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

Individual patient data meta-analysis of placebo-controlled trials of selective serotonin reuptake inhibitors submitted for regulatory approval in adult obsessive-compulsive disorder

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) are the preferred pharmacological treatment for obsessive-compulsive disorder (OCD). However, insufficient response is common and it remains unclear whether specific patient-level factors influence the likelihood of treatment response.

AIMS

To determine the efficacy and acceptability of SSRIs in adult OCD, and to identify patient-level modifiers of efficacy.

METHODS

We conducted an individual patient data meta-analysis (IPDMA) of industry-sponsored short-term, randomised, placebo-controlled SSRI trials submitted for approval to the Dutch regulatory agency to obtain marketing approval for treating OCD in adults. We performed a two-stage meta-analysis, using crude data of available trials. The primary outcome was the difference in Yale-Brown Obsessive-Compulsive Scale (YBOCS) change between active treatment and placebo. Secondary outcomes were differences in response (defined as the odds ratio of ≥35% YBOCS point reduction) and acceptability (defined as the odds ratio for all-cause discontinuation). We examined the modifying effect of baseline characteristics: age, gender, illness severity, depressive symptoms, weight, illness duration and history of antidepressant use.

RESULTS

After excluding three trials because of missing data, we analysed results from 11 trials (79% of all submitted trials, n = 2372). The trial duration ranged from 10 to 13 weeks. Mean difference of SSRIs relative to placebo was 2.65 YBOCS points (95% CI 1.85-3.46, p < 0.0001), equalling a small effect size (0.33 Hedges' g). The odds ratio for response was 2.21 in favour of active treatment (95% CI 1.72-2.83, p < 0.0001), with a number needed to treat of seven. Patient characteristics did not modify symptom change or response. Acceptability was comparable for SSRIs and placebo.

CONCLUSIONS

Our IPDMA showed that SSRIs are well accepted and superior to placebo for treating OCD. The effects are modest and independent of baseline patient characteristics.

Expectancy Effects, Failure of Blinding Integrity, and Placebo Response in Trials of Treatments for Psychiatric Disorders: A Narrative Review

Importance

Expectancy effects are significant confounding factors in psychiatric randomized clinical trials (RCTs), potentially affecting the interpretation of study results. This narrative review is the first, to our knowledge, to explore the relationship between expectancy effects, compromised blinding integrity, and the effects of active treatment/placebo in psychiatric RCTs. Additionally, we present statistical and experimental approaches that may help mitigate the confounding impact of expectancy effects. The review concludes with recommendations to enhance the reliability of RCTs in psychiatry.

Observations

The placebo response comprises both specific and nonspecific elements, with expectation being a key specific component. Evidence from experimental and clinical studies suggests that expectancy can influence treatment responses in RCTs. Blinding integrity may be compromised by perceived treatment efficacy and adverse effects, introducing bias into outcome assessments. Treatment expectations can lead to unblinding during RCTs, and meta-analytic data from studies in the fields of psychedelics and anxiety disorders indicate that this can influence effect sizes. Therefore, controlling for expectancy effects is essential when interpreting RCT results. Novel statistical methods, though still in need of further validation, offer strategies to address this issue. Another approach may involve experimental medicine models, which aim to develop objective improvement markers (readouts) less affected by expectancy effects.

Conclusions and Relevance

Expectancy effects represent a significant confound in psychiatric RCTs. We recommend collecting data on treatment expectations alongside monitoring blinding integrity to more accurately interpret study results. Additionally, developing objective readouts that are less confounded by expectancy effects offers another promising avenue for mitigating these confounding influences in psychiatric RCTs.

