In the brilliant book Doctoring Data, Dr Malcolm Kendrick quotes Michael Baum, Professor Emeritus of surgery and visiting Professor of medical humanities at University College London:
“Each year I play a game with the senior postgraduate students at a course for specialists in cancer run by the Royal College of Surgeons of England. I tell them that there are two potentially effective screening tools for prostate cancer, one which will reduce their chances of dying from the disease by between 20 and 30 per cent, while the other will save one life after 10,000 person-years of screening. As a consumer or as a public health official, which one would you buy into? They all vote for the first; yet the two programmes are the same, they were just packaged differently. To continue marketing screening in terms of relative risk reduction in breast cancer mortality is disingenuous in the extreme”. (Ref 1)
If doctors don’t understand the difference between relative and absolute risk, what chance do patients have? When the average British citizen sees a headline like this: “Statins slash cancer deaths by 50%”, they would most likely assume that if 100 people would die from cancer, 50 of those wouldn’t die if they were on statins. Health reporting doesn’t get much worse than that, as this story shows...
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