dinsdag 26 februari 2008

Antidepressants are ineffective for most patients, study finds

26th February 2008

There is little reason to prescribe antidepressants to the majority of depressed patients, according to a group of experts, led by Professor Kirsch at the University of Hull. In a study analysing data from clinical trials of antidepressants, leading psychologists found that antidepressants have no clinically significant effects in all cases apart from a small group of the most severely depressed patients. The paper, Initial Severity and Antidepressant Benefits: A Meta-Analysis of Data Submitted to the FDA, is being published today in the journal PLoS Medicine.

Before antidepressants are approved for licensing, they must undergo clinical trials that measure their ability to alleviate depression in comparison to the effects that patients experience when taking a placebo (a dummy tablet that contains no drug). The psychologists carried out an extensive analysis of clinical trial data submitted to obtain licensing for the most commonly-prescribed antidepressants.

Their analysis showed that in comparison to placebo effects, antidepressants do not have clinically significant effects in mildly depressed patients or in most patients who suffer from very severe depression. Furthermore, the apparent clinical effectiveness of antidepressants in the small group of extremely depressed patients is somewhat distorted. The seemingly good result came from fact that these patients’ response to the placebo decreased, rather than any notable increase in their response to antidepressants.

This is one of the most thorough investigations into the efficacy of new generation antidepressants, Selective Serotonin Re-uptake Inhibitors (SSRIs). Licensing authorities have approved the use of SSRIs, yet there are many doubts surrounding their clinical significance.

The team conducted a meta-analysis of all clinical trials, published and unpublished, of four of the most commonly prescribed SSRIs submitted to the US Food and Drug Administration for licensing approval. Conventional meta-analyses tend to use only published data which can, in the case of antidepressant medication, lead to reporting bias caused by multiple publication and selective reporting in sponsored studies.

Professor Irving Kirsch, from the Psychology department at the University of Hull, and lead researcher on the paper said, “The difference in improvement between patients taking placebos and patients taking antidepressants is not very great. This means that depressed people can improve without chemical treatments. Given these results, there seems little reason to prescribe antidepressant medication to any but the most severely depressed patients, unless alternative treatments have failed to provide a benefit. This study raises serious issues that need to be addressed surrounding drug licensing and how drug trial data is reported.”

Source: The University of Hull


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