Does inclusion of a placebo arm influence response to active antidepressant treatment in randomized controlled trials? Results from pooled and meta-analyses

Treatment expectations and clinical outcomes following repetitive transcranial magnetic stimulation for treatment-resistant depression

BACKGROUND

Patient expectations, including both positive (placebo) and negative (nocebo) effects, influence treatment outcomes, yet their impact on acute repetitive transcranial magnetic stimulation (rTMS) for treatment-resistant depression (TRD) is unclear.

METHODS

In this single-center retrospective chart review, 208 TRD patients completed the Stanford Expectation of Treatment Scale (SETS) before starting open-label rTMS treatment. Patients were offered two excitatory rTMS protocols (deep TMS or intermittent theta-burst stimulation), which stimulated the left dorsolateral prefrontal cortex. A minimum of 20 once daily treatments were provided, delivered over 4-6 weeks. Primary outcomes were 1) remission, measured by a post-treatment score of <8 on the Hamilton Depression Rating Scale (HAMD-17), and 2) premature discontinuation. The change in HAMD-17 scores over time was used as a secondary outcome. Physicians were blinded to SETS scores. Logistic and linear regression, adjusting for covariates, assessed SETS and HAMD-17 relationships.

RESULTS

Of 208 patients, 177 had baseline and covariate data available. The mean positivity bias score (positive expectancy minus negative expectancy subscale averages) was 0.48 ± 2.21, indicating the cohort was neutral regarding the expectations of their treatment on average. Higher positive expectancy scores were significantly associated with greater odds of remission (OR = 1.90, p = 0.003) and greater reduction in HAMD-17 scores (β = 1.30, p = 0.005) at the end of acute treatment, after adjusting for covariates. Negative expectancy was not associated with decreased odds of remission (p = 0.2) or treatment discontinuation (p = 0.8).

CONCLUSIONS

Higher pre-treatment positive expectations were associated with greater remission rates with open-label rTMS in a naturalistic cohort of patients with TRD.

Differential Outcomes of Placebo Treatment Across 9 Psychiatric Disorders: A Systematic Review and Meta-Analysis

Importance

Placebo is the only substance systematically evaluated across common psychiatric diagnoses, but comprehensive cross-diagnostic comparisons are lacking.

Objective

To compare changes in placebo groups in recent high-quality randomized clinical trials (RCTs) across a broad spectrum of psychiatric disorders in adult patients.

Data Sources

MEDLINE and the Cochrane Database of Systematic Reviews were systematically searched in March 2022 for the latest systematic reviews meeting predetermined high-quality criteria for 9 major psychiatric diagnoses.

Study Selection

Using these reviews, the top 10 highest-quality (ie, lowest risk of bias, according to the Cochrane Risk of Bias tool) and most recent placebo-controlled RCTs per diagnosis (totaling 90 RCTs) were selected, adhering to predetermined inclusion and exclusion criteria.

Data Extraction and Synthesis

Following the Cochrane Handbook, 2 authors independently carried out the study search, selection, and data extraction. Cross-diagnosis comparisons were based on standardized pre-post effect sizes (mean change divided by its SD) for each placebo group. This study is reported following the Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guideline.

Main Outcome and Measure

The primary outcome, pooled pre-post placebo effect sizes (dav) with 95% CIs per diagnosis, was determined using random-effects meta-analyses. A Q test assessed statistical significance of differences across diagnoses. Heterogeneity and small-study effects were evaluated as appropriate.

Results

A total of 90 RCTs with 9985 placebo-treated participants were included. Symptom severity improved with placebo in all diagnoses. Pooled pre-post placebo effect sizes differed across diagnoses (Q = 88.5; df = 8; P < .001), with major depressive disorder (dav = 1.40; 95% CI, 1.24-1.56) and generalized anxiety disorder (dav = 1.23; 95% CI, 1.06-1.41) exhibiting the largest dav. Panic disorder, attention-deficit/hyperactivity disorder, posttraumatic stress disorder, social phobia, and mania showed dav between 0.68 and 0.92, followed by OCD (dav = 0.65; 95% CI, 0.51-0.78) and schizophrenia (dav = 0.59; 95% CI, 0.41-0.76).

Conclusion and Relevance

This systematic review and meta-analysis found that symptom improvement with placebo treatment was substantial in all conditions but varied across the 9 included diagnoses. These findings may help in assessing the necessity and ethical justification of placebo controls, in evaluating treatment effects in uncontrolled studies, and in guiding patients in treatment decisions. These findings likely encompass the true placebo effect, natural disease course, and nonspecific effects.

When does the placebo effect have an impact on network meta-analysis results?

The placebo effect is the 'effect of the simulation of treatment that occurs due to a participant's belief or expectation that a treatment is effective'. Although the effect might be of little importance for some conditions, it can have a great role in others, mostly when the evaluated symptoms are subjective. Several characteristics that include informed consent, number of arms in a study, the occurrence of adverse events and quality of blinding may influence response to placebo and possibly bias the results of randomised controlled trials. Such a bias is inherited in systematic reviews of evidence and their quantitative components, pairwise meta-analysis (when two treatments are compared) and network meta-analysis (when more than two treatments are compared). In this paper, we aim to provide red flags as to when a placebo effect is likely to bias pairwise and network meta-analysis treatment effects. The classic paradigm has been that placebo-controlled randomised trials are focused on estimating the treatment effect. However, the magnitude of placebo effect itself may also in some instances be of interest and has also lately received attention. We use component network meta-analysis to estimate placebo effects. We apply these methods to a published network meta-analysis, examining the relative effectiveness of four psychotherapies and four control treatments for depression in 123 studies.

Baseline characteristics of a European patient population with difficult-to-treat depression (RESTORE-LIFE) treated with adjunctive vagus nerve stimulation

BACKGROUND

Major depressive disorder is a complex heterogeneous disorder. Treatment is especially challenging for patients with "difficult-to-treat depression" (DTD): a less stigmatizing and more clinically relevant framework defining depression that continues to cause significant burden despite usual treatment efforts.

METHODS

RESTORE-LIFE is a prospective, observational, multicenter, post-market study being conducted in Europe and is designed to reflect real-world clinical application of adjunctive Vagus Nerve Stimulation Therapy (VNS) for DTD. Baseline characteristics of RESTORE-LIFE patients were analyzed and compared to published treatment-resistant depression (TRD) trials.

RESULTS

This analysis includes the initial 98 RESTORE-LIFE patients who commenced treatment with VNS. Patients had a mean of 11.4 failed anti-depressant treatments, 1.1 suicide attempts, 87 % had prior electroconvulsive therapy, and 36 % had an endocrine/metabolic comorbidity. On average, disease severity was comparable to that in TRD trials (n = 15,463). However, RESTORE-LIFE patients appear to have been experiencing DTD for a longer duration and their DTD was characterized by a lack of positive mental health and meaningfulness of life, to a greater degree than by excess of negative mood. Despite high comorbidity rates in RESTORE-LIFE, VNS implantation was performed safely with no discontinuations due to surgical adverse events.

LIMITATIONS

RESTORE-LIFE enrolls any patient receiving adjunctive VNS for DTD. Prescription of VNS may be biased by differences in practices amongst sites and countries.

CONCLUSIONS

The present analysis offers insight into contemporary real-world use of VNS Therapy for DTD in Europe representing a comprehensive characterization of DTD and how this population may differ from those in the TRD literature.

Factors Related to Placebo Response in Randomized, Double-Blind Clinical Trials of Antidepressants in Children and Adolescents: A Meta-regression Analysis

BACKGROUND AND OBJECTIVE

Many randomized clinical trials (RCTs) for antidepressants in children and adolescents have failed to demonstrate efficacy due to a high placebo response. The aim of this study was to identify the potential factors affecting placebo response using meta-regression analysis of RCTs for antidepressants in children and adolescents using the Children's Depressive Rating Scale-Revised (CDRS-R) as the outcome.

METHODS

PubMed and ClinicalTrials.gov were searched for randomized, double-blind, placebo-controlled trials of antidepressants for the acute treatment of major depressive disorder in children and adolescents. The outcome used in the present study was the mean change of the CDRS-R total score from baseline to the last assessment for the primary efficacy in the placebo arm. Potential factors related to the placebo response, such as study design, operational, and patient factors, were explored using meta-regression.

RESULTS

The analyses included 23 trials. On multivariable meta-regression, setting up a placebo lead-in period was significantly associated with a smaller placebo response in the CDRS-R.

CONCLUSION

Setting up a placebo lead-in period should be considered in future clinical trials of antidepressants in adolescents and children.

The Lessebo Effect in Disease Modification Trials in Parkinson's Disease

BACKGROUND

The impact of expectation of benefit on outcomes is well established in Parkinson's disease (PD). A reduction of a treatment effect due to a perceived placebo allocation (lessebo effect) in randomized controlled trials (RCTs) was documented for symptomatic treatments.

OBJECTIVES

To evaluate the lessebo effect in disease modification RCTs (DMT) in PD.

METHODS

Subject-level meta-analyses of active treatment arms of DMT (n = 1149 subjects): FS-1, FS-TOO (probability of placebo allocation/P_(placebo)  = 0.33) and DATATOP, PRECEPT, QE2 (P_(placebo)  = 0.25). We tested the association between P_(placebo) and time to dopaminergic treatment initiation using a marginal Cox proportional hazards model.

RESULTS

The adjusted hazard ratio (P_(placebo)  = 0.25 vs. 0.33) for initiation of dopaminergic treatment was 1.15 (95% CI: 0.92-1.43).

