Epi Biostats Flashcards
What is prevalence, conceptually?
The amount of disease in a population at given time (snapshot)
What is the equation for prevalence?
Prevalence
- Prevalence = (number of people with disease) / (number of people in population)
- Prevalence = incidence x duration
How are prevalence measures useful?
Raise awareness of an important public health problem
Guide health resources such as more blood sugar testing
Direct funding for diabetes research
Warn of impending disease complications (i.e. kidney, eye disease)
What is prevalence NOT so helpful for?
Finding causes of disease.
What does incidence measure?
The development of new disease over time.
What is the equation for incidence?
Incidence = (new cases that develop over time) / (population initially free of disease)
What is incidence proportion?
Essentially incidence, but expressed as a percentage. You would likely see this term if you are studying a population who had some cases of disease at the beginning, and you were studying how many NEW cases developed over time.
What is the equation for incidence rate?
Incidence rate = (new cases of disease that develop over time) / (person-time at risk for disease)
What is incidence rate userful for?
Incidence rate corrects for difference in time between studies, or when individuals in a single study drop out early. Essentially, it makes it weighted.
How are incidence measures useful?
Measures rate at which disease develops over some period of time
Starts with disease-free individuals
Can clarify when a disease process begins
Can be used to investigate causes of disease
How do prevalence and incidence relate?
Prevalence = incidence x duration
One take-home point about potential quiz questions…
If there is no mention of time, it has to be prevalence. By definition, you need a measurement of time for it to be incidence.
