Lecture 2

Question 1

What is epidemiology?

Answer 1

The study of epidemics. It assesses the distribution of illness through pattern and frequency. Also finds causes of health outcomes through genetic, social, behavioral, and environmental causes (determinants of health).

Question 2

What’s the difference between incidence and prevalence of a disease?

Answer 2

Question 3

What is incidence?

Answer 3

The number of new cases of a characteristic that develop in a population within a specific time period.

Question 4

What is prevalence?

Answer 4

The proportion of a population that has a specific characteristic within a given time period, regardless of when they first developed the characteristic.

Question 5

What is absolute risk?

Answer 5

Incidence of disease

Question 6

What is relative risk?

Answer 6

risk in exposed / risk in unexposed
(a/a+b)/(c/c+d)

“The risk of disease is ___ higher in exposed than the risk in the unexposed”

Question 7

What is odds ratio?

Answer 7

odds that exposed person is case / odds that non-exposed person is case

OR

odds that a case was exposed / odds that a control was exposed
(a/c)/(b/d)

“Odds of a case being exposed are ___ higher than the odds of a control being exposed.”

Question 8

What is environmental epidemiology?

Answer 8

Studies impact of the environment on health (chemical, biological, physical, and surroundings (social, built, natural). Identifies ways to manage risks.

Basically: Exposure –> Disease

Question 9

What are 6 strengths of epidemiology.

Answer 9

1. There is no need to extrapolate across species. (Like experiments with animals and we find out the animal metabolizes the exposure differently so we have to change things/no longer understand)
2. There is no need to extrapolate from high exposures.
3. The study population includes all susceptible groups, such as the elderly, the young, the unwell, and the unemployed.
4. The study population is so large that sampling variation should not be a problem and confidence limits should be narrow.
5. Exposure levels are available from routine measurements, which may also detail daily variations. (like air quality in weather app)
6. Many of the health effects to be considered are routinely recorded by health professionals. (like asthma, cancer, etc.)

Question 10

What are challenges in epidemiology?

Answer 10

Associations may be non-causal due to: chance, bias, confounding

If you ignore interaction you may miss the truth

Lack of external validity (generalizability)

Question 11

What are Hill’s Causal Criteria?

Answer 11

1. Strength of Association
2. Consistency
3. Specificity
4. Temporality
5. Biological Gradient
6. Plausibility
7. Coherence
8. Experiment
9. Analogy

Question 12

What is strength of association?

Answer 12

Consistency of association is also addressed by similar findings over time.

Question 13

What is consistency?

Answer 13

Similar results over different study methods, designs, and populations

Question 14

What is specificity?

Answer 14

The exposure is associated with the outcome in question and no others

The outcome is associated with the exposure in question and no others

The exposure causes only one disease

Question 15

What is temporality?

Answer 15

Can establish that the potential cause precedes the disease

Question 16

What is biological gradient?

Answer 16

dose response relationship

Question 17

What is plausibility?

Answer 17

The relationship is consistent with the current body of knowledge regarding the etiology and mechanism of disease

Question 18

What is coherence?

Answer 18

Coherence between epidemiological and laboratory findings increases the likelihood of an effect.

Question 19

What is experiment? (causal)

Answer 19

When exposure is reduced or eliminated, does the risk of disease decrease?

Question 20

What is analogy?

Answer 20

Is the available evidence made more plausible by evidence in another area?

Question 21

What is bias?

Answer 21

Deviation of results or inferences away from the truth. Any trend (in the collection, analysis, interpretation, publication, or review of data) that can lead to conclusions that are systematically different from the truth.

Question 22

What is confounding in epidemiology?

Answer 22

In a study of whether Exposure A is a risk factor for Disease B…

X is a confounder if it is:
1. a risk factor for disease B
2. associated with Factor A
3. not in the causal pathway from A to B

Question 23

What is interaction in epi?

Answer 23

When the incidence of disease (in the presence of two or more risk factors) differs from the incidence expected to result from their individual effects.