CONCLUSIONS

We did not observe the lessebo effect in DMT. The necessary use of a placebo (and no active comparator) is a limitation. The prospective measurement of expectation of benefit could help to evaluate the many impacts of placebo use. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Influence of active versus placebo control on treatment responses in randomised controlled trials in rheumatoid arthritis

OBJECTIVES

To investigate whether treatment effects of pharmaceutical compounds compared with placebo controls are systematically different to the effects of the same compounds compared with active treatment controls in rheumatoid arthritis (RA) clinical trials.

METHODS

We systematically identified randomised controlled trials (RCTs) in RA, and matched active treatment arms with comparable regimens, populations, background therapy, and outcome reporting, by the nature of their control group (active comparator or placebo). Medline, EMBASE and CENTRAL were used to identify RCTs investigating disease modifying anti-rheumatic drug therapies until December 2021. Using mixed-model logistic regression we estimated OddsRatios (OR) for achieving an American College of Rheumatology (ACR) 20/50/70% response at weeks 12 and 24. Risk of bias was assessed using the Cochrane Tool.

RESULTS

We screened 8328 studies and included 40 for analysis after detailed review of 590 manuscripts; unique compounds had significantly higher responses in active comparator trials compared with their effects observed in placebo controlled trials, with ORs of 1.67 (95% CI 1.46 to 1.91; p<0.001) for ACR20, 1.50 (95% CI 1.29 to 1.75; p<0.001) for ACR50 and 1.65 (95% CI 1.30 to 2.10; p<0.001) for ACR70 (week 12); corresponding ORs for ACR 20, 50, and 70 (week 24) were 1.93 (95% CI 1.50 to 2.48; p<0.001), 1.75 (95% CI 1.32 to 2.33; p<0.001) and 1.68 (95% CI 1.21 to 2.34; p<0.001), respectively. Sensitivity analyses showed consistent results.

CONCLUSION

Placebo controlled trials lead to smaller effect sizes of active compounds in RCTs compared with the same compound in head-to-head trials. This difference may be explained by potential nocebo effects in placebo-controlled settings and needs to be considered when interpreting head-to-head and placebo-controlled trials, by patients, investigators, sponsors and regulatory agencies.

The lessebo effect in randomized controlled trials of rituximab in patients with rheumatoid arthritis: a meta-analysis

OBJECTIVE

The goal of this study was to assess the impact of negative expectations associated with receiving a placebo (the lessebo effect) on efficacy outcomes in randomized clinical trials (RCTs) of rituximab in patients with rheumatoid arthritis (RA).

METHODS

We performed a meta-analysis on the American College of Rheumatology 20%, 50%, and 70% (ACR20, 50, 70) response rates in the placebo and active (biosimilar)-controlled groups (reference-pbo and reference-bs) of rituximab showing an insufficient response to methotrexate or tumor necrosis factor. We evaluated the difference in ACR20, 50, 70 response rates between the two groups (reference-bs vs. reference-pbo).

RESULTS

Nine RCTs included a total of 2734 patients with RA. The pooled incidence of ACR20 response rate in the placebo- and active-controlled groups of the rituximab RCTs for RA was 53.1% (95% confidence interval [CI] 49.9-56.3%) and 75.0% (95% CI 71.2-78.4%), respectively. The difference in the ACR20 response rate between the placebo- and active-controlled groups was -20.9% (95% CI -26.9 to 61.9%, p < 0.001). The pooled incidence of ACR50 response rate in the placebo- and active-controlled groups of the rituximab RCTs for RA was 29.0% (95% CI 26.2-32.0%) and 47.4% (95% CI 43.2-51.6%), respectively. The ACR50 response rates were significantly higher in the active-controlled groups than in the placebo-controlled groups (-18.4%; 95% CI -18.4 to -13.4%, p < 0.001). The difference in the ACR70 response rate between the placebo- and active-controlled groups was -14.9% (95% CI -22.2 to -7.6%, p < 0.001). The ACR20, 50, 70 response rates were significantly higher in the active-controlled groups than in the placebo-controlled group.

CONCLUSION

This study shows that the use of a placebo can be associated with a clinically significant reduction in the magnitude of change of the ACR20, 50, 70 response rates in rituximab RCTs for RA. The lessebo effect has potential implications for the development of new treatments and appraisal of current treatment options for RA.

Machine Learning and Pharmacogenomics at the Time of Precision Psychiatry

Traditional medicine and biomedical sciences are reaching a turning point because of the constantly growing impact and volume of Big Data. Machine Learning (ML) techniques and related algorithms play a central role as diagnostic, prognostic, and decision-making tools in this field. Another promising area becoming part of everyday clinical practice is personalized therapy and pharmacogenomics. Applying ML to pharmacogenomics opens new frontiers to tailored therapeutical strategies to help clinicians choose drugs with the best response and fewer side effects, operating with genetic information and combining it with the clinical profile. This systematic review aims to draw up the state-of-the-art ML applied to pharmacogenomics in psychiatry. Our research yielded fourteen papers; most were published in the last three years. The sample comprises 9,180 patients diagnosed with mood disorders, psychoses, or autism spectrum disorders. Prediction of drug response and prediction of side effects are the most frequently considered domains with the supervised ML technique, which first requires training and then testing. The random forest is the most used algorithm; it comprises several decision trees, reduces the training set's overfitting, and makes precise predictions. ML proved effective and reliable, especially when genetic and biodemographic information were integrated into the algorithm. Even though ML and pharmacogenomics are not part of everyday clinical practice yet, they will gain a unique role in the next future in improving personalized treatments in psychiatry.

Placebo Effect in Randomized Trials of Major Depressive Disorder With Psychotic Features: A Systematic Review and Descriptive Meta-Analysis

BACKGROUND

In the 1980s, the response rate of major depressive disorder with psychotic features (MDD-Psy) to placebo pills was reported to be close to 0%. To our knowledge, this placebo response rate has not been systematically reassessed. We undertook a systematic review of randomized controlled trials (RCTs) that have used a placebo or sham control group for MDD-Psy.

METHODS

We searched MEDLINE and identified 9 relevant publications reporting on 10 studies comparing a placebo or sham interventions versus an active intervention. We extracted reported rates of response or of dropout for all causes associated with placebo versus active intervention(s) and aggregated response and dropout rates across trials.

RESULTS

Two sham-controlled electroconvulsive therapy (ECT) trials did not provide response rates. In the 3 pharmacotherapy studies published in the 1980s, 0 of 12 participants (0%) responded to placebo versus 13 of 38 (34.2%) responding to the active interventions. In contrast, 5 RCTs published in the 2000s, 114 of 339 participants (33.6%) randomized to placebo responded versus 149 of 373 participants (39.9%) randomized to active interventions; dropout rates were 71/236 (30.1%) for placebo versus 84/282 (29.8%) for the active interventions.

CONCLUSIONS

As expected, response rates to placebo pills in RCTs for MDD-Psy increased markedly from the 1980s to the 2000s. Methodological issues in the design and conduct of more recent RCTs may have contributed to the high placebo response. However, one needs to consider this placebo response rate when interpreting the result of recent trials of MDD-Psy, which typically have not included a "pure" placebo condition.

Rostral anterior cingulate network effective connectivity in depressed adolescents and associations with treatment response in a randomized controlled trial

The rostral anterior cingulate cortex (rACC) is consistently implicated in the neurobiology of depression. While the functional connectivity of the rACC has been previously associated with treatment response, there is a paucity of work investigating the specific directional interactions underpinning these associations. We compared the fMRI resting-state effective connectivity of 94 young people with major depressive disorder and 91 healthy controls. Following the fMRI scan, patients were randomized to receive cognitive behavioral therapy for 12 weeks, plus either fluoxetine or a placebo. Using spectral dynamic causal modelling, we examined the effective connectivity of the rACC with eight other regions implicated in depression: the left and right anterior insular cortex (AIC), amygdalae, and dorsolateral prefrontal cortex (dlPFC); and in the midline, the subgenual (sgACC) and dorsal anterior cingulate cortex (dACC). Parametric empirical Bayes was used to compare baseline differences between controls and patients and responders and non-responders to treatment. Depressed patients demonstrated greater inhibitory connectivity from the rACC to the dlPFC, AIC, dACC and left amygdala. Moreover, treatment responders illustrated greater inhibitory connectivity from the rACC to dACC, greater excitatory connectivity from the dACC to sgACC and reduced inhibitory connectivity from the sgACC to amygdalae at baseline. The inhibitory hyperconnectivity of the rACC in depressed patients aligns with hypotheses concerning the dominance of the default mode network over other intrinsic brain networks. Surprisingly, treatment responders did not demonstrate connectivity which was more similar to healthy controls, but rather distinct alterations that may have predicated their enhanced treatment response.

Efficacy and acceptability of next step treatment strategies in adults with treatment-resistant major depressive disorder: protocol for systematic review and network meta-analysis

INTRODUCTION

For major depression, a one-size-fits-all treatment does not exist. Patients enter a 'trial-and-change' algorithm in which effective therapies are subsequently applied. Unfortunately, an empirically based order of treatments has not yet been determined. There is a magnitude of different treatment strategies while clinical trials only compare a small number of these. Network meta-analyses (NMA) might offer a solution, but so far have been limited in scope and did not account for possible differences in population characteristics that arise with increasing levels of treatment-resistance, potentially violating the transitivity assumption. We; therefore, present a protocol for a systematic review and NMA aiming at summarising and ranking treatments for treatment-resistant depression (TRD) while covering a broad range of therapeutic options and accounting for possible differences in population characteristics at increasing levels of treatment-resistance.

