The prevalence of a chronic disease that affects mostly older individuals has been constant in a population for the last 15 years. As a result of worsening economic conditions that have no effect on the disease itself, many young healthy individuals emigrate from the population. Which of the following is the most likely effect of the emigration on the estimate of disease prevalence over the next few years?

Question

The prevalence of a chronic disease that affects mostly older individuals has been constant in a population for the last 15 years.  As a result of worsening economic conditions that have no effect on the disease itself, many young healthy individuals emigrate from the population.  Which of the following is the most likely effect of the emigration on the estimate of disease prevalence over the next few years?

Quizplus · Accepted Answer

Prevalence is the actual number of existing cases (old and new) of disease, either at a particular point in time (point prevalence), or during a period of time (period prevalence). These measures are calculated as follows: Point prevalence = (existing cases in a population) / (total number of people in the population) Period prevalence = (existing cases in a population in a period) / (total number of people in the population) Estimates of prevalence of disease (ie, point or period prevalence) in a population are affected by population dynamics: The emigration of healthy individuals will increase disease prevalence estimates by decreasing the population size (denominator). The immigration of cases will increase disease prevalence estimates by increasing the number of existing cases (numerator). The emigration of cases will decrease disease prevalence estimates by decreasing the number of existing cases (numerator). The immigration of healthy individuals will decrease disease prevalence estimates by increasing the population size (denominator). In this example, the prevalence of a chronic disease has been constant for the last 15 years; therefore, new cases have been balanced by cures or deaths of prevalent cases. If a large number of healthy individuals emigrate from the population, then the number of cases (numerator) would remain the same, but the population size would decrease (denominator). Therefore, estimates of disease prevalence would increase. Educational objective: Prevalence is the actual number of existing cases (old and new) of disease, either at a particular point in time (point prevalence), or during a period of time (period prevalence). Estimates of disease prevalence in a population are affected by population dynamics.

The Prevalence of a Chronic Disease That Affects Mostly Older