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

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.

The conundrum of depression clinical trials: one size does not fit all

In this paper we review the history of antidepressant (AD) development, since the discovery of imipramine in 1957 to the present day. Through this exploration we will show that the increasing placebo response is likely a red herring and that a higher magnitude of placebo response is not an adequate explanation for AD trials' high failure rates. As a better explanation for their lack of success, we will examine some of the fundamental flaws of AD clinical trials and their origins in historical forces. We focus on underpowering, which occurs as a consequence of unrealistic expectations for AD performance. In addition, we describe the lack of precision in the depression outcome measurements for the past 40 years and show how these measures contrast with those used in clinical trials of other chronic diseases, which use simpler outcome measures. Finally, we describe the role of regulatory agencies in influencing clinical trial design and how the assumption that 'one size fits all' for the past 60 years has led to flawed design of AD clinical trials.

Harnessing the power of placebos in movement disorders: Insights from Parkinson's disease in clinical research and practice

The placebo effect alongside the detrimental nocebo and lessebo effects associated with the use of placebos are well-recognized phenomena. Research conducted in the last two decades has demonstrated that the placebo effect is a measurable health benefit with well-known neurobiological correlates. In this review, we describe the current knowledge about how to best make use of the placebo effect to improve clinical research and optimize clinical care. We will cover four key topics: (1) setting the stage: historical perspectives on the use of placebos; (2) optimizing the use of placebos in clinical trials; (3) use of placebos in clinical practice; and (4) how can we minimize the ethical risks of using placebos? The adoption of the placebo-controlled trial as a standard in the therapeutic development reduced the placebo effect to background noise in a therapeutic signal. Strategies to minimize the placebo effect in clinical trials have been used to obtain positive efficacy results. In more recent years, new study paradigms encouraged a change in the views on placebos and the placebo effect. Alternative study designs and the development of biomarkers for a placebo response permit a better understanding of the contribution of the placebo effect to the results of interventional studies, without minimizing it. In clinical practice, optimizing the placebo effect (and reducing nocebo effects) has the potential to improve care for our patients, but raises ethical challenges. An enhanced patient-physician relationship would be central to any evidence-based intervention used in clinical care to heighten the placebo effect. © 2018 International Parkinson and Movement Disorder Society.

Use of Placebo in Clinical Trials of Psychotropic Medication

This position paper has been substantially revised by the Canadian Psychiatric Association's Research Committee and approved for republication by the CPA's Board of Directors on March 31, 2017. The original position paper¹ was developed by the Scientific and Research Council and approved by the Board of Directors on October 4, 1996.

Side effects can enhance treatment response through expectancy effects: an experimental analgesic randomized controlled trial

In randomized controlled trials, medication side effects may lead to beliefs that one is receiving the active intervention and enhance active treatment responses, thereby increasing drug-placebo differences. We tested these hypotheses with an experimental double-blind randomized controlled trial of a nonsteroidal anti-inflammatory drug with and without the addition of atropine to induce side effects. One hundred healthy volunteers were told they would be randomized to either combined analgesics that might produce dry mouth or inert placebos. In reality, they were randomized double blind, double-dummy to 1 of the 4 conditions: (1) 100 mg diclofenac + 1.2 mg atropine, (2) placebo + 1.2 mg atropine, (3) 100 mg diclofenac + placebo, or (4) placebo + placebo, and tested with heat-induced pain. Groups did not differ significantly in demographics, temperature producing moderate pain, state anxiety, or depression. Analgesia was observed in all groups; there was a significant interaction between diclofenac and atropine, without main effects. Diclofenac alone was not better than double-placebo. The addition of atropine increased pain relief more than 3-fold among participants given diclofenac (d = 0.77), but did not enhance the response to placebo (d = 0.09). A chain of mediation analysis demonstrated that the addition of atropine increased dry mouth symptoms, which increased beliefs that one had received the active medication, which, in turn, increased analgesia. In addition to this indirect effect of atropine on analgesia (via dry mouth and beliefs), analyses suggest that among those who received diclofenac, atropine directly increased analgesia. This possible synergistic effect between diclofenac and atropine might warrant future research.

Efficacy of antidepressants over placebo is similar in two-armed versus three-armed or more-armed randomized placebo-controlled trials

Previous studies have reported that effect sizes of antidepressants were larger in two-armed than in three-armed or more-armed (multiarmed) randomized trials, where the probability of being allocated to placebo is lower. However, these studies have not taken into account the publication bias, differences among antidepressants, or covariance in multiarmed studies, or examined sponsorship bias. We searched published and unpublished randomized-controlled trials that compared placebo with 21 antidepressants for the acute treatment of major depression in adults. We calculated the ratio of odds ratios (ROR) of drug response over placebo in two-armed versus multiarmed trials for each antidepressant, and then synthesized RORs across all the included antidepressants using the multivariate meta-analysis. A random-effects model was used throughout. Two hundred and fifty-eight trials (66 two-armed and 192 multiarmed trials; 80 454 patients; 43.0% with unpublished data) were included in the present analyses. The pooled ROR for response of two-armed trials over multiarmed trials was 1.09 (95% confidence interval: 0.96-1.24). The ROR did not materially change between types of antidepressants, publication year, or sponsorship. The differences between two-armed versus multiarmed studies were much smaller than were suggested in previous studies and were not significant.

Impact of demographic factors on the antidepressant effect: A patient-level data analysis from depression trials submitted to the Pharmaceuticals and Medical Devices Agency in Japan

A substantial and variable placebo response can cause unreliable findings in clinical trials designed to demonstrate the efficacy of antidepressants, and the high rate of failed trials represents a major obstacle in the development of new drugs for major depressive disorder (MDD). However, the influence of demographic and symptom factors on the antidepressant effect remains to be established. The purpose of this study was to estimate the magnitude of this influence. A patient-level meta-analysis of data from double-blind, randomized, placebo-controlled trials involving the use of antidepressants for adults with MDD was performed. Data from five confirmatory trials evaluating the efficacy of four antidepressants that were submitted to the Pharmaceuticals and Medical Devices Agency (PMDA) to support new drug applications were pooled (n = 1898). The change in the total score of 17-item Hamilton Depression Rating Scale (HDRS₁₇) was the primary outcome of interest in our analysis. The changes in the total HDRS₁₇ score in both the antidepressant medication group (ADM) and the placebo group (PBO) increased in relation to baseline symptom severity. Among older patients and those with a history of prior treatment with antidepressants, the changes in the total HDRS₁₇ score decreased in ADM and remained static in PBO. There were no notable clinical symptoms that influenced the change in the total HDRS₁₇ score. Baseline symptom severity, participant age and a history of previous treatment with antidepressants were suggested as moderators of the antidepressant effect. The drug-placebo difference in the estimated changes as a function of baseline symptom severity varied depending on the regression models used, and further studies are required to investigate appropriate models.

