DESIGN AND SETTING

We randomly selected 120 MT trials. We extracted data related to SALs from the original reports and classified them into 12 categories. After data extraction, specific limitations within each category were identified. A descriptive analysis was performed using frequencies and percentages for qualitative variables.

RESULTS

The number of SALs per trial article ranged from 0 to 8, and more than two-thirds of trials acknowledged at least two different limitations. Despite its small proportion, 9% of trials did not report SALs. The most common limitation declared, in almost half of our sample, related to sample size (47.5%) followed by limitations related to study length and follow-up (33.3%) and inadequate controls (32.5%).

CONCLUSION

Our results indicate that at least two different limitations are consistently acknowledged in MT trial reports, the most common being those related to sample size, study length, follow-up, and inadequate controls. Analysis of the reasons behind the SALs gives some insights about the main difficulties in conducting research in this field and may help develop strategies to improve future research.

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.

Efficacy and Safety of a 0.1% Tacrolimus Nasal Ointment as a Treatment for Epistaxis in Hereditary Hemorrhagic Telangiectasia: A Double-Blind, Randomized, Placebo-Controlled, Multicenter Trial

Hereditary hemorrhagic telangiectasia is a rare but ubiquitous genetic disease. Epistaxis is the most frequent and life-threatening manifestation and tacrolimus, an immunosuppressive agent, appears to be an interesting new treatment option because of its anti-angiogenic properties. Our objective was to evaluate, six weeks after the end of the treatment, the efficacy on the duration of nosebleeds of tacrolimus nasal ointment, administered for six weeks to patients with hereditary hemorrhagic telangiectasia complicated by nosebleeds, and we performed a prospective, multicenter, randomized, placebo-controlled, double-blinded, ratio 1:1 phase II study. Patients were recruited from three French Hereditary Hemorrhagic Telangiectasia (HHT) centers between May 2017 and August 2018, with a six-week follow-up, and we included people aged over 18 years, diagnosed with hereditary hemorrhagic telangiectasia and epistaxis (total duration > 30 min/6 weeks prior to inclusion). Tacrolimus ointment 0.1% was self-administered by the patients twice daily. About 0.1 g of product was to be administered in each nostril with a cotton swab. A total of 50 patients was randomized and treated. Mean epistaxis duration before and after treatment in the tacrolimus group were 324.64 and 249.14 min, respectively, and in the placebo group 224.69 and 188.14 min, respectively. Epistaxis duration improved in both groups, with no significant difference in our main objective comparing epistaxis before and after treatment (p = 0.77); however, there was a significant difference in evolution when comparing epistaxis before and during treatment (p = 0.04). Toxicity was low and no severe adverse events were reported. In conclusion, tacrolimus nasal ointment, administered for six weeks, did not improve epistaxis in HHT patients after the end of the treatment. However, the good tolerance, associated with a significant improvement in epistaxis duration during treatment, encouraged us to perform a phase 3 trial on a larger patient population with a main outcome of epistaxis duration during treatment and a longer treatment time.

Towards more credible shams for physical interventions: A Delphi survey

BACKGROUND/AIMS

In clinical trials of physical interventions, participant blinding is often poorly addressed and therapist blinding routinely omitted. This situation presents a substantial barrier to moving the field forward. Improving the success of blinding will be a vital step towards determining the true mechanisms of physical interventions. We used a Delphi approach to identify important elements of shams for physical interventions to maximise the likelihood of participant and therapist blinding in clinical trials.

METHODS

Two expert groups were recruited: (1) experts in research methodology and (2) experts in deceptive and/or hypnotic techniques including magic. Magicians were included because they were considered a potentially rich source of innovation for developing credible shams due to their unique skills in altering perceptions and beliefs. Three rounds of survey were conducted, commencing with an open-ended question. Responses were converted to single 'items', which participants rated in the following two rounds using a 9-point Likert scale, categorised as 'Not important' (0-3), 'Depends' (4-6) and 'Essential' (7-9). Consensus was pre-defined as ≥80% agreement within a 3-point category.

RESULTS

Thirty-eight experts agreed to participate (research methodology: n = 22; deceptive and/or hypnotic techniques: n = 16), and 30 experts responded to at least one round (research methodology: n = 19; deceptive and/or hypnotic techniques: n = 11). Of 79 items, five reached consensus in the 'Essential' category in both groups, which related to beliefs of participants (n = 3 items), interactions with researchers (n = 1 item) and standardisation of clinical assessments (n = 1 item). Thirteen additional items reached consensus in the 'Essential' category in one group. Experts in research methodology had one additional item reach consensus, related to authentic delivery of study information. The remaining 12 additional items that reached consensus in the deceptive and/or hypnotic techniques group related mainly to therapist attitude and behaviour and the clinical interaction.

