EPI2-5: Prevalence Defined

OBJECTIVES

At the end of this session you should understand the meaning of prevalence as a measure of occurrence and you should know when it can be measured and how to calculate it.

Three specific measures of disease occurrence will be presented. The one is a prevalence measure and the other two are incidence measures.

Prevalence:

The prevalence measure is simply called prevalence. Other terms in use include prevalence rate and prevalence proportion. It is not a rate as there is no time in the measure, but it is a proportion since it is simply one number divided by another.

The prevalence is defined as:

Example:

A factory with 10200 workers was screened for noise-induced hearing loss. After examination, 200 workers were found to have noise-induced hearing loss. The prevalence of noise-induced hearing loss was:

P = 200 / 10200 = 0.02 = 2%




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General Introduction to Occupational Health: Occupational Hygiene, Epidemiology & Biostatistics by Prof Jonny Myers is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.5 South Africa License
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