Absolute Risk Reduction (Arr) in a Clinical Trial 1

Question

Vignette: A new drug is being tested for its efficiency in treating a specific type of cancer. The clinical trial includes 2000 participants, half of whom are given the new drug and the other half a placebo. At the end of the trial, 400 patients in the drug group show significant improvement, while 200 patients in the placebo group show the same.

The researchers want to calculate the absolute risk reduction (ARR) to determine the effectiveness of the new drug over placebo. What is the ARR in this clinical trial?

Choices

A) 10%

B) 20%

C) 30%

D) 40%

E) 50%

Answer

B) 20%

Explanation

The Absolute Risk Reduction (ARR) is calculated by subtracting the event rate in the treatment group from the event rate in the control group. In this case, the event rate in the treatment group (those given the new drug) is 400/1000 = 40%, and the event rate in the control group (those given the placebo) is 200/1000 = 20%. Therefore, the ARR is 40% - 20% = 20%.

The Absolute Risk Reduction is a useful measure in assessing the effect of a specific treatment, as it shows the absolute difference in outcomes between a treatment and control group. In this case, the ARR tells us that the new drug reduced the risk of not showing significant improvement by 20% compared to the placebo.