From Efficacy to Effectiveness: Evaluating Psychedelic Randomized Controlled Trials for Trustworthy Evidence-Based Policy and Practice

The recent review of a new drug application for MDMA-assisted therapy for posttraumatic stress disorder by the United States' Food and Drug Administration (FDA) highlighted epistemological and methodological challenges for evidence assessments. Similar challenges will also be faced in reviews of other compounds in early- and late-stage development, like psilocybin for depression. The regulatory demand for two successful phase 3 randomized controlled trials (RCTs) seems problematic, given a current lack of agreement on what constitutes "success", particularly when psychoactive drug administration is concomitant with (psycho)therapy. These complex arrangements challenge the internal validity of estimated average treatment effect through comparison with conventional control conditions. This paper reviews the assumptions behind RCTs' current "gold-standard" status in the hierarchy of evidence-based medicine (EBM). Recapitulating known epistemic limits of randomization and blinding, it emphasizes the urgent need to avoid the extrapolation fallacy. The resulting argument is that the degree of trustworthiness that efficacy-reported in RCTs-will reliably predict effectiveness-in target populations outside RCTs-depends on what type of psychedelic treatments will be regulated. If "stand-alone" drugs for large-scale prescription and consumption, trustworthiness should be graded low. On the other hand, for regulation of drug-assisted (psycho) therapies, the degree of trustworthiness can be considered high. The reason being that these two treatment approaches are based on different causal claims with distinct external validities. Therefore, careful assessment of support factors in each is recommended to prevent detrimental consequences, from potential rejection of effective therapies up to medical reversal of eventually approved drugs.

Modifying Informed Consent to Help Address Functional Unmasking in Psychedelic Clinical Trials

Importance

There is unprecedented clinician, industry, and patient interest in the therapeutic development of psychedelic drugs. This is due to a combination of promising clinical trial results, positive media coverage, and the lack of novel pharmacologic treatments for psychiatric disorders in recent decades. However, the field faces a key methodological challenge: masking participants to treatment conditions in psychedelic clinical trials has been largely unsuccessful.

Objective

When participants can tell whether they received active drug or placebo, their responses to clinical assessments, questionnaires, and even their functional imaging and biological data can be influenced by preconceptions about treatment effects. Positive patient expectancies combined with ineffective masking may skew outcomes and inflate effect sizes. This complicates efforts to determine the safety and efficacy of psychedelic drugs. Here, we explore a method to help address this problem: modifying informed consent to obscure information about the study design.

Evidence Review

We reviewed all contemporary (2000-2024) clinical trials of psychedelic or methylenedioxymethamphetamine (MDMA) therapy and corresponded with the investigators to compile information on the use of modifications to informed consent in these studies.

Findings

Modifying informed consent to obscure details of the study design has been implemented in several psychedelic clinical trials and may offer a way to strengthen masking. However, this approach poses significant ethical risks. We examine examples of modifications used in the psychedelic literature, discuss the current regulatory landscape, and suggest strategies to mitigate risks associated with modified informed consent.

Conclusions and Relevance

Incorporating modified informed consent in future psychedelic clinical trials may improve interpretability and impact, but this has not been explicitly tested. Modifications to informed consent may not be appropriate in all cases, and risks to participants should be minimized by implementing appropriate guardrails.

Methods to address functional unblinding of raters in CNS trials

Treatment-emergent adverse events (TEAEs) associated with the unique properties of a pharmaceutical product may functionally unblind clinician ratings, obscure true medication effects, and affect confidence about clinical trial results. Central nervous system studies are particularly susceptible to functional unblinding because they rely on relatively subjective symptom assessments. Two different methods were used to examine possible functional unblinding in pooled data from three recent five-week, double-blind, placebo-controlled trials of xanomeline and trospium chloride (formerly known as KarXT) in participants with schizophrenia experiencing acute psychosis. Xanomeline/trospium is an M1/M4 muscarinic receptor agonist that may produce cholinergic side effects. First, we compared the scores of remote (site-independent) raters, blinded to TEAEs, who listened to audio recorded, site-based Positive and Negative Syndrome Scale (PANSS) interviews. Second, we conducted a post hoc analysis of participant subgroups with or without reported cholinergic-related TEAEs to ascertain whether cholinergic TEAEs influenced trial outcome. Remote ratings closely replicated 575 available "paired" site-based PANSS total scores at baseline and endpoint (intraclass correlation coefficient = 0.88 and 0.93, respectively). Both site-based and remote PANSS scores yielded significant improvement favouring xanomeline/trospium over placebo (both p < 0.0001) and yielded significantly greater treatment response (≥30% improvement from baseline) than placebo (both p < 0.0001). The significant improvement of PANSS scores favouring xanomeline/trospium over placebo was comparable in magnitude for all subgroups regardless of whether participants reported cholinergic-related TEAEs, or any TEAEs at all (all p < 0.001). In sum, the two different methods used to assess functional unblinding in these studies found no impact of cholinergic TEAEs, or any TEAEs, on the trial results. These methods may have utility across all clinical trials.

