Module 1/2/3 Flashcards
(186 cards)
Denominator?
the number of people in a study population
EGO and CGO?
Exposure group occurrence (EGO) = a/EG
Comparison group occurrence (CGO) = b/CG
Epidemiologists measure and compare?
Epidemiologists measure and compare dis-ease occurrences in different groups of people
group and population are used…?
interchangeably.
numerator?
the number of people from the study population in whom dis-ease occurs
numerical measures can be represented as… by..?
Numerical measures can be represented as categorical measures by dividing into different categories
Quanitive data can be?
Categorical or numerical
what do the arrows represent?
Arrows represent time (vertical is incidence, horizontal is prevalence )
what does ‘occurence’ measure?
An ‘occurrence’ describes the transition from a ‘non-dis-eased state’ to a ‘dis-eased state’
What does the circle and square (A,B,C,D) represent? (8)
The circle represents the study-specific denominators.
One exposure group (EG) and comparison group (CG)
Some studies have multiple exposure groups.
The square represents the numerators or dis-ease outcomes A, , b, c, d. (from left to right) A = EG and disease B= CG and disease C= EG and no disease D= CG and no disease
What happens when the study exposure is in numerical measures?
the numerical measures are often converted into categorical measures (two or more). When they are changed it is possible to calculate the occurance
what does the traingle represent?
The triangle represents the Participant Population (P)
What is a population?
A population is any group of people who share a specified common factor
What is Epidemiology?
The study of how much ‘dis-ease’ occurs in groups (populations) and of the factors that determine differences in dis-ease occurrence between two groups
what is incidence?
If the transition from a non-dis-eased state to a dis-eased state is an easily observable ‘event’ then epidemiologists count the occurrences as the number of events over a period of time ( incidence)
what is prevelance?
However if the transition is not easily observable , like transitioning from a non-diabetic to a diabetic state, then epidemiologists count the occurrences as the number of people with the dis-ease ‘state’ at a point in time (prevalence)
What question is involved in epidemiological thinking?
‘what’s the denominator?’
Why do epidemiolgists study negative events?
Epidemiologists tend to study negative events or states, like death or disease, because they are easier to measure than positive states of health such as degrees of wellbeing
why do we use Dis-ease instead of disease?
Use ‘dis-ease’ instead of ‘disease’ to encompass any health-related event or health-related state.
Eg. defining the prevalence of significant asthma as the proportion of a group of people who at the time of asking have had at least two severe asthma attacks in the previous one-year period
This is an example of? why?
This is called period prevalence because the outcome definition depends on the time period specified
How can people leave the prevalence of diseases? Therefore…?
People can leave the prevalence pool either by dying or if they are cured
Therefore a population with a high incidence of disease could have a low prevalence if the death rate or cure rate is also high (vice versa)
How do we often measure the prevelance of diseases?
Often measure the prevalence of diseases at two points of time and calculate the change in prevalence
The difference in prevalence between the two time points is in fact a measure of the incidence of disease over the period between the two time points. (e.g 10/100 had diabetes at one point in time and 20/100 people had diabetes 10 years later, then the prevelance of diabetes increased by 10/100 over 10 years)
how is incidence calculated?
Incidence is calculated by counting the number of onsets of disease (events) occurring during a period of time, and then dividing the numerator by the number of people in the study population.
EGO= a÷EG (/T) CGO= b÷CG (/T)
If the numerator is a count of a categorical then prevelance…?
if the numerator is the sum of the scores for a numerical..?
- If the numerator is a count of a categorical disease states, then prevalence will be a proportion
- If the numerator is the sum of the scores for a numerical outcome measured on everyone then the mean is similar to a measure of prevalence