Which of the following best describes an incidence rate?

Per the NAHQ CPHQ exam blueprint, incidence rates are fundamental epidemiologic measures used to evaluate risk and occurrence of new events over time. Incidence specifically measures new cases of a condition that develop within a defined population during a specified time period.

Option A correctly defines incidence by identifying new cases, specifying a timeframe, and using the population at risk as the denominator. This aligns directly with CPHQ expectations for differentiating incidence from prevalence.

Option C includes all cases (new and existing), which describes prevalence over a period rather than incidence. Option D reflects point prevalence, measuring cases at a single point in time. Option B is mathematically incorrect and does not represent a standard epidemiologic calculation.

The CPHQ framework emphasizes incidence rates for evaluating disease onset, effectiveness of prevention strategies, and population health trends, making Option A the correct and verified response.