Measuring Disease Flashcards
Epidemiology
study of the distribution and determinants of disease in populations
When defining a population for a study, who should be considered, and who should NOT be considered?
Consider - those at risk
Do not consider - those who have the disease already, are immune, or does not apply to them
Differentiate between a fixed (closed) population and a dynamic (open) population
Fixed - membership is permanent and population is defined by life event
Dynamic - membership is transient in which people can come and go
T/F? Prevalence, count, proportion and rate are all measurements of epidemiology.
FALSE - all but prevalence are measurements. prevalence is a measure of disease FREQUENCY
Proportion
Number of individuals within a defined group of interest, divided by the number of individual enumerated in a population
29 students at UNECDM have a dog. When a denominator is added - the total amount of students (400) at UNECDM - what does this become?
29 students = example of a count
once a denominator is added - 256 students total - it becomes a proportion
IAN Nerve damage following wisdom teeth extraction sometimes occurs. What type of measurement should be used here?
Proportion
*recall that proportions are useful for things that are in between common and rare occurrences
T/F? Proportions often include a time dimension.
FALSE
In proportions, numbers are (related/unrelated), and in ratios - the numbers are (related/unrelated)
related, unrelated
What is the denominator in a rate measurement?
time at risk for disease
Prevalence
Proportion of EXISTING disease cases compared to total population
Incidence
Proportion or rate of NEW disease cases compared to the population AT RISK of getting disease over a specified time period
Formula to measure prevalence
of existing / total persons in population of interest
The number of dental students at UNE with the flu in 2018 / the number of total dental students is…
an example of what type of prevalence?
period prevalence - proportion of population that experiences disease at any point during a specified time interval
The number of dentists that had needle sticks at the age of 26 on August 10th, 2017 is….
an example of what type of prevalence?
point prevalence
What factors can INCREASE prevalence?
- Longer duration
- prolongation of life without cure
- increased incidence
- in-migration of cases
- outmigration of healthy people
- in-migration of susceptible people
- better diagnosis and reporting
Incidence is a measurement of _____
risk
What are the key concepts of incidence?
New disease events
Population at risk
Follow up time
Cumulative Incidence
proportion of candidate population that BECOMES diseased over a specified time period
What is prevalence determined by?
Incidence and survival/cure
Why can identifying causal relationships in prevalence of a disease difficult?
Because prevalence is determined by incidence and survival, these two cannot be separated
An outbreak is similar to (endemic/epidemic/pandemic), except that it is at a more ____ level.
Epidemic, localized
When the occurrence of a disease occurs at an unusual or unexpected, elevated frequency - it is called a ____.
epidemic
T/F? The “at risk” population includes those who had the disease prior to the study and the anyone who gets it during.
false