The association between study design and antidepressant effects in psychedelic-assisted therapy: A meta-analysis

Different study designs of psychedelic trials may impact the blinding and expectance, leading to biased treatment effects. This study aimed to examine the association between antidepressant efficacy and study designs in psychedelic trials. Six databases were systematically searched. Eligible trials were required to investigate the efficacy of psychedelics (psilocybin, lysergic acid diethylamide [LSD], 3,4-Methylenedioxymethamphetamine [MDMA], and ayahuasca) in adult patients with depressive symptoms. We only considered oral psychedelic-assisted therapy without concomitant use of antidepressants. The primary outcome was the change in depressive symptoms. There were five study designs of psychedelic trials, including non-active-drug-as-placebo, active-drug-as-placebo, waitlist-as-control, fixed-order, and pre-post designs. In non-active-drug -as-placebo design, psilocybin (k = 4, Hedges' g [g] = 0.87, 95 % confidence intervals[CIs] = 0.58 to 1.16) and MDMA (k = 2, g = 0.65, 95%CIs = 0.26 to 1.05) were associated with large and medium effect sizes, respectively. In active-drug-as-placebo design, both psilocybin (k = 2, g = 0.71, 95%CIs = -0.01 to 1.43) and MDMA (k = 3, g = 0.53, 95%CIs = -0.23 to 1.28) were not statistically significant. In pre-post single-arm (k = 3, g = 2.51, 95%CIs = 1.00 to 4.02) and waitlist-as-control (k = 1, g = 2.88, 95%CIs = 1.75 to 4.00) designs, psilocybin showed a large effect size of antidepressant effect. Ayahuasca also showed a large effect size in both pre-post (k = 2, g = 1.88, 95%CIs = 1.18 to 2.57) and non-active-drug-as-placebo (k = 1, g = 1.60, 95%CIs = 0.84 to 2.36) designs. LSD was associated with a significant antidepressant effect only in non-active-drug-as-placebo design (k = 1, g = 1.49, 95%CIs = 0.80 to 2.17) but not in active-drug-as-placebo design (k = 1, g = 0.44, 95%CIs = -0.90 to 1.78). The antidepressant effects of psychedelics may be overestimated in studies with pre-post single-arm, non-active-drugs-as placebo, and waitlist-control designs. Restricted sample size, difficulty with establishing blinding for participants, and over expectancy limit the estimation of the antidepressant effect of psychedelic-assisted therapy.

Home-based transcranial direct current stimulation treatment for major depressive disorder: a fully remote phase 2 randomized sham-controlled trial

Transcranial direct current stimulation (tDCS) has been proposed as a new treatment in major depressive disorder (MDD). This is a fully remote, multisite, double-blind, placebo-controlled, randomized superiority trial of 10-week home-based tDCS in MDD. Participants were 18 years or older, with MDD in current depressive episode of at least moderate severity as measured using the Hamilton Depression Rating Scale (mean = 19.07 ± 2.73). A total of 174 participants (120 women, 54 men) were randomized to active (n = 87, mean age = 37.09 ± 11.14 years) or sham (n = 87, mean age = 38.32 ± 10.92 years) treatment. tDCS consisted of five sessions per week for 3 weeks then three sessions per week for 7 weeks in a 10-week trial, followed by a 10-week open-label phase. Each session lasted 30 min; the anode was placed over the left dorsolateral prefrontal cortex and the cathode over the right dorsolateral prefrontal cortex (active tDCS 2 mA and sham tDCS 0 mA, with brief ramp up and down to mimic active stimulation). As the primary outcome, depressive symptoms showed significant improvement when measured using the Hamilton Depression Rating Scale: active 9.41 ± 6.25 point improvement (10-week mean = 9.58 ± 6.02) and sham 7.14 ± 6.10 point improvement (10-week mean = 11.66 ± 5.96) (95% confidence interval = 0.51-4.01, P = 0.012). There were no differences in discontinuation rates. In summary, a 10-week home-based tDCS treatment with remote supervision in MDD showed high efficacy, acceptability and safety. ClinicalTrials.gov registration: NCT05202119.

