The “Relative risk” of 0.25 indicates-
**Core Concept**
Relative risk is a measure of the ratio of the probability of an event occurring in the exposed group versus the non-exposed group. It is used to quantify the association between an exposure and an outcome in epidemiological studies.
**Why the Correct Answer is Right**
A relative risk of 0.25 indicates that the exposed group has a 75% reduced risk of developing the outcome compared to the non-exposed group. This means that if 100 individuals in the non-exposed group develop the outcome, only 25 individuals in the exposed group would develop it. This is because the relative risk is the inverse of the risk ratio, and a value less than 1 indicates a reduced risk. In this case, the relative risk of 0.25 is equivalent to a risk ratio of 1/0.25 = 4, indicating a 75% reduced risk.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided.
**Option B:** This option is not provided.
**Option C:** This option is not provided.
**Option D:** This option is not provided.
**Clinical Pearl / High-Yield Fact**
When interpreting relative risk, it's essential to consider the baseline risk of the outcome in both groups, as a small change in relative risk can have a significant impact on absolute risk. Additionally, a relative risk of 0.25 is equivalent to a number needed to treat (NNT) of 4, indicating that 4 individuals need to be treated with the intervention to prevent 1 outcome.
**Correct Answer: D. The exposed group has a 75% reduced risk of developing the outcome compared to the non-exposed group.**