Question

A population of 9,000 men was examined in January 2014. Of these men, 6,000 were exposed to high levels of air pollution, and 3,000 were exposed to low levels of air pollution. At the physical examination, 90 cases of chronic bronchitis were identified, including 60 cases among the high-exposure group.

Calculate the prevalence:

	Cases	Population	Prevalence
High exposure group
Low exposure group
Total group

All of the men who were initially examined and did not have chronic bronchitis were followed by repeat examination over the next five years. These follow-up exams identified 268 new cases of bronchitis in the total group, including 30 cases among the low-exposure group.

Calculate the incidence:

	Cases	Population	Incidence
High Exposure Group
Low Exposure Group
Total Group

What can be said about the risk of chronic bronchitis over time based on the incidence and prevalence calculations?

Answer 1

Firstly definition of

PREVELANCE - refers to number of cases of a disease that are present in a particular population at a given time . It is often confused with incidence .

INCIDENCE- is the rate of newly diagnosed cases in a population.

In the above example one can say that risk of chronic bronchitis depends upon the exposure as the PREVELANCE of bronchitis in high exposure group is more than low exposure group . But over the time when after 5 years results were calculated it again showed that continued exposure also lead to bronchitis in low exposure patients also .