EBPS 3: Measuring Disease Occurrence Flashcards
Prevalence
the CURRENT disease cases in a population
- influenced by incidence, death, recovery
Incidence
development of NEW cases of disease
- harder to measure
Point prevalence
Proportion with disease at a particular point in time
Period prevalence
Proportion with disease at any point in time during the period
cumulative incidence
the proportion of people without the disease who develop new disease during a specific time period
incidence rate
new events / person-time.
time to event analysis
survival analysis
Cumulative incidence over time
Kaplan-Meier time-to-event plot
a graphical representation that shows the estimated survival probability or cumulative incidence over time for a group of subjects in a study, particularly in medical or survival analysis research.
Disease
an event or condition that occurs in a person at a particular time and lasts for a particular duration until it resolves, or the person dies.
issues with using the average incidence rate as a measurement of disease occurrence:
1) It’s generally harder and less intuitive to interpret than cumulative incidence
2) not all follow-up time is the same
Which type of measurement is more useful?
- If we want to know about the BURDEN of disease in a population, then prevalence is what we’re looking for.
- If we want to know about or study the CAUSES of disease, how to PREVENT a disease, or TRENDS OVER TIME in disease occurrence, then incidence is what we want.
- often want to study the causes of disease or how to prevent it, so incidence is what we want, but it’s hard to measure than prevalence
Average incidence rate
events / person-time
Rate
Must have time in denominator
- E.g., incidence rate = events/person-year
Proportion
Numerator is subset of denominator (between 0-1)
- E.g., cumulative incidence = # developing disease/ # total
Risk
Ambiguous/general term
