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The value of experience

Most forms of complementary and alternative medicine have a long history of usage. One could say they have been 'field-tested' for hundreds of years in millions of patients.

Most forms of complementary and alternative medicine have a long history of usage. One could say they have been 'field-tested' for hundreds of years in millions of patients.

Does this collective experience not outweigh the evidence from clinical trials? After all, such studies are usually only short-term, and investigate only small samples. Many CAM practitioners therefore feel strongly that this sort of experience is more important than scientific evidence.

What they seem to forget is that experience can turn out to be a method of reaching entirely the wrong conclusion. Many examples exist where experience has seriously and consistently misled our forefathers. Blood letting, for instance, was used for hundreds of years in most medical cultures for most medical conditions. Clinicians were so impressed by its apparent powers that, when trial data finally demonstrated a lack of effectiveness, they initially trusted their experience and disbelieved the evidence.

And there are, of course, many examples from modern times as well. One of my favourites is mammary artery ligation. This surgical technique was used for coronary artery disease in order to shunt more blood into the stenosed coronaries. It seemed to work: patients suffered less angina after the operation. Then someone had the bright idea to do a proper sham-controlled trial. Its results showed that a sham operation (simply doing the skin incision but no more) was as effective as the arterial ligation.

Because of the fact that experience is so often a misguided guide, conventional medicine has taken decisive steps towards becoming evidence-based. In CAM, however, the perception of the supremacy of experience over evidence continues almost unabated. Authors of CAM books, for instance, recommend almost any treatment for any condition. We have shown that 120 CAM modalities for addiction, 131 for arthritis, 119 for asthma and 133 for cancer were recommended in just 7 bestselling books on CAM (Ernst E, Pittler MH, Wider B, Boddy K. The desktop guide to complementary and alternative medicine. Edinburgh; 2nd edition. Edinburgh: Mosby/Elsevier. 2006.)

I think it is time now that CAM learns this important lesson: evidence tops experience, not vice versa. And ideally both should complement each other.

Professor Edzard Ernst Professor Edzard Ernst

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