Factors impacting the efficacy of venlafaxine extended release 75-225 mg/day in patients with major depressive disorder: exploratory post hoc subgroup analyses of a randomized, double-blind, placebo-controlled study in Japan

PURPOSE

To explore the potential factors impacting the efficacy of venlafaxine extended release (ER) and treatment differences between 75 mg/day and 75-225 mg/day dose in patients with major depressive disorder (MDD).

METHODS

We performed exploratory post hoc subgroup analyses of a randomized, double-blind, placebo-controlled study conducted in Japan. A total of 538 outpatients aged 20 years or older with a primary diagnosis of MDD who experienced single or recurrent episodes were randomized into three groups: fixed-dose, flexible-dose, or placebo. Venlafaxine ER was initiated at 37.5 mg/day and titrated to 75 mg/day for both fixed-dose and flexible-dose group, and to 225 mg/day for flexible-dose group (if well tolerated). Efficacy endpoints were changes from baseline at Week 8 using the Hamilton Rating Scale for Depression-17 items (HAM-D₁₇) total score, Hamilton Rating Scale for Depression-6 items score, and Montgomery-Asberg Depression Rating Scale total score. The following factors were considered in the subgroup analyses: sex, age, HAM-D₁₇ total score at baseline, duration of MDD, duration of current depressive episode, history of previous depressive episodes, history of previous medications for MDD, and CYP2D6 phenotype. For each subgroup, an analysis of covariance model was fitted and the adjusted mean of the treatment effect and corresponding 95% CI were computed. Due to the exploratory nature of the investigation, no statistical hypothesis testing was used.

RESULTS

Venlafaxine ER improved symptoms of MDD compared with placebo in most subgroups. The subgroup with a long duration of MDD (>22 months) consistently showed greater treatment benefits in the flexible-dose group than in the fixed-dose group.

CONCLUSION

These results suggest that a greater treatment response to venlafaxine ER (up to 225 mg/day) can be seen in patients with a longer duration of MDD. Further investigations are needed to identify additional factors impacting the efficacy of venlafaxine ER.

Magnitude and pattern of placebo response in clinical trials of antiepileptic medications: Data from the Food and Drug Administration 1996-2016

This study aimed to replicate and extend the findings of previous investigations looking at treatment responses in antiepileptic clinical trials over time and to examine the effects of subject age and duration of treatment. To address the potential biases of published literature, we examined the reported data from 14 investigational antiepileptic drugs (AEDs) (34 trials, 59 treatment arms, 10,783 patients) reviewed and approved by the US FDA (1996-2016). For each treatment arm, we recorded drug and placebo response (percent reduction in seizure frequency), calculated effect sizes, and examined these measures over time. Regression analysis showed that placebo response has increased significantly over time (R²=0.292, p=0.001) from 5% to 20% reduction in seizure frequency in 20years. Response to drug treatment appears to have increased in parallel but the trend was not statistically significant (p=0.143). Effect sizes have remained stable over time (p=0.084). Treatment duration was not related to treatment response or outcomes. Including younger patients in trials appeared to predict lower drug response (β=1.44, p=0.012) and effect size (β=0.014, p=0.047) but not placebo response (p=0.141). These FDA-reviewed and source-verified data support and extend prior findings from published literature that response to placebo treatment is noticeably increasing over time, nearly quadrupling in magnitude, while AED efficacy remains the same due to a parallel increase in drug response. The rise in placebo response appears to be an ongoing phenomenon rather than a mere historical artifact. Future design and interpretation of data from clinical trials of investigational antiepileptic drugs can be informed by these observations.

Advancing psychiatric pharmacogenomics using drug development paradigms

Drugs used to treat psychiatric disorders, even when taken as directed, fail to provide adequate relief for a sizeable proportion of patients. Despite our advancements in understanding human genetics and development of high-throughput tools to probe variation, pharmacogenomics has yielded marginal ability to predict drug response for psychiatric disorders. Here, I review the current pharmacogenomics paradigm, identifying opportunities to incorporate drug development strategies designed to increase the probability of delivering a successful molecule to the clinic. This includes using in-depth pharmacokinetic profiles, clear measures of target engagement and target-specific pharmacodynamic responses orthogonal to clinical response. The complex pharmacological profiles psychiatric drugs require re-examination of simplified clinical response-oriented pharmacogenetic hypotheses, in favor of a more complete patient profile.

Treatment of premenstrual dysphoria with continuous versus intermittent dosing of oral contraceptives: Results of a three-arm randomized controlled trial

BACKGROUND

Although traditionally dosed combined oral contraceptives (COCs) (21 days of active pills, 7 days of inactive pills) have not been demonstrated as superior to placebo for the treatment of premenstrual dysphoria (PMD), some randomized controlled trials (RCTs) indicate that oral contraceptives administered with a shortened or eliminated hormone-free interval are superior to placebo. However, results of such trials are mixed, and no existing studies have directly compared continuous and intermittent dosing schedules of the same oral contraceptive. The present study compared placebo, intermittent dosing of oral contraceptives, and continuous dosing of contraceptives for the treatment of PMD.

METHODS

Fifty-five women with prospectively confirmed PMD completed a three-arm, RCT in which they were randomized to 3 months of placebo (n = 22), intermittent drospirenone/ethinyl estradiol dosed on a 21-7 schedule (n = 17), or continuous drospirenone/estradiol (n = 16) following a baseline assessment month.

RESULTS

All three groups demonstrated similar, robust reductions in premenstrual symptoms over time. A marked placebo response was observed.

CONCLUSIONS

The study fails to replicate a uniquely beneficial effect of continuous COC on PMD. Additional work is needed to understand the psychosocial context bolstering the placebo response in women with PMD.

[What place for placebo in clinical trials conducted on psychiatric patients?]

Placebo effect remains a crucial issue in current clinical trials. Most clinical trials rely on the hypothesis of equivalent placebo response rates in both placebo and specific drug arms ("additive model"). But contrary to this dominant and rarely questioned hypothesis, several aspects may influence placebo response. A few recent meta-analyses and reviews have shown evidence for several clinical and methodological factors, which are able to modulate placebo response. In psychiatry research, placebo response has been mainly explored through antidepressant trials. In early clinical trials, drug-placebo differences were initially significant and robust. However, more recent clinical trials have not yielded similar results, and rather show narrowed antidepressant-placebo differences. Several factors may be involved in this absence of comparability: intrinsic properties of new antidepressants, changes in clinical criteria and classifications, symptomatic remission rather than global remission criteria, industrial and institutional constraints. Moreover, results from antidepressant trials (laboratory conditions) remain hardly fully transposable to clinical routine (ecological conditions).

