Number Needed to Treat is an aggregate measure of clinical benefit that medical study geeks love because it has a comprehensibility lacking in odds ratios and relative benefit percentages.

It represents the number of patients that would need to receive a treatment for one of the patients to avoid an adverse outcome (death, stroke, development of diabetes, high cholesterol). For instance, say we want to want to put people on a Mediterranean Diet after a first heart attack. How many heart patients would we have to put on a Mediterranean Diet to save one life? Here’s the answer from thennt.com: 30!

That’s pretty good, especially with no known harm. And it’s easy to conceptualize.

I was reminded of how few people ever come into contact with the NNT when I read the excellent thread in this NPR post.

If you don’t know the NNT metric, click that link and learn about it. It’s a great way of conceptualizing the benefit of interventions, and it may even help you think about your own work in a different way.