The Number Needed to Treat

I've written in the past about using data in understanding medical recommendations, particularly in the context of cancer screening, what with new recommendations about PSA (and mammogram) testing. You can see my earlier posts here, here, and here.

Today I am adding a new (for non-statisticians) concept, the number needed to treat. Put simply, the Number Needed to Treat is the number of people who need to take a medication, or have a procedure, in order, statistically, for someone to have a good outcome. Here's a great video, from the website TheNNT.com, explaining the concept:

Here's a link to the NNT's explanation in writing, for those of you who prefer to learn by reading.

Decisions about what procedure to have, or whether to start taking a medication, require the exercise of judgment. Adding the number needed to treat gives you one more piece of information to consider. If the number needed to treat is large, and the side effects sound daunting, then perhaps you might make a different judgment than when the number needed to treat is smaller. Among many other great features of the site is a quiz. The quiz gives you basic information about the medication (how the medicine is delivered, its cost) and the numbers (how many trials, how many patients, how many trials showed a benefit). Unlike other quizzes, this one is designed to help you practice weighing different factors about a medication. Because value judgments are involved, your answers may differ from the site's answers, but there is always an explanation.

There's a lot more to this site that I will take up in future posts. For now, this concept is definitely worth a look.