Control conditions for randomised trials of behavioural interventions in psychiatry: a decision framework

In psychiatry, comparative analyses of therapeutic options and the aggregation of data from clinical trials across different therapeutic approaches play an important role in clinical decision making, treatment guidelines, and health policy. This approach assumes that trials of pharmacological and behavioural therapies generally produce the same level of evidence when properly designed. However, trial design for behavioural interventions has some unique characteristics and control groups vary widely, which influence the effects observed in any given trial. In this Personal View, we review various control conditions typically used in psychiatry, outline their effect on the internal validity and expected effect size of a trial, and propose a decision framework for choosing a control condition depending on the risk to the patient population and the stage of development of the therapeutic intervention. We argue that the choice of control group and its justification need to be taken into consideration when comparing behavioural and pharmacological therapies.

Variation in Placebo Effect Sizes in Clinical Trials of Oral Interventions for Management of the Behavioral and Psychological Symptoms of Dementia (BPSD): A Systematic Review and Meta-Analysis

Increasing placebo effect sizes over time have been reported in randomized controlled trials (RCTs) for outcomes related to psychiatric symptoms. The Neuropsychiatric Inventory (NPI) is a key outcome measure in clinical trials of the behavioral and psychological symptoms of dementia (BPSD). Accurate placebo effect size estimates for NPI are needed for sample size calculations in order to adequately power future studies. This study investigated variation in placebo effect sizes for NPI in RCTs testing oral interventions for BPSD. A search of PubMed was conducted in April 2016 for two-armed, double-blinded, placebo-controlled RCTs testing any oral intervention for management of BPSD using the NPI. Meta-analysis was conducted of baseline versus end of treatment placebo group data of included studies. Twenty-five RCTs published from 2000 to 2015 were included. Substantial variation in placebo effect sizes was detected. Participants in placebo groups showed greater improvements in recent studies compared with earlier studies. Subgroup analyses indicated robustness of this finding. From 2000 to 2008 there was no significant change in total NPI scores within placebo groups (12 studies; 1,056 participants), whereas from 2009 to 2015 there was significant improvement (mean difference: -2.68; 95% confidence interval: -4.38, -0.99; z = 3.10; p = 0.002, random effects; I² = 76%; 13 studies; 1,170 participants). This increase in NPI effect sizes in placebo groups has important implications for power calculations for future clinical trials of BPSD. Effect size estimates for NPI need to be based on more recent studies.

Phase II Proof-of-Concept Trial of the Orexin Receptor Antagonist Filorexant (MK-6096) in Patients with Major Depressive Disorder

BACKGROUND

We evaluated the orexin receptor antagonist filorexant (MK-6096) for treatment augmentation in patients with major depressive disorder.

METHODS

We conducted a 6-week, double-blind, placebo-controlled, parallel-group, Phase II, proof-of-concept study. Patients with major depressive disorder (partial responders to ongoing antidepressant therapy) were randomized 1:1 to once-daily oral filorexant 10 mg or matching placebo.

RESULTS

Due to enrollment challenges, the study was terminated early, resulting in insufficient statistical power to detect a prespecified treatment difference; of 326 patients planned, 129 (40%) were randomized and 128 took treatment. There was no statistically significant difference in the primary endpoint of change from baseline to week 6 in Montgomery Asberg Depression Rating Scale total score; the estimated treatment difference for filorexant-placebo was -0.7 (with negative values favoring filorexant) (P=.679). The most common adverse events were somnolence and suicidal ideation.

CONCLUSIONS

The interpretation of the results is limited by the enrollment, which was less than originally planned, but the available data do not suggest efficacy of orexin receptor antagonism with filorexant for the treatment of depression. (Clinical Trial Registry: clinicaltrials.gov: NCT01554176).

Has the rising placebo response impacted antidepressant clinical trial outcome? Data from the US Food and Drug Administration 1987-2013

More than fifteen years ago, it was noted that the failure rate of antidepressant clinical trials was high, and such negative outcomes were thought to be related to the increasing magnitude of placebo response. However, there is considerable debate regarding this phenomenon and its relationship to outcomes in more recent antidepressant clinical trials. To investigate this, we accessed the US Food and Drug Administration (FDA) reviews for sixteen antidepressants (85 trials, 115 trial arms, 23,109 patients) approved between 1987 and 2013. We calculated the magnitude of placebo and antidepressant responses, antidepressant-placebo differences, as well as the effect sizes and success rates, and compared these measures over time. Exploratory analysis investigated potential changes in trial design and conduct over time. As expected, the magnitude of placebo response has steadily grown in the past 30 years, increasing since 2000 by 6.4% (r=0.46, p<0.001). Contrary to expectations, a similar increase has occurred in the magnitude of antidepressant response (6.0%, r=0.37, p<0.001). Thus, the effect sizes (0.30 vs. 0.29, p=0.42) and the magnitude of antidepressant-placebo differences (10.5% vs. 10.3%, p=0.37) have remained statistically equivalent. Furthermore, the frequency of positive trial arms has gone up in the past 15 years (from 47.8% to 63.8%), but this difference in frequency has not reached statistical significance. Trial design features that were previously associated with a possible lower magnitude of placebo response were not implemented, and their relationship to the magnitude of placebo response could not be replicated. Of the 34 recent trials, two implemented enhanced interview techniques, but both of them were unsuccessful. The results of this study suggest that the relationship between the magnitude of placebo response and the outcome of antidepressant clinical trials is weak at best. These data further indicate that antidepressant-placebo differences are about the same for all of the sixteen antidepressants approved by the FDA in the past thirty years.

Placebo and nocebo reactions in randomized trials of pharmacological treatments for persistent depressive disorder. A meta-regression analysis

BACKGROUND

We aimed to investigate placebo and nocebo reactions in randomized controlled trials (RCT) of pharmacological treatments for persistent depressive disorder (PDD).

METHODS

We conducted a systematic electronic search and included RCTs investigating antidepressants for the treatment of PDD. Outcomes were the number of patients experiencing response and remission in placebo arms (=placebo reaction). Additional outcomes were the incidence of patients experiencing adverse events and related discontinuations in placebo arms (=nocebo reaction). A priori defined effect modifiers were analyzed using a series of meta-regression analyses.

