How To Calculate: The Number Needed to Treat (NNT)

The Number Needed to Treat (NNT) is a measure used in epidemiology and clinical research to determine the number of individuals who need to receive a specific treatment over a defined period to prevent one additional adverse outcome, or to achieve one additional beneficial outcome. In your case, you are calculating the NNT to prevent one additional heart attack event based on the Absolute Risk Reduction (ARR). Here's a bit more theory behind it: Absolute Risk Reduction (ARR): ARR is a measure of how much a particular treatment or intervention reduces the risk of an adverse event compared to a control group or baseline. It is calculated as the difference in the event rate (risk) between the treated group and the control group. In your scenario, the ARR is 5.1%, which means that the treatment reduces the risk of a heart attack by 5.1 percentage points compared to not receiving the treatment. NNT Formula: The NNT is calculated using the formula: NNT = 1 / ARR The NNT represents the number of patients that need to be treated for a certain period to prevent one additional adverse outcome. In this case, you're calculating the NNT to prevent one additional heart attack. Interpreting the NNT: A lower NNT indicates that the treatment is more effective, as it takes fewer patients to be treated to prevent one adverse event. Conversely, a higher NNT suggests that the treatment is less effective, as more patients need to be treated to prevent a single adverse event. In your case, with an ARR of 5.1%, the NNT is approximately 20. This means that you would need to treat 20 individuals with the given treatment to prevent one additional heart attack event compared to not providing the treatment. A lower NNT would indicate a more potent treatment in reducing the risk of heart attacks, while a higher NNT would suggest a less effective treatment. Problems: The proportion of any normal distribution that lies within ±2 standard deviations of the mean is? A) 50% B) 68% C) 95% D) 99% If the calculated absolute risk reduction (ARR) for heart attack event was 5.1%, what would be the number needed to treat? A) 11 B) C) 3.2 D) 20