Difference Between Prevalence and Incidence

Prevalence vs Incidence

Prevalence and incidence are terms used in medical terminology to indicate how widespread a disease may be as well as the rate of its occurrence. Both prevalence as well as incidence have significance for doctors and scientists and they analyze the figures of both to decide of future course of action and treatment procedures. People confuse between prevalence and incidence and use them interchangeably which is incorrect and this article will explain the differences between prevalence and incidence to enable readers to have a clearer understanding.

If you are a doctor or a scientist working on treatment of breast cancer you have got to know its prevalence as well as its incidence in your city. Prevalence refers to actual number of breast cancer patients in the city that is a ratio you can calculate by dividing cancer patients with the total population of your city. On the other hand incidence refers to the new cases of breast cancer in a single year that has surfaced in your city. This is again a ratio where you divide the new cases of breast cancer with the total population. Obviously incidence is a ratio that is always smaller than prevalence.

While calculating prevalence, those diagnosed this year are also taken into account. It is the burden of a disease that is new cases plus old cases whereas incidence relates to new cases only. Thus it is clear that prevalence and incidence are related but two different measures of distribution of a disease in a population. There can be situations of high prevalence but low incidence and vice versa. Even in a situation of low incidence of a disease in a population, there can be pockets with high incidence which are a cause of concern for the scientists. When studying the risk of a particular disease, it is always incidence and not prevalence that is given importance as incidence reveals the risk a certain population is at in relation to a particular disease. High incidence ratio always refers to high risk rate.

Prevalence vs Incidence

• Prevalence refers to a condition which tells us how widespread a disease is in a population whereas incidence refers to new cases of the disease in the population in a year.

• Prevalence is the ratio of total number of patients diagnosed and getting treatment to the total population whereas incidence is the ration of total new cases in a population divided by total population

• In studying etiology of a disease, it is incidence which is more important.

  • Leovigildo Manalo

    So, what statistical application will be used to analyze the incidence cases?