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.
Time February 15, 2007
When the NNT statistic was first developed in 1988, it was intended to help you make a decision about whether or not to take a drug. After all, having it put in simple terms such as “Out of every 50 people who take this drug, perhaps one heart attack will be prevented, and the other 49 people will receive no benefit,” puts things into perspective … a perspective that the drug companies do not want you to see.
One of the most blatant examples of how drug companies have hidden NNT for their own self-serving purposes lies with cholesterol drugs. These drugs, which can cause side effects like liver damage, muscle weakness, cognitive impairment and many, many others, are touted as miracle pills that can slash your risk of a heart attack by more than one-third.
Well, BusinessWeek actually did a story on this very topic earlier this year, and they found the REAL numbers right on Pfizer’s own newspaper ad for the cholesterol-lowering drug Lipitor. Upon first glance, the ad boasts that Lipitor reduces heart attacks by 36 percent. But there is an asterisk. And when you follow the asterisk, you find the following in much smaller type:
"That means in a large clinical study, 3% of patients taking a sugar pill or placebo had a heart attack compared to 2% of patients taking Lipitor."
What this means is that for every 100 people who took the drug over 3.3 years, three people on placebos, and two people on Lipitor, had heart attacks. That means that taking Lipitor resulted in just one fewer heart attack per 100 people.
The NNT, in this case, is 100. 100 people have to take Lipitor for more than three years to prevent one heart attack. And the other 99 people, well, they’ve just dished out hundreds of dollars and increased their risk of a laundry list of side effects for nothing.Not to mention that this study was funded by the industry, which means their results may already be skewed, and the actual benefit may be even LESS than what they found.
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.
The Moral of the Story: Don’t Trust the Drug Companies
They have many tricks up their sleeves other than NNT, and they are masters at twisting the results of their studies to appear in a positive light. So anytime you hear about how great a drug is, be very suspicious. You wouldn’t simply buy a car without finding out the real bottom line, right? So don’t blindly accept the numbers that the drug companies peddle either.
One thing you can do is ask your doctor or pharmacist to tell you the NNT for any prescription you’re considering.
Even better is to assume that most drugs offer little benefit, and only take them as an absolute last option. You have the power to take control of your health and thrive without the need for drugs. The drug companies want you to believe otherwise, but now you too know better.