EXTREME SPORTS, RISK AND MICROMORTS

Living is dangerous. We’re all dying, but most of us strive to stay alive for as long as possible. Still, many of us want to explore and experience as much as we can in this time. This often puts us at higher risk of adverse events than the average couch potato, but hopefully these activities also bring extra pleasure and excitement to our lives. And how big are the risks anyway?

David Spiegelhalter is Professor of the Public Understanding of Risk at the University of Cambridge in the UK and his professional background is in medical statistics. He’s written an interesting piece on risk and extreme sports.

Micromorts and the risk of living
In the 70s, researchers at Stanford came up with the micromort to help compare risk.
Micromort is the risk out of a million of dying from a particular event. 1 micromort also happens to be about the daily risk of dying of external causes. So a micromort can be seen as the average “ration” of lethal risk that people are exposed to daily, and which we should therefore not be unduly worried about. Of course, this average figure disguises huge variability. But 1 micromort per day – that’s the risk of living.

Are extreme sports extremely risky?
Well, maybe not. Skydiving is at 10 micromorts. Scuba diving is about the same at 8 micromorts. But so is a marathon. Or just 4 days in the life of a 30 year old, or 1 day in the life of a 50 year old*. So at 50, skydiving is pretty much risk free (statistically, that’s not true, but it sounds cool that way). 10 micromorts is also roughly equivalent to the risk of a 100 km motorbike ride, or 4000 km in a car. Or having a general anaesthetic for emergency surgery – where 10 micromorts is the risk of dying just from causes related directly to the anaesthesia.

But then there’s mountaineering. Extreme mountaineering. Mount Everest is the classic example. From the first attempts before Hillary and Tenzing and up to 2011 there have been 219 deaths, which is 1 for every 25 that actually reach the summit. Of course many more climb, and die, than those that reach the summit. Out of the 20,000 mountaineers climbing above 8,000 metres in the Himalayas between 1990 and 2006, an estimated 238 people died, a rate of around 12,000 micromorts per climb. That’s over a 1000 skydives.

And you can increase the risk for parachuting by jumping off a ground object instead of an aircraft. Base jumping from Kjerag outside Stavanger in Norway has a 430 micromort risk. But you can still jump off Kjerag 27 times instead of climbing an 8000 metre peak in the Himalayas.

How to manage and mitigate the risk
As we try to do in anaesthesia, it’s a good thing to be well trained and prepared. Doing an antartic expedition Scott style will add a lot of micromorts to your risk. The British Sub-Aqua Club (BSAC) has halved the risk of fatalities from diving compared to non-members – 5 and 10 micromorts, respectively, implying that training and awareness helps. Similarly, you will probably find great differences in risk if you stratify the incidents in the mountain mortality review.

The last word is that risk is not always what it seems, and even then, you can do a lot to manage that risk. Putting perspective on risk puts life into perspective.

Mountain mortality: a review of deaths that occur during recreational activities in the mountains, Postgrad Med J, 2009

How dangerous is BASE jumping? An analysis of adverse events in 20,850 jumps from the Kjerag Massif, Norway, J Trauma, 2007

Review paper of diving fatalities spanning 1998-2009, British Sub-Aqua Club (BSAC) 2010.

*The risk of dying for a 30 and a 50 year old is higher than the 1 micromort, as these numbers include all causes of death, not just the external ones that were calculated to constitute 1 micromort per day.

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2 Responses to EXTREME SPORTS, RISK AND MICROMORTS

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