HealthNewsReview.org | Independent Expert Reviews of News Stories | Holding Health and Medical Journalism Accountable

Why does this Matter?

• Many news stories tell us how wonderful a new treatment, test, product or procedure may be. Few provide helpful numbers to back that up.
• We have seen that news stories, drug ads, and some studies in journals tend to report benefits as the relative reduction in the frequency of something bad happening. For instance a drug is said to reduce the risk of hip fracture by 50 percent. But the absolute risk reduction is really only from 2 in 100 who don't take the drug to 1 in 100 who do take it. It is true that 1 percent is half - or 50% - of 2 percent. But we think the relative risk number tends to inflate the impression of how much impact the drug has. The absolute risk reduction is 1 percent (2 percent minus 1 percent). When you hear about treatments that have an effect of 20 percent, 30 percent, 40 percent or higher, we encourage you to ask yourself, "50 percent of what?" That will help you remember: it may only be from 2 in 100 to 1 in 100.
• Another question you might ask is, "How many people have to be treated in order to prevent even one problem?" With cholesterol-lowering stating drugs, the number might be 50. TIME magazine once published a column on the Number Needed to Treat (NNT), calling it "Medicine's Secret Stat." And BusinessWeek published a story on the NNT for statin drugs.
• If you hear glowing patient anecdotes about how well something worked, always ask yourself if that was a representative example. A single unchallenged exaggerated success story can throw the whole framing of benefits out of balance.