A 1% surgery risk:
does 1 in 100
have to die?
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The full narration of the video.
A one percent risk doesn't mean one in every hundred patients must die. Plenty of people see a number like this when they sign a surgery consent form. So what does it actually mean? Let's try it with a raffle box.
The box holds a hundred balls: ninety-nine white, one red. Each patient reaches in with eyes closed. Draw the red one, and you're the one percent. The ball goes back in, and the next person draws.
So every time someone reaches in, there's still exactly one red ball. If someone before you drew red, you're no safer. If nobody has yet, it isn't your turn either. So how many red balls will a hundred people pull? Let's have a computer really do it.
Group one: no red at all. Group two: two. Group three: one. After a thousand groups, we line them up and count. Groups with no red ball: about thirty-seven percent. Groups with exactly one: also about thirty-seven.
Two: nearly twenty percent. Three or more: under ten. Out of a hundred, everyone might be fine, or two or three might not make it. But over tens of thousands of groups, the reds add up to very nearly one per hundred.
One percent describes that long-run average. And here's what matters more: everyone's box is different. Older, weaker heart and lungs, an emergency operation: more red balls. Young, healthy, planned ahead: fewer.
That one percent mixes many patients' boxes together, an average counted from past operations. Its proper name is surgical mortality risk. Doctors have risk calculators that take about twenty details, like age and medical history, to estimate your own box. When you get the number, ask your doctor: is this the average, or worked out for me? As for what to choose, follow your doctor.
One more odd thing: say the same number differently, and people choose differently. In one study, people saw the same surgery data. Told as chances of living, more of them chose surgery. Told as chances of dying, fewer did, doctors included. One percent won't make it, and ninety-nine percent will be fine, are the very same sentence.
Which version makes you feel calmer?
A raffle box
100 balls: 99 white, 1 red. Each patient draws one, then puts it back.
Drawing the red ball is that 1%. Because every ball goes back, there is always exactly one red ball when the next person reaches in. If someone before you drew red, you are not safer. If nobody did, you are not "due". Thinking otherwise is called the gambler's fallacy, and we explained it before.
A computer drew
1,000 groups
Each group has 100 people, each with a 1% risk. Over 1,000 groups: about 37% had no red ball, about 37% had exactly one, nearly 20% had two, and under 10% had three or more.
Out of 100 people, all may be fine, or two or three may die.
Draw tens of thousands of groups, and the total gets very close to one per 100. The 1% is that long-run average, not a quota for every 100 people.
Everyone's box
is different
The 1% you see mixes many patients' boxes together. It is an average counted from past operations. Its formal name is surgical mortality risk, and it shows up in the pre-op talk and on the consent form.
Doctors also have risk calculators. They enter about twenty items, like age, medical history and whether it is an emergency, to estimate your own box.
When you get this number, you can ask: is this the average for everyone, or for my case? For the actual decision, follow your doctor.
Same number,
different words
One study showed people the same surgery data. Framed as the chance of surviving, more people chose surgery. Framed as the chance of dying, fewer did. Doctors reacted the same way.
"1% die" and "99% are fine" say the same thing.
puts your mind at ease?
Quick check
100 people have the same surgery, each with a 1% risk. Which is true?
Like a raffle box where every ball goes back: each draw has the same odds, and the count per 100 changes every time.
