Epidemiology & Risk Assessment

Question 1

Define: Epidemiology.

Answer 1

“The study of the distribution and determinants of disease frequency in human populations”

Question 2

How does the definition of epidemiology relate to its aims and/or goals?

Answer 2

Epidemiology focuses on: - Determinants of Disease - Distribution of Diseases - The Frequency of Disease - Populations Affected

Question 3

Draw the epidemiological triad of disease causation. List examples of causative factors that might fit into each part of the triad.

Answer 3

Examples: - Agent: Microbe, pollutant, nutritional deficiency,radiation - Host: Genetics, behaviors, social factors, physical state - Environment: Physical, Biological, Social

Question 4

Draw the epidemiological triad of disease distrubtion

Answer 4

Question 5

Define/describe: Epidemic

Answer 5

(Time) Short term outbreak above previous frequency in that population; Relative to usual frequency of the disease

Question 6

Define/describe: Epidemic Threshold

Answer 6

The minimum number of cases (or deaths) that would support the conclusion than an epidemic is underway

Question 7

Define/describe: Pandemic

Answer 7

An epidemic on a worldwide scale; Large numbers of people affected across international borders.

Question 8

Define/describe: Endemic

Answer 8

Disease that is found consistently in a specific geographic region.

Question 9

Define/describe: Periodic Outbreaks

Answer 9

Disease with cyclical patterns in their emergence (ex. Flu)

Question 10

Define/describe: Secular Trends

Answer 10

The long-term change in morbidity or mortality rates for a given health related state or event in a specified population.

Question 11

Define/describe: Disease Frequency

Answer 11

Counting the number of cases of a disease

Question 12

Define/describe: Prevalence

Answer 12

The number of EXISTING cases of a disease or health condition in a population at some designated time

Question 13

Define/describe: Incidence

Answer 13

The number of NEW cases of a disease or health condition in a population at some designated time

Question 14

Define/describe: Risk Factors

Answer 14

Demographic variables such as age, sex, and race

Question 15

Compare and contrast Clinical Medicine and Epidemiology

Answer 15

Clinical Medicine: examines disease in individuals Epidemiology: examines disease in populations

Question 16

Explain why epidemiologists often adjust health statistics using the direct and indirect methods.

Answer 16

These adjustments levelize the data so that it can be propagated to larger populations

Question 17

Describe the basic steps in a risk assessment. What difficulties or uncertainties exist at each step? Explain.

Answer 17

1) Hazard Identification 2) Dose-Response Assessment (Determine TRV) 3) Exposure Assessment (find EE) 4) Risk Characterization (Quotient = EE/TRV)

Question 18

Apply the triad of disease causation and distribution to: Snow’s investigation of cholera in London

Answer 18

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

Question 19

Apply the triad of disease causation and distribution to: The case study of mercury in the Amazon

Answer 19

They found that the mercury most prevalent in the Amazon. From further investigation, found that it came from erosion due to deforestation.

Question 20

Apply the triad of disease causation and distribution to: Shanna Swan’s investigation of reproductive problems in men

Answer 20

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

Question 21

Compare and contrast the design and data analysis of Cohort and Case Control Studies.

Answer 21

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.

Question 22

Define/interpret: Standardized Mortality (SMR)

Answer 22

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

Question 23

Define/interpret: Relative Risk Indices (RR)

Answer 23

Incidence rate in exposed / Incidence rate in non-exposed

Question 24

Define/interpret: Odds Ratio (OR)

Answer 24

Odds Ratio (OR); =1, no association…. =2, 2x greater increase in exposure, <1, protective factor

Question 25

Define/interpret: Confidence Intervals

Answer 25

Usually 95%, if both the low and high region has a RR over 1, shows statistical correlation for elevated exposure