Which factor decreases disease prevalence?

Which factor decreases disease prevalence?

• A. Decrease in incidence
• B. Increased incidence
• C. Longer duration of disease
• D. In-migration of diseased individuals

Answer: (A)

Prevalence is the proportion of people in a population who have the disease at a given time, and it is shaped by how often new cases arise (incidence) and how long people live with the disease (duration). If incidence decreases, fewer new cases occur and, over time, the number of people living with the disease shrinks, lowering prevalence. In contrast, increasing incidence adds more new cases and raises prevalence; longer duration means people stay diseased longer and also raises prevalence; inflow of diseased individuals increases the number of existing cases, raising prevalence. So lowering incidence is the factor that decreases prevalence.

Prevalence is the proportion of people in a population who have the disease at a given time, and it is shaped by how often new cases arise (incidence) and how long people live with the disease (duration). If incidence decreases, fewer new cases occur and, over time, the number of people living with the disease shrinks, lowering prevalence. In contrast, increasing incidence adds more new cases and raises prevalence; longer duration means people stay diseased longer and also raises prevalence; inflow of diseased individuals increases the number of existing cases, raising prevalence. So lowering incidence is the factor that decreases prevalence.