Differences
This shows you the differences between two versions of the page.
| Both sides previous revision Previous revision Next revision | Previous revision | ||
| nnt [2025/02/07 14:58] – [Examples of Low NNT] andrewtaustin | nnt [2025/02/07 15:09] (current) – [Numbers Needed to Treat (NNT)] andrewtaustin | ||
|---|---|---|---|
| Line 1: | Line 1: | ||
| - | ====== Numbers Needed to Treat (NNT) ====== | + | {{tag> |
| + | ====== Numbers Needed to Treat (NNT) ====== | ||
| The Number Needed to Treat (NNT) is an important concept in evidence-based medicine (EBM). It represents the average number of patients who must be treated with a specific therapy or intervention for one additional patient to benefit compared to a control group (often a placebo or standard of care). The NNT is derived as the inverse of the Absolute Risk Reduction (ARR), providing a practical measure of clinical effectiveness. | The Number Needed to Treat (NNT) is an important concept in evidence-based medicine (EBM). It represents the average number of patients who must be treated with a specific therapy or intervention for one additional patient to benefit compared to a control group (often a placebo or standard of care). The NNT is derived as the inverse of the Absolute Risk Reduction (ARR), providing a practical measure of clinical effectiveness. | ||
| + | |||
| + | In short, NNT represents the number of patients who must be treated to prevent one additional negative outcome or achieve one additional positive outcome. | ||
| ===== Definition and Calculation ===== | ===== Definition and Calculation ===== | ||
| - | Absolute Risk (AR): The proportion of patients experiencing an event in a group (e.g., 10% of patients have a heart attack in a control group). | + | **Absolute Risk (AR)**: The proportion of patients experiencing an event in a group (e.g., 10% of patients have a heart attack in a control group). |
| - | Absolute Risk Reduction (ARR): The difference in the absolute risk between the treatment group and the control group. | + | |
| - | Formula: //ARR = AR_control - AR_treatment// | + | **Absolute Risk Reduction (ARR)**: The difference in the absolute risk between the treatment group and the control group. |
| - | Number Needed to Treat (NNT): The inverse of the absolute risk reduction. | + | |
| - | Formula: //NNT = 1 / ARR// | + | **Formula**: //ARR = AR_control - AR_treatment// |
| + | |||
| + | **Number Needed to Treat (NNT)**: The inverse of the absolute risk reduction. | ||
| + | |||
| + | **Formula**: //NNT = 1 / ARR// | ||
| For example, if the incidence of a particular outcome (e.g., myocardial infarction) in a control group is 10% and the incidence in the treatment group is 5%, the ARR is 0.05 (or 5%). | For example, if the incidence of a particular outcome (e.g., myocardial infarction) in a control group is 10% and the incidence in the treatment group is 5%, the ARR is 0.05 (or 5%). | ||