Should the patient really get the drug?
I recently gave a lecture to 70 primary care physicians here in Stockholm, titled “should the patient really get the drug?”. The lecture seemed to generate quite a bit of cognitive dissonance among some in the audience, based on the somewhat aggressive discussion that followed the lecture, which suggests to me that much of what I was saying was stuff they had literally never been exposed to before – not at any point in medical school, and not at any point during their careers after medical school either. Cognitive dissonance is good. It’s the first step towards change.
I thought it would be interesting to re-write the lecture as an article, so that more people can hopefully achieve similar levels of cognitive dissonance. Please feel free to share it with any doctors you know that you think might benefit from an expanded perspective. Anyway, here we go.
Let’s imagine a common patient. Every primary care physician meets this patient, or someone much like her, on an almost daily basis. She’s 75 years old, and overweight. She experienced a wrist fracture two years ago, and was subsequently diagnosed with osteoporosis. She has high cholesterol levels, but she’s never had a heart attack or other “cardiovascular event”. On top of that, she has type 2 diabetes, chronic knee pain due to osteoarthritis, and high blood pressure. She was diagnosed with depression a few years ago, after her husband died.
Our patient takes seven drugs every day:
- Alendronate, because of her weak bones.
- Atorvastatin, because of her high cholesterol levels.
- Sertraline, because of her depression.
- Metformin, because of her type 2 diabetes.
- Insulin, also because of her type 2 diabetes.
- Paracetamol (a.k.a. acetaminophen), because of her knee pain.
- Enalapril, because of her high blood pressure.
So, the question is, are these drugs doing her any good?
Well, to answer that question, we need to consider NNT (Number Needed to Treat). NNT is the number of patients who need to take a drug for one patient to achieve a noticeable benefit.
For alendronate, the NNT is 20, i.e. if you treat 20 people for a couple of years, you prevent one fracture. For atorvastatin the NNT is 200, i.e. you need to treat 200 people for five years or so in order to prevent one heart attack. For sertraline, the NNT is 7, which means that you need to treat seven people in order to have a noticeable effect on depression in one patient. Note that this doesn’t mean that one out of seven gets cured of their depression, it just means that there is a noticeable difference on a rating scale for depression.
For metformin, the NNT is 14 – If you treat 14 type 2 diabetics with metformin for ten years, you prevent one death. For enalapril, the NNT is 70 – If you treat 70 people with high blood pressure with enalapril for five years or so, you prevent one stroke.
For insulin, however, there is no NNT, because insulin has not been shown to result in any benefit on any clinically relevant outcome, even though big studies have been carried out that have included thousands of patients and followed them for five or ten years. Note here that we’re talking about insulin for type 2 diabetics. When it comes to type 1 diabetes, insulin is pretty much magical – you don’t even need to do a randomised trial in order to show benefit. People with type 1 diabetes virtually return from the dead when treated with insulin. But when it comes to type 2 diabetes, there is no benefit, at least not to any hard outcomes. All insulin has been shown to do is reduce blood sugar, but it’s never been shown to result in any meaningful patient oriented benefit for type 2 diabetics.
The same is true for paracetamol/acetaminophen. When it comes to patients with knee pain due to osteoarthritis, the drug doesn’t provide any benefit whatsoever.
Ok, so we have seven drugs, and we know what their NNT’s are. If we plus the probabilities of benefit together, then we get the probability that our 75-year old woman will benefit in some way from at least one of the drugs she’s taking. So, what probability of benefit do we get?
We get 30%. Only 30%.
What that means is that there is a 70% probability that this woman doesn’t benefit at all from any of the seven drugs that she takes every day for years on end!
More at......
https://sebastianrushworth.com/2022/06/14/should-the-patient-really-get-the-drug/