METHODS AND ANALYSIS

Randomised controlled trials will be included that compared next-step pharmacological, neuromodulation or psychological treatments for treatment-resistant depression (TRD; ie, failure to respond to ≥1 adequate antidepressant drug trial(s) in the current episode) to each other or to a control condition. Primary outcomes will be the proportion of patients who responded to (efficacy) and dropped out of (acceptability) the allocated treatment. A random effects NMA will be conducted, synthesising the evidence for each outcome and determining the differential efficacy of treatments. Heterogeneity in treatment nodes will be reduced by considering alternative geometries of the network structure and by conducting a meta-regression examining different levels of TRD. Local and global methods will be applied to evaluate consistency. The Cochrane Risk of Bias 2 tool, Confidence in Network Meta-Analysis and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework will be used to assess risk of bias and certainty.

ETHICS AND DISSEMINATION

This review does not require ethical approval.

Postmarketing safety surveillance data reveals protective effects of botulinum toxin injections against incident anxiety

Randomized controlled trials (RCTs) have shown an antidepressant effect of glabellar botulinum toxin (BoNT) injections. In the FDA Adverse Event Reporting System (FAERS) database, BoNT injection is associated with reduced incidence rates of depression across various non-psychiatric indications, which confirms the previous findings independently of specific expectations to an antidepressant effect of BoNT. The rationale of using BoNT to treat depression is to interrupt proprioceptive body feedback that may reinforce negative emotions. Negative emotions also occur in other mental disorders, suggesting a transdiagnostic therapeutic potential of BoNT in psychiatry. Here we report an analysis of the FAERS database, in which we found that, compared to alternative treatments, BoNT injections were associated with lower incidence of anxiety symptoms and related disorders. Among seven indications/injection sites, we found this protective effect of BoNT in cosmetic use/facial muscles, migraine/facial and head muscles, spasms and spasticity/upper and lower limbs, torticollis and neck pain/neck muscles, and sialorrhea/parotid and submandibular glands (reporting odds ratios 0.79-0.27). These findings are encouraging for possible future RCTs on the use of BoNT as a treatment for anxiety and related disorders.

Who benefits most from expectancy effects? A combined neuroimaging and antidepressant trial in depressed older adults

Depressed patients' expectations of improvement drive placebo effects in antidepressant clinical trials, yet there is considerable heterogeneity in the magnitude of expectancy effects. The present study seeks to identify those individuals who benefit most from expectancy effects using baseline neuroimaging and cognitive measures. Older adult outpatients diagnosed with major depressive disorder (MDD) participated in a prospective, 8-week clinical trial in which expectancy was experimentally manipulated and its effects on depression outcome measured. Based on the literature, we selected a priori 12 cognitive and brain-based variables linked to depression and expectancy, together with demographic variables, and incorporated them into a combined moderator. The combined moderator was developed as a weighted combination of the individual moderators, and was used to identify individuals who benefited most from expectancy effects. The combined moderator was found to predict differential change in depression severity scores between the high- vs. low-expectancy groups with a medium-size effect (Spearman effect size: 0.28). While at the sample level no expectancy effect was found, the combined moderator divided older adults with MDD into those who did and those who did not improve as the result of expectancy manipulation, with those benefiting from the manipulation showing greater processing speed, executive function, and frontostriatal white matter tract integrity. The findings suggest that it is possible to identify a subgroup of older adult individuals with MDD for whom expectancy manipulation results in greater antidepressant treatment response, supporting a precision medicine approach. This subgroup is characterized by distinct cognitive dysfunction and neuroimaging impairments profiles.

Magnitude of the Placebo Response Across Treatment Modalities Used for Treatment-Resistant Depression in Adults: A Systematic Review and Meta-analysis

IMPORTANCE

The placebo effect in depression clinical trials is a substantial factor associated with failure to establish efficacy of novel and repurposed treatments. However, the magnitude of the placebo effect and whether it differs across treatment modalities in treatment-resistant depression (TRD) is unclear.

OBJECTIVE

To examine the magnitude of the placebo effect in patients with TRD across different treatment modalities and its possible moderators.

DATA SOURCES

Searches were conducted on MEDLINE, Web of Science, and PsychInfo from inception to June 21, 2021.

STUDY SELECTION

Randomized clinical trials (RCTs) were included if they recruited patients with TRD and randomized them to a placebo or sham arm and a pharmacotherapy, brain stimulation, or psychotherapy arm.

DATA EXTRACTION AND SYNTHESIS

Independent reviewers used standard forms for data extraction and quality assessment. Random-effects analyses and standard pairwise meta-analyses were performed.

MAIN OUTCOMES AND MEASURES

The primary outcome was the Hedges g value for the reported depression scales. Secondary outcomes included moderators assessed via meta-regression and response and remission rates. Heterogeneity was assessed with the I2 test, and publication bias was evaluated using the Egger test and a funnel plot. Cochrane Risk of Bias Tool was used to estimate risks.

RESULTS

Fifty RCTs were included involving various types of placebo or sham interventions with a total of 3228 participants (mean [SD] age, 45.8 [6.0] years; 1769 [54.8%] female). The pooled placebo effect size for all modalities was large (g = 1.05; 95% CI, 0.91-1.1); the placebo effect size in RCTs of specific treatment modalities did not significantly differ. Similarly, response and remission rates associated with placebo were comparable across modalities. Heterogeneity was large. Three variables were associated with a larger placebo effect size: open-label prospective treatment before double-blind placebo randomization (β = 0.35; 95% CI, 0.11 to 0.59; P = .004), later year of publication (β = 0.03; 95% CI, 0.003 to 0.05; P = .03), and industry-sponsored trials (β = 0.34; 95% CI, 0.09 to 0.58; P = .007). The number of failed interventions was associated with the probability a smaller placebo effect size (β = -0.12; 95% CI, -0.23 to -0.01, P = .03). The Egger test result was not significant for small studies' effects.

CONCLUSIONS AND RELEVANCE

This analysis may provide a benchmark for past and future clinical RCTs that recruit patients with TRD standardizing an expected placebo effect size.

Slowed Processing Speed Disrupts Patient Expectancy in Late Life Depression

OBJECTIVE

Slowed processing speed and executive dysfunction are associated with poor outcomes in Late Life Depression (LLD), though it is unclear why. We investigated whether these variables interfere with the development of positive treatment expectancies in an antidepressant trial.

METHODS

Depressed older subjects were randomized to Open (intended to increase patient expectancy) or Placebo-controlled (termed 'Hidden,' intended to decrease expectancy) administration of antidepressant medication for 8 weeks. Analysis of covariance analyzed the between-group difference on expectancy (Credibility and Expectancy Scale [CES]) and depression (Hamilton Rating Scale for Depression [HRSD], Clinical Global Impressions [CGI] Severity). Moderator analyses examined whether these Open versus Hidden differences varied based on higher versus lower processing speed and executive function.

RESULTS

Among the 108 participants, a significant between-group difference was observed on expectancy (effect size [ES, Cohen's d] = 0.51 on CES Item 2; ES = 0.64 on Item 4), indicating the manipulation was effective. Processing speed as measured by the Stroop Color-Word Test (number color-words named in congruent condition) was a significant moderator of the Open versus Hidden effect on expectancy. Depressive symptom improvement was greater on average for Open versus Hidden participants who received active drug (CGI-severity ES = 1.25, HRSD ES = 0.41), but no neurocognitive moderators of the between-group difference reached statistical significance.

CONCLUSIONS

Slowed processing speed impairs the development of expectancies in antidepressant trials for LLD, which may help explain lower antidepressant response among older adults. Future studies may address whether interventions to optimize treatment expectancies are capable of improving treatment outcomes.

The Impact of Failed Antidepressant Trials on Outcomes in Children and Adolescents with Anxiety and Depression: A Systematic Review and Meta-Analysis

Objective: To identify predictors of medication-placebo differences in double-blind placebo-controlled antidepressant trials in children and adolescents with anxiety and depression. Methods: Clinical trials in patients <18 years of age with major depressive disorder or generalized, separation or social anxiety disorders were obtained from PubMed, the Cochrane Database and clinicaltrials.gov searches from inception through 2019. Forty-nine trials (43 published and 6 unpublished) of anxiety (κ = 13) and depression (κ = 36) evaluated 19 antidepressants in 8642 child and adolescent patients; placebo and medication response rates, trial characteristics, disorder, medication class, and funding source were extracted. Antidepressant-placebo differences were examined using Bayesian hierarchical models and estimates of response were determined for trial design, disorder, and medication class variables. Using meta-regression, correlates of antidepressant-placebo difference and placebo response were examined. Results: Funding source differentiated medication-placebo differences regardless of disorder. Industry trials had larger placebo response rates (mean difference: 0.189 ± 0.066, credible interval [CrI]: 0.067 to 0.33, p = 0.0008) and smaller medication-placebo differences (-0.235 ± 0.078, CrI: -0.397 to -0.086, p = 0.005) compared with federally funded trials. However, medication response was similar for industry- and federally-funded studies (-0.046 ± 0.042, CrI: -0.130 to 0.038, p = 0.252). Conclusions: The impact of study sponsorship on trial outcome supports the assertion that industry-funded trials with high placebo response rates and small drug-placebo differences are "failed trials" and should not be described as "negative trials" or used to determine public health estimates of antidepressant efficacy in children and adolescents with anxiety and depression. Identifying the proper role and value of industry-funded trials is critical to establishing the evidence base for antidepressants in youth.

