What do they really mean in research studies?
Absolute risk of a disease is your risk of developing the disease over a time period. Absolute risk is most simply the difference between two risks. The same absolute risk can be expressed in different ways. For example, say you have a 1 in 10 risk of developing a certain disease in your life. This can also be said to be a 10% risk, or a 0.1 risk. Relative risk is used to compare the risk in two different groups of people. For example, the groups could be smokers and non-smokers. All sorts of groups are compared to others in medical research to see if belonging to a group increases or decreases your risk of developing certain diseases. Relative risk tells you absolutely nothing about the actual risk you are taking. |
It turns out, relative risk is a favorite way for advertisers and researchers to manipulate the data and our fears to sell their products.
Product X decreases your chance of getting cancer by 50%! - they exclaim.
Let’s take the Shingles vaccine as an example.
The vaccine lowers your risk of getting shingles, right? But how much?
Relative Risk statement: You have a 33% lower chance of getting shingles with the vaccine. Absolute Risk statement: Your odds go from 3% to 2% of getting shingles with the vaccine. |
Advertisements for this vaccine are always going to go with the Relative Risk statement, because it sounds better. But when you see the Absolute risk probability, it may not seem worth it to take a vaccine which doesn’t actually convey many benefits (a 1% reduction in odds) and may have side effects.
Want to learn more? This website is fun and easy to read and has great examples! https://atlasbiomed.com/blog/absolute-vs-relative-risk/
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