The Latest Health Scare, In Perspective

by Simon Oxenham

Two days ago the normally reasonable Guardian newspaper published one of the most irresponsible and ill thought out health claims in years, perhaps since the MMR-autism scandal. The Guardian's harrowing video account describes the apparently mortal risk of taking the contraceptive pill. The extremely emotive video contains footage of blood, guts and open surgery and heart wrenching accounts of parents who tragically have lost children who were taking contraceptives.

The entire film is emotive and compelling, but only spends a minuscule amount of time buried at the end of the video, actually describing the risk. When it does describe the risk, it conflates the risk of getting a blood clot with the risk of death, citing the father of a girl who was taking the contraceptive pill at the time of her death saying: "If you had a room full of 10,000 women and you told them that... a few of you in this room are going to die from this." The report even likens the risk to the risk of death by smoking.

"This needs to have a big old label, right on the front, like cigarettes say - this can kill you - this needs to say the same thing"

Last year the British National Health Service (NHS) responded to the scare, then raised by the Daily Mail, describing the coverage as "poor and puzzling". As the NHS explains, the risk in a given year that someone will have a blood clot is normally two per ten thousand. Depending on the type of contraceptive, that risk rises ever so incredibly slightly to up to 13.7 cases of blood clots per ten thousand people. Let's visualize that:

For most types of contraceptive, the rate of blood clots are lower still, ranging from five per ten thousand to twelve per ten thousand depending on the type of contraceptive. Whatever way you look at it, the increase in risk is tiny - and remember, those numbers don't represent deaths, they represent blood clots. Death is still unlikely after a blood clot. The increase in risk of blood clots caused by contraceptives is actually smaller than the increase in risk of blood clots caused by pregnancy itself! Furthermore, the likelihood of a blood clot is moderated by plenty of other risk factors such as age, weight and family history of blood clots - which should all be considered by the doctor before contraceptives are prescribed.

For comparison, the risk of death from smoking is vizualised below. Smoking causes one in five of all deaths (in the US):

Note not just the gigantic difference in risk, but the many caveats. Smoking currently causes one in five of all deaths in the US. Not the deaths of one in five smokers - most people don't smoke, but smoking is so dangerous it still causes one in five of all deaths. Hormonal contraceptives on the other hand cause the risk of blood clots, which in rare cases may lead to death, to increase by a very small fraction of a percentage point.

To compare the risk of death from blood clots caused by contraceptives to the risk of death from smoking is patently absurd.

Reference: NHS Behind The Headlines Hat tip: Vox

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