Psychedelics as an intervention for psychological, existential distress in terminally ill patients: A systematic review and network meta-analysis

BACKGROUND

The interest in psychedelics as a therapeutic intervention for existential distress of people with terminal illness grounds on their mechanism of action and effect on the spiritual/existential aspects accompanying end-of-life experiences.

AIMS

This systematic review and network meta-analysis aimed at examining the efficacy and safety of psychedelic compounds for existential distress in terminally ill people.

METHODS

PubMed, CINAHL, PsycINFO, EMBASE, and clinicaltrials.gov were searched for randomized controlled trials (RCTs) administering psychedelics for existential distress in people with terminal illnesses. Meta-analysis estimated the standardized mean difference (SMD) and odds ratio (OR), with corresponding 95% confidence intervals (95% CI), between treated and control groups in pairwise and network comparisons, using random-effects models. Post-treatment measures of depression and anxiety, as proxies of existential distress, and tolerability were the primary outcomes.

RESULTS

Nine studies, involving 606 participants (362 treated with psychedelics: psilocybin, ketamine, 3,4-methylenedioxymethamphetamine, and lysergic acid diethylamide (LSD)) were included. The meta-analysis supported the efficacy of psychedelics on depression (SMD: -0.80 (95% CI: -0.98, -0.63)) and anxiety (SMD: -0.84 (95% CI: -1.20, -0.48)). Network meta-analysis identified psilocybin as the most effective compound for depression, and LSD for anxiety. However, head-to-head comparison between psychedelics did not reach statistical significance. The rates of treatment discontinuation and adverse events between psychedelics and controls were comparable.

CONCLUSIONS

Psychedelics, especially psilocybins and LSD, showed promising effects on depression and anxiety in people with terminal illnesses. Limitations include the small number of RCTs, methodological issues related to blinding, and the lack of direct comparisons between psychedelic compounds. Larger studies and comparative research are needed to consolidate these findings.

SAS macro programme for Bang's Blinding Index to assess and visualise the success of blinding in randomised controlled trials

This paper aims to present a Statistical Analysis Software (SAS) macro %BBIplus, offering estimation and visualisation methods for the Bang's Blinding Index (BBI) for randomised controlled trials (RCTs) with various designs. We developed the SAS macro programme %BBIplus to facilitate the implementation of BBI. This user-friendly programme allows for easy and rapid estimation and visualisation of BBI across different scenarios, including pairwise comparison RCTs with two arms, double-dummy design RCTs with three arms and factorial design RCTs with four arms. The programme requires no pre-existing data set, and users only need to input the number of individuals of correct, uncertain or wrong guesses in each intervention or control group. We illustrate the functionality of %BBIplus using blinding assessment data from three previously published RCTs: BBR (adjunctive berberine reduces antipsychotic-associated weight gain and metabolic syndrome in patients with schizophrenia: a randomised controlled trial), SELECT-TDCS (the sertraline versus electrical current therapy for treating depression clinical study: results from a factorial, randomised controlled trial) and ELECT-TDCS (trial of electrical direct-current therapy versus escitalopram for depression) studies. The programme estimates the BBI for each arm, providing point estimates, 95% CI and associated p values. Additionally, %BBIplus can visualise the estimations through forest plots and make the judgement for the success of blinding easily and rapidly. This tool caters to the needs of clinical trial investigators, offering a comprehensive solution for estimating and visualising the blinding index under various RCT designs.

The blinding status and characteristics in acupuncture clinical trials: a systematic reviews and meta-analysis

BACKGROUND

Sham acupuncture is a widely accepted control in acupuncture clinical trials. Given the nature of acupuncture, it is warranted to assess the blinding of sham-controlled trials. Despite the sham acupuncture design having been widely used, the overall blinding of sham acupuncture and the characteristics of blinding assessment in acupuncture trials are unclear. This research aims to assess the blinding status of acupuncture clinical trials and explore the blinding assessment characteristics in acupuncture trials.

