A new study of 10 years of medical research in one of the very top journals shows that reversals are not uncommon.  This is where later evidence shows that a new medical practice is no better or worse than older practice (or doing nothing).

40% of the studies that examined a current practice found it shouldn’t have been adopted.

The problem is partly that tests of new practice tend to be biased towards being positive. So later, better, studies are going to find that a good number of their findings were wrong.

Also practice tends to adopt invasive practices perhaps due to patient pressure, and doctor desire, to “do something, rather than nothing”. Though there are also reversals to current practices that refuse to take up something new (e.g. vaccinate, take aspirin) because of some (often theory-based) fear, which turns out to be unfounded.

This shows that the advance of…