Protocol for a systematic review and meta-analysis of the placebo response in treatment-resistant depression: comparison of multiple treatment modalities

INTRODUCTION

The high placebo response in depression treatment trials is a major contributing factor for randomised control trial failure to establish efficacy of novel or repurposed treatments in treatment-resistant depression (TRD) and major depressive disorder in general. Though there have been a number of meta-analyses and primary research studies evaluating the placebo response in non-TRD, placebo response in TRD is poorly understood. It is important to understand the placebo response of TRD as treatments are only moderately effective and up to 1/3 of patients will experience TRD.

METHODS AND ANALYSIS

We will conduct a search of electronic databases (MEDLINE and PsychINFO) from inception to 24th January 2020 including randomised, placebo-controlled trials of pharmacological, somatic and psychological interventions for adults with TRD. TRD will be defined as a failure to respond to at least two interventions of adequate dose or duration. We will also search reference lists from review articles. We will perform several meta-analyses to quantify the placebo response for each treatment modality. Regression analysis will explore potential contributing demographic and clinical variables to the placebo response. We will use Cochrane risk of bias tool.

ETHICS AND DISSEMINATION

There is no research ethics board approval required. The dissemination plan is to publish results in a peer-reviewed academic journal.

PROSPERO REGISTRATION NUMBER

190 465.

Probiotics as a treatment for prenatal maternal anxiety and depression: a double-blind randomized pilot trial

Probiotic use may be an efficacious treatment option to effectively manage symptoms of prenatal maternal anxiety and depression. Our primary aim was to test feasibility and acceptability for a probiotic randomized controlled trial (RCT) in pregnant women with pre-existing symptoms. This double-blind pilot RCT included 40 pregnant women with low-risk pregnancies and elevated depressive symptoms and/or anxiety. Once daily, participants orally consumed a probiotic (Ecologic Barrier) or a placebo, from 26 to 30 weeks gestation until delivery. A priori key progression criteria for primary outcomes were determined to decide whether or not a full RCT was feasible and acceptable. Secondary outcomes included depressive symptoms, anxiety, stress, and maternal bonding to offspring. In 19 months, 1573 women were screened; following screening, 155 women (10%) were invited for participation, of whom 135 (87%) received study information, and 40 women (30%) were included. Four out of six a priori determined criteria for success on feasibility and acceptability were met. After 8 weeks of intervention, there was no significant difference between the probiotic and placebo groups for secondary outcomes. The pilot trial was feasible and acceptable, but hampered by recruitment method and study design. Secondary endpoints did not reveal differences between the groups for improving maternal mood.

The association between placebo arm inclusion and adverse event rates in antidepressant randomized controlled trials: An examination of the Nocebo Effect

BACKGROUND

Antidepressant efficacy is influenced by patient expectations and, in randomized controlled trials (RCTs), the probability of receiving a placebo. It is unclear whether tolerability demonstrates a similar pattern. This study aimed to determine whether study design influences adverse event (AE) rates in antidepressant trials for subjects receiving active treatment or placebo.

METHODS

RCTs comparing one antidepressant to another antidepressant, placebo, or both in major depressive disorder (MDD) (1996-2018) were retrieved from Medline and PsycINFO. Clinicaltrials.gov was searched for unpublished trials. Of 1,997 studies screened, 77 trials were included. Studies were classified as drug-drug, drug-drug-placebo, or drug-placebo based on design and overall number of subjects experiencing any AE was recorded. Subgroup meta-analysis of proportions and meta-regression techniques were used to compare AE rates across study designs in patients receiving active antidepressant treatment and placebo.

RESULTS

Among the actively treated, AE rates were lower in drug-drug trials (58.5%) compared to drug-drug-placebo (75.7%) and drug-placebo (76.4%) (the model reported coefficients for percent differences between AE rates of different study designs were B=17.0, p<0.001 and B=17.8, p<0.001, respectively). AE rates in patients receiving placebo were not different between study designs.

LIMITATIONS

The present study is limited by the diverse range of study populations, variability in reporting of AEs, and specific antidepressants employed in the included trials.

CONCLUSIONS

The inclusion of a placebo arm in the study design was unexpectedly associated with higher rates of AEs among patients receiving active medication in antidepressant trials. This observation has important implications for interpretation of trial tolerability findings.

Antidepressant prescriptions have not fully reflected evolving evidence from cumulative network meta-analyses and guideline recommendations

OBJECTIVES

This study compares three major elements of evidence-based medicine (EBM) practices, namely evidence synthesis, clinical practice guidelines (CPGs), and real-world prescriptions in the United States, regarding antidepressant treatments of major depression over the past 3 decades.

STUDY DESIGN AND SETTING

We conducted network meta-analyses (NMAs) of antidepressants every 5 years up to 2016 based on a comprehensive data set of double-blind randomized controlled trials. We identified CPGs and extracted their recommendations. We surveyed the prescriptions in the United States at 5-year intervals up to 2015.

RESULTS

Most drugs recommended by CPGs presented favorable performance in efficacy and acceptability in NMAs. However, CPG recommendations were often in terms of drug classes rather than individual drugs, whereas NMAs suggested distinctive difference between drugs within the same class. The update intervals of all CPGs were longer than 5 years. All the antidepressants prescribed frequently in the United States were recommended by CPGs. However, changes in prescriptions did not correspond to alterations in CPGs or to apparent changes in the effects indicated by NMAs. Many factors including marketing efforts, regulations, or patient values may have played a role.

CONCLUSION

Enhancements including accelerating CPG updates and monitoring the impact of marketing on prescriptions should be considered in future EBM implementation.

Visualizing the evolution of evidence: Cumulative network meta-analyses of new generation antidepressants in the last 40 years

It is often challenging to present the available evidence in a timely and comprehensible manner. We aimed to visualize the evolution of evidence about antidepressants for depression by conducting cumulative network meta-analyses (NMAs) and to examine whether it could have helped the selection of optimal drugs. We built a Shiny web application that performs and presents cumulative NMAs based on R netmeta. We used a comprehensive dataset of double-blind randomized controlled trials of 21 antidepressants in the acute treatment of major depression. The primary outcomes were efficacy (treatment response) and acceptability (all-cause discontinuation), and treatment effects were summarized via odds ratios. We evaluated the confidence in evidence using the CINeMA (Confidence in Network Meta-Analysis) framework for a series of consecutive NMAs. Users can change several conditions for the analysis, such as the period of synthesis, among the others. We present the league tables and two-dimensional plots that combine efficacy, acceptability and level of confidence in the evidence together, for NMAs conducted in 1990, 1995, 2000, 2005, 2010, and 2016. They reveal that through the past four decades, newly approved drugs often showed initially exaggerated results, which tended to diminish and stabilize after approximately a decade. Over the years, the drugs with relative superiority changed dramatically; but as the evidence network grew larger and better connected, the overall confidence improved. The Shiny app visualizes how evidence evolved over years, emphasizing the need for a careful interpretation of relative effects between drugs, especially for the potentially amplified performance of newly approved drugs. HIGHLIGHTS: Network meta-analysis is considered to be a proper way of demonstrating the available evidence, since it allows comparisons between multiple interventions, and has been proved to be statistically powerful. It is challenging to present the voluminous results of NMA in an efficient and comprehendible manner. Evidence evolution based on the relatively new method NMA has not been investigated yet. The results of NMA should not only include the effects but also the confidence in the evidence, which can help interpret the findings appropriately. Effective use of rapidly developing statistical analysis and presentation tools such as Shiny package in R, may facilitate and simplify the visualization of NMA output. We should stay conservative towards new drugs, as their performance was often shown to be exaggerated initially, and it took time to become stable.

Neurostimulation Methods in the Treatment of Depression: A Comparison of rTMS, tDCS, and Venlafaxine Using a Pooled Analysis of Two Studies

BACKGROUND

There are no head-to-head studies comparing the antidepressant effect of transcranial direct current stimulation (tDCS) with repetitive transcranial magnetic stimulation (rTMS). This pooled analysis compared indirectly the antidepressant efficacy and acceptability of rTMS, tDCS, and the antidepressant venlafaxine (VNF) extended-release.

METHODS

The analysis (n=117, both patients with treatment-resistant depression (TRD) and non-TRD were included) examined pooled data from two 4-week, single-centered, two-armed, double-blind, randomized studies (EUDRACT n. 2005-000826-22 and EUDRACT n. 2015-001639-19). The antidepressant efficacy of right-sided low-frequency rTMS (n=29) vs VNF (n=31) and left-sided anodal tDCS (n=29) vs VNF (n=28) was evaluated. The primary outcome was a change in the Montgomery-Åsberg Depression Rating Scale (MADRS) score from baseline to the treatment endpoint at week 4. The response was defined as a ≥50% reduction in the MADRS score and remission as the MADRS score ≤10 points, both were calculated for the primary treatment endpoint at week 4.

RESULTS

Mean change in total MADRS scores from baseline to week 4 was 7.0 (95% CI, 4.8-9.1) points in the rTMS group, 7.6 (95% CI, 5.5-9.8) in the tDCS group, and 8.9 (95% CI, 7.4-10.4) among patients in the VNF group, a non-significant difference (F(2111)=0.62, p=0.54). Similarly, neither the response rates nor remission rates for rTMS (response 31%; remission 17%), tDCS (24%, 17%), or VNF (41%; 27%) significantly differed among treatment groups (χ ²=2.59, p=0.28; χ ²=1.66, p=0.44). Twenty patients (17%) dropped out of the studies in a similar proportion across groups (rTMS 3/29, tDCS 6/29, VNF 11/59, χ ²=1.41, p=0.52).

