James Davies on a new Lancet study about whether anti-depressants work

CRESIDA’s James Davies was on BBC’s Newsnight last night debating a new Lancet study on whether anti-depressants work.  Click below for the full debate, which starts at 24.34m.

A modified version of his response to the study, published in The Times this morning, is below:

Antidepressants Work – Really? A classic example of misrepresenting insignificant conclusions

Cipriani’s et al new article on whether antidepressants work has generated much excitement in the psychiatric community. The study has been represented by the Royal College of Psychiatrists as “finally putting to bed the controversy on anti-depressants”. This statement is irresponsible and unsubstantiated, as the study actually supports what we have already known for a long time, that differences between placebo and antidepressants are so minor that they are actually clinically insignificant, hardly registering at all in a person’s actual experience.

But even these clinically insignificant differences can be potentially accounted for by the way in which the data was analysed (artificially categorising people into ‘responders and non-responders’). We know this can inflate the difference between people on drug and people on placebo. Finally, as most people on the antidepressant would have experienced some noticeable physical or mental alterations, and as a consequence realised they are on the active drug, the placebo effect of the antidepressant would have been boosted, also helping explain these tiny differences away.

Furthermore, the study does not bury the controversy around the damaged caused by unnecessary long-term prescribing, the costs lost to the NHS, and the associated harms and disabling withdrawal effects these drugs elicit in many patients.

The study’s findings are also highly limited, and do not support increasing antidepressant prescribing or usage. The trials only covered short-term antidepressant usage (8 weeks) in people with severe or moderate depression. As clinicians do not prescribe these drugs for only 8 weeks (most people take antidepressants for many months and years), the study tells us nothing about their affects over the long or medium-term. In fact, there is no evidence that long-term use has any benefits, and in real world trials (STAR-D study) outcomes are very poor.

Finally, the authors were unable to obtain relevant unpublished data for many antidepressants. This is concerning given unpublished data is mostly characterised by its being overwhelmingly negative. If that unpublished data had been included it is possible the study would have found no benefit over placebo, or even lower efficacy than placebo for many drugs.

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