How excited would you be about a medication that lowered your risk of cardiovascular death, heart attack, or stroke by 1.5%? Excited enough to spend a few thousand dollars a year on the drug? I expect not.
What if, instead, the drug reduced those same terrible outcomes by 20%? That’s probably enough benefit to interest some in the drug.
Well, those statistics come from the same clinical trial, evaluating the same drug. In fact, they present the exact same results, but they simply do it in different ways. The 1.5% number refers to the absolute reduction in the risk of those outcomes—the drug reduced the two-year risk of cardiovascular death, heart attack, and stroke from 7.4% to 5.9%. That’s an important reduction by any account. That’s on par with many medications that have become critical in combating cardiovascular diseases. But that 1.5% reduction sounds much less impressive than the “20% reduction” that the authors describe in the discussion section of their New England Journal article, and was repeated, practically verbatim, by the physician who wrote an accompanying editorial in the same journal.
How can these experts claim a 20% reduction in risk when the study showed only a 1.5% reduction? Because 1.5% is approximately 20% of 7.4%. When summarizing the impact of this drug, the researchers and the editorialist chose to emphasize the relative risk reduction of the treatment rather than the absolute risk reduction.
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