Before revision: For example, if a population contains 1,000 persons and 28 develop a condition since the disease first occurred until two years later, the cumulative incidence proportion is 28 cases per 1,000 persons, i.e.
After revision: For example, if a population contains 1,000 persons and 28 develop a condition from the time the disease first occurred until two years later, the cumulative incidence proportion is 28 cases per 1,000 persons, i.e.