METHODS

This meta-analysis included all the acupuncture clinical trials published in English that performed blinding assessments and reported the results. We searched PubMed, Embase, and Web of Science for randomized controlled trials (RCTs) from inception to April 2024. The primary outcome is Bang's Blinding Index (Bang's BI) and 95% credibility interval (CrI) was pooled using a Bayesian hierarchical model. The study adheres to the PRISMA guidelines.

RESULTS

Sixty-four eligible studies published from 1999 to 2024 were included. The mean of Bang's BI was - 0.24 (95% CrI - 0.34 to - 0.14, tau2 = 0.13) for the sham acupuncture group and 0.41 (95% CrI 0.32 to 0.49, tau2 = 0.10) for the verum acupuncture group. The characteristics of blinding showed that 62.50% of the trials had a Bang's BI greater than 0 in the verum group and less than 0 in the sham group; in 28.15% of the trials, the Bang's BI was greater than 0 in the verum group and greater than 0 in the sham group. Subgroup analysis revealed that area, number of research centers, treatment sessions, acupoints number, and evaluation timepoint can influence blinding results.

CONCLUSION

Overall blinding status in current acupuncture clinical trials shows a majority correctly guessing for the verum group and opposite guessing for the sham group. However, in some acupuncture trials, the blinding of sham acupuncture might be compromised. Factors such as the Asian population, penetrating sham needling, and querying participants about their group assignment during the study increase the risk of unblinding and warrant careful consideration in sham acupuncture control design. Furthermore, researchers should closely monitor the blinding status of sham acupuncture and transparently report details of blinding assessments.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42023403595.

Learning how to make use of dissociative therapies

Dissociative therapies are being increasingly explored for their psychiatric applications, although questions remain about how they work and how best to use them. In exploring these questions, this review highlights six key areas of clinical relevance: (1) The possible contributions of functional unblinding when interpreting efficacy data; (2) The degree to which the therapeutic effects of dissociative therapies can be distinguished from the transient forms of relief seen with recreational drug use; (3) Understanding the construct of dissociation as it is tasked with describing the function of dissociative drugs; (4) The investigation of subjective drug effects as predictors of therapeutic outcome; (5) Similarities and differences in the effects of dissociative and classic psychedelics; and (6) The anticipated need for judicious prescribing/deprescribing resources as dissociative therapies proliferate.

A simple blinding index for randomized controlled trials

Blinding is an essential part of many randomized controlled trials. However, its quality is usually not checked, and when it is, common measures are the James index and/or the Bang index. In the present paper we discuss these two indices, providing examples demonstrating their considerable weaknesses and limitations, and propose an alternative method for measuring blinding. We argue that this new approach has a number of advantages. We also provide an R-package for computing our blinding index.

The relationship between blinding integrity and medication efficacy in randomised-controlled trials in patients with anxiety disorders: A systematic review and meta-analysis

BACKGROUND

Blinding is thought to minimise expectancy effects and biases in double-blind randomised-controlled trials (RCTs). However, whether blinding integrity should be assessed and reported remains debated. Furthermore, it is unknown whether blinding failure influences the outcome of RCTs in anxiety disorders. We carried out a systematic review to understand whether blinding integrity is assessed and reported in anxiolytic RCTs. A secondary aim was to explore whether blinding integrity is associated with treatment efficacy.

METHOD

Our protocol was pre-registered (PROSPERO CRD42022328750). We searched electronic databases for placebo-controlled, randomised trials of medication in adults with generalised and social anxiety disorders, and in panic disorder, from 1980. We extracted data regarding blinding integrity and treatment efficacy. Risk of bias was assessed with the Cochrane risk of bias tool. Where possible, we subsequently calculated Bang's Blinding Index, and assessed the association between blinding integrity and treatment effect size.

