Which term describes the proportion of new cases among those at risk during a specific period?

Which term describes the proportion of new cases among those at risk during a specific period?

• A. Incidence proportion
• B. Prevalence
• C. Incidence rate
• D. Case fatality rate

Answer: (A)

The main idea here is measuring how many new cases arise in a group over a defined time among people who were at risk at the start. The incidence proportion, also called cumulative incidence or risk, answers that by showing the fraction of initially disease-free individuals who develop the disease during the period. For example, if 1,000 people are disease-free at the beginning of the year and 60 become cases by year's end, the incidence proportion is 60 divided by 1,000, or 6%. This is distinct from prevalence, which counts all existing cases at a given time (not just new ones). It also differs from the incidence rate, which uses person-time to account for how long each person is at risk. And it differs from the case fatality rate, which looks at deaths among those who already have the disease.

The main idea here is measuring how many new cases arise in a group over a defined time among people who were at risk at the start. The incidence proportion, also called cumulative incidence or risk, answers that by showing the fraction of initially disease-free individuals who develop the disease during the period. For example, if 1,000 people are disease-free at the beginning of the year and 60 become cases by year's end, the incidence proportion is 60 divided by 1,000, or 6%.

This is distinct from prevalence, which counts all existing cases at a given time (not just new ones). It also differs from the incidence rate, which uses person-time to account for how long each person is at risk. And it differs from the case fatality rate, which looks at deaths among those who already have the disease.