There were quite a few really interesting responses to my previous newsletter attempting to answer the question “Should my dad be on Lipitor?” that inspired today’s follow up on cholesterol levels.
In that post, I mentioned that I think we prescribe too many statins for people who haven’t had heart attacks - an opinion that might make some of my colleagues think I’m an idiot.
After all, the national guidelines on cholesterol management recommend a statin for anyone who has a 10 year risk of a heart attack of more than 7.5%.
I think that this is insane.
We massively overstate the benefits of these medications with such a liberal guideline. The best case scenario is that taking a daily statin reduces risk of a first heart attack over a 10 year period of time from 8% down to 4%. And this may even overestimate the expected benefit.
There are caveats of course - some people certainly should be on these medications even without a prior heart attack or stroke - but I think the blanket recommendations get it wrong.
What’s the deal with this risk calculator?
Take a look at risk calculation according to the guidelines:
There is a lot of information that this calculator doesn’t incorporate that should be part of every patient’s cardiovascular disease risk assessment:
Family history
Chronic kidney disease
Chronic inflammatory disease
Insulin resistance without frank diabetes
Coronary artery calcium score
But perhaps my biggest problem with the risk calculator is that it totally oversimplifies the way the we look at your cholesterol bloodwork.
What do doctors get wrong about cholesterol numbers?
Cholesterol is considered a risk factor for heart disease because there are several different particles carrying cholesterol through our bloodstream that can get stuck in the walls of our arteries and lead to the development of heart disease.
The cardiovascular risk from these cholesterol particles can be thought of as a traffic problem.
The more cholesterol particles we have traveling through our bloodstream, the higher our risk of getting them stuck in the artery walls and leading to heart disease.
In other words, the more cars on the road, the greater the traffic.
To continue our traffic analogy - if you want to know the traffic on 1st Avenue and I tell you that there’s 1000 people going uptown on that road, you’d probably feel like that didn’t provide enough information about the amount of traffic you should expect.
This is what a standard cholesterol panel tells you. A measurement of LDL on a cholesterol panel is an LDL-cholesterol measurement, not a particle measurement.
To understand the traffic, wouldn’t it be helpful for us to know if our 1000 hypothetical passengers were traveling in 1000 cars or in 10 buses?
The standard cholesterol panel only tells us information about the number of passengers on the road, but not the number of vehicles that they’re traveling in.
Without more specialized testing, you’re left guessing about the total number of vehicles, the amount of traffic, and your risk of heart disease based on cholesterol numbers.
But isn’t a standard cholesterol panel a good proxy for the traffic numbers?
Sure - on average, across a population, the standard bloodwork gives a good estimation about the total amount of traffic.
But why should you care about the average numbers across a population when you’re making individual decisions about your own medications?
If your cholesterol numbers track with your particle numbers, we call that concordance. And if you’re concordant, that’s great, and a standard cholesterol panel may be just fine for you. But there are lots of patients who have discordant cholesterol and particle numbers.
And if you are one of these patients, the traffic in your arteries is best predicted by vehicles, not passengers.
The test that needs to be done - and that I do on all of my own patients - is measurement of a substance called apolipoprotein B (or ApoB), which measures the total number of cars on the road.
This discussion went on longer than anticipated, so I think it’s time to wrap up. There’s a lot more about personalized heart disease risk that we’ll save for later newsletters.
PS: If you’re enjoying my newsletter, please subscribe and share on social media!