CONCLUSION

Our current analysis found a comparable efficacy and acceptability in all three treatment modalities (rTMS, tDCS, and VNF) and clinical relevance for the acute treatment of major depressive disorder.

Design and conduct of confirmatory chronic pain clinical trials

The purpose of this article is to provide readers with a basis for understanding the emerging science of clinical trials and to provide a set of practical, evidence-based suggestions for designing and executing confirmatory clinical trials in a manner that minimizes measurement error. The most important step in creating a mindset of quality clinical research is to abandon the antiquated concept that clinical trials are a method for capturing data from clinical practice and shifting to a concept of the clinical trial as a measurement system, consisting of an interconnected set of processes, each of which must be in calibration for the trial to generate an accurate and reliable estimate of the efficacy (and safety) of a given treatment. The status quo of inaccurate, unreliable, and protracted clinical trials is unacceptable and unsustainable. This article gathers aspects of study design and conduct under a single broad umbrella of techniques available to improve the accuracy and reliability of confirmatory clinical trials across traditional domain boundaries.

Phased Haplotype Resolution of the SLC6A4 Promoter Using Long-Read Single Molecule Real-Time (SMRT) Sequencing

The SLC6A4 gene has been implicated in psychiatric disorder susceptibility and antidepressant response variability. The SLC6A4 promoter is defined by a variable number of homologous 20–24 bp repeats (5-HTTLPR), and long (L) and short (S) alleles are associated with higher and lower expression, respectively. However, this insertion/deletion variant is most informative when considered as a haplotype with the rs25531 and rs25532 variants. Therefore, we developed a long-read single molecule real-time (SMRT) sequencing method to interrogate the SLC6A4 promoter region. A total of 120 samples were subjected to SLC6A4 long-read SMRT sequencing, primarily selected based on available short-read sequencing data. Short-read genome sequencing from the 1000 Genomes (1KG) Project (~5X) and the Genetic Testing Reference Material Coordination Program (~45X), as well as high-depth short-read capture-based sequencing (~330X), could not identify the 5-HTTLPR short (S) allele, nor could short-read sequencing phase any identified variants. In contrast, long-read SMRT sequencing unambiguously identified the 5-HTTLPR short (S) allele (frequency of 0.467) and phased SLC6A4 promoter haplotypes. Additionally, discordant rs25531 genotypes were reviewed and determined to be short-read errors. Taken together, long-read SMRT sequencing is an innovative and robust method for phased resolution of the SLC6A4 promoter, which could enable more accurate pharmacogenetic testing for both research and clinical applications.

Network meta-analysis results against a fictional treatment of average performance: Treatment effects and ranking metric

BACKGROUND

Network meta-analysis (NMA) produces complex outputs as many comparisons between interventions are of interest. The estimated relative treatment effects are usually displayed in a forest plot or in a league table and several ranking metrics are calculated and presented.

METHODS

In this article, we estimate relative treatment effects of each competing treatment against a fictional treatment of average performance using the "deviation from the means" coding that has been used to parametrize categorical covariates in regression models. We then use this alternative parametrization of the NMA model to present a ranking metric (PreTA: Preferable Than Average) interpreted as the probability that a treatment is better than a fictional treatment of average performance.

RESULTS

We illustrate the alternative parametrization of the NMA model using two networks of interventions, a network of 18 antidepressants for acute depression and a network of four interventions for heavy menstrual bleeding. We also use these two networks to highlight differences among PreTA and existing ranking metrics. We further examine the agreement between PreTA and existing ranking metrics in 232 networks of interventions and conclude that their agreement depends on the precision with which relative effects are estimated.

CONCLUSIONS

A forest plot with NMA relative treatment effects using "deviation from means" coding could complement presentation of NMA results in large networks and in absence of an obvious reference treatment. PreTA is a viable alternative to existing probabilistic ranking metrics that naturally incorporates uncertainty.

Impact of Clinical Outcome Measures on Placebo Response Rates in Clinical Trials for Chronic Constipation: A Systematic Review and Meta-analysis

OBJECTIVES

Chronic constipation (CC) is a recurrent functional bowel disorder worldwide. The purpose of this study is to examine its pooled placebo response rate and compare placebo response level in randomized controlled trials (RCTs) with different endpoint assessments.

METHODS

PubMed, Cochrane Library, and Embase were electronically searched for therapeutic RCTs of CC with placebo control. Data extraction and assessment of risk of bias were performed independently by 2 reviewers. All the statistical calculation and analysis were performed using R 3.6.0. Our protocol has registered in PROSPERO with registration number: CRD42019121287.

RESULTS

There were 46 studies included with 5,992 constipated patients allocated to the placebo arm in total. The pooled placebo response rate was 28.75% (95% confidence interval: 23.83%-33.67%) with significant heterogeneity among trials ((Equation is included in full-text article.)= 93.6%). Treatment efficacy assessed using subjective improvement had a significantly higher placebo response rate than that assessed with improvement in complete (spontaneous) bowel movements or composite improvement (41.40% vs 18.31% or 20.35%, P < 0.001). According to the results of meta-regression, active treatment and endpoint assessment were most likely to lead to the huge heterogeneity among studies.

DISCUSSION

Patients with CC have significant response level to placebo. Based on findings in this study, we do not recommend subjective improvement as endpoint while designing therapeutic RCTs for chronic constipated patients.

Placebo prevents rumination: An experimental study

BACKGROUND

Rumination is a risk factor for the development and maintenance of depressive symptoms and represents an important target for the treatment of depression. In the present study, we aimed to examine whether rumination can be reduced when participants are led to believe that they would receive medication that would prevent them from ruminating.

METHODS

In healthy participants (N= 91), an initial dysphoric state was induced via mood-suggestive music and autobiographic recall. Subsequently, participants were randomly assigned to one of two groups: an experimental group that received a deceptive active placebo via intranasal application accompanied by expectancy-enhancing instructions vs. a no-treatment control group. Then, rumination was induced via a rumination-activating task. The primary outcome was current rumination; experienced sadness was considered a secondary outcome.

RESULTS

Consistent with the hypothesis, participants receiving the placebo reported a significantly lower increase in current rumination (d= 0.57) and a higher decrease in sadness (d= 0.69) after the experimental induction than the control group.

LIMITATIONS

The external validity of this study might be limited due to the highly educated student sample.

CONCLUSIONS

The results suggest that rumination processes as well as experienced sadness can be positively influenced by placebo treatment. To evaluate its clinical potential, placebo-induced expectancy effects in rumination research should be further examined, particularly with clinically depressed patients. Also, the results imply that clinicians might consider the effects of expectations on patients' rumination tendencies, for example by explicitly addressing patients' expectations about rumination, mood, and the treatment in general.

Treatment Response of Add-On Esketamine Nasal Spray in Resistant Major Depression in Relation to Add-On Second-Generation Antipsychotic Treatment

In this meta-analysis, we aimed to estimate and compare the efficacy of add-on treatment of antidepressants with esketamine nasal spray and second-generation antipsychotics in patients with nonpsychotic major depressive disorder and inadequate response to antidepressants. Searching for acute-phase, double-blind, placebo-controlled, randomized trials, we found 22 second-generation antipsychotic (n = 8363) and 3 intranasal esketamine (n = 641) studies. Mean change in the Montgomery Åsberg Depression Rating Scale total score served as outcome. We determined a higher mean difference (vs placebo) for the pooled esketamine nasal spray trials (mean difference = 4.09, 95% confidence interval: 2.01 to 6.17) than for the pooled second-generation antipsychotic augmentation trials (mean difference  = 2.05, 95% confidence interval: 1.51 to 2.59). Thus, the effect size for intranasal esketamine was nearly twice as high as those for the second-generation antipsychotics. This indicates high efficacy of add-on esketamine nasal spray in treatment-resistant major depressive disorder compared with other well-established, evidence-based pharmacological options such as augmentation with second-generation antipsychotics.

[The role of placebo and nocebo mechanisms in depressive diseases and their treatment]

BACKGROUND

There is substantial evidence that placebo and nocebo effects occur during treatment with antidepressants. A better understanding of the underlying mechanisms of these effects is necessary to optimize the outcome of treatment and to make clinical studies more sensitive.

METHODS

Placebo and nocebo mechanisms were analyzed based on empirical studies and the results are summarized in a narrative review.

RESULTS

Clinical studies and also experimental mechanism-oriented studies underline the effects of placebo and nocebo mechanisms in the treatment with antidepressants.

CONCLUSION

The success of treatment in the use of antidepressants can be increased and the probability of side effects can be reduced by the effective use of placebo mechanisms and reduction of nocebo effects. The results emphasize the influence of clinician-patient interactions, the role of the treatment context and previous experiences with other treatments of the patient. Simultaneously, the results of this research field stimulate a new understanding of mental disorders, in particular depression and also provide points of reference for optimization of psychotherapeutic treatment.

Nocebo and lessebo effects

The power of placebos is commonly associated with the placebo effect. In contrast, detrimental effects related to the use of a placebo are little studied and less well recognized. This chapter covers the nocebo and lessebo effects defined, respectively, as expectation of harm in the form of adverse events in a placebo arm and reduction of therapeutic benefit due to the uncertainty of being allocated to placebo. The lessebo effect is a more recent concept and has been described only in depression, schizophrenia and Parkinson's disease. The nocebo response was evaluated in many neurological diseases, including epilepsy, multiple sclerosis, Parkinson's disease, Alzheimer's disease, restless leg syndrome, among others. Meta-analyses of randomized controlled trials in these conditions reveal a significant variability of the magnitude of the nocebo response and that factors related to study design, study participants or neurological disease can be associated with a nocebo response, although with the opposing findings across conditions. The knowledge about neurobiological mechanisms of the nocebo effect is poor for neurological diseases, and most of the information has been generated in pain. Functional neuroimaging suggests the existence of a distinct network for the anticipation and the experience of a hyperalgesia nocebo response. Different types of neurotransmitters have been involved, including cholecystokinin, dopamine and opioids. Recognizing the potential impact of nocebo and lessebo effects, mitigating strategies are in development with application to clinical research and clinical practice, such as a contextualized informed consent process, alternative study designs and enhancement of patient-physician communication.

