Wilson also performed another estimable service: he highlighted the difference between relative risk and absolute risk. Relative risk is the statistical difference in outcome between a control group and a group taking an active drug in a study, whereas absolute risk is the actual number of people who might actually benefit from the drug. Most randomized clinical trials only report relative risk, which often inflates the benefits of the drug being studied.
So, as Wilson explained:
The rate of heart attacks, for example, was 0.37 percent, or 68 patients out of 8,901 who took a sugar pill. Among the Crestor patients it was 0.17 percent, or 31 patients. That 55 percent relative difference between the two groups translates to only 0.2 percentage points in absolute terms — or 2 people out of 1,000.
And then he goes on to put the difference into even clearer context:
Stated another way, 500 people would need to be treated with Crestor for a year to avoid one usually survivable heart attack. "That’s statistically significant but not clinically significant,” said Dr. Steven W. Seiden, a cardiologist in Rockville Centre, N.Y., who is one of many practicing cardiologists closely following the issue.
Well done, Duff!
On another note, I just wanted to let readers know that I am taking a hiatus from weekly blogging. I may still wade in now and then to blog about a timely issue (when I can't resist), but it's time to turn my attention to another project.