Health literacy is might be the most important concept to understand when you work as a doctor who takes care of patients.
Understanding a person’s health literacy is the key to communicating effectively about medical concepts.
And unfortunately, low health literacy is one of the major risk factors for someone to have poor health.
Health literacy isn’t a skill that’s easily improved, as it’s actually a function of a number of other skills - to be health literate requires some reading ability and some mathematical understanding along with analytical skills like ability to weigh risks and benefits.
Improving the health literacy of my readers is one of the things that I try to focus on in this newsletter.
Today we are going to focus on heart disease prevention concepts that everyone should understand in order to think through whether different treatments make sense for you, given your values and preferences.1
The first concept: risk reduction
I’ve had many patients tell me that they didn’t want to take any medicine unless they “really had to” take it.
When I dig into what “really have to” means, what I’ve found is that people often don’t want to take a medication unless it’s definitely going to prevent something bad from happening.
But there’s no magic bullet that prevents you from having a heart attack - we can’t just give you a treatment that ensures you won’t have something bad happen.
As they say, prediction is hard, especially about the future.2
If we knew what was going to happen, then medicine would be easy and you could just go to the oracle instead of the doctor.
Since we don’t have certainty about what will happen down the road, we use things like risk calculators to help estimate the likelihood of something bad happening.3
Your doctor can help you make a probabilistic assessment of your likelihood of having a heart attack over the next 10-30 years, but that assessment is going to be based on population-wide data and will always be an incomplete and imprecise way of determining any individual’s risk.
Every single method of estimating risk gets things wrong, but that doesn’t mean that they don’t have value.
All models are wrong, but some models are useful.
Thinking in probabilities is not intuitive for people, but it’s the way that we should be thinking about heart disease.
And so when we recommend a treatment for something like hypertension or hyperlipidemia,4 we are doing it to reduce risk, not because we think it’s definitely going to prevent a heart attack.
The corollary to risk reduction: absolute versus relative risk
On average, treating high blood pressure lowers the chance of a stroke or a heart attack by about 40% over a few years of a treatment period.
On average, treating hyperlipidemia lowers the chance of a heart attack or a stroke by about 25% over a few years of a treatment period.5
The magnitude of benefit that you receive depends on your initial risk to begin with.
If you have a 50% risk of a heart attack and we lower that risk to 30% by treating your hypertension, that’s pretty damn good and I think most people would take that.
But if you have a 5% risk and we lower it to 3% with medical treatment, a lot of people wouldn’t be interested in going on medications.
This gets to the concept of relative risk versus absolute risk.
Both of those hypothetical situations have a 40% relative risk reduction, but the absolute risk reduction is very different.
And so understanding where you are is vital to understand how likely any preventive treatment is to benefit you.
For some people, any risk reduction makes sense to take a medication that doesn’t have side effects.
For others, small absolute risk reductions aren’t worth taking a daily pharmacologic therapy.
Risk is partly based on cumulative exposure and partly based on luck
The concept of “cholesterol years” is gaining traction in the preventive cardiology space.
This is the idea that cumulative exposure to one of the risk factors for heart disease dictates our risk.
It’s why you see that most people in the preventive space believe in starting treatment earlier rather than later:6
But exposure over time doesn’t explain everything.
We’ve all heard an anecdote of a person who “did everything right” and still had a heart attack, and I’ve certainly seen quite a few cases like this.7
A lot of heart attacks seem to be based on luck and circumstance rather than just exposure to risk factors over time.
And so while there’s something to be said for earlier treatment being compelling when it comes to cumulative risk, the uncertain nature of disease progression and the way that luck plays a role is another thing to consider when we contemplate medical treatment.
Another really important concept: asymmetric risk
We’ve been talking so far about risk and risk reduction, but it’s vital to understand that all risk isn’t the same.
If you have a 5% chance of having a heart attack, then there’s a 95% chance that you won’t and you will be fine.
And even in that 5% chance of a heart attack, the likelihood that you will die or have your life forever changed because you develop heart failure from the heart attack isn’t all that high.
A lot of heart attacks are mild and end up with either medical therapy or a stent but ultimately no major change in the quality of a person’s life.
But the point here is that the risk of a really terrible outcome may be small, but its impact on your life could be catastrophic.
There is asymmetry in the risk when it comes to preventive medicine.
The risk of that terrible outcome - like a huge heart attack or a life changing stroke - is really quite low, but the consequences of that rare event happening are devastating to you.8
The risk of overtreatment is high, but ultimately that’s a pretty inconsequential risk to take - you have side effects from the treatment and we stop the treatment and consider something else.
The concept is asymmetric risk is part of why, in my opinion, the most boring controversy in medicine is the concern about statin side effects.
The reason that I think it’s a boring controversy is that the stakes are so low - if you have side effects, we stop the drug, and the side effects go away.
If you don’t have side effects, then you can stay on the medication and go on with the rest of your life while you benefit from a reduction in heart attack and stroke risk.
Understanding that even if the numerical likelihood of something happening is low, the possibility of that rare outcome forever changing your life may change your own personal risk tolerance and medical decision making.
Ultimately, your values and preferences matter more than your doctor’s concept of risk
At the end of the day, I don’t think that my job is to order people around about what medications they should and shouldn’t be taking.9
Yes, I do sometimes practice that type of medicine when my impression is that the situation needs it - or when someone asks me “doctor, what do you think I should do?”
But when people understand these concepts - risk reduction, absolute versus relative, cumulative exposure and the role of luck, asymmetric risk - it’s easy to get a sense of whether treatment makes sense in the individual context.
Understanding risk and then integrating it with your personal preferences and values makes most preventive medicine straightforward.
So I’m hopeful that this discussion might help make your next doctor’s visit a little bit more productive.
My opinion is that most medical care should be personalized so that you’re making decisions taking into account a person’s goals and preferences. Medicine by algorithm isn’t great with the concept of personalizing, which is why I try to work differently.
Not clear to me if this famous quote is from Yogi Berra or Niels Bohr.
I’ve written before about the problems with risk calculators and how they miss a lot of important clinical information that pertains to likelihood of developing heart disease.
The medical (and precise) term for high cholesterol.
Both of those numbers are approximations from heterogeneous studies. The actual benefit is going to be different based on how well you control the problem and how long you treat someone for.
One of the strong counterarguments to the notion of early treatment is that this is a hypothesized benefit rather than one that’s been proven in very long term clinical trials. I find the “cholesterol years” hypothesis to be compelling, but let’s be honest that it’s a hypothesis rather than certain fact.
The exposure over time concept explains a lot of overall heart disease - total burden of plaque in the arteries probably correlates very well with cumulative risk factor exposure. But a heart attack is caused by one of those plaques bursting and causing a blood clot, which is the part of this process that’s really beyond our predictive capabilities. That’s where luck comes in - we don’t know who is going to rupture a plaque and who is going to have their plaques stabilize over time.
There’s a similarity between asymmetric risk and the mathematical concept of expected value. I also think of the barbell investment strategy as having some applicability here - understanding that not all risk is equal really matters when we are making decisions.
If you’re wondering why I’m only talking about prescription medications and not about lifestyle changes like exercise and diet, it’s because that’s what a lot of the decision making in a doctor’s visit is about. I spend a significant amount of my time talking with patients about exercise and diet, but I don’t think that’s what most of my patients are hoping to get out of our visit.