The Shocking Story of the Celebrity Face of Lipitor- Understanding Absolute and Relative Risks in Critical Appraisal
Have a good look at the above advertisement.
Your patient has seen this advertisement and asks you: “Out of a 100 people, how many people would not have a heart attack by taking Lipitor?”
a) 36 out of 100
b) 67 out of 100
c) 1 out of 100
d) 6 out of 100
Hints:
1. Look at the bottom left corner.
2. Your patient is interested in the Absolute Risk Reduction (ARR), not the Relative Risk Reduction (RRR).
3. Answer is at the end of this post along with explanation of Absolute and Relative Risks in a short video.
If you got that right, well done! If you didn’t, don’t worry you’re not alone. Similar questions have been posed to doctors, executives and researchers across the world with very poor results.
In one study (Fahey 1995 BMJ), only 3 out of 140 executives wanted to see further information before committing to making a purchasing decision when numbers on 4 cardiac rehabilitation programmes were given. The others made a decision purely on numbers. In her meta-analysis on the effect of presenting information in terms of absolute risks vs. relative risks, Covey (Medical Decision Making, 2007) analysed 13 experiments that consistently showed that physicians can be manipulated by framing the treatment effect differently.
So what happened to Dr Jarvik, the celebrity endorsement for Lipitor and the inventor of the artificial heart? The NY times writes the following:
“The campaign had come under scrutiny from a Congressional committee that is examining consumer drug advertising and has asked whether the ads misrepresented Dr. Jarvik and his credentials. Although he has a medical degree, Dr. Jarvik is not a cardiologist and is not licensed to practice medicine… One television ad depicted Dr. Jarvik as an accomplished rower gliding across a mountain lake, but the ad used a body double for the doctor, who apparently does not row… The committee disclosed that Pfizer had agreed to pay Dr. Jarvik at least $1.35 million under a two-year contract that expires next month.”
Inventor of the artificial heart? Well that was questioned as well. So much for direct to consumer advertising (DTCA); a 4 billion industry. Let’s get back to doing what we’re good at. Read the full article.
Have a look at the following video for some further information into Absolute and Relative Risks.
Click on bottom right corner (Tube) to view on large screen mode.
The correct answer is option c) 1 out of 100 (Absolute Risk Reduction). The 36 percent reduction mentioned is the Relative Risk Reduction (used because 36% sounds better than than 1% ARR, although ARR is a more accurate and transparent measure of effect). The NNT for lipitor is 100.