Measuring and describing disease [Epidemiology] Flashcards
Define epidemiology.
study of how often diseases occur in different people and why
Define demography.
the composition of a particular human population
What does DALY stand for? Define it.
Disability Adjusted Life Years
a measure of disease burden that combines years of life lost from ill-health, disability or premature death
What is an ‘exposure’?
the variable that we are trying to associate with a change in health status
What is an ‘outcome’?
The effect of the exposure on the health status of a population
Is ‘exposure’ an independent variable or dependent variable?
independent variable
Is ‘outcome’ an independent variable or dependent variable?
dependent variable
What model do epidemiologist use to demonstrate how populations, health and disease change over time?
Epidemiologic Transition Model
What 3 groups can prevention strategies be divided into?
Primary
Secondary
Tertiary
Define primary prevention. Give an example in the context of hypertension.
BEFORE YOU ARE SICK
the prevention of disease through the control of exposure to risk factors
- Eg. reducing salt in you diet reduces the risk of developing hypertension
Define secondary prevention. Give an example in the context of hypertension.
PREVENT PROGRESSION OF SICKNESS
the application of available measures to detect early departures from
health and to introduce appropriate treatment and interventions
- Eg. controlling hypertension with antihypertensive drugs to progression
Define tertiary prevention. Give an example in the context of hypertension.
ENABLES RETURN TO FUNCTION AFTER BEING SICK
the application of measures to reduce or eliminate long-term impairments
and disabilities, minimising suffering caused by existing departures from
good health and to promote the patient’s adjustments to their condition.
- Eg. rehabilitation for someone who’s had a stroke so that they can return as close as possible to their pre-morbid activities
What is the difference between mortality and morbidity?
Mortality is what kills people
Morbidity is quality of life
What are the 4 measures of frequency?
Odds
Prevalence
Cumulative Incidence
Incidence rate
Define odds and a measure of frequency. What does it show?
PROBABILITY RATIO
The ratio of the probability (P) of an event to the probability of its complement (1-P)
Define prevalence as a measure of frequency. What does it show?
SNAPSHOT
The proportion of individuals in a population who have the disease or attribute of interest to the disease at a specific time-point
reflects occurrence + duration of disease
Define cumulative incidence as a measure of frequency. What does it show?
What is it also known as? (2)
NEW EVENTS
the proportion of the population with a new event in a given time period
AKA :
- incidence proportion
- risk
Define incidence rate as a measure of frequency. What does it show?
NEW EVENTS PER PERSON-TIME
the number of new cases per unit of person time
What are the pros and cons of using prevalence as a measure of frequency?
prevalence provides no indication of new cases of disease
useful to evaluate trends
good for chronic diseases
bad for short diseases
What are the pros and cons of using cumulative incidence as a measure of frequency?
- can only calculate with follow-up period
- can’t have any NEW subjects
- may have competing risk
good for short diseases
What are the pros and cons of using incidence rate as a measure of frequency?
accounts for time of follow up as well as when new event occurred
suitable for studies where cumulative incidence is problematic
What does person-time mean in the context of incidence rate?
person time: measures the time a participant spends in the study (units: years/days/hours)
Define standardisation
a process that allows us to adjust for a particular factor
Name 2 types of standardisation and briefly explain them.
direct
a type of adjustment that allows us to compare like-for-like between populations
indirect
useful when we have only high-level data about outcomes but are unable to make a direct comparison
How do we present the result of direct/indirect type of standardisation?
direct: gives comparable incidence
(100 strokes / 100k people / year)
indirect: gives a ratio out of 100
Name 3 different types of variation
unwarranted variation
explained variation
statistical artefact
A hospital is found to have a higher mortality rate than the national average. This hospital is deemed to be dangerous. What type of variation is this and what is the explanation of this variation?
unwarranted
there is an issue that needs to be fixed
A hospital is found to have a higher mortality rate than the national average. This hospital does more high-risk procedures. What type of variation is this and what is the definition of this type of variation?
explained variation
there is a good reason behind the statistic
A hospital is found to have a higher mortality rate than the national average. This hospital is great at recording deaths that other hospitals What type of variation is this and what is the definition of this type of variation?
statistic artefact
the statistics are recorded better than other places (therefore number seems higher/more concerning)
What do we call individual-type data (more specific)?
ie. we know WHO died
granular data
What do we call data not limited to one patient?
ie. we know HOW MANY died
aggregate data
