According to a new review, published in the journal PLOS One on September 30th, medical literature has overestimated the efficacy of talking therapies by nearly a quarter, in part because papers showing poor results are much less likely to make it into scientific journals – a phenomenon researchers call “publication bias”.
While the exaggerations related to the efficacy of antidepressant medication had been known to medical professionals for decades, this is the first analysis to ever account for unpublished trials of interventions involving talking therapies for depression.
The study has showed that engaging in a course of therapy based on any of the well-researched methodologies, such as cognitive behavioural therapy or psychodynamic therapy, makes people with depression about 20% more likely to recover, as compared to merely discussing the problem with their doctor on a regular basis. Previous estimations had this figure at around 30 percent.
This paper is the latest contribution to an ongoing retrenchment across science whereby researchers are looking back to past research to try and weed out unreliable results, arrived at through publication bias and statistical manipulation.
In the study, a research team led by Ellen Driessen from the VU University in Amsterdam, looked at all of the available trials funded by the National Institutes of Health between 1972 and 2008, and found that as many as 13 of them – all bearing unimpressive results – were left unpublished, mostly because the authors of these papers thought a finding of no benefit hardly stood a chance at landing in a journal.
After accounting for all the unpublished data, the effectiveness of therapy for treating depression dropped down a significant 25 percent.
“That seems to be the magic number, a quarter – about the same as you see in the pharma trials,” said co-author Dr. Erick Turner, an Associate Professor of Psychiatry at Oregon Health & Science University, and the lead author on the 2008 paper detailing bias in the aforementioned drug trials.
As the research team had no access to the designs of the available studies, it is hard to tell whether the authors massaged any data to make it look more robust – an issue that came up in several drug trials.
Steven Hollon of Vanderbilt University, a co-author on the study, said the way to look at these results is that both antidepressant drugs and talking therapies are modestly effective, a combination of the two being best, although psychotherapy has a slight edge on the drugs due to its preventative influence in terms of relapse.
While slightly disappointing, these findings did not come as big surprise to those who use talking therapies in their practice. “Depression is a tough disorder to treat, and it’s very difficult also to judge treatments because the symptoms of the depression naturally wax and wane – it’s a moving target,” said Dr. Stefan Hofmann, a Professor of Psychology at Boston University, who was not involved in the study.
“There’s a sense of desperation out there because we do need something new, and there’s very little on the horizon.”