Position statement of the European Psychiatric Association (EPA) on the value of antidepressants in the treatment of unipolar depression

This position statement will address in an evidence-based approach some of the important issues and controversies of current drug treatment of depression such as the efficacy of antidepressants, their effect on suicidality and their place in a complex psychiatric treatment strategy including psychotherapy. The efficacy of antidepressants is clinically relevant. The highest effect size was demonstrated for severe depression. Based on responder rates and based on double-blind placebo-controlled studies, the number needed to treat (NNT) is 5–7 for acute treatment and four for maintenance treatment. Monotherapy with one drug is often not sufficient and has to be followed by other antidepressants or by comedication/augmentation therapy approaches. Generally, antidepressants reduce suicidality, but under special conditions like young age or personality disorder, they can also increase suicidality. However, under the conditions of good clinical practice, the risk–benefit relationship of treatment with antidepressants can be judged as favourable also in this respect. The capacity of psychiatrists to individualise and optimise treatment decisions in terms of ‘the right drug/treatment for the right patient’ is still restricted since currently there are no sufficient powerful clinical or biological predictors which could help to achieve this goal. There is hope that in future pharmacogenetics will contribute significantly to a personalised treatment. With regard to plasma concentration, therapeutic drug monitoring (TDM) is a useful tool to optimize plasma levels therapeutic outcome. The ideal that all steps of clinical decision-making can be based on the strict rules of evidence-based medicine is far away from reality. Clinical experience so far still has a great impact.

Antidepressant-placebo differences for specific adverse events in major depressive disorder: A systematic review

BACKGROUND

Adverse events (AEs) are known to occur while patients are treated with placebos, part of the so-called nocebo effect. Yet evidence is limited regarding the likelihood that specific AEs occurring with antidepressant treatment are or are not due to nocebo effects.

METHODS

This study identified 56 placebo-controlled, randomized controlled trials (RCTs) of antidepressant monotherapy for adults with major depressive disorder that reported AE rates in sufficient detail for comparison. Poisson regression analyses compared rates of AEs according to antidepressant class weighted by study population to determine which separated from placebo. A "nocebo index" was also calculated (with 0 defined as the lowest rate and 1 or higher indicating the same or greater rate of an AE in the placebo group).

RESULTS

Numerous AEs did not differ statistically between antidepressant classes and placebo including worsening psychiatric symptoms, all forms of pain, weight gain and respiratory symptoms. Nevertheless, a number of AEs were significantly more common in antidepressants than placebos across multiple antidepressant classes. These were predominantly neurological, sexual and anticholinergic effects. Several AEs that separated statistically between antidepressants and placebos nevertheless had moderate nocebo indices (≥0.5). For example, dizziness in SSRIs separated significantly from placebo (OR 1.50, 95%CI 1.13-1.99) but had a nocebo index of 0.67.

LIMITATIONS

This study relied on multiple RCTs with subtle design differences.

CONCLUSIONS

This study identified several AEs that are likely the physiological result of antidepressants and many that likely represent nocebo effects. These results should inform clinical decision making and discussions with patients.

Treatment of Symptomatic Convergence Insufficiency in Children Enrolled in the Convergence Insufficiency Treatment Trial-Attention & Reading Trial: A Randomized Clinical Trial

SIGNIFICANCE

These data confirm the effectiveness of office-based vergence/accommodative therapy for improving convergence in children with symptomatic convergence insufficiency. They also highlight the importance of using a primary outcome measure that is as objective as possible rather than relying solely on self-reported symptoms for studies of binocular vision in children.

PURPOSE

The purpose of this study was to report changes in clinical signs and symptoms of convergence insufficiency (secondary outcome measures) from a multicenter clinical trial (Convergence Insufficiency Treatment Trial–Attention & Reading Trial [CITT-ART]) evaluating the effectiveness of vergence/accommodative therapy for improving reading and attention in children with symptomatic convergence insufficiency.

METHODS

Three hundred eleven children aged 9 to 14 years with symptomatic convergence insufficiency were randomly assigned to 16 weeks of office-based vergence/accommodative therapy or to placebo therapy. Improvements in (1) near point of convergence (NPC), (2) positive fusional vergence (PFV), and (3) self-reported symptoms (Convergence Insufficiency Symptom Survey [CISS] score) were compared after 16 weeks of treatment.

RESULTS

Mean NPC improved 10.4 cm in the vergence/accommodative and 6.2 cm in the placebo therapy group (mean difference of −4.2 cm [95% confidence interval {CI}, −5.2 to −3.2 cm; P < .001]); mean PFV increased 23.2 and 8.8Δ in the vergence/accommodative and placebo therapy groups, respectively (mean difference of 14.4Δ [95% CI, 12.1 to 16.8Δ; P < .001]). The mean CISS score improved 11.8 and 10.4 points in the vergence/accommodative and placebo therapy groups, respectively (mean difference of 1.5 points [95% CI, −3.8 to +0.8 points; P = .21]).

CONCLUSIONS

Our results demonstrate that office-based vergence/accommodative therapy is effective for improving the NPC and PFV in children with symptomatic convergence insufficiency. However, given that both treatment groups had a similar reduction in self-reported symptoms, it may not be prudent to use the CISS alone as a measure of successful treatment.

A Randomized Trial to Evaluate OnabotulinumtoxinA for Prevention of Headaches in Adolescents With Chronic Migraine

OBJECTIVE

As a post-approval commitment, this dose-ranging study was undertaken to evaluate efficacy and safety of onabotulinumtoxinA in adolescents.

BACKGROUND

In adolescents, migraine is often undiagnosed or misdiagnosed and can present unique management challenges. OnabotulinumtoxinA was approved for prevention of chronic migraine (CM) in adults in 2010.

METHODS

This multicenter, double-blind, parallel-group, randomized trial assessed a single treatment of onabotulinumtoxinA (155 U or 74 U) vs placebo (intramuscular saline) administered via the recommended fixed-dose fixed site paradigm in adolescents with CM aged 12 to <18 years. The primary efficacy measure was change in frequency of headache days from baseline at week 12; other measures included change in frequency of headache days at weeks 4 and 8 and change in frequency of severe headache days. Safety and tolerability were assessed.

RESULTS

Of 125 randomized patients (onabotulinumtoxinA 155 U, n = 45; onabotulinumtoxinA 74 U, n = 43; placebo, n = 37), all were included in the primary efficacy analysis, and 115 (92.0%) completed the study. Lack of efficacy was the primary reason for discontinuing (n = 4; 3.2%); no patients discontinued because of adverse events. All treatments reduced frequency of headache days at week 12, with no significant differences between treatments. The mean (95% confidence interval) changes from baseline in the frequency of headache days during the 28-day period ending at week 12 (primary endpoint) were -6.3 (-8.5, -4.2), -6.4 (-8.8, -4.0), and -6.8 (-9.6, -4.1) days in the onabotulinumtoxinA 155 U, onabotulinumtoxinA 74 U, and placebo groups, respectively (P ≥ .474). All treatments reduced frequency of severe headache days and were well-tolerated; serious adverse events (n = 3) were considered unrelated to treatment and resolved without sequelae. The most commonly reported treatment-emergent adverse events were neck pain (n = 8), upper respiratory tract infection (n = 7), migraine, and nasopharyngitis (n = 5 each).

CONCLUSION

Although this study did not meet its efficacy endpoints, onabotulinumtoxinA was well tolerated in this adolescent population. Given previous data demonstrating the benefits of onabotulinumtoxinA in adults with CM, additional studies with design modifications, including adequate statistical power, to assess the efficacy of multiple treatment cycles of onabotulinumtoxinA for CM prevention in adolescents may be informative.

A Pilot Randomized Treatment-Controlled Trial Comparing Vitamin B6 with Broad-Spectrum Micronutrients for Premenstrual Syndrome

Objective: Premenstrual syndrome (PMS) affects 20%-30% of women but current medical treatments are limited in their efficacy. The objective of this study was to compare efficacy of a broad-spectrum micronutrient formula (consisting mainly of minerals and vitamins) to a single vitamin (B6) for treatment of PMS, for which B6 has already been shown to be efficacious. Methods: This double-blind, randomized, treatment-controlled trial allocated 78 (72 completed) regularly menstruating women with PMS to consume micronutrients or vitamin B6 (80 mg/day) daily following a two-cycle baseline period, for three menstrual cycles. The primary outcome measure, Daily Record of Severity of Problems (DRSP), established PMS as well as tracked change in five PMS symptoms: psychological, somatic, total symptoms, impact ratings, and worst day ratings. Results: Linear-mixed model analyses indicated both treatments produced comparable reduction in PMS symptoms with medium effect sizes (ES) across all PMS variables as measured by the DRSP (micronutrient ES = 0.50-0.56; B6 ES = 0.43-0.56), with 72% of the micronutrient and 60% of the vitamin B6 group identified as in full remission in PMS symptoms after three cycles. The micronutrient-treated participants showed greater improvement than the B6 group (between group d = 0.51, p < 0.05) in health-related quality of life. For those women (n = 28) who met criteria for premenstrual dysphoric disorder (PMDD), the DRSP ES were larger for those who had been in the micronutrient condition (ES = 1.28-1.67) as compared with those on B6 (ES = 0.50-0.75), although the group differences were not statistically reliable. There were no group differences in side effects, nor any serious adverse effects reported. Conclusions: Both treatments provided similar benefit for reducing PMS symptoms, with greater effect of micronutrients on quality of life as well as potential clinical benefit of micronutrients for PMDD. This study provides further efficacy data on B6 and also identifies the nutritionally broader spectrum intervention as possibly having specific advantages for those whose symptoms are more severe. As this is the first study to investigate these treatments for PMDD, systematic replication is required.

