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. 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 prevalence and the incidence.

Calculate the prevalence of chronic bronchitis in the low-exposure group:

Answer 1

The prevalence of chronic bronchitis in the low-exposure group is calculated by adding the initial and new cases (total 60) and dividing by the total number of men in the group (3,000), resulting in a prevalence of 2% or 20 cases per 100 men.

Step-by-step explanation:

To calculate the prevalence of chronic bronchitis in the low-exposure group, we need to consider both the initial cases identified and the new cases that developed over the follow-up period. Initially, we don't have specific information about cases in the low-exposure group, so we can assume that out of the 90 cases, the remaining 30 (90-60) were from the low-exposure group. After five years, an additional 30 cases were identified in the low-exposure group. Hence, the total number of cases in the low-exposure group is 60 (30 initial + 30 new).

The prevalence of chronic bronchitis in the low-exposure group is calculated by dividing the total number of cases by the total number of individuals in the group. The formula for prevalence is:

Prevalence = (Total number of cases in the group) / (Total number of individuals in the group)

Substituting the values :

Prevalence = 60 cases / 3,000 men

This simplifies to:

Prevalence = 0.02

The prevalence can be expressed as a percentage:

Prevalence = 2%

or as the number of cases per 100 men:

Prevalence = 20 cases per 100 men