It is not clear whether the effects of cognitive-behavioural therapy and other psychotherapies have been overestimated because of publication bias.
To examine indicators of publication bias in randomised controlled trials of psychotherapy for adult depression.
We examined effect sizes of 117 trials with 175 comparisons between psychotherapy and control conditions. As indicators of publication bias we examined funnel plots, calculated adjusted effect sizes after publication had been taken into account using Duval & Tweedie's procedure, and tested the symmetry of the funnel plots using the Begg & Mazumdar rank correlation test and Egger's test.
The mean effect size was 0.67, which was reduced after adjustment for publication bias to 0.42 (51 imputed studies). Both Begg & Mazumbar's test and Egger's test were highly significant (P<0.001).
The effects of psychotherapy for adult depression seem to be overestimated considerably because of publication bias.
"That is, the original confidence interval went from 0.53, 1.12 to 0.05, 1.61, with both confidence intervals being positive and not including zero in the range. For other studies, the results were more mixed, wherein the significant treatment effects were only affected at more stringent adjustments based on psychotherapist effects (Budge et al., 2013; Cuijpers et al., 2010; Ruiz, 2012; Worthington et al., 2011). "
[Show abstract][Hide abstract] ABSTRACT: Psychotherapists are known to vary in their effectiveness with their clients, in randomized clinical trials as well as naturally occurring treatment settings. The fact that therapists matter has 2 effects in psychotherapy studies. First, if therapists are not randomly assigned to modalities (which is rare) this may bias the estimation of the treatment effects, as the modalities may have therapists of differing skill. In addition, if the data are analyzed at the client level (which is virtually always the case) then the standard errors for the effect sizes will be biased due to a violation of the assumption of independence. Thus, the conclusions of many meta-analyses may not reflect true estimates of treatment differences. We reexamined 20 treatment effects selected from 17 meta-analyses. We focused on meta-analyses that found statistically significant differences between treatments for a variety of disorders by correcting the treatment effects according to the variability in outcomes known to be associated with psychotherapists. The results demonstrated that after adjusting the results based on most small estimates of therapist effects, ∼80% of the reported treatment effects would still be statistically significant. However, at larger estimates, only 20% of the treatment effects would still be statistically significant after controlling for therapist effects. Although some meta-analyses were consistent in their estimates for treatment differences, the degree of certainty in the results was considerably reduced after considering therapist effects. Practice implications for understanding treatment effects, namely, therapist effects, in meta-analyses and original studies are provided. (PsycINFO Database Record
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Psychotherapy Theory Research Practice Training 09/2015; 52(3):321-328. DOI:10.1037/pst0000014 · 3.01 Impact Factor
"Publication biases have not only been found in drug studies but also in psychotherapy trials (Cuijpers et al., 2010; Flint et al., 2014). Psychotherapy trials usually have markedly smaller sample sizes than drug trials and there is a risk that small studies with negative results are not published. "
[Show abstract][Hide abstract] 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.
International clinical psychopharmacology 04/2015; 30(4). DOI:10.1097/YIC.0000000000000078 · 2.46 Impact Factor
"The EPDS was administered at screening. The Beck Depression Inventory-II (BDI-II; Beck et al., 1996) is a widely used, reliable measure of mood with both general and perinatal populations (e.g., Cuijpers et al., 2010; O'Hara et al., 1984). Continuous scores on the BDI-II were used as the primary outcome measure. "
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