Wednesday, February 03, 2010

Antidepressants Work No Better Than a Placebo

An article in Newseek discusses meta-analyses by Irving Kirsch and others which show that anti-depressants work no better than a placebo. There are lessons to be learned about the methodology of medical research and about the marketing strategies of drug companies. Also of interest is the role played by the FDA:
Two other factors are at work in the widespread rejection of Kirsch's (and, now, other scientists') findings about antidepressants. First, defenders of the drugs scoff at the idea that the FDA would have approved ineffective drugs. (Simple explanation: the FDA requires two well-designed clinical trials showing a drug is more effective than a placebo. That's two, period—even if many more studies show no such effectiveness. And the size of the "more effective" doesn't much matter, as long as it is statistically significant.)

Libertarian critics of the FDA often claim that the FDA is risk-averse when permitting potentially beneficial remedies and procedures, because the political cost to the regulators of unsuccessful applications of a remedy or procedure outweighs the political benefit to regulators of successful applications of the remedy or procedure. One death caused by a drug ignites a political firestorm, even if the the drug has saved hundreds or thousands.

Why, then, did the FDA give a pass to antidepressants in the absence of evidence of effectiveness? Perhaps the FDA does not have as much an incentive to care about effectiveness as about risk. If the FDA has no reason to suspect politically dangerous amounts of ill effects from a remedy, perhaps they will permit it even if there is insufficient evidence that it is effective. In both cases, though, the FDA does not seem to function the way in which its supporters claim.
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