Raising Placebo Efficacy in Antidepressant Trials Across Decades Explained by Small-Study Effects: A Meta-Reanalysis

BACKGROUND

Recent meta-analyses reported placebo response rate in antidepressant trials to be stable since the 1970s. These meta-analyses however were limited in considering only linear time trends, assessed trial-level covariates based on single-model hypothesis testing only, and did not adjust for small-study effects (SSE), a well-known but not yet formally assessed bias in antidepressant trials.

METHODS

This secondary meta-analysis extends previous work by modeling nonlinear time trends, assessing the relative importance of trial-level covariates using a multimodel approach, and rigorously adjusting for SSE. Outcomes were placebo efficacy (continuous), based on the Hamilton Depression Scale, and placebo response rate.

RESULTS

Results suggested that any nonlinear time trends in both placebo efficacy (continuous) and response rate were best explained by SSE. Adjusting for SSE revealed a significant gradual increase in placebo efficacy (continuous) from 1979 to 2014. A similar observation was made for placebo response rate, but did not reach significance due higher susceptibility to SSE. By contrast, trial-level covariates alone were found to be insufficient in explaining time trends.

CONCLUSION

The present findings contribute to the ongoing debate on antidepressant placebo outcomes and highlight the need to adjust for bias introduced by SSE. The results are of clinical relevance because SSE may affect the evaluation of success or failure in antidepressant trials.

Neurobiology of placebo effect in Parkinson's disease: What we have learned and where we are going

The placebo effect is a phenomenon produced when an inert substance administered like a regular treatment improves the clinical outcome. Parkinson's disease (PD) is one of the main clinical disorders for which the placebo response rates are high. The first evidence of the neurobiological mechanisms underlying the placebo effect in PD stems from 2001, when de la Fuente-Fernandez and colleagues demonstrated that a placebo injection led to the release of dopamine in the striatal nuclei of PD measured with positron emission tomography technology. Since then, several studies have been conducted to investigate the neurobiological underpinnings of placebo responses. This article presents a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Of an initial yield of 143 papers, 19 were included. The lessons learned from these studies are threefold: (i) motor improvement is dependent on the activation of the entire nigrostriatal pathway induced by dopamine release in the dorsal striatum; (ii) the magnitude of placebo-induced effects is modulated by an expectancy of improvement, which is in turn related to the release of dopamine within the ventral striatum; (iii) the functioning of the neural pathways underlying the placebo response can be tuned by prior exposure and learning strategies. In conclusion, although the neural network underlying the placebo effect in PD has been largely confirmed and accepted, what remains to be established is how, when, and where the expectation of reward (mediated by the ventral striatum) interacts with the primary motor system (mediated by the dorsal striatum) to induce clinical improvement in motor symptoms. © 2018 International Parkinson and Movement Disorder Society.

Antidepressant discontinuation in treatment resistant depression

Treatment-resistant depression (TRD) is a growing problem in psychiatric practice with some 15–20% of depressed patients becoming chronically depressed and perhaps as many as 40% in tertiary settings. Several groups have championed the idea that TRD may be attributed to the long-term treatment with antidepressant drugs (AD). Subjects with the short form of the serotonin transporter gene (both heterozygotes and homozygotes) have an increased risk for depression in the setting of adversity compared to people with the long form. Moreover, these same individuals have a reduced likelihood of responding well to antidepressants, with reports of no response, delayed response, and increased side effects. This hypothesis needs to be examined in a randomized clinical trial. The study will examine the effect of discontinuation versus continuation of serotonergic antidepressants on disease progression in patients with treatment resistant depression. We will recruit 30 subjects and assess the depressive symptoms and disease progression. Genetic testing will be performed to optimize clinical outcome in both groups, but will also be used to evaluate if the short form of the serotonin transporter predicts disease progression and long-term antidepressant treatment response.

Placebo mechanisms in depression: An experimental investigation of the impact of expectations on sadness in female participants

INTRODUCTION

We aimed to examine whether drug-associated expectations have an impact on the experience of sadness. We hypothesized that participants who received an active placebo nasal spray (but were told that it was an antidepressant that would protect them from experiencing negative emotions) would become less sad than the control groups.

METHODS

128 healthy female participants were randomly allocated to one of four groups: the experimental group, which received an active placebo and the expectancy-modifying instructions ("Protection: the spray protects from experiencing negative emotions", n = 32), or one of three different control groups ("Sensitization": the spray sensitizes to negative emotions", n = 31; "Placebo: the spray is a placebo", n = 32; and "Control: no nasal spray", n = 32) RESULTS: In line with our hypotheses, the experimental group experienced significantly less sadness after having watched a sadness provoking film sequence compared to the three control groups, with medium- to large effect sizes (Hedge´s gs 0.59-0.87).

DISCUSSION

Our results suggest that sadness can be significantly influenced by placebos in the short-term. Our study further suggests that knowledge about the effect of placebos on depressive symptoms should be utilized in clinical practice. However, depression is a complex disorder and antidepressants address a wide range of symptoms associated with depression such as suicidal thoughts, disturbed sleep and loss of energy. Further research on the placebo effects associated with the antidepressant treatment is needed.

LIMITATIONS

concern generalizability to treatment because sadness is only one potential symptom of depression and antidepressants often also address other symptoms.

Neural mechanisms of expectancy-based placebo effects in antidepressant clinical trials

BACKGROUND

Patient expectancy of therapeutic improvement is a primary mediator of placebo effects in antidepressant clinical trials, but its mechanisms are poorly understood. This study employed a novel antidepressant trial design, with integrated functional magnetic resonance imaging (fMRI), to manipulate patient outcome expectancy and examine its neural mediators.

METHOD

Twenty-three depressed outpatients, in a randomized controlled trial were assigned to either Open (high outcome expectancy) or Placebo-controlled (low outcome expectancy) treatment with citalopram for eight weeks. fMRI scans were acquired before and after the expectancy manipulation (before medication treatment), while participants performed a masked emotional face task. Focusing on an amygdala region-of-interest (ROI), we tested a model where reduction in amygdala activation mediated outcome expectancy effects on the slope of change in depressive symptoms.

RESULTS

Following the manipulation, significant differences between conditions were found in neural activation changes in the amygdala, as well as in superior temporal gyrus, insula, and thalamus. Findings support the proposed mediation model according to which activation in the left amygdala ROI decreased significantly in the Open as opposed to the Placebo-controlled group following randomization (p = 0.009) for sad vs. neutral face contrast. The reduced left amygdala activation, in turn, was a significant predictor of decreased depressive symptoms during the trial (p = 0.007), and the mediation model was significant.

CONCLUSIONS

Results from this study, the first designed to identify the neural mechanisms of expectancy augmentation in an antidepressant randomized control trial, suggest that therapeutic modulation of amygdala activity may be an important pathway by which patient outcome expectancy influences depressive symptoms. CLINICALTRIALS.

GOV IDENTIFIER

NCT01919216; Trial name: Placebo Effects in the Treatment of Depression: Cognitive and Neural Mechanisms, URL: https://clinicaltrials.gov/ct2/show/NCT01919216.

Comparative Efficacy and Acceptability of Pharmacological, Psychotherapeutic, and Combination Treatments in Adults With Posttraumatic Stress Disorder: A Network Meta-analysis

IMPORTANCE

Posttraumatic stress disorder (PTSD) is a prevalent mental disorder, with a high risk of chronicity, comorbidity, and functional impairment; PTSD is complicated to treat, and the debate on the best treatment approach is ongoing.

OBJECTIVE

To examine comparative outcomes and acceptability of psychotherapeutic and pharmacological treatments and their combinations in adults with PTSD.

DATA SOURCES

Embase, MEDLINE, PsycINFO, Cochrane Controlled Trials Register, and PSYNDEX were searched for studies published from January 1, 1980, to February 28, 2018. Reference lists of included studies and of previously published guidelines and systematic reviews were also searched.

STUDY SELECTION

Of 11 417 records identified, 12 published randomized clinical trials (RCTs) comprising 922 participants, contributing 23 direct comparisons between psychotherapeutic and pharmacological treatments or their combinations were included.

DATA EXTRACTION AND SYNTHESIS

Standardized mean differences (SMDs) and odds ratios were aggregated using random-effects network and pairwise meta-analyses. Risk of bias and indirectness was rated for each study, and network confidence was rated using the Confidence in Network Meta-Analysis framework.

MAIN OUTCOMES AND MEASURES

The primary outcome was the comparative benefit between 2 treatment approaches to PTSD symptom improvement, and secondary outcome was the comparative acceptability of the treatment approaches, as indicated by patient dropout rates before treatment termination.

