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Cuijpers, P., Sijbrandij, E.M., Koole, S.L., Andersson, G., Beekman, A.T. & Reynolds, C.F. (2014). Adding psychotherapy to antidepressant medication in depression and anxiety disorders: A meta-analysis. World Psychiatry, 13(1), 56-67.

Anxiety and depressive disorders occur at a high rate and are very burdensome to those who suffer. These disorders are also related to high levels of health care costs, loss of productivity, and lower quality of life. Both pharmacological and psychotherapeutic interventions are effective, yet in recent years there has been a trend for patients to receive psychotropic interventions alone rather than psychotherapy. Cuijpers and colleagues (2014) conducted a meta analysis comparing pharmacotherapy alone versus pharmacotherapy combined with psychotherapy. Studies in the meta analysis included a variety of disorders such as depressive disorders and anxiety disorders. (Meta analysis is an important tool to review and combine the effects of interventions across a large number of studies. Rather than simply counting studies with positive, neutral, or negative findings, meta analysis allows one to calculate an effect size, average the effect sizes across different studies, and look at predictors or moderators of the effects. Aggregated effect sizes in a meta analysis are much more reliable [i.e., dependable] than any single study result). Cuijpers and colleagues’ meta analysis included 52 studies with 3,623 patients. Most studies tested cognitive behavioral therapy, though a large minority also included interpersonal psychotherapy and psychodynamic therapy. Most studies used selective serotonin reuptake inhibitors (SSRI), though some included tricyclic antidepressants and others. There was a moderately large overall difference between pharmacotherapy versus combined pharmacotherapy plus psychotherapy for major depression, panic disorder, and obsessive compulsive disorder (OCD). That is, adding psychotherapy resulted in a clinically meaningful improvement above and beyond pharmacotherapy alone. There were no significant differences found for type of antidepressant medication or for type of psychotherapy. Eleven studies included a placebo control condition to which medication alone vs medication plus psychotherapy was compared. The effect of combining medication and psychotherapy was twice as large as the effect of medication alone when compared to a placebo control condition. Nineteen studies followed patients after treatment (from 3 to 24 months post treatment), and the superiority of combined treatment versus medication alone remained strong and significant well into follow up.

Practice Implications

There has been a trend over the past decade to provide medication as a first line of treatment for depression and anxiety disorders. However, the results of this meta analysis indicate that monotherapy with medication alone is not optimal treatment for most patients, and that psychotherapy results in additive clinically meaningful improvement for most patients. The additive effects of psychotherapy are especially pronounced for major depression, panic disorder, and OCD.

Cuijpers, P., Huibers, M., Ebert, D.D., Koole, S.L., & Andersson, G. (2013). How much psychotherapy is needed to treat depression? A metaregression analysis. Journal of Affective Disorders, 147, 1-13.

The question of the number of psychotherapy sessions and of frequency sessions (i.e., number of sessions per week) that are optimal for good outcomes could have implications for how psychotherapy is practiced and how it is reimbursed. In my August 2013 PPRNet Blog, I reported on research that indicated half of patients recover after 21 sessions of psychotherapy. However, that also means that half do not recover in that number of sessions. Many of those who do not recover require another 29 sessions to recover. Research and practice in psychotherapy is largely based on a “one-session-per-week” model. Some researchers, however, have found that an increase in the frequency sessions per week could improve or speed up outcomes. Cuijpers and colleagues (2013) did a meta-regression to assess these questions for short-term psychotherapies for depression. (Meta-regression is a type of meta-analysis in which predictors from many studies are aggregated and their averaged effects on the aggregated outcome are assessed. This produces much more reliable findings than are possible from a single study.) The authors assessed predictors such as the number and frequency of sessions, and they looked at symptom outcomes for depression. The authors found 70 controlled studies that included 5403 patients. More than two-thirds of the studies included CBT as the psychotherapy. Average length of treatment was 11 sessions, and the maximum number of sessions was 24. The number of sessions across studies ranged from .44 to 2 per week, and the average per week was 1. The overall effect size for the treatment was medium sized (g = .59), though the effect became smaller (g = .40) when publication bias was corrected. (Publication bias refers to the likelihood that some less favorable studies or results were not published thus creating an overestimation of the effect of the treatment. See my May 2013 PPRNet Blog). Cuijper and colleagues’ meta-regression showed a small but significant association between greater number of sessions and outcomes for depression; but more importantly, a greater number of sessions per week had a considerably larger positive influence on the effects of psychotherapy for depression.

Practice Implications

The findings from Cuijpers and colleagues (2013) meta-regression are particularly relevant to time limited treatment of depression with CBT. The total number of sessions was less important than the frequency of sessions per week. The results suggest that increasing the intensity or frequency of CBT sessions per week might result in a more efficient therapy and faster relief for patients with depression.

Author email: p.cuijpers@vu.nl

Niemeyer, H., Musch, J., & Pietrowsky, R. (2013). Publication bias in meta-analyses of the efficacy of psychotherapeutic interventions for depression. Journal of Consulting and Clinical Psychology, 81, 58-74.

Meta-analyses are important ways of summarizing effects of medical and psychological interventions by aggregating effect sizes across a large number of studies. (Don’t stop reading, I promise this won’t get too statistical). The aggregated effect size from a meta analysis is more reliable than the findings of any individual study. That is why practice guidelines almost exclusively rely on meta analyses when making practice recommendations (see for example the Resources tab on this web site). However meta analyses are only as good as the data (i.e., studies) that go into them (hence, the old adage: “garbage in, garbage out”). For example, if the studies included in a meta analysis are a biased representation of all studies, then the meta analysis results will be unreliable leading to misleading practice guidelines. One problem that leads to unreliable meta analyses is called publication bias. Publication bias often refers to the tendency of peer reviewed journals not to publish studies with non-significant results (e.g., a study showing a treatment is no better than a control condition). Publication bias may also refer to active suppression of data by researchers or industry. Suppression of research results may occur because an intervention’s effects were not supported by the data, or the intervention was harmful to some study participants. In medical research, publication bias can have dire public health consequences (see this TED Talk). There is lots of evidence that publication bias has lead to a significant over-estimation of the effects of antidepressant medications (see Turner et al (2008) New England Journal of Medicine). Does publication bias exist in psychotherapy research, and if so does this mean that psychotherapy is not as effective as we think? A recent study by Niemeyer and colleagues (2013) addressed this question with the most up to date research and statistical techniques. They collected 31 data sets each of which included 6 or more studies of psychotherapeutic interventions (including published and unpublished studies) for depression. The majority of interventions tested were cognitive behavioral therapy, but interpersonal psychotherapy, and brief psychodynamic therapy were also included. The authors applied sophisticated statistical techniques to assess if publication bias existed. (Briefly, there are ways of assessing if the distribution of effect sizes across data sets fall in a predictable pattern called a “funnel plot” – specific significant deviations from this pattern indicate positive or negative publication bias). Niemeyer and colleagues found minimal evidence of publication bias in published research of psychotherapy for depression. This minimal bias had almost no impact on the size of the effect of psychotherapy for depression.

Practice Implications

This is a very important result indicating that despite a minor tendency toward a selective publication of positive results, the efficacy of all reviewed psychotherapy interventions for depression remained substantial, even after correcting for the publication bias. Niemeyer and colleagues’ findings demonstrate that publication bias alone cannot explain the considerable efficacy of psychotherapy for depression. Psychotherapeutic interventions can still be considered efficacious and recommended for the treatment of depression.

Author email address: helen.niemeyer@hhu.de