Disease Occurance And Study Designs Flashcards
What is the target population of a study?
Population to which we want to generalize our results
What is the source population of a study?
Population from which subjects were drawn
What is the study population?
Group actually studies
What type of measure of disease occurrence, is the number of animals that have the disease (or other condition of interest) ?
Count
What type of measure of disease occurrence is the count of animals with the disease as a fraction of the total?
Proportion (Prevalence)
What type of measure of disease occurrence is the number of diseased animals compared to healthy individuals ?
Ratio
What type of measure of disease occurrence is the frequency a disease occurs in a population over the time?
Rates (eg incidence)
What is point prevalence? What type of study usually determines this?
Proportion of animals disease at any point in time
Cross-sectional study
What is period prevalence ?
Proportion of the study population that is diseased during a specific period of time
=(#cases/period of time) / (total population/period of time)
What is incidence? What kind of studies do we use this in
The number of new cases of disease that occurs in the population over time
Prospective studies -> clinical trials/prospective cohort
What is a cumulative incidence?
Proportion of disease-free individuals that become diseased in a specified period of time
= (#new cases / time) / (total population/time)
What is a specific type of cumulative incidence used in outbreak and is usually applied to a narrowly defined population?
Attack rate
= (#new cases/time) / (#exposed/time)
What type of rate can be used when animals enter and leave a study population? How is it calculated?
Incidence rate
= (#new cases/time) / (sum of length of time that each animal is at risk)
T/F: prevalence is dependent on incidence and duration of disease
True
-> the longer old cases survive, the higher the prevalence
What is the best measure to access overall burden of disease?
Prevalence
What is the best measure to access increase or decrease in frequency of disease?
Incidence