Epidemiology Flashcards
What is Odds Ratio?
Ratio of odds of exposure in the diseased group to odds of exposure in the control group (ad/bc from 2x2 contingency table).
What is Relative Risk?
Proportion of the absolute risk of disease in exposed group [a/(a+b) in 2x2 table] to the absolute risk of disease in unexposed group [c/(c+d) in 2x2 table] aka incidence of disease in exposed/incidence of disease in unexposed group.
What is Attributable Risk (aka Attributable Risk Difference)?
Attributable Risk is the difference between the risk of disease in exposed group and risk of disease in unexposed group (a/(a+b) minus c/(c+d) from 2x2 contingency table).
What is incidence of a disease?
The occurrence of new cases of a disease in a population during a specified time period
What is prevalence of a disease?
The total number of existing cases [new + old] of a disease in a population at a specific time point [day or time; aka Point Prevalence] or during a specified time period [month or year; aka Period Prevalence]
What are 2 main types of epidemiological studies?
Descriptive and Analytical
What are the 3 essential components studied in descriptive epidemiology?
Time, place, and person/animal
[who, what, when, where]
True or False: Observational studies are always only descriptive?
False; Observational studies can be descriptive and or analytical/experimental
What are 2 types of analytical studies?
Observational and Experimental
What are 2 types of analytical observational studies?
- Cohort
- Case control
Name 2 types of experimental analytical studies?
- Clinical trials
- Community trials or ecological studies.
What are primary determinants of a disease?
Factors which can exert a major effect in inducing a disease (e.g. and infectious agent causing an infectious disease)
What are secondary determinants of a disease?
Predisposing, enabling and or reinforcing factors
What is infectivity of a microorganism?
The ability of a micro-organism to infect, survive and multiply within a host
(No of index cases/no of population at risk)
Pathogenicity of a micro-organism refers to?
The capacity to cause disease; depends on agent properties such as toxin production, tissue damaging enzymes etc.
(number of disease cases/total number infected)
What is virulence of a micro-organism?
Virulence is the ability to produce serious illness or death, indicated by fatality rate.
What is an epidemic curve?
Is a histogram displaying the number of cases [y-axis] of an illness by date of illness onset [x-axis}
What information does an epidemic curve provide?
Outbreak information on pattern of spread, magnitude, outliers, time trend, incubation period of an illness.
What is the threshold level of an epidemic?
The minimum population density required to allow a contact transmitted epidemic to commence
(epidemic occurs when population density is above the threshold level)
Which measure determines the epidemic threshold level?
Basic reproduction number R0; epidemic occurs at R0 > 1
Parasite population will only establish in community if?
R0 > 1
Name 6 epidemiological disease patterns?
sporadic, endemic, hyper-endemic, epidemic, outbreak, and pandemic
What is a sporadic disease pattern?
Disease occurrence at irregular intervals (time and space)
Describe an endemic?
Occurrence of a disease in a defined population at the usual rate, at moderately regular intervals.
