How Does Cumulative Incidence Compare to Incidence Rate?
While cumulative incidence measures the proportion of a population that develops a disease over a specified period, the incidence rate (or incidence density) accounts for the time each individual is at risk. The incidence rate is calculated as:
\[ \text{Incidence Rate} = \frac{\text{Number of New Cases}}{\text{Total Person-Time at Risk}} \]
The incidence rate is more appropriate in dynamic populations where individuals may enter or leave the study at different times.
