Epidemiology & Risk Assessment Flashcards
Define: Epidemiology.
“The study of the distribution and determinants of disease frequency in human populations”
How does the definition of epidemiology relate to its aims and/or goals?
Epidemiology focuses on: - Determinants of Disease - Distribution of Diseases - The Frequency of Disease - Populations Affected
Draw the epidemiological triad of disease causation. List examples of causative factors that might fit into each part of the triad.
Examples: - Agent: Microbe, pollutant, nutritional deficiency,radiation - Host: Genetics, behaviors, social factors, physical state - Environment: Physical, Biological, Social
Draw the epidemiological triad of disease distrubtion
Define/describe: Epidemic
(Time) Short term outbreak above previous frequency in that population; Relative to usual frequency of the disease
Define/describe: Epidemic Threshold
The minimum number of cases (or deaths) that would support the conclusion than an epidemic is underway
Define/describe: Pandemic
An epidemic on a worldwide scale; Large numbers of people affected across international borders.
Define/describe: Endemic
Disease that is found consistently in a specific geographic region.
Define/describe: Periodic Outbreaks
Disease with cyclical patterns in their emergence (ex. Flu)
Define/describe: Secular Trends
The long-term change in morbidity or mortality rates for a given health related state or event in a specified population.
Define/describe: Disease Frequency
Counting the number of cases of a disease
Define/describe: Prevalence
The number of EXISTING cases of a disease or health condition in a population at some designated time
Define/describe: Incidence
The number of NEW cases of a disease or health condition in a population at some designated time
Define/describe: Risk Factors
Demographic variables such as age, sex, and race
Compare and contrast Clinical Medicine and Epidemiology
Clinical Medicine: examines disease in individuals Epidemiology: examines disease in populations
Explain why epidemiologists often adjust health statistics using the direct and indirect methods.
These adjustments levelize the data so that it can be propagated to larger populations
Describe the basic steps in a risk assessment. What difficulties or uncertainties exist at each step? Explain.
1) Hazard Identification 2) Dose-Response Assessment (Determine TRV) 3) Exposure Assessment (find EE) 4) Risk Characterization (Quotient = EE/TRV)
Apply the triad of disease causation and distribution to: Snow’s investigation of cholera in London
The street with the most cases of Cholera had a water source that was the cause of the cholera. Using the distribution of infected individuals
Apply the triad of disease causation and distribution to: The case study of mercury in the Amazon
They found that the mercury most prevalent in the Amazon. From further investigation, found that it came from erosion due to deforestation.
Apply the triad of disease causation and distribution to: Shanna Swan’s investigation of reproductive problems in men
Atrazine, when injected into male and female frogs, caused various reproductive problems in the men because the chemical combines with testosterone to produce a hormone similar to estrogen
Compare and contrast the design and data analysis of Cohort and Case Control Studies.
Cohort Studies: - Classify groups based on exposures –> compare to look for different rates of disease; - Relative Risk = Incidence rate in exposed / non-exposed - Advantages: Cause to effect, can study multiple effects of single exposure, good for rare exposures, minimize bias - Disadvantages: Take a long time, Costly, Subjects lost to follow-up Case Control Studies: - Classify groups based on presence or absence of a particular disease –> Look back in time and conduct an interview of past exposure to various risk factors - Odds Ratio (OR); =1, no association…. =2, 2x greater increase in exposure, <1, protective factor - Advantages: Smaller sample sizes, quick and easy to complete, cost effective, useful for studies of rare diseases and those with long latent periods, can examine multiple casual factors. - Disadvantages: Provide indirect estimate of risk, timing of exposure-disease relationship can be difficult to determine, particularly prone to recall and selection bias, inefficient for studying rare exposures, cannot directly determine incidence rates.
Define/interpret: Standardized Mortality (SMR)
A quantity, expressed as either a ratio or percentage quantifying the increase or decrease in mortality of a study cohort with respect to the general population
Define/interpret: Relative Risk Indices (RR)
Incidence rate in exposed / Incidence rate in non-exposed
Define/interpret: Odds Ratio (OR)
Odds Ratio (OR); =1, no association…. =2, 2x greater increase in exposure, <1, protective factor
Define/interpret: Confidence Intervals
Usually 95%, if both the low and high region has a RR over 1, shows statistical correlation for elevated exposure
