Now, say you’re pushing 50. You’re healthy, but your doctor suggests you start taking a baby aspirin. Just in case, you know? That NNT is 2,000. That’s how many people have to take a daily aspirin for one (nonfatal) heart attack to be prevented. Statistically speaking: Not especially helpful.
It’s unfortunate, then, that the NNT is not a statistic that’s routinely conveyed to either doctors or patients. But you can look it up on a site that you’ve probably never heard of: TheNNT.com. Started by David Newman, a director of clinical research at Icahn School of Medicine at Mount Sinai hospital, the site’s dozens of contributors analyze the available studies, crunch the numbers on benefits and harms, and then post the results. While a low NNT is generally “good” and a high NNT is “bad,” you also have to consider the severity of both the illness and the drug’s side effects. Which is why the team added a color-coding system: Green for when a treatment makes sense, yellow for when more study is needed, red for when the harms and the benefits cancel each other out, and black when the harms outweigh the benefits.
Newman’s goal for the site is nothing short of a revolution in medical practice. He wants doctors to base their treatments on good scientific evidence, not tradition, hunch, and the fear that patients will see them as doing nothing. And he wants patients to start demanding such care. That’s the big picture, anyway. For now, he’d be happy if he could just get people looking at medicine in a different way. “People tend to think that if it’s a medical intervention, there’s science behind it,” he says. Unfortunately, that’s often not the case. “It is a lie to tell patients to do something without telling them, ‘You should know we’ve done lots of research on this and we can’t find any benefit to it.’”