CONCLUSION

Experts agreed that, for shams to be believable, consideration of cognitive influences is essential. Contrary to the focus of previous shams for physical interventions, replicating the tactile sensation of the active treatment was not considered an essential part of sham development. Therefore, when designing sham-controlled clinical trials, researchers should carefully consider the cognitive credibility of the entire intervention experience, and not just the indistinguishability of the sham intervention itself. The findings provide new guidance to researchers on important contributors to blinding in physical intervention trials.

Evidence and gap map of studies assessing the effectiveness of interventions for people with disabilities in low-and middle-income countries

Background

There are approximately 1 billion people in the world with some form of disability. This corresponds to approximately 15% of the world's population (World Report on Disability, 2011). The majority of people with disabilities (80%) live in low- and middle-income countries (LMICs), where disability has been shown to disproportionately affect the most disadvantaged sector of the population. Decision makers need to know what works, and what does not, to best invest limited resources aimed at improving the well-being of people with disabilities in LMICs. Systematic reviews and impact evaluations help answer this question. Improving the availability of existing evidence will help stakeholders to draw on current knowledge and to understand where new research investments can guide decision-making on appropriate use of resources. Evidence and gap maps (EGMs) contribute by showing what evidence there is, and supporting the prioritization of global evidence synthesis needs and primary data collection.

Objectives

The aim of this EGM is to identify, map and describe existing evidence of effectiveness studies and highlight gaps in evidence base for people with disabilities in LMICs. The map helps identify priority evidence gaps for systematic reviews and impact evaluations.

Methods

The EGM included impact evaluation and systematic reviews assessing the effect of interventions for people with disabilities and their families/carers. These interventions were categorized across the five components of community-based rehabilitation matrix; health, education, livelihood, social and empowerment. Included studies looked at outcomes such as, health, education, livelihoods, social inclusion and empowerment, and were published for LMICs from 2000 onwards until January 2018. The searches were conducted between February and March 2018. The EGM is presented as a matrix in which the rows are intervention categories (e.g., health) and subcategories (e.g., rehabilitation) and the column outcome domains (e.g., health) and subdomains (e.g., immunization). Each cell lists the studies for that intervention for those outcomes, with links to the available studies. Included studies were therefore mapped according to intervention and outcomes assessed and additional filters as region, population and study design were also coded. Critical appraisal of included systematic review was done using A Measurement Tool to Assess Systematic Reviews' rating scale. We also quality-rated the impact evaluation using a quality assessment tool based on various approaches to risk of bias assessment.

Results

The map includes 166 studies, of which 59 are systematic reviews and 107 impact evaluation. The included impact evaluation are predominantly quasiexperimental studies (47%). The numbers of studies published each year have increased steadily from the year 2000, with the largest number published in 2017.The studies are unevenly distributed across intervention areas. Health is the most heavily populated area of the map. A total of 118 studies of the 166 studies concern health interventions. Education is next most heavily populated with 40 studies in the education intervention/outcome sector. There are relatively few studies for livelihoods and social, and virtually none for empowerment. The most frequent outcome measures are health-related, including mental health and cognitive development (n = 93), rehabilitation (n = 32), mortality and morbidity (n = 23) and health check-up (n = 15). Very few studies measured access to assistive devices, nutrition and immunization. Over half (n = 49) the impact evaluation come from upper-middle income countries. There are also geographic gaps, most notably for low income countries (n = 9) and lower-middle income countries (n = 34). There is a fair amount of evidence from South Asia (n = 73) and Sub-Saharan Africa (n = 51). There is a significant gap with respect to study quality, especially with respect to impact evaluation. There appears to be a gap between the framing of the research, which is mostly within the medical model and not using the social model of disability.

Conclusion

Investing in interventions to improve well-being of people with disabilities will be critical to achieving the 2030 agenda for sustainable development goals. The EGM summarized here provides a starting point for researchers, decision makers and programme managers to access the available research evidence on the effectiveness of interventions for people with disabilities in LMICs in order to guide policy and programme activity, and encourage a more strategic, policy-oriented approach to setting the future research agenda.

Pacing in vasovagal syncope: Physiology, pacemaker sensors, and recent clinical trials-Precise patient selection and measurable benefit

The role of pacing in vasovagal syncope (VVS) is considered from a physiological basis. Most VVS patients lose consciousness due to hypotension before severe bradycardia/asystole occurs. Patients who benefit from dual-chamber pacing typically are older with highly symptomatic, late-onset, frequent and severe syncope with short/no prodrome and documented severe cardioinhibition. Tilt testing is of value in patients with recurrent unexplained syncope to identify important hypotensive susceptibility stemming from reduced venous return and stroke volume (SV). A negative tilt test in vasovagal patients with spontaneous asystole documented by an implantable/insertable loop recorder is associated with lower syncope recurrence rates after pacemaker implantation. Pacing may be more effective if triggered by sensor detection of a parameter changing earlier in the reflex than bradycardia when SV may still be relatively preserved. In this regard, detection of right ventricular impedance offers promise. Conservatism is recommended, limiting pacing in VVS to a small subset of symptomatic older patients with clearly documented cardioinhibition and paying particular attention to the timing of loss of consciousness in relation to asystole/bradycardia. Understanding VVS physiology permits application of well-timed, appropriate pacing that yields benefit for highly symptomatic patients.

