There’s one medical statistic doctors do not discuss openly 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 today’s 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.
But that could be changed if you ask for the NNT up front the next time you’re handed a prescription.
Many Drugs are “Worse Than a Lottery Ticket” According to Dr. Nortin M. Hadler, professor of medicine at the University of North Carolina at Chapel Hill, in Business Week:
"Anything over an NNT of 50 is worse than a lottery ticket; there may be no winners."
Well, the NNT for some cholesterol-lowering drugs has been figured at 250 and up, even after taking them for five years!
"What if you put 250 people in a room and told them they would each pay $1,000 a year for a drug they would have to take every day, that many would get diarrhea and muscle pain, and that 249 would have no benefit? And that they could do just as well by exercising? How many would take that?" Dr. Jerome R. Hoffman, professor of clinical medicine at the University of California at Los Angeles, asked Business Week.
The answer, of course, is few to none. And that is exactly why you have probably never heard of NNT before.