Upon reviewing all of GlaxoSmithKline’s data from both published and unpublished trials of the antidepressant paroxetine, researchers found the drug provided almost no benefits over placebo for either depression or anxiety, according to a study in PLOS One.
The Wayne State University researchers, in collaboration with Harvard’s Irving Kirsch, stated that evaluating the efficacy of antidepressant medications on depression and anxiety has until now been hampered by a lack of access to pharmaceutical companies’ unpublished trials. “Here, for the first time, we assess the efficacy of a selective serotonin reuptake inhibitor (SSRI) in the treatment of both anxiety and depression, using a complete data set of all published and unpublished trials sponsored by the manufacturer.”
They found that the published literature tended to overestimate the efficacy of the drug, and overall the drug provided tiny benefits of only 2-3 points on common rating scales for depression and anxiety — much of which was due to placebo effects. “The available empirical evidence indicates that paroxetine provides only a modest advantage over placebo in treatment of anxiety and depression,” they wrote. “We demonstrated that individuals given placebo exhibited 79% of the magnitude of change compared to paroxetine.”
“These findings have important clinical implications,” the researchers commented. “The obvious alternative for the treatment of both anxiety and depression is psychotherapy intervention. However, direct comparisons of acute phase treatment for pharmacotherapy and psychotherapy in the treatment of major depression generally have yielded no significant differences between the treatment modalities. Fewer clinical trials have directly compared antidepressants and psychotherapy in the treatment of anxiety disorders, although the available literature indicates similar comparability between antidepressants and psychotherapy.”