Measuring Health in Populations - Lecture Sixteen Flashcards
Measuring Disease Occurrence
Why measure disease occurrence in populations?
Health status
Trends over time
Impact among different groups
Define prevalence
The proportion of a population who have the disease at a point in time
Prevalence - why?
Burden of disease
Resource allocation
Prevalence - calculation
Number of people with the disease at a given point in time / Total number of people in the population at that point in time
Prevalence - reporting
Measure of occurrence Exposure or outcome Population Time point Value
Prevalence limitation
Difficult to assess the development of disease
Is influenced by the duration of the disease
Incidence
think formula one
The occurrence of new cases of an outcome in a population during a specific period of follow-up
What is an Incidence Proportion
The proportion of an outcome-free population that develops the outcome of interest in a specified time period
the proportion of rase car drivers that crash in a race
Incidence proportion calculation
Number of people who develop the disease in a specified period / Number of people at risk of developing the disease at the start of the period
What might people not be considered ‘at risk’ at the start of a study?
They already have the condition
The condition is something that they cannot develop
How to calculate
Incident proportion
New cases during the time period / Population at risk at the beginning of the time period
Incidence proportion reporting
Measure of occurrence Outcome Population Time period Value
Incidence proportion limitations
Assumes a ‘closed’ population (does not account for people coming or going) e.g. someone might die or move away
Highly dependent on the time period (longer time period = higher incidence proportion)
Incidence rate
the rate at which new cases of the outcome of interest occur in a population
Why do we calculate Incident rate
To see how quickly new cases of the condition developing in the population