RESULTS

Twenty-three trials were included in the analyses. We found a pooled placebo response rate of 31% and a placebo remission rate of 22%. The pooled adverse event rate and related discontinuations were 57% and 4%, respectively. All placebo arm outcomes were positively associated with the corresponding medication arm outcomes. Placebo response rate was associated with a greater proportion of patients with early onset depression, a smaller chance to receive placebo and a larger sample size. The adverse event rate in placebo arms was associated with a greater proportion of patients with early onset depression, a smaller proportion of females and a more recent publication.

CONCLUSIONS

Pooled placebo and nocebo reaction rates in PDD were comparable to those in episodic depression. The identified effect modifiers should be considered to assess unbiased effects in RCTs, to influence placebo and nocebo reactions in practice.

LIMITATIONS

Limitations result from the methodology applied, the fact that we conducted only univariate analyses, and the number and quality of included trials.

A randomised cross-over study assessing the "blue pyjama syndrome" in major depressive episode

This paper introduces a “blue pyjama syndrome” (whereby wearing hospital pyjamas results in an exaggerated impression of severity). We performed a 5-day, prospective, randomized, cross-over study in a French mood disorder unit for inpatients. At Day 1 (D1) and Day 5 (D5), two 5-minute video interviews were recorded with patients in pyjamas or in day clothes (the sequence was randomly allocated). Psychiatrists unaware of the study objective assessed the videos and scored their clinical global impressions (CGI, with scores ranging from 1 to 7). Of 30 participants with major depressive episode selected for inclusion, 26 participants (69% women) provided useable data for an evaluation by 10 psychiatrists. Pyjamas significantly increased the psychiatrists’ CGI ratings of disease severity by 0·65 [0·27; 1·02] points. The psychiatrists’ global impressions also rated patients as significantly less severe at D5 in comparison with D1 by −0·66 [−1·03; −0·29] points. The “blue pyjama syndrome” is in the same order of magnitude as the difference observed after a week of hospitalisation. This potentially calls into question the reliability and validity of observer ratings of depression.

Brain Mechanisms of the Placebo Effect: An Affective Appraisal Account

Placebos are sham medical treatments. Nonetheless, they can have substantial effects on clinical outcomes. Placebos depend on a person's psychological and brain responses to the treatment context, which influence appraisals of future well-being. Appraisals are flexible cognitive evaluations of the personal meaning of events and situations that can directly impact symptoms and physiology. They also shape associative learning processes by guiding what is learned from experience. Appraisals are supported by a core network of brain regions associated with the default mode network involved in self-generated emotion, self-evaluation, thinking about the future, social cognition, and valuation of rewards and punishment. Placebo treatments for acute pain and a range of clinical conditions engage this same network of regions, suggesting that placebos affect behavior and physiology by changing how a person evaluates their future well-being and the personal significance of their symptoms.

The unfulfilled promise of the antidepressant medications

Australia has one of the highest rates of antidepressant use in the world; it has more than doubled since 2000, despite evidence showing that the effectiveness of these medications is lower than previously thought. An increasing placebo response rate is a key reason for falling effectiveness, with the gap between response to medications and placebo narrowing. Psychotherapies are effective treatments, but recent evidence from high-quality studies suggests that their effectiveness is also modest. Combined treatment with medication and psychotherapy provides greater effectiveness than either alone. The number of patients receiving psychotherapy had been declining, although this trend is probably reversing with the Medicare Better Access to Mental Health Care initiative. Antidepressant medications still have an important role in the treatment of moderate to severe depression; they should be provided as part of an overall treatment plan that includes psychotherapy and lifestyle strategies to improve diet and increase exercise. When medications are prescribed, they should be used in a way that maximises their chance of effectiveness.

Clinical Experience With Desvenlafaxine in Treatment of Patients With Fibromyalgia Syndrome

Two multicenter, randomized, placebo-controlled, adaptive-design trials of desvenlafaxine for fibromyalgia syndrome (FMS) were conducted. In study 1, male and female patients were randomized to a 27-week treatment with placebo or desvenlafaxine 50, 100, 200, or 400 mg/d. In study 2, female patients were randomized to an 8-week treatment with placebo, desvenlafaxine 200 mg/d, or pregabalin 450 mg/d after a placebo run-in. The primary efficacy end point was change from baseline in numeric rating scale (NRS) pain score. Protocol-specified interim analyses were planned after 12 (study 1) and 8 (study 2) weeks of treatment. Safety data were collected. In all, 697 patients were randomly assigned to treatment in study 1. At the interim analysis (n = 346), none of the desvenlafaxine doses met the efficacy criteria (mean [SE] advantage over placebo, -0.21 [0.36] to 0.04 [0.35]), and the study was terminated. Study 2 was stopped for business reasons before the planned interim analysis. NRS scores in week 8 were -1.98 (0.37), -1.60 (0.37), and -1.70 (0.38) for placebo (n = 26), desvenlafaxine 250 mg/d (n = 24), and pregabalin 450 mg/d (n = 21), respectively; neither active treatment differed significantly from placebo. Desvenlafaxine was generally safe and well tolerated. Efficacy of desvenlafaxine for pain associated with FMS was not demonstrated.

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

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

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

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

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

Patient Expectancy as a Mediator of Placebo Effects in Antidepressant Clinical Trials

OBJECTIVE

Causes of placebo effects in antidepressant trials have been inferred from observational studies and meta-analyses, but their mechanisms have not been directly established. The goal of this study was to examine in a prospective, randomized controlled trial whether patient expectancy mediates placebo effects in antidepressant studies.

METHOD

Adult outpatients with major depressive disorder were randomly assigned to open or placebo-controlled citalopram treatment. Following measurement of pre- and postrandomization expectancy, participants were treated with citalopram or placebo for 8 weeks. Independent samples t tests determined whether patient expectancy differed between the open and placebo-controlled groups, and mixed-effects models assessed group effects on Hamilton Depression Rating Scale (HAM-D) scores over time while controlling for treatment assignment. Finally, mediation analyses tested whether between-group differences in patient expectancy mediated the group effect on HAM-D scores.

RESULTS

Postrandomization expectancy scores were significantly higher in the open group (mean=12.1 [SD=2.1]) compared with the placebo-controlled group (mean=11.0 [SD=2.0]). Mixed-effects modeling revealed a significant week-by-group interaction, indicating that HAM-D scores for citalopram-treated participants declined at a faster rate in the open group compared with the placebo-controlled group. Patient expectations postrandomization partially mediated group effects on week 8 HAM-D.

