If the relative risk is less than 1 for a negative health outcome, what does this indicate about risk in the exposed group?

• A. Increased risk in the exposed group.
• B. Decreased risk in the exposed group.
• C. No difference in risk.
• D. Not enough information to interpret.

Answer: (B)

Relative risk compares how often the adverse outcome occurs in the exposed group versus the unexposed group. When this ratio is less than one, the exposed group has fewer events, meaning the risk is reduced in those who were exposed. For example, if 2% of the exposed develop the outcome and 4% of the unexposed do, the relative risk is 0.5, signaling a decreased risk with exposure. If the ratio were greater than one, risk would be higher in the exposed group; if it were about one, there would be no difference. Not enough information would be needed only if you couldn’t compute the ratio from the data.