RESULTS

Of the 247 RCTs that met inclusion criteria, we were able to obtain assessments of blinding integrity from nine (3.64%). Overall, blinding failed in five of these trials (55.56%), but blinding was intact in 80% of placebo arms. We found a significant association between reduced blinding integrity among assessors and increased treatment effect size (betas < -1.30, p's < 0.001), but this analysis involved only four studies of which two were outlying studies. In patients, we saw a non-significant trend where reduced blinding integrity in the placebo groups was associated with increased treatment efficacy, which was not present in active medication arms. [Correction added on 19 August 2024, after first online publication: Results of the RCTs and its assessment of blinding integrity have been updated.] CONCLUSION: Consistent with work in other psychiatric disorders, blinding integrity is rarely reported in anxiolytic RCTs. Where it is reported, blinding appears to often fail. We found signals that suggest unblinding of clinician assessors (driven by two studies with complete unblinding), and of patients in placebo arms, might be associated with larger treatment effect sizes. We recommend that data regarding blinding integrity, along with the reasons patients and assessors offer for their beliefs regarding group allocation, are systematically collected in RCTs of anxiolytic treatment.

Systematic Review: Assessment of Blinding Integrity in 161 Randomized Controlled Trials of Medications for Attention-Deficit/Hyperactivity Disorder

We carried out the first systematic review assessing if assessment of blinding was conducted in randomized controlled trials (RCTs) investigating medications for ADHD. We analyzed 161 double-blind RCTs of ADHD medications. We found only 1 RCT in which participants' awareness of study arm allocation was assessed and reported. Our findings are not meant to invalidate the evidence on the benefits of ADHD medications, which is supported by a large body of evidence. However, our findings suggest an opportunity to improve reporting of clinical trials in ADHD.

Evidence versus expectancy: the development of psilocybin therapy

SUMMARY

Although the development of psilocybin therapy has come as a surprise to many, modern research with the drug has been ongoing for 25 years. Psilocybin therapy is composed of psilocybin dosing sessions embedded within a wider process of psychoeducation, psychological support and integration. Early phase clinical trial evidence is promising, particularly for treatment-resistant depression. However, masking probably fails and expectancy effects may be a part of the mechanism of change. Disambiguating between drug and expectancy effects is a necessary part of the development process, yet this is difficult if masking fails. Hitherto, masking and expectancy have not been routinely measured in psilocybin or other medication trials. Doing so represents an opportunity for research and may influence psychiatry more widely. In this opinion piece I summarise the clinical development process of psilocybin therapy thus far, discussing the hope, the hype, the challenges and the opportunities along the way.

Treatment guesses in the Treatment for Adolescents with Depression Study: Accuracy, unblinding and influence on outcomes

OBJECTIVE

We evaluated the presence and impact of unblinding during the influential Treatment for Adolescents with Depression Study (ClinicalTrials.gov Identifier: NCT00006286).

METHOD

Our analysis was part of a Restoring Invisible and Abandoned Trials reanalysis. Treatment for Adolescents with Depression Study trialled fluoxetine, placebo, cognitive behaviour therapy or their combination, in treating adolescents with major depressive disorder. We analysed the accuracy of guesses of fluoxetine or placebo allocation, and their effects on change in Children's Depression Rating Scale-Revised at 12 weeks.

RESULTS

Of 221 participants allocated to fluoxetine or placebo, 151 adolescents (68%) had their guess about pill-treatment-arm allocation recorded at week 6, and guesses were recorded for 154 independent evaluators, 159 parents and 164 pharmacotherapists. All of these groups guessed treatment allocation more accurately than would be expected by chance (60-66% accuracy; all p-values ⩽ 0.004). Guesses did not become more accurate between 6 and 12 weeks and were not predicted by adverse events, though event documentation was poor. Treatment guess had a substantial and statistically significant effect on outcome (Children's Depression Rating Scale-Revised change mean difference 9.12 [4.69; 13.55], β = 0.334, p < 0.001), but actual treatment arm did not (1.53 [-2.83; 5.89], β = 0.056, p = 0.489). Removing guess from the analysis increased the apparent effect of treatment arm, making it almost statistically significant at the conventional alpha-level of 0.05 (p = 0.06).

CONCLUSIONS

For Treatment for Adolescents with Depression Study, treatment guesses strongly predicted outcomes and may have led to the exaggeration of drug effectiveness in the absence of actual effects. The integrity of double-blinding in trials should be routinely assessed and reported.

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.

