A public health physician is analyzing the epidemiology of a chronic respiratory condition in a stable community of 50,000 residents. On January 1, a comprehensive health survey identifies 1,000 residents who already have the condition. Throughout the year, an additional 490 residents are newly diagnosed with the condition. By the end of the year, none of the affected individuals have died or moved away, and there is no immigration or emigration. Which of the following is the cumulative incidence of the condition in this community over the 1-year period?
- A
- Answer
- C
- D
- E
Answer
The correct cumulative incidence is 1.0%.
The correct answer accurately calculates cumulative incidence by dividing the number of newly diagnosed cases (490) by the population at risk (50,000 total residents minus 1,000 existing cases = 49,000). The resulting proportion, 490 / 49,000, equals 0.01 or 1.0%. This accurately reflects the risk of developing the disease in the susceptible community members over the one-year period.
Step-by-Step Solution
Key Concept
Cumulative incidence is calculated as the number of new cases of a disease during a specific time period divided by the number of individuals initially at risk (excluding those who already have the disease).