CONCLUSIONS

Patient expectancy is a significant mediator of placebo effects in antidepressant trials. Expectancy-related interventions should be investigated as a means of controlling placebo responses in antidepressant clinical trials and improving patient outcome in clinical treatment.

Placebo Intervention Enhances Reward Learning in Healthy Individuals

According to the placebo-reward hypothesis, placebo is a reward-anticipation process that increases midbrain dopamine (DA) levels. Reward-based learning processes, such as reinforcement learning, involves a large part of the DA-ergic network that is also activated by the placebo intervention. Given the neurochemical overlap between placebo and reward learning, we investigated whether verbal instructions in conjunction with a placebo intervention are capable of enhancing reward learning in healthy individuals by using a monetary reward-based reinforcement-learning task. Placebo intervention was performed with non-invasive brain stimulation techniques. In a randomized, triple-blind, cross-over study we investigated this cognitive placebo effect in healthy individuals by manipulating the participants’ perceived uncertainty about the intervention’s efficacy. Volunteers in the purportedly low- and high-uncertainty conditions earned more money, responded more quickly and had a higher learning rate from monetary rewards relative to baseline. Participants in the purportedly high-uncertainty conditions showed enhanced reward learning, and a model-free computational analysis revealed a higher learning rate from monetary rewards compared to the purportedly low-uncertainty and baseline conditions. Our results indicate that the placebo response is able to enhance reward learning in healthy individuals, opening up exciting avenues for future research in placebo effects on other cognitive functions.

Additional considerations are required when preparing a protocol for a systematic review with multiple interventions

OBJECTIVES

The number of systematic reviews that aim to compare multiple interventions using network meta-analysis is increasing. In this study, we highlight aspects of a standard systematic review protocol that may need modification when multiple interventions are to be compared.

STUDY DESIGN AND SETTING

We take the protocol format suggested by Cochrane for a standard systematic review as our reference and compare the considerations for a pairwise review with those required for a valid comparison of multiple interventions. We suggest new sections for protocols of systematic reviews including network meta-analyses with a focus on how to evaluate their assumptions. We provide example text from published protocols to exemplify the considerations.

CONCLUSION

Standard systematic review protocols for pairwise meta-analyses need extensions to accommodate the increased complexity of network meta-analysis. Our suggested modifications are widely applicable to both Cochrane and non-Cochrane systematic reviews involving network meta-analyses.

Different Disclosed Probabilities to Receive an Antiemetic Equally Decrease Subjective Symptoms in an Experimental Placebo Study: To Be or Not to Be Sure

PURPOSE

The purpose of this study was to examine whether the disclosed probability of receiving an antiemetic affects nausea.

METHODS

Forty-eight healthy participants (mean [SD] age, 26.8 [5.4] years; 50% female) were exposed to 5 × 2 minutes of nauseogenic body rotations on 2 days. On day 2, participants were randomized to 3 experimental groups that were given different instructions concerning the probability of receiving an antiemetic remedy (100%, 50%, or 0% probability), whereas all received an inert substance. Subjective symptoms, behavioral (rotation tolerance) measures, and physiologic (electrogastrogram) measures of nausea were assessed and mediator and moderator analyses performed for effects of expectations and psychological characteristics on outcomes.

FINDINGS

Disclosed probabilities of both 100% and 50% significantly reduced subjective symptoms of nausea in an equal manner compared with the 0% probability group from day 1 to day 2. This effect was found for neither rotation tolerance nor myoelectric gastric activity. Expectations and psychological characteristics did not affect the results found. Post hoc analyses revealed that women only seem to be susceptible to this placebo effect.

IMPLICATIONS

Nausea is susceptible to placebo effects independent of the disclosed probability of receiving a drug and of explicit expectations. In line with placebo research, this effect is probably attributable to central mechanisms, and it is speculated that it could be related to the reward circuitry and social interactions.

Factors influencing the outcome of deep brain stimulation: Placebo, nocebo, lessebo, and lesion effects

Deep brain stimulation (DBS) is a well-established treatment option for movement disorders, especially for Parkinson's disease (PD). There is a need to determine the role of expectation of benefit and the use of placebo to better understand the effects of electrode placement including the (micro)lesion effect. These factors must be understood to better interpret and attribute the therapeutic value of DBS. In this review, we critically present currently available data on the placebo, nocebo, lessebo, and lesion effects in the context of DBS. We provide a discussion of strategies that have the potential for controlling these effects in the setting of future DBS trials. We conclude that there is a need to standardize definitions for nocebo and (micro)lesion effects and that there are intrinsic limitations in defining the effect of expectation of benefit in DBS. These issues will be challenging to overcome especially with current technology and available study designs. New stimulation paradigms, better study designs, and the use of adaptive closed-loop DBS devices may facilitate a more accurate assessment of the placebo, nocebo, and lessebo effects in future DBS trials.

Placebo response rates in antidepressant trials: a systematic review of published and unpublished double-blind randomised controlled studies

BACKGROUND

Previous studies have shown that placebo response rates in antidepressant trials have been increasing since the 1970s. However, these studies have been based on outdated or limited datasets and have used inappropriate statistical methods. We did a systematic review of placebo-controlled randomised controlled trials of antidepressants to examine associations between placebo-response rates and study and patient characteristics.

METHODS

In this systematic review, we searched for published and unpublished double-blind randomised placebo-controlled trials of first-generation and second-generation antidepressants for acute treatment of major depression in adults (update: Jan 8, 2016). The log-transformed proportions of placebo response, defined as 50% or greater reduction in depression severity score from baseline, were meta-analytically synthesised for each year. We then looked for a structural break point in the secular changes in these characteristics through the years and examined the influence of the study year and other trial and patient characteristics on the response rates through meta-regression.

FINDINGS

We identified 252 placebo-controlled trials (26 324 patients on placebo) done between 1978 and 2015. There was a structural break in 1991, and since then, the average placebo response rates in antidepressant trials have remained constant in the range between 35% and 40% (relative risk [RR] 1·00, 95% CI 0·97-1·03, p=0·99, for every 5-year increase). The length of the study and the number of study centres were significant factors (RR 1·03, 95% CI 1·01-1·05 for 1 more week in trial length; 1·32, 1·11-1·57 for multicentre vs single-centre trials).

INTERPRETATION

Contrary to the widely held belief, the average placebo response rates in antidepressant trials have been stable for more than 25 years. This new evidence should have an effect on the interpretation of the scientific literature and the future of psychopharmacology, both from a clinical and methodological point of view.

FUNDING

Japan Society for Promotion of Science, Great Britain Sasakawa Foundation.

