Archive | 06/06/2008
Evil

Medicine’s Secret Stat: NNT

One of the best-kept statistical secrets in medicine is called the Number Needed to Treat, or NNT. You won’t hear doctor’s talking about it though…

The idea of NNT is fairly simple. Clinical trials evaluate how much better people do on a particular medicine versus placebo. 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 has an NNT of 50 for heart attacks, then 50 people have to take the drug in order to prevent just one heart attack.

Pharmaceutical companies tend to keep this number quiet and focus on broader statistics. But that could be changed if you ask for the NNT up front the next time you’re handed a prescription.

In Business Week, Dr. Nortin M. Hadler, professor of medicine at the University of North Carolina at Chapel Hill, admits: “Anything over an NNT of 50 is worse than a lottery ticket; there may be no winners.”