Thursday, March 06, 2008

Take two and call me in the morning

I found this article by Barbara Rowlands in the The Independent utterly fascinating. The story reports on a study of the placebo effect, which turns out to be much more powerful than previously thought.
Last week an analysis of clinical trial data on modern antidepressants, carried out by Irving Kirsch, professor of psychology at the University of Hull, and his team, found that leading brands of antidepressants worked little better than placebos in all but the most depressed patients. Much of the reporting of the story concluded that antidepressants may be useless. But, interestingly, the study found that patients' response to placebos was "exceptionally large". So it wasn't so much that antidepressants didn't work but that placebos can work very well indeed.

The article mentions a 5-year-old study that
...found that not being told they were receiving morphine cut the effect of the pain relief on the patients in half. And only those who were told they were getting tranquillisers became calmer; those who received diazepam without being told got no relief whatsoever.

It also discusses the surgical (as opposed to pharmaceutical) placebo effect:
In 1959, an American cardiologist called Leonard Cobb conducted a trial on 17 patients who were due to undergo a common procedure used for angina, in which tiny incisions were made in the chest and knots tied in two arteries to try to increase the blood flow to the heart. When Cobb compared it to placebo surgery – he made incisions but did not tie the arteries – the sham operations proved just as successful.
The point made in the end, via a quote from "Dr Richard Kradin, a psychologist and physician at Massachusetts General Hospital, Boston, and associate professor at Harvard Medical School," is that
"As medical science became more scientific, there was a way in which it tended to eschew any contribution by the placebo effect – and that's a mistake. Doctors need to be aware that how they interact with their patients has a great deal to do with the outcomes they are going to get."

To me, this goes a long way to explaining why things like homeopathic "remedies" (which are mentioned in the article and, yes, the quote marks are supposed to indicate my skepticism) can garner such a following. The placebo effect is just as good, if not better, than real medicine in some cases. It also depends on what you believe. The story quotes Michael Hyland, professor of health psychology at the University of Plymouth: "If you are non-spiritual, you'd be much better off taking Prozac, which is not only largely placebo but is contextualised as a medical drug."

See Ben Goldacre's Bad Science blog for lots of stuff on homeopathy. I just went to that site to get the URL and was gratified to see he's mentioned the study, too, in a nicely titled post: All bow before the might of the placebo effect, it is the coolest strangest thing in medicine.

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