Rod Jackson Flashcards
What is the study if epidemiology
Frequency or occurence of disease in populations
Why do epidemiologists measure the frequency of health + disease in different populatuions
Find out the causes of poor health and how to improve it
What is the goal of epidemiology
Measure the frequency of health and disease in different populations to find out the causes of poor health and how to improve it.
What is the numerator
Cases of disease
What is the denominator
The population
Why do we measure the frequency of disease in different populations?
If frq of disease is different between two populations (or in same population at different times, can help identify the causes
What is age standardisation
Adjust or standardise the age structures of each population so they can be meaningfully compared, and take into account the differences between the denominators.
What is the equation of epidemiology
Epidemiology = N/D
What are EGO and CGO
The occurence of risk of dis-ease in populations
Equation for EGO and CGO
EGO = a/EG
CGO = b/CG
What are the design features of a cohort study
- start with a group pf participants
- allocate them into at least two groups by measuring things
- follow over time
What is incidence
If the number of dis-ease events that occur are counted forward from a starting point, over a period of time
What is prevalence
If the number of people with dis-ease are counted at one point in time, then T = 1
Does incidence or prevalence have a numerical outcome
Incidence
What are the two ways to define prevalence
- Categorical measure (categories): Prevalence of fast heart rates/people in population
- Numeral measure (numbers): average heart race = sum of every persons heart rate/people in population
What study allows incidence and prevalence to be measured at the same time
Cross-sectional
What are the different ways to measure numerator when measuring prevalence
If its difficult to measure when a disease event occurs or it occurs frequently, often measure if (yes/no) it has occured during a prior period but not the total occurences.
What are the strengths of incidence
- Determined by only dis-ease risk in population (clean measures)
- includes events (N) population (D) and time (T)
What is the weakness of using incidence
Difficult to observe events over time
What is the strength of prevalence
Relatively easy to measure as you ‘stop time’ and count
What are the weaknesses of prevalence
- Determined only by incidence, cure and death rate (dirty measure)
- includes only events (N) and population (D) - less info
What are RCT’s
Like cohort studies, but participants are randomly allocated to EG and CG.
What is the best study to answer effects of treatments
RCTs but only if its ethical and practical
How to calculate risk difference
EGO - CGO
What happens if RD = CGO
Risk difference = 0
How to calculate risk ratio
EGO/CGO
What happens if EGO = CGO
Risk difference = 0
What happnes if RR < 1
This is relative risk reduction (RRR)