Comparative efficacy of placebos in short-term antidepressant trials for major depression: a secondary meta-analysis of placebo-controlled trials

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.

Vibration of effects resulting from treatment selection in mixed-treatment comparisons: a multiverse analysis on network meta-analyses of antidepressants in major depressive disorder

OBJECTIVE

It is frequent to find overlapping network meta-analyses (NMAs) on the same topic with differences in terms of both treatments included and effect estimates. We aimed to evaluate the impact on effect estimates of selecting different treatment combinations (ie, network geometries) for inclusion in NMAs.

DESIGN

Multiverse analysis, covering all possible NMAs on different combinations of treatments.

SETTING

Data from a previously published NMA exploring the comparative effectiveness of 22 treatments (21 antidepressants and a placebo) for the treatment of acute major depressive disorder.

PARTICIPANTS

Cipriani et al explored a dataset of 116 477 patients included in 522 randomised controlled trials.

MAIN OUTCOME MEASURES

For each possible treatment selection, we performed an NMA to estimate comparative effectiveness on treatment response and treatment discontinuation for the treatments included (231 between-treatment comparisons). The distribution of effect estimates of between-treatment comparisons across NMAs was computed, and the direction, magnitude and statistical significance of the 1st and 99th percentiles were compared.

RESULTS

4 116 254 different NMAs concerned treatment response. Among possible network geometries, 172/231 (74%) pairwise comparisons exhibited opposite effects between the 1st and 99th percentiles, 57/231 (25%) comparisons exhibited statistically significant results in opposite directions, 118 of 231 (51%) comparisons derived results that were both significant and non-significant at 5% risk and 56/231 (24%) treatment pairs obtained consistent results with only significant differences (or only non-significant differences) at 5% risk. Comparisons based on indirect evidence only were associated with greater variability in effect estimates. Comparisons with small absolute values observed in the complete NMA more frequently obtained statistically significant results in opposite directions. Similar results were observed for treatment discontinuation.

CONCLUSION

In this multiverse analysis, we observed that the selection of treatments to be included in an NMA could have considerable consequences on treatment effect estimations.

TRIAL REGISTRATION

https://osf.io/mb5dy.

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.

No benefit of antidepressants in inpatient treatment of depression. A longitudinal, quasi-experimental field study

RATIONALE

Antidepressants (AD) are mostly considered indispensable for the treatment of major depression. The vast majority of depressive inpatients are treated with AD. However, there is a growing body of studies indicating that the effectiveness of AD is greatly overestimated due to methodological issues with the AD efficacy studies (e.g., publication bias, unintentional unblinding, confusion between withdrawal symptoms and relapse).

OBJECTIVES

The benefit of the additional use of AD in the inpatient treatment of depression with intensive cognitive-behavioral therapy (CBT) has been investigated in a naturalistic design.

METHODS

Depressiveness was assessed using the Beck Depression Inventory (BDI-II) during a preliminary interview (T0), at admission (T1), at discharge (T2), and at a 6-month follow-up (T3). Two study phases were compared: During Phase A, AD were recommended in accordance with the German guideline. In Phase B, AD were no longer recommended, and they were only prescribed upon explicit request from patients. In phase A (N = 574), 60.3% of all patients were taking AD at discharge. In Phase B (N = 424), 27.9% of patients were on AD at discharge. Apart from the difference in AD usage, the two treatment conditions were similar, and the samples did not significantly differ in terms of age, sex, diagnoses, history of suicide attempts, comorbid anxiety disorders, and unemployment.

RESULTS

In both study phases, BDI-II scores were strongly decreased at T2 and T3, respectively, compared with T1. The BDI-II scores of the two phases did not differ at any of the measurement time points. Depression changes were similar in both phases. In sequential multiple regression analyses with the total sample, AD were no significant predictors for the reduction of depression at either T2 or T3.

CONCLUSIONS

The inpatient CBT was effective in depression. The effectiveness of CBT is not improved by the additional use of AD. The current prescribing practices of AD should be questioned.

Irving Kirsch opens a window on antidepressant medications

When it comes to antidepressant medications - popular, backbone drugs of modern psychiatry - even learned scholars and savvy clinicians find it difficult to separate honest, rigorous research from that which thrives on hidden agendas and ulterior motives. Fortunately, a mounting corpus of data-based studies, mostly meta-analyses, casts new and critical light on the clinical efficacy, side effects, and therapeutic outcomes of antidepressants. Spearheading these efforts over the past few decades, Irving Kirsch and colleagues have challenged the hegemonic view of antidepressants as an effective therapeutic intervention. Notably, Kirsch illuminates the small difference between antidepressants and placebos in mitigating depression-a difference that may be statistically significant yet fails to reach clinical significance. This piece sketches the important contributions Kirsch has made to the scientific understanding of antidepressant medications.

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.

Newer generation antidepressants and withdrawal effects: reconsidering the role of antidepressants and helping patients to stop

In England, the prescribing of antidepressants, primarily the newer generation antidepressant classes, has steadily increased over recent years. There is ongoing debate about how the efficacy of these drugs is viewed, their place in therapy and the harms associated with stopping them. Much of the evidence of their efficacy comes from short-term placebo-controlled trials which tend not to include outcomes that are of greatest relevance to patients, such as social functioning or quality of life, but rather restrict outcomes narrowly to symptom measures. On such measures these studies do not demonstrate clinically significant differences from placebo for depression. A range of adverse effects are also recognised, often greater in naturalistic studies of long-term antidepressants users than those measured in short-term efficacy studies, including emotional numbing, sexual difficulties, fatigue and weight gain. There is increasing recognition that withdrawal symptoms from antidepressants are common and that these symptoms can be severe and long-lasting in some patients. Recent guidance on how to stop antidepressants in a tolerable way has been presented by the Royal College of Psychiatrists. We believe that increasing awareness about the difficulty that some patients have in stopping antidepressants should lead to more cautious prescribing practice, with antidepressants given to fewer patients and for shorter periods of time. This article discusses the perceived benefits and harms of antidepressant use.