Four decades of outcome research on psychotherapies for adult depression: An overview of a series of meta-analyses.

Abstract

Depressive disorders are highly prevalent (Alonso et al., 2004; Kessler et al., 1994), have a high incidence (Waraich, Goldner, Somers, & Hsu, 2004), and they are associated with a substantial loss of quality of life for patients and their relatives (Saarni et al., 2007; Ustun, Ayuso-Mateos, Chatterji, Mathers, & Murray, 2004). These disorders are also associated with increased mortality rates (Cuijpers, Vogelzangs et al., 2014), high levels of service use, and enormous economic costs (Greenberg & Birnbaum, 2005; Smit et al., 2006). Major depression is currently ranked fourth worldwide in disease burden. Depression is expected to rank first in disease burden in high-income countries by the year 2030 (Mathers & Loncar, 2006). It is not surprising therefore that several treatments of depression have been developed in the past decades and that a considerable body of research has examined the effects of these treatments. There are two main categories of treatments for depression: biological treatments (mostly antidepressant medications) and psychological treatments. Both types have been examined extensively. Since the 1970s about 500 randomized controlled trials have examined the effects of psychological treatments on depression.It is now about 10 years since we started to build a comprehensive database of randomized trials examining the effects of psychological treatments of depression. Since that time we have updated this database every year (Cuijpers, van Straten, Smit, Mihalopoulos, & Beekman, 2008). We have used this database to answer several research questions with meta-analyses. We have published more than 70 of such meta-analyses. We have examined which psychotherapies are effective, whether psychotherapy is as effective as pharmacotherapy, and whether combined treatments are more effective than psychotherapy or pharmacotherapy alone. We have also examined the effects of the therapies in specific target groups, settings and subtypes of depression, as well characteristics of the therapies, such as the format (individual, group, self-help), and the number of sessions. We have examined the quality of the trials and how this affects their outcomes of the therapies, as well as the problem of publication bias. In this article we will give an overview of the results of these meta-analyses. We already provided an overview in an earlier article (Cuijpers, Andersson, Donker, & Van Straten, 2011). However, since then a considerable number of new meta-analyses have been published. This article can be seen as an update of this earlier overview.A Database of Randomized Trials of Psychotherapies for Adult DepressionThe methods used for building the database and the analyses used in the meta-analyses have been published in a methods article (Cuijpers, Van Straten, Smit et al., 2008). The general methods we used in these meta-analyses have been described in a manual that is freely available (Cuijpers, 2016b). In brief, the database was developed through a comprehensive literature search (of works dating from 1966), and is updated every year. We searched major bibliographical databases (PsycINFO, PubMed, Embase, Cochrane Central Register of Controlled Trials). We include all randomized trials in which at least one arm is a psychological treatment for adults (>18 years) with a depressive disorder according to a diagnostic interview or an elevated level of depressive symptomatology (as indicated by a score above a cut-off score on a validated self-report depression scale like the Beck Depression Inventory).We calculate standardized mean effects (Cohen's d or Hedges' g) for each comparison between a psychotherapy and a comparison group, indicating the difference between these groups in terms of standard deviations. Effect sizes of 0.8 can be assumed to be large, while effect sizes of 0.5 are moderate, and effect sizes of 0.2 are small (Cohen, 1988). An effect size is, however, still a statistical concept with no direct indication for clinical relevance. …