We read information about pharmaceutical drugs and how they will lower cholesterol or blood sugar by a huge percent. So we should jump on the bandwagon and begin taking them, right? I am reading an excellent book called The Great Cholesterol Myth by Dr. Stephen Sinatra and Dr. Jonny Bowden. I highly recommend it. It’s clear, easy to read and understand and grounded in facts. In fact, I plan to buy a copy for my husband’s doctor before his next visit and highlight some pages!
They did an excellent explanation of the difference between absolute versus relative risk. Depending on which number is being used will make a huge difference in whether you would get any real benefit from using the drug. All too often, relative risk is used.
Absolute risk is the real reduction in risk you get from using the specific drug. They used a great illustration that really make the distinction clear to me. They said what if you are on a game show and you get to choose 90% of the money behind door #1 or 10% of the money behind door #2? If there was the same amount of money behind both doors – it’s a no-brainer. Choose 90% of door #1. The point is, unless you know how much money is behind both doors, it’s impossible to know which choice is better.
So knowing the real, absolute number is very important in making these decisions. Knowing a percentage alone really means nothing, unless you know what it is a percentage of! What if there was $100 behind both doors. 90% sounds like a lot. However, if you chose that door and found it was only $90 you would be disappointed. But it is 90% of 100 so technically it’s the truth.
Lipitor advertises a 33% reduction in heart attack risk in their ads. What they don’t tell us is that it’s a relative risk number. If there are 100 randomly chosen men not on any medications. Of those 100 men, statistics say 3 are likely to have a heart attack over a 5 year period. That’s 3% of the total number of men. However, if you put those men on Lipitor, only 2 men would be expected to suffer a heart attack (that’s 2%). The reduction from 3 men to 2 is a 33% reduction, which is a relative number, although technically true. The absolute risk reduction is only 1%. (Doesn’t sound that impressive when you see the actual numbers, does it?)
Wouldn’t you rather know the absolute risk?
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