A study published in this week’s Public Library of Science (PLoS) Medicine, an open-access scientific journal, raises doubts about dispensing such drugs so freely. Irving Kirsch, of the University of Hull, and his colleagues scrutinised the clinical trials for several new antidepressants, taking care to include those never published (but which, by law, have to be reported to the FDA). They found that SSRIs did not help the vast majority of depressed people much more than placebos did. The net benefits over placebos did not usually reach the level considered big enough to be of clinical significance by Britain’s National Institute for Health and Clinical Excellence (NICE).
This study points to two factors that bedevil proponents of SSRIs: publication bias and the power of placebos. Dr Kirsch believes published data “give an exaggerated view of a drug’s benefit.” People with very severe depression did see benefits above the NICE threshold, but even that was not a ringing endorsement. Dr Kirsch explains that this was not because SSRIs worked much better in the very seriously depressed, but rather that the effectiveness of placebos dropped off sharply in such people, making the drug look better.