Medicine's Dirty Little Secret
May 08, 2008
There‘s one medical statistic doctors don‘t much talk about despite its importance. It‘s called number needed to treat, or NNT. It’s a measure developed in the past 20 years, and it’s one of the best-kept statistical secrets in medicine.
The idea of NNT is simple enough. Most clinical trials look at how much better people do on a particular medicine. NNT answers the question: How many people have to take a particular drug to avoid one incidence of a medical issue (such as a heart attack, or recurrence of cancer)? For example, if a drug had an NNT of 50 for heart attacks, then 50 people have to take the drug in order to prevent one heart attack.
That doesn’t sound like a lot, so pharmaceutical companies tend to keep the number quiet and focus on broader, U.S. population-based statistics. But that could be changed if you ask for the NNT up front the next time you‘re handed a prescription.