My thanks to Dr. John Mandrola of theheart.org/Medscape Cardiology for the idea for this post. Dr. Mandrola is an interventional cardiologist but I forgive him for that because he also reads the fine print and dares to question the status quo, particularly when it comes to preventive medicine.
An interesting paper came out this month in the on-line medical journal Open Heart (a branch of the British Medical Journal) about one particular area of prevention – heart attack. The researchers used data from a class of cholesterol drugs called statins, such as Lipitor, which have been shown to have a significant benefit in preventing ischemic heart disease (the study cites evidence that statins can decrease cardiovascular death by 20-30%, a number in some dispute). You can find the whole thing here: http://openheart.bmj.com/content/3/1/e000343.full#aff-1.
The researchers crunched a bunch of numbers and talked to a bunch of people, and these were the results, in part:
- 50 year old smoker with high blood pressure and high cholesterol could have his life extended by up to two years by taking a statin.
- An healthy 50 year old who starts preventive treatment with a statin at 50 can see a lifespan gain of a mean of 7 months.
- BUT, of 100 of those healthy 50 year old men, 93 will see no life extending benefit at all. The other 7 gain a mean of 99 months. 99 months!
- Starting statins later than 50 does not increase the life extending benefit. Quite the opposite.
- Of those healthy 100 50-year-olds, there is no way to tell which ones will be in the group of 7.
But here’s the most interesting part of the study – The researchers went down to the Underground (it’s a UK study) and asked around 400 people a simple question: “Which would you choose – to take a medication that would guarantee you one extra year of life or to take a medication that gives you a 2% chance of living an extra 10 years?” Then they extended the question – “How about if the medication gave you a 10% chance of living an extra 10 years?” and so on up to a 50% chance. As you might expect, as the percent chance of getting the 10 years went up, more people chose the chance option. But, there was always a significant percentage of people who never took the chance option.
So in a certain sense, taking a primary preventive medication, in this case a statin, is a game of chance. Do you choose to take the medication in the hope you are one of the 7 or do you opt out based on the probability that you’re not? How much risk are you willing to assume, all other things being equal? The answers to these questions varies greatly among individuals.
Of course, there are many other factors that go into the decision to start a medication to prevent an illness you might or might not ever get. There are considerations about side effects, cost, life-style, quality of life, etc. However, all or most of those considerations are also subject to probabilities and subjective preferences. Plus, you could die of something besides heart disease that you didn’t take a drug to prevent (or maybe you did but we all have to die of something and sometimes bad stuff just happens.) The take-home is that medicine is not an exact science and every person is different. What is an acceptable risk for one is an unacceptable gamble for another. Here’s what Dr. Mandrola says:
The point of this work is that it brings statistics, probability, and cognitive psychology to the doctor-patient relationship. When it comes to treating people with risk factors, not diseases, embracing uncertainty has always been important. But, now, as technology increasingly measures the human condition and creates more risk factors, comfort with gambling in medical decisions has never been more vital.