Comparative efficacy and acceptability of first-generation and second-generation antidepressants in the acute treatment of major depression: protocol for a network meta-analysis

INTRODUCTION

Many antidepressants are indicated for the treatment of major depression. Two network meta-analyses have provided the most comprehensive assessments to date, accounting for both direct and indirect comparisons; however, these reported conflicting interpretation of results. Here, we present a protocol for a systematic review and network meta-analysis aimed at updating the evidence base and comparing all second-generation as well as selected first-generation antidepressants in terms of efficacy and acceptability in the acute treatment of major depression.

METHODS AND ANALYSIS

We will include all randomised controlled trials reported as double-blind and comparing one active drug with another or with placebo in the acute phase treatment of major depression in adults. We are interested in comparing the following active agents: agomelatine, amitriptyline, bupropion, citalopram, clomipramine, desvenlafaxine, duloxetine, escitalopram, fluoxetine, fluvoxamine, levomilnacipran, milnacipran, mirtazapine, nefazodone, paroxetine, reboxetine, sertraline, trazodone, venlafaxine, vilazodone and vortioxetine. The main outcomes will be the proportion of patients who responded to or dropped out of the allocated treatment. Published and unpublished studies will be sought through relevant database searches, trial registries and websites; all reference selection and data extraction will be conducted by at least two independent reviewers. We will conduct a random effects network meta-analysis to synthesise all evidence for each outcome and obtain a comprehensive ranking of all treatments. To rank the various treatments for each outcome, we will use the surface under the cumulative ranking curve and the mean ranks. We will employ local as well as global methods to evaluate consistency. We will fit our model in a Bayesian framework using OpenBUGS, and produce results and various checks in Stata and R. We will also assess the quality of evidence contributing to network estimates of the main outcomes with the GRADE framework.

ETHICS AND DISSEMINATION

This review does not require ethical approval.

PROSPERO REGISTRATION NUMBER

CRD42012002291.

How Health Professionals Conceptualize and Represent Placebo Treatment in Clinical Trials and How Their Patients Understand It: Impact on Validity of Informed Consent

Context

Previous studies suggested that many patients, who have given their informed consent to participate in randomized controlled trials (RCT), have somewhat limited understanding of what a placebo treatment is. We hypothesized that the relationship between patients and their health professionals plays a central role in this understanding.

Methods

We interviewed 12 patients included in RCTs (nine suffering from Parkinson’s disease and three from Huntington’s disease) and 18 health professionals involved with RCTs (eight principal investigators, four associated physicians and six clinical research associates). Semi-structured interviews were conducted after the RCTs had ended but before the treatment allocation was revealed.

Results

Only two patients clearly understood the aim of placebo-controlled RCTs. Only one principal investigator said she asks all her patients whether they agree to participate in RCTs. The seven others said they only ask patients who seem more likely to be compliant. Their selection criteria included docility and personality traits associated in other studies with enhanced placebo responses. According to 13 of the 18 health professionals, their relationship with patients may influence the amplitude of the placebo response. All but one clinical research associates added that the placebo response could result from a “maternal” type of care. All principal investigators said they have a strong influence on their patient's decision to participate. Finally, when interviewees were asked to narrate a memory of a medically unexplained healing, in eight of 11 physicians' narratives the beneficiary was a child while in 10 of 12 patients' narratives it was an adult.

Conclusion

Our observations suggest that the interrelationship between health professionals and patients involved in RCTs could be compared to that between parents and children. Therefore, adherence to formal rules regarding informed consent does not ensure a balanced relationship between patients and health professionals.

Mechanisms of the placebo effect in pain and psychiatric disorders

Placebo effect research over the past 15 years has improved our understanding of how placebo treatments reduce patient symptoms. The expectation of symptom improvement is the primary factor underlying the placebo effect. Such expectations are shaped by past experiences, contextual cues and biological traits, which ultimately modulate one's degree of response to a placebo. The body of evidence that describes the physiology of the placebo effect has been derived from mechanistic studies primarily restricted to the setting of pain. Imaging findings support the role of endogenous opioid and dopaminergic networks in placebo analgesia in both healthy patients as well as patients with painful medical conditions. In patients with psychiatric illnesses such as anxiety disorders or depression, a vast overlap in neurological changes is observed in drug responders and placebo responders supporting the role of serotonergic networks in placebo response. Molecular techniques have been relatively underutilized in understanding the placebo effect until recently. We present an overview of the placebo responder phenotypes and genetic markers that have been associated with the placebo effect in pain, schizophrenia, anxiety disorders and depression.

Neuro-Bio-Behavioral Mechanisms of Placebo and Nocebo Responses: Implications for Clinical Trials and Clinical Practice

The placebo effect has often been considered a nuisance in basic and particularly clinical research. This view has gradually changed in recent years due to deeper insight into the neuro-bio-behavioral mechanisms steering both the placebo and nocebo responses, the evil twin of placebo. For the neuroscientist, placebo and nocebo responses have evolved as indispensable tools to understand brain mechanisms that link cognitive and emotional factors with symptom perception as well as peripheral physiologic systems and end organ functioning. For the clinical investigator, better understanding of the mechanisms driving placebo and nocebo responses allow the control of these responses and thereby help to more precisely define the efficacy of a specific pharmacological intervention. Finally, in the clinical context, the systematic exploitation of these mechanisms will help to maximize placebo responses and minimize nocebo responses for the patient's benefit. In this review, we summarize and critically examine the neuro-bio-behavioral mechanisms underlying placebo and nocebo responses that are currently known in terms of different diseases and physiologic systems. We subsequently elaborate on the consequences of this knowledge for pharmacological treatments of patients and the implications for pharmacological research, the training of healthcare professionals, and for the health care system and future research strategies on placebo and nocebo responses.

A Meta-Analysis of Executive Dysfunction and Antidepressant Treatment Response in Late-Life Depression

OBJECTIVE

Depressed older adults with executive dysfunction (ED) may respond poorly to antidepressant treatment. ED is a multifaceted construct and different studies have measured different aspects of ED, making it unclear which aspects predict poor response. Meta-analytic methods were used to determine whether ED predicts poor antidepressant treatment response in late-life depression and to determine which domains of executive functioning are responsible for this relationship.

METHODS

A Medline search was conducted to identify regimented treatment trials contrasting executive functioning between elderly responders and nonresponders; only regimented treatment trials for depressed outpatients aged 50 and older were included. Following the most recent PRISMA guidelines, 25 measures of executive functioning were extracted from eight studies. Six domains were identified: cognitive flexibility, planning and organization, response inhibition, selective attention, verbal fluency, and the Dementia Rating Scale Initiation/Perseveration composite score (DRS I/P). Hedge's g was calculated for each measure of executive functioning. A three-level Bayesian hierarchical linear model (HLM) was used to estimate effect sizes for each domain of executive functioning.