A Systematic Review of Study Design and Placebo Controls in Psychedelic Research

Introduction

Effective blinding is especially challenging in randomized controlled trials (RCTs) involving psychedelics due to the inherent alterations in consciousness that these compounds induce. In this systematic review and exploratory analysis, we aim at synthesizing the methodologies used in RCTs involving classic psychedelics and identify procedures that can help minimize unblinding and bias.

Methods

We completed a literature search that included prospective RCTs published between 1963 and January 2023, in which participants were randomized to receive either a classic psychedelic or placebo.

Results

A total of 1402 papers were included in the initial search. After eligibility criteria were applied, 50 papers from 48 clinical trials were included. Most studies were double blinded (n = 34), used a within-subjects design (n = 32 studies), and included inert placebos (n = 35). The majority of studies did not report on the integrity of blinding procedures (n = 34 studies); however, in studies that did, blinding was unsuccessful.

Conclusion

To improve blinding and lower expectancy effects, we suggest incorporating active placebos and utilizing dose response or active comparator study designs.

Are the results of open randomised controlled trials comparing antipsychotic drugs in schizophrenia biased? Exploratory meta- and subgroup analysis

A recent meta-epidemiological study did not reveal major differences between the results of blinded and open randomised-controlled trials (RCTs). Fewer patients may consent to double-blind RCTs than to open RCTs, compromising generalisability, making this question very important. However, the issue has not been addressed in schizophrenia. We used a database of randomised, acute-phase antipsychotic drug trials. Whenever at least one open and one blinded RCT was available for a comparison of two drugs, we contrasted the results by random-effects meta-analysis with subgroup tests. The primary outcome was overall symptoms as measured by the Positive and Negative Syndrome Scale, supplemented by seven secondary efficacy and side-effect outcomes. We also examined whether open RCTs were biased in favour of more recently introduced antipsychotics, less efficacious or more prone to side-effects antipsychotics, and pharmaceutical sponsors. 183 RCTs (155 blinded and 28 open) with 34715 participants comparing two active drugs were available. The results did not suggest general differences between open and blinded RCTs, which examined two active drugs. Only 12 out of 122 subgroup tests had a p-value below 0.1, four below 0.05, and if a Bonferroni correction for multiple tests had been applied, only one would have been significant. There were some exceptions which, however, did not always confirm the originally hypothesized direction of bias. Due to the relatively small number of open RCTs, our analysis is exploratory, but this fundamental question should be given more scientific attention. Currently, open RCTs should be excluded from meta-analyses, at least in sensitivity analyses.

Personality change in a trial of psilocybin therapy v. escitalopram treatment for depression

BACKGROUND

Psilocybin Therapy (PT) is being increasingly studied as a psychiatric intervention. Personality relates to mental health and can be used to probe the nature of PT's therapeutic action.

METHODS

In a phase 2, double-blind, randomized, active comparator controlled trial involving patients with moderate-to-severe major depressive disorder, we compared psilocybin with escitalopram, over a core 6-week trial period. Five-Factor model personality domains, Big Five Aspect Scale Openness aspects, Absorption, and Impulsivity were measured at Baseline, Week 6, and Month 6 follow-up.

RESULTS

PT was associated with decreases in neuroticism (B = -0.63), introversion (B = -0.38), disagreeableness (B = -0.47), impulsivity (B = -0.40), and increases in absorption (B = 0.32), conscientiousness (B = 0.30), and openness (B = 0.23) at week 6, with neuroticism (B = -0.47) and disagreeableness (B = -0.41) remaining decreased at month 6. Escitalopram Treatment (ET) was associated with decreases in neuroticism (B = -0.38), disagreeableness (B = -0.26), impulsivity (B = -0.35), and increases in openness (B = 0.28) at week 6, with neuroticism (B = -0.46) remaining decreased at month 6. No significant between-condition differences were observed.

CONCLUSIONS

Personality changes across both conditions were in a direction consistent with improved mental health. With the possible exception of trait absorption, there were no compelling between-condition differences warranting conclusions regarding a selective action of PT (v. ET) on personality; however, post-ET changes in personality were significantly moderated by pre-trial positive expectancy for escitalopram, whereas expectancy did not moderate response to PT.

