Study suggests limited efficacy for antidepressants
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Fluoxetine: one of six antidepressant drugs whose efficacy was scrutinised |
Clinically significant responses to newer antidepressant medicines are seen only in the most severely depressed patients, a new analysis of data suggests. The analysis was reported by national newspapers some of whose headlines suggested that these therapies do not work at all.
Irving Kirsch, of the department of psychology, University of Hull, along
with colleagues based in the US, examined data from all clinical trials
submitted to the US Food and Drug Administration for marketing approval
of fluoxetine, venlafaxine, nefazodone, paroxetine, sertraline and citalopram.
They report that the overall effect of these drugs is below the recommended
criteria for clinical significance used by the National Institute for
Health and Clinical Excellence. In addition, the increased efficacy observed
for severely depressed patients is due to a lower response to placebo
among these patients rather than a higher response to the medicines.
“Given these data, there seems little evidence to support the prescription
of antidepressant medication to all but the most severely depressed patients,
unless alternative treatments have failed,” the researchers say.
Their conclusions were immediately picked up by the national media. Ian
Maidment, chairman of the United Kingdom Psychiatric Pharmacy Group,
and senior pharmacist at Kent and Medway NHS and Social Care Partnership
Trust, told The Journal that, in some ways, the national media had picked
up the wrong message. “The analysis showed that antidepressants
are better than placebo. What wasn’t clear was how clinically significant
that difference was.”
He added that the meta-analysis shows that antidepressants are effective
in severe depression, which is in line with National Institute for Health
and Clinical Excellence recommendations that people with mild illness
should not receive antidepressants first line. Mr Maidment also pointed
out that the researchers only used one outcome measure. “If they
had used other measures to evaluate efficacy, such as response or relapse
rates, they might have got different answers. In addition, analysis of
long-term post-licensing studies might have given a different message,” he
said.
Mr Maidment stressed the importance of targeting the right population
for antidepressant treatment. “Like all treatments, for some people
antidepressant therapies won’t work. For others, they will.”
He also pointed out that there is limited evidence to support the use
of psychological therapies, which are increasingly seen as an alternative
to pharmacological therapy. Furthermore, many patients will benefit from
a combination of psychological and pharmacological therapies, he said.
Steven Bazire, pharmacy services director, Norfolk & Waveney Mental
Health Partnership NHS Trust, added: “It is quite clear that antidepressants
do work. The antidepressant response is better than the placebo response.” He
acknowledged that people can and do get better without antidepressant
treatment since a depression is self-limiting. “However, the question
is, how much damage do they do to themselves in the meantime. How many
people harm themselves before they get better?”
He also pointed out that epidemiological studies had shown a clear association
between lower suicide rates and higher levels of antidepressant use.
The study is published online in the free-access journal PLoS Medicine (2008;5:e45). |
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