Meta-analysis of the placebo response in antidepressant trials

Division of Clinical Psychology and Psychotherapy, University of Marburg, Germany.
Journal of Affective Disorders (Impact Factor: 3.38). 03/2009; 118(1-3):1-8. DOI: 10.1016/j.jad.2009.01.029
Source: PubMed


Improvements in placebo groups of antidepressant trials account for a major part of the expected drug effects. We aimed to determine overall effect sizes of placebo and drug effects in antidepressant trials, and to analyze whether the placebo effect in antidepressant trials also occurs for patient self-perception, general psychopathology, and quality of life.
Search terms covered different variants of pharmacotherapy for patients with depressive disorders from January 1980 to December 2005 in the databases Medline/Pubmed, PsychInfo and CENTRAL, a.o. We included RCTs with a placebo group and an antidepressant group in people with depression.
We computed within group effect sizes for several outcome variables and integrated them using random-effect models. A total of 96 studies were included. Mean effect size in the placebo group for primary outcome variables was d=1.69 (95% CI=1.54-1.84) compared to 2.50 in the drug group (95% CI=2.30-2.69). There was a major difference between placebo effect sizes assessed with observer ratings (d=1.85, 95% CI=1.69-2.01) versus patient self-perception (d=0.67; 95% CI=0.49-0.85). The effect sizes in placebo groups in 2005 were more than twice as great as those in 1980, but only for observer ratings, not for patient self-ratings. The result was partly due to increased homogeneity of samples of recently published trials.
The placebo effect accounted for 68% of the effect in the drug groups. Whereas clinical trials need to control the placebo effect, clinical practice should attempt to use its full power.


Available from: Yvonne Nestoriuc
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    • "However, these treated versus control effect sizes cannot be used for comparisons of psychological therapies and medications . In psychotherapy trials, the control condition is mostly a waiting list, which usually has a low pre–post effect size, whereas drugs are usually compared with a pill placebo, which has a larger effect (Rief et al., 2009). Moreover, patients are mainly interested in the question 'How much will my anxiety improve with the treatment?' – which is reflected by the pre–post effect size. "
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    ABSTRACT: To our knowledge, no previous meta-analysis has attempted to compare the efficacy of pharmacological, psychological and combined treatments for the three main anxiety disorders (panic disorder, generalized anxiety disorder and social phobia). Pre-post and treated versus control effect sizes (ES) were calculated for all evaluable randomized-controlled studies (n=234), involving 37 333 patients. Medications were associated with a significantly higher average pre-post ES [Cohen's d=2.02 (1.90-2.15); 28 051 patients] than psychotherapies [1.22 (1.14-1.30); 6992 patients; P<0.0001]. ES were 2.25 for serotonin-noradrenaline reuptake inhibitors (n=23 study arms), 2.15 for benzodiazepines (n=42), 2.09 for selective serotonin reuptake inhibitors (n=62) and 1.83 for tricyclic antidepressants (n=15). ES for psychotherapies were mindfulness therapies, 1.56 (n=4); relaxation, 1.36 (n=17); individual cognitive behavioural/exposure therapy (CBT), 1.30 (n=93); group CBT, 1.22 (n=18); psychodynamic therapy 1.17 (n=5); therapies without face-to-face contact (e.g. Internet therapies), 1.11 (n=34); eye movement desensitization reprocessing, 1.03 (n=3); and interpersonal therapy 0.78 (n=4). The ES was 2.12 (n=16) for CBT/drug combinations. Exercise had an ES of 1.23 (n=3). For control groups, ES were 1.29 for placebo pills (n=111), 0.83 for psychological placebos (n=16) and 0.20 for waitlists (n=50). In direct comparisons with control groups, all investigated drugs, except for citalopram, opipramol and moclobemide, were significantly more effective than placebo. Individual CBT was more effective than waiting list, psychological placebo and pill placebo. When looking at the average pre-post ES, medications were more effective than psychotherapies. Pre-post ES for psychotherapies did not differ from pill placebos; this finding cannot be explained by heterogeneity, publication bias or allegiance effects. However, the decision on whether to choose psychotherapy, medications or a combination of the two should be left to the patient as drugs may have side effects, interactions and contraindications.
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    • "Antidepressant drugs tend to fail in late-stage clinical trials after a significant investment has been made. The need to improve the quality of clinical trials, the patients they recruit and to control for a placebo effect that in clinical trials accounts for approximately two-thirds of antidepressant drug effect has been dealt with elsewhere (Nutt and Goodwin, 2011; Rief et al., 2009), and will not be discussed in this review. Even if an antidepressant drug is approved, frequent market access and commercial failures due to lack of compelling differentiation in the clinical profile make an unpromising case for further antidepressant drug development. "
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    Journal of Psychopharmacology 10/2014; 29(5). DOI:10.1177/0269881114553252 · 3.59 Impact Factor
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    • "During the last decade , clinical trial designs became simplified to standard randomized con - trolled trials , and clinical samples were more and more arti - ficially restricted . Both steps limited scientific insight and generalizability of trial results ( Rief et al . , 2009 ; Enck et al . , 2013 ) . Series of smaller trials performed on patient populations selected on the basis of iatrogenic comorbidity or on disease subtyping , potentially combined with adaptive or sequential designs , could increase our insight in processes and treatment developments ( Fava et al . , 2013 ) . These small trials may actua"
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    ABSTRACT: Comorbidity is a well-established and documented phenomenon in mental disorders and medicine with heuristic value. The concept of comorbidity remains however poorly defined and lacks a comprehensive and coherent theoretical framework. There is a need to develop coherent methodological strategies in order to promote a fuller understanding of the implications of comorbidity and to exploit its potential value with regard to etiopathogenic and therapeutic issues. This position paper makes recommendations of improved methodological standards and procedures and discusses a range of options that can provide incremental information that is likely to improve therapeutic outcomes. Copyright © 2013 John Wiley & Sons, Ltd.
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