Escitalopram versus other antidepressive agents for major depressive disorder: a systematic review and meta-analysis

BACKGROUND

Escitalopram is selective serotonin reuptake inhibitors (SSRIs) and one of the most commonly prescribed newer antidepressants (ADs) worldwide. We aimed to explore the efficacy, acceptability and tolerability of escitalopram in comparison with other ADs in the acute-phase treatment of major depressive disorder (MDD).

METHODS

Medline/PubMed, EMBASE, the Cochrane Library, CINAHL, and Clinical Trials.gov were searched from inception to July 10, 2023. Trial databases of drug-approving agencies were hand-searched for published, unpublished and ongoing controlled trials. All randomized controlled trials comparing escitalopram against any other antidepressant for patients with MDD. Responders and remitters to treatment were calculated on an intention-to-treat basis. For dichotomous data, risk ratios (RRs) were calculated with 95% confidence intervals (CI). Continuous data were analyzed using standardized mean differences (with 95% CI) using the random effects model.

RESULTS

A total of 30 studies were included in this meta‑analysis, among which sixteen trials compared escitalopram with another SSRI and 14 compared escitalopram with a newer AD. Escitalopram was shown to be significantly more effective than citalopram in achieving acute response (RR 0.67, 95% CI 0.50-0.87). Escitalopram was also more effective than citalopram in terms of remission (RR 0.53, 95% CI 0.30-0.93).

CONCLUSIONS

Escitalopram was superior to other ADs for the acute phase treatment of MDD in terms of efficacy, acceptability and tolerability. However, no significant difference was found between escitalopram and other ADs in early response or follow-up response to treatment of MDD.

Unblinding and demand characteristics in the treatment of depression

Blinding of treatment allocation in clinical trials in psychiatry is regarded as an ideal. The potential impact of unblinding chimes with a general concern for psychological research: so-called demand characteristics can undermine confidence in findings from experimental and clinical studies. Scepticism can result in nihilism. The reliance on subjective report of symptoms in clinical trials of drug efficacy in depression provides an important example. It is regularly implied that if subjective effects, including specific adverse reactions, unblind participants to an active treatment then evidence for its efficacy is suspect. In fact, the strong association between dose and subjective effects does not translate into a strong relationship with efficacy in randomised controlled trials (RCTs) of conventional antidepressant drugs; this observation falsifies the proposition that unblinding is the principal mechanism driving RCT outcomes in studies of depression. Instead, changes in brain function, that occur soon after treatment starts, do predict treatment outcomes and align with our understanding of neurotransmitter effects from neuroscience. Psychedelic experience for the treatment of depression must be unblinding, but the effect results directly from serotonergic receptor activation and changes in brain connectivity. Where such effects are part of a novel mechanism of action, a strong dose response relationship would be expected, irrespective of unblinding. We highlight the importance of exploring blinding as a mechanism, confirming dose-related outcomes, and dissociating unblinding effects from efficacy. Unblinding does not necessarily invalidate the subjective experience of sustained recovery from depression.

Current concerns on journal article with preprint: Anesthesia and Pain Medicine perspectives

Preprints are preliminary research reports that have not yet been peer-reviewed. They have been widely adopted to promote the timely dissemination of research across many scientific fields. In August 1991, Paul Ginsparg launched an electronic bulletin board intended to serve a few hundred colleagues working in a subfield of theoretical high-energy physics, thus launching arXiv, the first and largest preprint platform. Additional preprint servers have since been implemented in different academic fields, such as BioRxiv (2013, Biology; www.biorxiv.org) and medRxiv (2019, Health Science; www.medrxiv.org). While preprint availability has made valuable research resources accessible to the general public, thus bridging the gap between academic and non-academic audiences, it has also facilitated the spread of unsupported conclusions through various media channels. Issues surrounding the preprint policies of a journal must be addressed, ultimately, by editors and include the acceptance of preprint manuscripts, allowing the citation of preprints, maintaining a double-blind peer review process, changes to the preprint's content and authors' list, scoop priorities, commenting on preprints, and preventing the influence of social media. Editors must be able to deal with these issues adequately, to maintain the scientific integrity of their journal. In this review, the history, current status, and strengths and weaknesses of preprints as well as ongoing concerns regarding journal articles with preprints are discussed. An optimal approach to preprints is suggested for editorial board members, authors, and researchers.