Prevalence vs Incidence
Knowing the difference between prevalence and incidence can be of use due to the fact that 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 on future course of action and treatment procedures. People are confused 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 what each of these terms mean exactly.
What does Prevalence mean?
If you are a doctor or a scientist working on the treatment of breast cancer, you have got to know its prevalence in your city. Prevalence refers to the 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. 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.
What does Incidence mean?
On the other hand, if you are a doctor or a scientist working on the treatment of breast cancer you have got to know its incidence in your city too. 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 prevalence takes into consideration new cases plus old cases, incidence relates to new cases only. 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 that 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.
What is the difference between Prevalence and Incidence?
• Prevalence refers to a condition that 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 the total number of patients diagnosed and getting treatment to the total population whereas incidence is the ratio of total new cases in a population divided by total population
• In studying etiology of a disease, it is incidence that is more important.
Thus, it is clear that prevalence and incidence are related but two different measures of distribution of a disease in a population. Therefore, knowing what each term actually stands for can be beneficial to anyone.
So, what statistical application will be used to analyze the incidence cases?
incidence is new cases divided by total population at risk.Person at risk changes depending what disease. For example, ovarian cancer only happens in women, women who have ovaries. So if population is given. You need to identify who are the women from men in that population. Then filter out those who have ovarian cancer (hence, person AT risk, not with the disease) and those that lack ovaries. This will leave you with all women at risk.