RESULTS

The effect of planning and organization was significantly different from zero (Bayesian HLM estimate of domain effect size: 0.91; 95% CI: 0.32-1.58), whereas cognitive flexibility, response inhibition, selective attention, verbal fluency, and the DRS I/P composite score were not.

CONCLUSION

The domain of planning and organization is meaningfully associated with poor antidepressant treatment response in late-life depression. These findings suggest that therapies that focus on planning and organization may provide effective augmentation strategies for antidepressant nonresponders with late-life depression.

Comparison of the Levels of Pro-Inflammatory Cytokines Released in the Vastus Lateralis Muscle of Patients with Fibromyalgia and Healthy Controls during Contractions of the Quadriceps Muscle--A Microdialysis Study

Objective

Fibromyalgia is associated with central hyperexcitability, but it is suggested that peripheral input is important to maintain central hyperexcitability. The primary aim was to investigate the levels of pro-inflammatory cytokines released in the vastus lateralis muscle during repetitive dynamic contractions of the quadriceps muscle in patients with fibromyalgia and healthy controls. Secondarily, to investigate if the levels of pro-inflammatory cytokines were correlated with pain or fatigue during these repetitive dynamic contractions.

Material and Methods

32 women with fibromyalgia and 32 healthy women (controls) participated in a 4 hour microdialysis session, to sample IL-1β, IL-6, IL-8, and TNF from the most painful point of the vastus lateralis muscle before, during and after 20 minutes of repeated dynamic contractions. Pain (visual analogue scale; 0–100) and fatigue Borg’s Rating of Perceived Exertion Scale; 6–20) were assessed before and during the entire microdialysis session.

Results

The repetitive dynamic contractions increased pain in the patients with fibromyalgia (P < .001) and induced fatigue in both groups (P < .001). Perceived fatigue was significantly higher among patients with fibromyalgia than controls (P < .001). The levels of IL-1β did not change during contractions in either group. The levels of TNF did not change during contractions in patients with fibromyalgia, but increased in controls (P < .001) and were significantly higher compared to patients with fibromyalgia (P = .033). The levels of IL-6 and IL-8 increased in both groups alike during and after contractions (P’s < .001). There were no correlations between pain or fatigue and cytokine levels after contractions.

Conclusion

There were no differences between patients with fibromyalgia and controls in release of pro-inflammatory cytokines, and no correlations between levels of pro-inflammatory cytokines and pain or fatigue. Thus, this study indicates that IL-1β, IL-6, IL-8, and TNF do not seem to play an important role in maintenance of muscle pain in fibromyalgia.

Age and sex as moderators of the placebo response – an evaluation of systematic reviews and meta-analyses across medicine

Predictors of the placebo response (PR) in randomized controlled trials (RCT) have been searched for ever since RCT have become the standard for testing novel therapies and age and gender are routinely documented data in all trials irrespective of the drug tested, its indication, and the primary and secondary end points chosen. To evaluate whether age and gender have been found to be reliable predictors of the PR across medical subspecialties, we extracted 75 systematic reviews, meta-analyses, and meta-regressions performed in major medical areas (neurology, psychiatry, internal medicine) known for high PR rates. The literature database used contains approximately 2,500 papers on various aspects of the genuine PR. These ‘meta-analyses’ were screened for statistical predictors of the PR across multiple RCT, including age and gender, but also other patient-based and design-based predictors of higher PR rates. Retrieved papers were sorted for areas and disease categories. Only 15 of the 75 analyses noted an effect of younger age to be associated with higher PR, and this was predominantly in psychiatric conditions but not in depression, and internal medicine but not in gastroenterology. Female gender was associated with higher PR in only 3 analyses. Among the patient-based predictors, the most frequently noted factor was lower symptom severity at baseline, and among the design- based factors, it was a randomization ratio that selected more patients to drugs than to placebo, more frequent study visits, and more recent trials that were associated with higher PR rates. While younger age may contribute to the PR in some conditions, sex does not. There is currently no evidence that the PR is different in the elderly. PR are, however, markedly influenced by the symptom severity at baseline, and by the likelihood of receiving active treatment in placebo- controlled trials.

Rethinking psychopharmacotherapy: The role of treatment context and brain plasticity in antidepressant and antipsychotic interventions

Emerging evidence indicates that treatment context profoundly affects psychopharmacological interventions. We review the evidence for the interaction between drug application and the context in which the drug is given both in human and animal research. We found evidence for this interaction in the placebo response in clinical trials, in our evolving knowledge of pharmacological and environmental effects on neural plasticity, and in animal studies analyzing environmental influences on psychotropic drug effects. Experimental placebo research has revealed neurobiological trajectories of mechanisms such as patients' treatment expectations and prior treatment experiences. Animal research confirmed that "enriched environments" support positive drug effects, while unfavorable environments (low sensory stimulation, low rates of social contacts) can even reverse the intended treatment outcome. Finally we provide recommendations for context conditions under which psychotropic drugs should be applied. Drug action should be steered by positive expectations, physical activity, and helpful social and physical environmental stimulation. Future drug trials should focus on fully controlling and optimizing such drug×environment interactions to improve trial sensitivity and treatment outcome.

Antidepressants versus placebo in major depression: an overview

Although the early antidepressant trials which included severely ill and hospitalized patients showed substantial drug-placebo differences, these robust differences have not held up in the trials of the past couple of decades, whether sponsored by pharmaceutical companies or non-profit agencies. This narrowing of the drug-placebo difference has been attributed to a number of changes in the conduct of clinical trials. First, the advent of DSM-III and the broadening of the definition of major depression have led to the inclusion of mildly to moderately ill patients into antidepressant trials. These patients may experience a smaller magnitude of antidepressant-placebo differences. Second, drug development regulators, such as the U.S. Food and Drug Administration and the European Medicines Agency, have had a significant, albeit underappreciated, role in determining how modern antidepressant clinical trials are designed and conducted. Their concerns about possible false positive results have led to trial designs that are poor, difficult to conduct, and complicated to analyze. Attempts at better design and patient selection for antidepressant trials have not yielded the expected results. As of now, antidepressant clinical trials have an effect size of 0.30, which, although similar to the effects of treatments for many other chronic illnesses, such as hypertension, asthma and diabetes, is less than impressive.

