Tuesday, September 21, 2010

Risky business

At my annual physical exam last week, my primary care doctor employed a widely used web-based calculator to plug in cholesterol levels and other risk factors to estimate my likelihood of having a heart attack during the next ten years. I thought this was a neat idea until it produced an answer of 8%.

Wait, you mean I have a one in twelve risk of a heart attack over the next decade? That sounded really high. She calmly and thoughtfully explained that the main value of the algorithm was to help make a judgment about prescribing statins or other interventions that could lower risk. She also noted that anything under 10% at my age was a very good number.

So, I was going to write this post to tell this story and to make the point that these kinds of estimates can be shocking for the uninformed unless we have a context within which to interpret them.

I was also going to assert that the estimates give an impression of precision that may not be valid. What is the standard deviation around the estimate? How often is the actual estimate found to be true?

And, then, like a deus ex machina, the New York Times published this story about the very heart risk calculator that we had been using. The pertinent excerpt:

A new study finds that a widely used version of the ubiquitous heart attack risk calculator is flawed, misclassifying 15 percent of patients who would use it — almost six million Americans, of whom almost four million are inappropriately shifted into higher-risk groups that are more likely to be treated with medication.

Wow. So I revert to my doctor's excellent advice about diet, exercise, and other life style factors as the main things on which to focus over the next ten years.

10 comments:

Anne Marie said...

Was just talking to @diharrison about this very topic this afternoon. So if you had access to your primary care record and you had found out that your doctor had already made that calculation, how would it have been best to explain the meaning? Do any existing systems do this well?

This is exactly the kind of interaction (doctor-initiated, based on a protocol) that would seem not to neccessitate a face-to-face interaction. What would have been lost or gained through using other media to get this message to you? Do you even need to be informed that you are 'low risk'? You should still take the same general health measures as everyone else after all.

Thanks for sharing,
Anne Marie

The Medical Quack said...

Don't you just love the fact that we are now exploring accuracy in the data and queries we use:) It's been one topic I have been looking at quite a bit too. One instance in particular was the rating of MDs and hospitals, one of those topics we all kind of love to dispute:)

Anyway, I stumbled upon the fact that HealthGrades who touts their excellence, was listing "dead doctors" and I think all the information is still there as I found my former obgyn on the list who passed away from breast cancer over 7 years ago, and it even shows she takes HeatlthNet! So, here we go with finding accuracy with data on the web. I'm sure I didn't make too many friends with the post since Heatlhgrades was just purchased by a private equity firm and investors thought they didn't pay enough?? With inaccurate data as such who need more money?

Anyway, here's the link to the post and maybe you might want to see if the MDs at your hospital are up to date here too:)

http://ducknetweb.blogspot.com/2010/09/healthgrades-and-other-md-rating-and.html

There are also several other sites listing my same deceased MD too so that data base may be sold for use with other referral sites too I am guessing.

We do need and deserve accurate data today in all areas of healthcare, especially from those who profess and market their services as the authorities:) You can't always believe everything you read and hear today.

Anonymous said...

If I am reading the NYT article correctly, they make the original calculator available. (see sentence in article that highlights 'original calculator.') Now that you're being an e-patient, it would be interesting to plug your values into that supposedly more accurate calculator, and let us know what you get for comparison - unless it's horrible. (:

nonlocal

Paul Levy said...

I think I'll just ride a few extra miles on the bicycle instead . . .

Leigh Hamby said...

These kinds of things make me wonder about any sinister intentions of our healthcare industry to mislabel the well as "sick" (see work of H Gil Welch from Dartmouth) and if that will change if/when incentives change for us in the future. Currently we can often get paid more for "sick" than we can for keeping you "well"

Roz said...

I've ditched the car and do the school run by foot now which is a good 2 1/2 miles each day! Keeps the dog fit too :)

76 Degrees in San Diego said...

Ditch the bike and get an elipitical.

http://www.cdc.gov/homeandrecreationalsafety/bikeinjuries.html

Daniel said...

From Facebook:

This is an interesting topic. A few years ago, I calculated a risk score for a patient. I was trying to impress on him that he was at very high risk for a cardiovascular event, and indeed, his risk score turned out to be about 30%. To my surprise, he seemed reassured by this, telling me, "So the odds are in my favor, doc. I probably won't have a heart attack".

David said...

From Facebook:

Not the best risk communication from your primary in the first place, nor is the calculator, even if accurate. Risk is subjective, a feeling. The same number can feel completely different from one person to the next, and prompt significantly different behavioral response. Such tools are based on the presumption that humans can be rational about risk, an irrational presumption that flies in the face of overwhelming scientific evidence and real world experience that confirms that when it comes to risk we are AFFECTIVEs, not rationalists.

Paul Levy said...

No, my PCP did a fine job on the topic. Sorry if I left another impression.