| 1. |
- Cuijpers, Pim, et al.
(author)
-
Continuous and dichotomous outcomes in studies of psychotherapy for adult depression: A meta-analytic comparison
- 2010
-
In: JOURNAL OF AFFECTIVE DISORDERS. - : Elsevier Science B.V., Amsterdam.. - 0165-0327 .- 1573-2517. ; 126:3, s. 349-357
-
Research review (peer-reviewed)abstract
- Background: In treatment research on depressive disorders, outcomes can be based on continuous outcomes but also on dichotomous outcomes. Although it is possible to convert the two types of outcomes to each other, it has not been tested whether this results in systematic differences. Method: We selected studies on psychotherapy for adult depression from an existing database, in which both continuous and dichotomous outcomes were presented. We calculated effect sizes using both types of outcomes, and compared the results. Results: Although there were considerable differences between the two types of outcomes in individual studies, both types of outcomes resulted in very similar pooled effect sizes. The pooled effect size based on the continuous outcome were somewhat more conservative (d = 0.59: OR = 2.92) than the one based on the dichotomous outcome (d = 0.64; OR = 3.17). Heterogeneity was higher in the analyses based on the continuous outcomes than in those based on the dichotomous outcomes. Sensitivity analyses and subgroup analyses confirmed that the pooled effect sizes were very similar, that the effect sizes were somewhat smaller when the continuous outcomes are used, and that heterogeneity was higher in the analyses based on the continuous outcomes. Conclusion: Overall, the two types of outcomes result in comparable pooled effect sizes and can both be used in meta-analyses. However, the results of the two types of outcomes should not be used interchangeably, because there may be systematic differences in heterogeneity and subgroup analyses.
|
|
| 2. |
- Cuijpers, Pim, et al.
(author)
-
Efficacy of cognitive-behavioural therapy and other psychological treatments for adult depression: meta-analytic study of publication bias
- 2010
-
In: British Journal of Psychiatry. - : Royal College of Psychiatrists. - 0007-1250 .- 1472-1465. ; 196:3, s. 173-178
-
Research review (peer-reviewed)abstract
- Background: It is not clear whether the effects of cognitive-behavioural therapy and other psychotherapies have been overestimated because of publication bias. Aims: To examine indicators of publication bias in randomised controlled trials of psychotherapy for adult depression. Method: 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 & Tweedies procedure, and tested the symmetry of the funnel plots using the Begg & Mazumdar rank correlation test and Eggers test. Results The mean effect size was 0.67, which was reduced after adjustment for publication bias to 0.42 (51 imputed studies). Both Begg & Mazumbars test and Eggers test were highly significant (Pandlt;0.001). Conclusions: The effects of psychotherapy for adult depression seem to be overestimated considerably because of publication bias. Declaration of interest: None.
|
|
| 3. |
- Cuijpers, Pim, et al.
(author)
-
Psychotherapy for chronic major depression and dysthymia: A meta-analysis
- 2010
-
In: Clinical Psychology Review. - : Elsevier BV. - 0272-7358 .- 1873-7811. ; 30:1, s. 51-62
-
Research review (peer-reviewed)abstract
- Although several studies have examined the effects of psychotherapy on chronic depression and dysthymia, no meta-analysis has been conducted to integrate results of these studies. We conducted a meta-analysis of 16 randomized trials examining the effects of psychotherapy on chronic depression and dysthymia. We found that psychotherapy had a small but significant effect (d=0.23) on depression when compared to control groups. Psychotherapy was significantly less effective than pharmacotherapy in direct comparisons (d=-031), especially SSRIs, but that this finding was wholly attributable to dysthymic patients (the studies examining dysthymia patients were the same studies that examined SSRIs). Combined treatment was more effective than pharmacotherapy alone (d=0.23) but even more so with respect to psychotherapy alone (d=0.45), although again this difference may have reflected the greater proportion of dysthymic samples in the latter. No significant differences were found in drop-out rates between psychotherapy and the other conditions. We found indications that at least 18 treatment sessions are needed to realize optimal effects of psychotherapy. We conclude that psychotherapy is effective in the treatment of chronic depression and dysthymia but probably not as effective as pharmacotherapy (particularly the SSRIs).
|
|