Suggestibility as a predictor of response to antidepressants: A preliminary prospective trial

BACKGROUND

The growing awareness that so many do not respond adequately to antidepressant (AD) pharmacotherapy has sparked research seeking to characterize those who do. While the pharmacological mechanisms of AD treatment have been extensively evaluated, much remains unknown about the placebo component of the response to medication. This study examined the association between suggestibility levels and response to ADs amongst depressed patients.

METHODS

Twenty unipolar depression outpatients, recruited before starting AD monotherapy, received clear, standardized instructions that the therapeutic effects of AD, though not side effects, would require 2-4 weeks. At baseline (T1), 1 week (T2), and 1 month (T3), participants were evaluated for depressive symptoms, using the Hamilton Rating Scale for Depression-17 items (HAM-D); for anxiety by the Hamilton Rating Scale for Anxiety (HAM-A); for side effects by the Antidepressant Side Effect Checklist (ASEC); and for suggestibility, using the Multidimensional Iowa Suggestibility Scale (MISS).

RESULTS

High levels of baseline suggestibility were associated with less improvement in depression level and more side-effects during the first week. In accordance with our hypothesis the more suggestible patients improved more between T2 and T3. No significant correlations were found between baseline suggestibility levels and change in anxiety.

LIMITATIONS

Small sample size and a self-report questionnaire assessing suggestibility were limitations.

CONCLUSION

This study offers a potentially new and clinically useful approach to understanding and predicting who will respond to AD treatment. Suggestibility seems to play a role, presumably by shaping expectation, in response to AD treatment. We hope that this avenue will be further explored.

Two Phase III randomised double-blind studies of fixed-dose TC-5214 (dexmecamylamine) adjunct to ongoing antidepressant therapy in patients with major depressive disorder and an inadequate response to prior antidepressant therapy

OBJECTIVES

To evaluate the neuronal nicotinic channel modulator TC-5214 (dexmecamylamine) as adjunct therapy in patients with major depressive disorder (MDD) and inadequate response to prior antidepressant treatment.

METHODS

Study 004 (D4130C00004) and Study 005 (D4130C00005) comprised an 8-week open-label antidepressant (SSRI/SNRI) treatment period followed by an 8-week randomised, active treatment with twice-daily TC-5214 (0.5, 2 or 4 mg in Study 004; 0.1, 1 or 4 mg in Study 005) or placebo, adjunct to ongoing SSRI/SNRI. Primary efficacy endpoint was change in MADRS total score from randomisation (Week 8) to treatment end (Week 16). Secondary endpoints included MADRS response and remission, and changes in SDS and HAM-D-17-item scores. Safety and tolerability were monitored throughout.

RESULTS

Studies 004 and 005 randomised 640 and 696 patients, respectively, to TC-5214 or placebo. No statistically significant improvements in MADRS total score or any secondary endpoints were seen with TC-5214 versus placebo in either study at treatment end. The most commonly reported adverse events (> 10%) with TC-5214 were constipation, dizziness and dry mouth.

CONCLUSIONS

TC-5214 adjunct to antidepressant was generally well tolerated. However, the studies were not supportive of an antidepressant effect for TC-5214 in patients with MDD and inadequate response to prior antidepressant therapy.

The effects of blinding on the outcomes of psychotherapy and pharmacotherapy for adult depression: A meta-analysis

BACKGROUND

Randomized trials with antidepressants are often run under double blind placebo-controlled conditions, whereas those with psychotherapies are mostly unblinded. This can introduce bias in favor of psychotherapy when the treatments are directly compared. In this meta-analysis, we examine this potential source of bias.

METHODS

We searched Pubmed, PsycInfo, Embase and the Cochrane database (1966 to January 2014) by combining terms indicative of psychological treatment and depression, and limited to randomized trials. We included 35 trials (with 3721 patients) in which psychotherapy and pharmacotherapy for adult depression were directly compared with each other. We calculated effect sizes for each study indicating the difference between psychotherapy and pharmacotherapy at post-test. Then, we examined the difference between studies with a placebo condition and those without in moderator analyses.

RESULTS

We did not find a significant difference between the studies with and those without a placebo condition. The studies in which a placebo condition was included indicated no significant difference between psychotherapy and pharmacotherapy (g=-0.07; NNT=25). Studies in which no placebo condition was included (and patients and clinicians in both conditions were not blinded), resulted in a small, but significant difference between psychotherapy and pharmacotherapy in favor of pharmacotherapy (g=-0.13; NNT=14).

CONCLUSIONS

Studies comparing psychotherapy and pharmacotherapy in which both groups of patients (and therapists) are not blinded (no placebo condition is included) result in a very small, but significantly higher effect for pharmacotherapy.

Understanding the non-pharmacological correlates of self-reported efficacy of antidepressants

OBJECTIVE

To explore the non-pharmacological correlates of the perceived effectiveness of antidepressants (ADs), thereby enhancing understanding of the mechanisms involved in recovery from depression while taking ADs.

METHOD

An online survey was completed by 1781 New Zealand adults who had taken ADs in the previous 5 years.

RESULTS

All 18 psychosocial variables measured were associated with depression reduction, and 16 with improved quality of life (QoL). Logistic regression models revealed that the quality of the relationship with the prescriber was related to both depression reduction and improved QoL. In addition, depression reduction was related to younger age, higher income, being fully informed about ADs by the prescriber, fewer social causal beliefs for depression and not having lost a loved one in the 2 months prior to prescription. Furthermore, both outcome measures were positively related to belief in 'chemical' rather than 'placebo' effects.

CONCLUSION

There are multiple non-pharmacological processes involved in recovery while taking ADs. Enhancing them, for example focusing on the prescriber-patient relationship and giving more information, may enhance recovery rates, with or without ADs.

Empirically derived criteria cast doubt on the clinical significance of antidepressant-placebo differences

Meta-analyses indicate that antidepressants are superior to placebos in statistical terms, but the clinical relevance of the differences has not been established. Previous suggestions of clinically relevant effect sizes have not been supported by empirical evidence. In the current paper we apply an empirical method that consists of comparing scores obtained on the Hamilton rating scale for depression (HAM-D) and scores from the Clinical Global Impressions-Improvement (CGI-I) scale. This method reveals that a HAM-D difference of 3 points is undetectable by clinicians using the CGI-I scale. A difference of 7 points on the HAM-D, or an effect size of 0.875, is required to correspond to a rating of 'minimal improvement' on the CGI-I. By these criteria differences between antidepressants and placebo in randomised controlled trials, including trials conducted with people diagnosed with very severe depression, are not detectable by clinicians and fall far short of levels consistent with clinically observable minimal levels of improvement. Clinical significance should be considered alongside statistical significance when making decisions about the approval and use of medications like antidepressants.