Epidemiology

Question 1

Causality

Answer 1

Multifactorial aetiology

Despite cases of a “link”, still many other factors like genetics, behavioural, social, domestic.

Question 2

Occupational diseases

Answer 2

Factors in the work environment are predominant and essential in causation

Question 3

Work Related Diseases

Answer 3

Can also occur outside the work place.

Partially caused by adverse working conditions

Question 4

Point prevalence

Answer 4

Rate of a disease is the proportion of the population at risk who are affected at a GIVEN TIME

Question 5

Incidence

Answer 5

Rate of disease refers to NEW CASES only.
Defined as proportion of the population at risk who DEVELOP the condition within a stated time period.
Indicates risk of contracting the disease.

Question 6

Prevalence

Answer 6

Proportion of cases in a population at a given time. Indicates how widespread the disease is.
Prevalence = Incidence x average duration
This depends partly on the rate at which new cases occur (incidence) and on duration

Question 7

Incidence vs Prevalence

Answer 7

Incidence is preferred but are more difficult to estimate.

Question 8

Relative Risk

Answer 8

The ratio of incidence of a disease in an exposed population to the incidence in an unexposed population
In Cohort Studies.
Incidence in exposed group/Incidence in non exposed group

Question 9

Cohort Study

Answer 9

Prospective Study in general
Measures Relative Risk

Observe one or more defined population over a period of time starting in past or present. Identify all that become sick or die (incident cases) and those who do not.

Question 10

Case Control Study (Case referent)

Answer 10

Retrospective
Odds Ratio

Select a series of cases of the disease of concern and a series of people without the disease but of the same population.
Then compare exposure history of 2 groups
Measures incidence as over time.
Not as effective as Cohort

Question 11

Cross Sectional Study

Answer 11

(Prevalence Study) - Cannot measure incidence
Measured at a particular point in time (not longitudinal)
This is often used on current employees in Occy setting

Question 12

Best for rare diseases

Answer 12

Case control

Question 13

Best for latency

Answer 13

Cohort

Is most expensive

Question 14

Recall Bias

Answer 14

Can occur if occupational histories of cases are more or less complete/accurate than those of non cases.
Those with negative affect are more likely to remember exposure history.
A form of information bias

Question 15

Confounding

Answer 15

Where the measured effect of one agent is distorted by the effect of others.
The other agent is the confounder.

EG. relationship between oral cancer and ETOH
But more smokers in drinking group (tobacco is the confounder)

Question 16

Period Prevalence

Answer 16

Proportion of a population who have a disease over a defined period.

Question 17

Direct Standardization

Answer 17

Simply a weighted average of sex and age specific rates

Question 18

Indirect Standardization

Answer 18

Comparison of observed cases of disease to expected cases of disease

Question 19

Odds Ratio

Answer 19

Odds of disease in a person exposed to a risk factor divided by the odds in someone who is unexposed.

Question 20

Experimental Studies

Answer 20

Assess the effect of a planned intervention on outcomes of interest.

Question 21

Hawthorne Effect

Answer 21

Those studied act differently because they are being studied.
Form of information bias

Question 22

Selection Bias

Answer 22

Healthy worker effect

Self selection

Question 23

Information bias

Answer 23

Hawthorne effect

Recall bias

Question 24

Healthy Worker Effect

Answer 24

Those that do an arduous manual job are likely to healthier than those that do not.

Question 25

Self Selection

Answer 25

Those who chose to take part in studies may be different to the general population (they may be healthier, more likely to be exposed to a substance)

Question 26

Type 1 Error

Answer 26

False Positive

Question 27

Type 2 Error

Answer 27

False Negative

Question 28

Attributable Risk

Answer 28

Number of cases with a disease attributed to an exposure.

RISK DIFFERENCE - Risk in exposed group minus risk in non exposed group.

Question 29

Sensitivity

Answer 29

Percentage of true positives in a sample

Question 30

Specificity

Answer 30

Percentage of true negatives

Question 31

Bradford Hill Criteria

Answer 31

Set of nine criteria to provide epidemiologic evidence of a causal relationship.
Specificity is included, sensitivity is NOT.

Question 32

Synergisitc

Answer 32

It works together to increase the effect.

It produces a combined effect greater than the sum of their separate effects.

Question 33

p value

Answer 33

Aim to be as low as possible <0.05

If so suggests study is statistically valid.

Question 34

RR Values

Answer 34

RR = 1 No diff between exposed and non exposed group
RR >1 Increased risk of outcome in exposed group
RR<1 Decreased risk of outcome in exposed group