In comparing incidence rates between groups, use of age-specific incidence rates controls for difference in the age composition of the groups.

• A. False
• B. True
• C. Not applicable
• D. Not sure

Answer: (B)

Differences in age distribution can distort comparisons of how often a disease occurs, because risk often varies with age. By calculating incidence within each age group (age-specific rates), you compare groups within the same age bands, so age acts less as a confounder. When you want an overall comparison, these age-specific rates can be combined through standardization to produce an age-adjusted rate, ensuring the comparison isn’t biased by different age structures. Therefore, using age-specific incidence rates to compare groups does control for differences in age composition.