Which statement is true about incidence measures?

• A. Cumulative incidence and incidence rate
• B. Point prevalence and period prevalence
• C. Mortality rate and case fatality rate
• D. Prevalence and incidence

Answer: (A)

Incidence measures focus on new disease occurrences over time rather than the existing pool of cases. Cumulative incidence (incidence proportion) estimates the risk that a person free of the disease at the start will develop it during a defined period, usually expressed as a proportion. Incidence rate (incidence density) estimates how fast new cases occur, accounting for the amount of person-time at risk (often expressed as cases per person-time, like per 1,000 person-years). Both are about new cases, so they are the incidence measures in question.

The other options mix prevalence concepts (point and period prevalence) with mortality concepts (mortality rate and case fatality rate) or pair prevalence with incidence, which does not describe incidence measures.