RESULTS

No treatment approach was found to be superior at the end of treatment (for all, 95% CI included 0). At the last follow-up, psychotherapeutic treatments showed greater benefit than pharmacological treatments in both network (SMD, -0.83; 95% CI, -1.59 to -0.07) and pairwise (SMD, -0.63; 95% CI, -1.18 to -0.09, 3 RCTs) meta-analyses. No difference was found between combined treatments and psychotherapeutic treatments at long-term follow-up, and combined treatments were associated with better outcomes than pharmacological treatments in the network meta-analysis (SMD, -0.96; 95% CI, -1.87 to -0.04), but not in the pairwise meta-analysis, which included 2 RCTs (SMD, -1.02; 95% CI, -2.77 to 0.72). No evidence was found for differential acceptability of the 3 treatment approaches.

CONCLUSIONS AND RELEVANCE

These results suggest superiority of psychotherapeutic treatments over pharmacological treatments; network, but not pairwise, meta-analyses suggest superiority of combined treatments over pharmacological treatments in improving PTSD symptom severity in the long term. The scarcity of reported long-term findings hampers definite conclusions and demonstrates the need for robust evidence from large-scaled comparative trials providing long-term follow-up data.

Impact of placebo arms on outcomes in antidepressant trials: systematic review and meta-regression analysis

Background

There is debate in the literature as to whether inclusion of a placebo arm may alter characteristics of antidepressant trials. However, previous research has focused on response rates of various antidepressants on average only, ignoring potential differences among drugs or other aspects of trial findings. Little is known about the impact of a placebo arm on all-cause dropout and dropout due to adverse events.

Methods

We carried out a systematic review of published and unpublished double-blind randomized controlled trials (RCTs) for the acute treatment of unipolar major depression (update: January 2016). The probability of being allocated to placebo (π) was the exposure of interest, and we examined its influence on responders (efficacy), all-cause dropouts (acceptability) and dropouts due to adverse events (tolerability), while accounting for differences in drugs, trials and patient characteristics in multivariate random effects meta-regression.

Results

We included 421 studies (68 305 participants) comparing 16 antidepressants or placebo; π ranged from 20% to 50%. Response rate was lower [risk ratio (RR) 0.87; 95% confidence interval (CI) 0.83, 0.92] and all-cause dropout rate higher (RR 1.19; 95% CI 1.08, 1.31) for the same antidepressants in placebo-controlled trials compared with head-to-head trials. The probability of responding decreased by 3% (95% CI 2-5%) for every 10% increase in π, whereas the risk of all-cause dropout increased by 4% (95% CI 1-7%). Tolerability was unaffected by π. Response rate was inversely correlated with dropouts due to any cause (correlation coefficient -0.48; 95% CI -0.58, -0.36) and due to adverse events (-0.34; 95% CI -0.44, -0.23).

Conclusions

For the same antidepressant, response rate was on average smaller and dropouts higher when placebo was included; however, no association was found with dropouts due to adverse events. Decreased patient expectations, larger dropout rates and use of inappropriate statistical methods to impute missing data may explain this phenomenon. The findings call for caution in the integration of randomized evidence involving placebo arms.

Placebo Effects in Psychotherapy: A Framework

The issue of placebo response and the extent of its effect on psychotherapy is complex for two specific reasons: i) Current standards for drug trials, e.g., true placebo interventions, double-blinding, cannot be applied to most psychotherapy techniques, and ii) some of the "nonspecific effects" in drug therapy have very specific effects in psychotherapy, such as the frequency and intensity of patient-therapist interaction. In addition, different psychotherapy approaches share many such specific effects (the "dodo bird verdict") and lack specificity with respect to therapy outcome. Here, we discuss the placebo effect in psychotherapy under four aspects: a) nonspecific factors shared with drug therapy (context factors); b) nonspecific factors shared among all psychotherapy traditions (common factors); c) specific placebo-controlled options with different psychotherapy modalities; and d) nonspecific control options for the specific placebo effect in psychotherapy. The resulting framework proposes that the exploration and enumeration of context factors, common factors, and specific factors contributes to the placebo effects in psychotherapy.

Placebo Effect in the Treatment of Depression and Anxiety

The aim of this review is to evaluate the placebo effect in the treatment of anxiety and depression. Antidepressants are supposed to work by fixing a chemical imbalance, specifically, a lack of serotonin or norepinephrine in the brain. However, analyses of the published and the unpublished clinical trial data are consistent in showing that most (if not all) of the benefits of antidepressants in the treatment of depression and anxiety are due to the placebo response, and the difference in improvement between drug and placebo is not clinically meaningful and may be due to breaking blind by both patients and clinicians. Although this conclusion has been the subject of intense controversy, the current article indicates that the data from all of the published meta-analyses report the same results. This is also true of recent meta-analysis of all of the antidepressant data submitted to the Food and Drug Administration (FDA) in the process of seeking drug approval. Also, contrary to previously published results, the new FDA analysis reveals that the placebo response has not increased over time. Other treatments (e.g., psychotherapy and physical exercise) produce the same benefits as antidepressants and do so without the side effects and health risks of the active drugs. Psychotherapy and placebo treatments also show a lower relapse rate than that reported for antidepressant medication.

Predictors of Placebo Response in Pharmacological Clinical Trials of Negative Symptoms in Schizophrenia: A Meta-regression Analysis

We conducted a meta-regression analysis of all double-blind, randomized, placebo-controlled clinical trials (DBRCTs) reporting effects of drug and placebo on negative symptoms in people with stable schizophrenia and predominant or prominent negative symptoms to assess predictors of placebo response in these individuals. We used Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines for systematic reviews and meta-analyses to conduct a systematic literature search to identify DBRCTs assessing treatment efficacy on negative symptoms, as primary outcome, in patients with stable schizophrenia and predominant or prominent negative symptoms. We used Cohen's d, with 95% CIs, as the effect size measure for placebo response, based on negative symptom change scores from baseline to endpoint (range 4 to 24 wk) in the placebo-treated group. We included 18 DBRCTs from 17 publications, assessing the effect of 13 drugs vs placebo on negative symptoms and comprising 998 patients, in the meta-regression analyses. Overall, drugs showed greater efficacy than placebo in reducing negative symptoms, with small effect size (Cohen's d: 0.208, P = .020). Placebo response was significant (P < .001) and clinically relevant (Cohen's d: 2.909), but there was significant heterogeneity and high risk of publication bias. Multivariable meta-regression analyses showed that larger numbers of arms in the trial, larger numbers of study sites and industry sponsorship were significant moderators of placebo response in this population. Our results suggest that some clinical trial design and operational factors affect the level of placebo response in such studies, thus highlighting the need for designs better suited to assess these outcomes.

Evidence synthesis, practice guidelines and real-world prescriptions of new generation antidepressants in the treatment of depression: a protocol for cumulative network meta-analyses and meta-epidemiological study

INTRODUCTION

Depressive disorders are the most common, burdensome and costly mental disorders. Their treatments have developed through the past decades and we now have more than a dozen new generation antidepressants, while a series of guidelines have been published to provide recommendations over the years. However, there still may exist important gaps in this evidence synthesis and implementation process. Systematic reviews may not have been conducted in the most unbiased, informative and timely manners; guidelines may not have reflected the most up-to-date evidence; clinicians may not have changed their clinical decision-makings in accordance with the relevant evidence. The aim of this study is to examine the gaps between the ideally synthesised evidence, guideline recommendations and real-world clinical practices in the prescription of new generation antidepressants for major depression through the past three decades.

METHODS AND ANALYSIS

We will conduct cumulative network meta-analyses (cNMAs) based on the comprehensive systematic review which has identified published and unpublished head-to-head randomised controlled trials comparing the following antidepressants in the acute phase treatment of major depression: agomelatine, amitriptyline, bupropion, citalopram, clomipramine, desvenlafaxine, duloxetine, escitalopram, fluoxetine, fluvoxamine, levomilnacipran, milnacipran, mirtazapine, nefazodone, paroxetine, reboxetine, sertraline, trazodone, venlafaxine, vilazodone and vortioxetine. The primary outcomes will be the proportions of patients who responded (efficacy) and who withdrew from treatment for any reasons (acceptability). We will conduct a random effects cNMA to synthesise evidence and obtain a comprehensive ranking of all new generation antidepressants based on their surface under the cumulative ranking curves. We will identify series of international clinical practice guidelines for the treatment of major depression of adults and summarise their recommendations. We will estimate real-world prescription patterns of antidepressants in the nationally representative samples in USA in the Medical Expenditure Panel Survey. We will compare and evaluate the gaps between the rankings according to cNMAs conducted at 5-year intervals between 1990 and 2015, recommendations in guidelines published in the ensuing 5 years and actual practices thereafter.

ETHICS AND DISSEMINATION

This review does not require ethical approval. We will disseminate our findings through publications in peer-reviewed journals and presentations at conferences.

TRIAL REGISTRATION NUMBER

UMIN000031898.

What does the latest meta-analysis really tell us about antidepressants?

A recent meta-analysis of antidepressant trials is the largest conducted to date. Although it claims to prove antidepressant effectiveness beyond dispute, the main outcome is response rates, which are derived from continuous data in a process that can inflate differences between groups. The standardised mean difference of 0.3 is in line with other meta-analyses that show small differences between antidepressants and placebo that are unlikely to be clinically significant. Other factors likely to exaggerate the effects are discussed, and evidence on associations between antidepressant effects and severity and outcomes of long-term treatment is considered. Clinicians need to have open discussions with patients about the limitations of antidepressant research, the lack of evidence that antidepressants correct a chemical imbalance or other brain abnormality, and the range of adverse effects and mental and physical alterations they can produce.