Clinical trials of antidepressant medications are producing meaningless results

Abstract

A recent alert from the UK Committee on Safety of Medicines stated that the dangers of treatment of depression with paroxetine outweigh the benefits in those under 18. Such a warning should focus our minds on the evidence on which clinical practice is based. Antidepressant treatment of depression in the under-18s has been thought to be justified because clinical trials show that it works so well in over-18s. But is that a reasonable assessment of the evidence? Kirsch et al (2002) use the analogy of ‘The Emperor's New Clothes' to describe the findings from their meta-analysis of randomised placebo-controlled trials of antidepressants. They conclude that antidepressant medication appears to have only a small effect on outcome over and above placebo. In this analogy psychiatry is the emperor, drug trials are the fraudsters and the deception is being revealed by a growing body of critical opinion proposing that, once methodological problems with clinical trials are taken into account, antidepressants either do not work at all or have an effect that is so small as to be clinically unimportant (Andrews, 2001; Moncrieff, 2002). A large number of randomised placebo-controlled trials of antidepressants have been carried out over the past decades, mostly funded by the pharmaceutical industry, and it is now recognised that about 50% of negative trials go unpublished (Thase, 1999). Meanwhile, unipolar depression has jumped into the top five of the world's total burden of disease, and there is an imperative need for effective and safe treatments. Do we need more randomised controlled trials (RCTs) of antidepressant medications, or has that research paradigm outlived its usefulness? In this month's debate, Professor Gordon Parker, University of New South Wales and Black Dog Institute, Australia, and Drs Ian Anderson and Peter Haddad from the University of Manchester discuss whether clinical trials for antidepressant medication produce meaningless results.