PharmD Info

NNT stands for "Number Needed to Treat". It is a statistical measure used in medical research to determine the effectiveness of a particular treatment. The NNT represents the number of patients who need to be treated with a specific intervention to achieve one additional positive outcome compared to a control group.

To calculate NNT, you need to know two pieces of information: the event rate in the control group and the event rate in the treated group. The event rate refers to the proportion of patients in each group who experience the outcome of interest (such as a cure or improvement in symptoms).

Here's an example scenario to help explain how to calculate NNT:

Let's say you are conducting a clinical trial to evaluate a new medication for migraine headaches. You randomly assign 100 patients with migraine headaches to receive either the new medication or a placebo (a control group). After one month of treatment, you find that 20% of the patients in the medication group have experienced a significant reduction in the frequency and severity of their migraines, while only 10% of the patients in the placebo group experienced the same improvement.

To calculate the NNT in this case, you would first calculate the absolute risk reduction (ARR), which is the difference in event rates between the treated and control groups:

ARR = 20% - 10% = 10%

Next, you would calculate the NNT using the following formula:

NNT = 1 / ARR

In this case, the NNT would be:

NNT = 1 / 0.10 = 10

This means that for every 10 patients treated with the new medication, one additional patient will experience a significant reduction in the frequency and severity of their migraines compared to the placebo group.