Module 1 - Measuring Distribution & Determinnants Of Pop Health Flashcards
What is the main goal of epidemiology?
Main goal is to study the frequency of dis-ease in populations
Epidemiologists ALWAYS start with the population and then count the number of cases
Why measure the disease frequency in diff pops?
If dis-ease frequency (distribution) is diff in two pops, it can help us determine the causes (determinants)
How to calculate frequency ?
E = Numerator (no. Cases)/ Denominator (pop no.)
Epidemiologists definition of pop?
A group of people who share one or more common features
Definition of dis-ease?
Narrow - absense of death, dis-ease, disability
Broad - The ability to do what matters most to you
Numerator? Denominator?
Numerator - Cases of dis-ease
Denominator - Population
E = N/D
Why do epidemiologists often age standardise measures of dis-ease frequency before making comparisons between populations?
It’s critical epidemiologists age adjust/standardise populations dis-ease frequency before comparison - this allows for meaningful comparison - like for like.
E.g Sweden older pop than Panama = more deaths
Pakeha older pop than Maori = more pakeha die, however, more Maori die in each age range
Frequency at one point in time or over a period of time?
E = (N/D) / T
E = (cases of dis-ease / pop ) / Time
Define GATE?
G - Graphic
A - Approach
T - To
E - Epidemiology
What is PECOT?
It is an acronym for the components of the GATE framework P - Participants (Pop) E - Exposure Group C - comparison Group O - Outcome T - Time
EG & CG
EG - Exposure Group
CG - Comparison Group
Which exposure group can be chosen EG or CG?
Any, as long as you state it clearly
PECOT Outcomes?
A&B or (C & D) are numerators
Mostly use those with dis-ease as numerators A & B
Goal of epidemiology?
Calculate dis-ease frequency
But more specifically calculate:
Exposure group Occurrence (EGO)
Comparison group occurrence (CGO)
Comparison Groups tend to be ?
Your typical ‘normal’ group
If outcome is health use ?
C&D
Time arrows
Down - Over a period of time
Across - At one point in time
Cohort vs cross-sectional studies
Cohort - follow over time; can also measure prevalence - either beginning or at any point
Cross-sectional - relevant dis-ease events counted at the same time - can only measure prevalence
Death rate?
100% or 1per person per lifetime
What is Incidence?
Dis-ease occurrence over a period of time
E= N/D
What is prevalence ?
Where the number of people with dis-ease are counted at one point in time
Less perfect measurement - people can leak out of the prevalence pool - death or cured
When to use incidence or prevalence ?
Incidence - if easy to observe disease (death, road crash)
Prevalence - if hard to observe when disease occurs we measure IF It has occurred (psych disorder, obesity, diabetes)
Prevalence pool?
How much drizzle in the prevalence pool after the drizzle has fallen
Incidence and prevalence : categorical or numerical measurement ?
Incidence - Always involves counting (yes/no) disease EVENTS
Prevalence - involves counting categorical disease EVENTS or measuring numerical disease STATES
Prevalence - time measured backwards?
Measure a period of time E.g if someone has had a symptom in the last 3 months
Is time included in prevalence calculation?
No
Is time involved in incidence calculations ?
Yes
What determines incidence?
Numerator = Depends on number of events that happen during a specified time
What determines prevalence ?
Depends on how much drizzle (events - incidence) get into the pool AND how much leaks out (deaths or cured) before study
If you want to know how fast a car can go? You measure?
Incidence
If you want to know how worn out a car is ?
You measure prevalence