Sunday, 31 January 2010

The drugs do work?

An interesting article in the NY Times by psychiatrist Richard Friedman:
Last week, The Journal of the American Medical Association published a study questioning the effectiveness of antidepressant drugs. The drugs are useful in cases of severe depression, it said. But for most patients, those with mild to moderate cases, the most commonly used antidepressants are generally no better than a placebo.
...the authors of the new analysis gave themselves an additional handicap: they decided to exclude a whole class of studies, those that tried to correct for the so-called placebo response.
Another drawback of the study is that its conclusions are based on studies that included only two antidepressants — when there are 25 or so on the market. By contrast, when the Food and Drug Administration wanted to investigate the safety of antidepressants, it analyzed data from some 300 clinical trials, with nearly 80,000 patients, involving about a dozen antidepressants.
Every once in a while, a landmark study comes along and overturns everyone’s cherished ideas about a particular treatment. But the current study is not one of them. So it would be a shame if it discouraged depressed patients from taking antidepressants.
Neuroskeptic has blogged about this study before (Fournier et al 2010 JAMA 303(1)), but it is worth noting that, despite my criticisms of Irving Kirsch's meta-analysis of the FDA data on antidepressant efficacy, even when I reanalysed the data I found that the NICE threshold for 'clinical significance' was met at around a baseline severity of 26 points on the Hamilton scale. In this study by Fournier et al the threshold was met around a baseline severity of 25 points.

My analysis could only correct for baseline severity on a per trial basis whereas the above study was a patient level meta-analysis which is a better approach when available. So while the above study did include only two antidepressants (one of which was the older tricyclic class, although these are thought to be similarly effective to the newer SSRIs, just with more side-effects) it is consistent with the study by Kirsch et al, even given the criticisms of it I've previously raised.

So I don't think Friedman's criticism holds up, I think a more sensible attack is that the NICE threshold is entirely arbitrary, an argument I made at the time of Kirsch's paper.

1 comment:

Neuroskeptic said...

The "it's only two drugs" point is a bit lame - if paroxetine and imipramine don't work, the prospects for the rest are hardly hopeful.

Then he says that by excluding trials with a placebo run-in, you're "bound to show a comparatively small average difference between drug treatment and placebo treatment." That's an admission that lots of people respond to placebo & antidepressants are no better.

I think the point he's ultimately trying to make that if you're not a "placebo responder" (and no-one thinks of themselves as such, do they?) antidepressants are good, at least if you try them until you find the right one.