3. Incidence

Incidence proportion is worked out by dividing the number of new cases of disease or health event by a population at risk over a specified time period.

The relevant time period must be stated.

The value of 10ⁿ is set at 100 (10²) to give the percentage but can also be different as mentioned above (see 2.2.1).

Note: Incidence proportion does not take into account:

• dropouts (loss to follow-up) during the observation period.
• When people developed the outcome.