Epidemiology 2: Measures of Disease

Question 1

What are the 8 steps in an outbreak investigation

Answer 1

1. Establish that an outbreak exists
2. Determine key questions
3. Define cases and non-cases
4. Record all events
5. Collect data on epidemiologic factors
6. Look for patterns and associations between risk factors and disease
7. Form and test hypothesis about disease control
8. Plan and implement control methods

Question 2

When establishing if an outbreak exists what is it important to note first to help you determine if one actually does exist?

Answer 2

note any changes in awareness, record keeping, observation, or population composition

Question 3

What should you calculate to determine if there is an outbreak

Answer 3

prevalence or incidence depending on the situation

Question 4

What key questions should be asked during an outbreak investigation?

Answer 4

who gets sick/who doesnt
where?
when?
case connections?
what do we know?
what do we need to know?

Question 5

When recording all events what method should be used?

Answer 5

Line listing

Question 6

What data should be collected on epidemiologic factors?

Answer 6

host, agent, environment, time

Question 7

When looking for patterns and associations between risk factors and disease, what should be looked at? What should be compared?

Answer 7

Look at where, agent, when, host, environment, prev/incidence
compare those with/without disease

Question 8

Why should hypothesis be tested before just solving the problem?

Answer 8

cost of dx, intervention, and other alternatives if problem will go away on its own

Question 9

What is a plan and the implementation of control methods based on

Answer 9

outbreak investigation

Question 10

Explain the parallels between outbreak investigation, clinical examination, and clinical reasoning

Answer 10

Clinical reasoning is used in order to look at an outbreak and clinical examination of individuals and find connections between cases in order to find a definitive answer and carry on with control methods and treatment options

Question 11

What does a measure of 1.0 indicate in disease occurrence?

Answer 11

incidence/prevalence are same in both groups

Question 12

What does a measure of >1.0 mean in disease occurrence?

Answer 12

incidence/prevalence is higher for those with the risk factor

Question 13

What does a measure of <1.0 mean in disease occurrence?

Answer 13

incidence/prevalence is lower for those with the risk factor

Question 14

How is ratio of incidence rates calculated?

Answer 14

Risk ratio = incidence with risk factor/incidence without risk factor

Question 15

How to calculate how many times more at risk one group is from another

Answer 15

prevalence ratio = prevalence with risk factor/prevalence without risk factor

Question 16

What are two ways to find the difference between incidence rates?

Answer 16

Attributable risk = incidence with risk factor - incidence without risk factor

Attributable fraction (exp) = attributable risk/incidence in high risk group

Question 17

What are two ways to find the difference between prevalence rates?

Answer 17

Attributable prevalence = prevalence with risk factor - prevalence without risk factor

Attributable fraction of prevalence (exp) = attributable risk/prevalence of high risk group

Question 18

Define outbreak

Answer 18

occurrence of disease in an area at level exceeding normal expected number of cases

Question 19

When referring to outbreak, what does normal expected number of cases depend on?

Answer 19

location, disease, or season

Question 20

How would one know if the difference in prevalence or incidence is due to chance?

Answer 20

P values

Question 21

What does a lower p-value mean?

Answer 21

more likely due to chance

Question 22

How to determine certainty of estimate of effect size

Answer 22

confidence interval