Blinding Strategies in Dry Needling Trials: Systematic Review and Meta-Analysis

BACKGROUND

Blinding of participants and therapists in trials of physical interventions is a significant and ongoing challenge. There is no widely accepted sham protocol for dry needling.

PURPOSE

The purpose of this review was to summarize the effectiveness and limitations of blinding strategies and types of shams that have been used in dry needling trials.

DATA SOURCES

Twelve databases were searched from inception to February 2016.

STUDY SELECTION

Trials that compared active dry needling with a sham that simulated dry needling were included.

DATA EXTRACTION

The main domains of data extraction were participant/therapist details, intervention details, blinding strategies, blinding assessment outcomes, and key conclusions of authors. Reported blinding strategies and sham types were synthesized descriptively, with available blinding effectiveness data synthesized using a chance-corrected measurement of blinding (blinding index).

DATA SYNTHESIS

The search identified 4894 individual publications with 27 trials eligible for inclusion. In 22 trials, risk of methodological bias was high or unclear. Across trials, blinding strategies and sham types were heterogeneous. Notably, no trials attempted therapist blinding. Sham protocols have focused on participant blinding using strategies related to group standardization and simulation of tactile sensations. There has been little attention given to the other senses or cognitive strategies to enhance intervention credibility. Nonpenetrating sham types may provide effective participant blinding.

LIMITATIONS

Trials were clinically and methodologically diverse, which limited the comparability of blinding effectiveness across trials. Reported blinding evaluations had a high risk of chance findings with power clearly achieved in only 1 trial.

CONCLUSIONS

Evidence-based consensus on a sham protocol for dry needling is required. Recommendations provided in this review may be used to develop sham protocols so that future protocols are more consistent and potentially more effective.

Design characteristics, risk of bias, and reporting of randomised controlled trials supporting approvals of cancer drugs by European Medicines Agency, 2014-16: cross sectional analysis

OBJECTIVE

To examine the design characteristics, risk of bias, and reporting adequacy of pivotal randomised controlled trials of cancer drugs approved by the European Medicines Agency (EMA).

DESIGN

Cross sectional analysis.

SETTING

European regulatory documents, clinical trial registry records, protocols, journal publications, and supplementary appendices.

ELIGIBILITY CRITERIA

Pivotal randomised controlled trials of new cancer drugs approved by the EMA between 2014 and 2016.

MAIN OUTCOME MEASURES

Study design characteristics (randomisation, comparators, and endpoints); risk of bias using the revised Cochrane tool (bias arising from the randomisation process, deviations from intended interventions, missing outcome data, measurement of the outcome, and selection of the reported result); and reporting adequacy (completeness and consistency of information in trial protocols, publications, supplementary appendices, clinical trial registry records, and regulatory documents).

RESULTS

Between 2014 and 2016, the EMA approved 32 new cancer drugs on the basis of 54 pivotal studies. Of these, 41 (76%) were randomised controlled trials and 13 (24%) were either non-randomised studies or single arm studies. 39/41 randomised controlled trials had available publications and were included in our study. Only 10 randomised controlled trials (26%) measured overall survival as either a primary or coprimary endpoint, with the remaining trials evaluating surrogate measures such as progression free survival and response rates. Overall, 19 randomised controlled trials (49%) were judged to be at high risk of bias for their primary outcome. Concerns about missing outcome data (n=10) and measurement of the outcome (n=7) were the most common domains leading to high risk of bias judgments. Fewer randomised controlled trials that evaluated overall survival as the primary endpoint were at high risk of bias than those that evaluated surrogate efficacy endpoints (2/10 (20%) v 16/29 (55%), respectively). When information available in regulatory documents and the scientific literature was considered separately, overall risk of bias judgments differed for eight randomised controlled trials (21%), which reflects reporting inadequacies in both sources of information. Regulators identified additional deficits beyond the domains captured in risk of bias assessments for 10 drugs (31%). These deficits included magnitude of clinical benefit, inappropriate comparators, and non-preferred study endpoints, which were not disclosed as limitations in scientific publications.

CONCLUSIONS

Most pivotal studies forming the basis of EMA approval of new cancer drugs between 2014 and 2016 were randomised controlled trials. However, almost half of these were judged to be at high risk of bias based on their design, conduct, or analysis, some of which might be unavoidable because of the complexity of cancer trials. Regulatory documents and the scientific literature had gaps in their reporting. Journal publications did not acknowledge the key limitations of the available evidence identified in regulatory documents.