Republic of Mathematics blog

Statistics of heart health

Posted by: Gary Ernest Davis on: September 11, 2010

This is a true story that I tell my statistics students.

When they hear it they tell me to listen to my doctor and my wife, both of whom have my best interests to heart, and to follow their advice.

So, here it is.

I have had checks on my blood pressure and tests for my cholesterol levels.

My blood pressure is a little high: 140/90. My LDL cholesterol levels are high and  HDL cholesterol levels are low (I do not remember the exact results).

My family physician, a gentle, concerned doctor who does not like doing tests to excess, tells me he is worried.  The Framingham Heart Study data suggests, given my age, weight, blood pressure, and cholesterol levels, that I have  a little more than a 25% chance of a major heart incident within 10 years.

At this point, my dear wife, who is in the consultation room with me, is worried that I am about to have a heart attack. My doctor explains that a “major heart incident” is not necessarily a heart attack.

Being a mathematician I put the following to him. Since I have a 25% chance of a major heart incident within 10 years, according to the Framingham Heart Study data, the odds are with me: I have a 75% chance of NOT having a major heart incident within 10 years.

Frustrated by my impeccable quantitative reasoning, my doctor adopts a different tack. He tells me that he has a large practice, and that he sees many patients.

“You” he says, “are an outlier in terms of indicators for heart problems”.

He tells me that there are 4 people in his practice who are out on a limb, as it were, for indicators of potential major heart issues, and I am one of them.

I understand this reasoning. Outliers stand out. That’s why they are called outliers. I am really out there on a limb. Who would not be concerned?

Then he tells me the deadly clincher: “One of these four died last week from a heart attack.”

This, of course, was meant to drive home the seriousness of the situation.

But, ever resourceful, I pointed out to him that, there you are: the one in four has had the heart attack already, so I’m safe!

He had no reply. My wife was dumbstruck.

Taking pity on my physician for his inability to attack my logic, I promised him, and my wife, that I would ignore my impeccable logic and follow his advice.

Thus far, EKG’s and ongoing tests indicate I am healthy.

The moral?

Statistics is a vital part of quantitative reasoning, but just because there’s very little chance of being hit by lightning doesn’t mean you won’t be.

1 Response to "Statistics of heart health"

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