
Definition
of Several Key Terms 


What
is incidence?
Incidence is a measure of disease that allows us
to determine a person’s probability of being diagnosed with a disease
during a given period of time. Therefore, incidence is the number of
newly diagnosed cases of a disease. An incidence rate is the number
of new cases of a disease divided by the number of persons at risk for
the disease. If, over the course of one year, five women are diagnosed
with breast cancer, out of a total female study population of 200 (who
do not have breast cancer at the beginning of the study period), then
we would say the incidence of breast cancer in this population was 0.025.
(or 2,500 per 100,000 womenyears of study) ^Back
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What
is prevalence?
Prevalence
is a measure of disease that allows us to determine a person’s likelihood
of having a disease. Therefore, the number of prevalent cases is the
total number of cases of disease existing in a population. A prevalence
rate is the total number of cases of a disease existing in a population
divided by the total population. So, if a measurement of cancer is taken
in a population of 40,000 people and 1,200 were recently diagnosed with
cancer and 3,500 are living with cancer, then the prevalence of cancer
is 0.118. (or 11,750 per 100,000 persons) ^Back
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What
is morbidity?
Morbidity
is another term for illness. A person can have several comorbidities
simultaneously. So, morbidities can range from Alzheimer’s disease to
cancer to traumatic brain injury. Morbidities are NOT deaths. Prevalence
is a measure often used to determine the level of morbidity in a population. ^Back
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What
is mortality?
Mortality
is another term for death. A mortality rate is the number of deaths
due to a disease divided by the total population. If there are 25 lung
cancer deaths in one year in a population of 30,000, then the mortality
rate for that population is 83 per 100,000. ^Back
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From
“Basic Statistics”
http://www.health.state.ny.us/nysdoh/chronic/basicstat.htm
^Back
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For
more information, please contact:
Hongjie Wang
Lyman Maynard Stowe Library
University of Connecticut Health Center
wang@nso.uchc.edu
Tel: 8606794053 
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