Introduction/ Measures and Frequency of Association.

Question 1

What does a disease determinant result in?

Answer 1

A change in disease status between populations.

Question 2

Who is widely considered the fist epidemiologist?

Answer 2

Hippocrates (460-370bc).

Question 3

If a disease is present at stable frequencies what can it be described as?

Answer 3

An endemic.

Question 4

If something is classed as ‘not deadly’, what can it also be described as?

Answer 4

Trivial.

Question 5

Acute events rarely occur with a chronic condition. True or False?

Answer 5

False, they can occur.

Question 6

John Gaunt is widely known for being the first person to systematically collect data, including birth and death rates of populations. What did this collection quantify the death rate of children to be?

What are two other examples of data that were collected?

Answer 6

1/3 dead by the age 5.

This is still the case in developing countries.

1. Plague deaths.
2. Incidence rate of rickets.

Question 7

Who is known for the first ever clinical trial? What was it for?

Answer 7

James Lund and scurvy.

Question 8

What was the first big geograohical study to be conducted?

Answer 8

John Snow/ Cholera.

Question 9

What observation found in the distribution of colon cancer showed the importance of the environment in this disease?

Answer 9

The migration of the Japanese to Hawaii. Incidence went from being exceptionally rare to the same as the caucasian population within 40 years.

Question 10

What type of cancer can be caused by Hep C?

Answer 10

Liver.

Question 11

What is the main determinant of liver cancer in Europe? What did it used to be?

Answer 11

Obesity high alcohol consumption leading to fatty liver disease.

Question 12

What is a time series?

Answer 12

The distribution and prevalence of something in a population over a period of time.

Question 13

In the 60’s cardiovascular mortality was much higher in Europe than today. What percentage has it decreased by?

Answer 13

25%.

Question 14

Despite increased levels of obesity there has been a reduction in systolic bp over the last few decades. Why?

Answer 14

Improved hypertension treatments and reduction of hidden salts in food.

Question 15

What chronic disease has not changed in levels in the last 40ys?

Answer 15

Cancer.

Question 16

Is there a law regarding salt content in food in the UK?

Answer 16

No.

Question 17

In the mid 70’s alcohol was linked to colorectal cancer. What chemical compound was responsible for this link and where was this compound specifically found?

Answer 17

Nitrosamine, found in dark beer.

Question 18

One the link between alcohol and colorectal cancer was made what intervention(s) was made to prevent this link from occurring in the future?

Answer 18

1. Gas ovens used to produce beer were replaced by electric (gas was reacting with natural amines producing the nitrosamine).
2. Beer was tested from the 1980’s for nitrosamine.

Question 19

What three things make up the epidemiological triad?

Answer 19

1. Host/ internal environment.
2. External environment.
3. Agent/ potential cause.

Question 20

Which is more descriptive/analytical, classical or modern epidemiology?

Answer 20

Classical.

Question 21

Which is more experimental, classical or modern epidemiology?

Answer 21

Classical.

Question 22

Which is focused on risk factors opposed to causes, classical or modern epidemiology?

Answer 22

Modern.

Question 23

Which is focused more on chronic disease, classical or modern epidemiology?

Answer 23

Modern (but classical is also).

Question 24

Since the development of modern epidemiology diseases have been able to be spit into what?

Answer 24

Subtypes.

Question 25

Breast cancer has how many known subtypes?

Answer 25

12.

Question 26

Does breast cancer before or after menopause have an increased risk of being Her2+?

Answer 26

After.

Question 27

What four diseases combined were responsible for 80% of all NCD's in 2013?

Answer 27

1. CVD. 2. Cancer. 3. Respiratory disease. 4. Broad sense diabetes.

Question 28

What disease has virtually no known cause apart from high levels of radiation exposure?

Answer 28

Brain cancer.

Question 29

What type of studies did data from EPIC result in?

Answer 29

Etiological studies.

Question 30

How many additional people have become obese in the last 25 years?

Answer 30

1 billion.

Question 31

What does your BMI have to be to be considered obese?

Answer 31

30-35.

Question 32

What does your BMI have to be to be considered overweight?

Answer 32

25-30.

Question 33

What does your BMI have to be to be considered malnourished?

Answer 33

<18.5.

Question 34

What is the immediate problem of the obesity crisis?

Answer 34

The rise of diabetes.

Question 35

100 million had diabetes in 1980. How many had it in 2010?

Answer 35

400 million.

Question 36

Most cancers seem to be a ____% higher disk in diabetics.

Answer 36

30-40.

Question 37

What percentage of women over 50 in Qatar did the Imperial Qatar study identify as diabetic?

Answer 37

50%.

Question 38

Blood pressure control measures have been successful in Europe and North America, partially due to pharma. Where in the world have they not been successful?

Answer 38

Asia and South America.

Question 39

Longer life is not thought to correlate with the number of years of healthy life. True or false?

Answer 39

False.

Question 40

Obesity is not a 'medical problem'. What is is instead?

Answer 40

A societal problem.

Question 41

What does causal inference aim to do?

Answer 41

Identify determinants of disease and eliminate the casual effects of the exposure of a disease.

Question 42

What type of measures do continuous variables provide?

Answer 42

Summary measures.

Question 43

What type of measures do discrete variables provide?

Answer 43

Frequency measures.

Question 44

Name 3 frequency measures.

Answer 44

Proportion, rate, odds.

Question 45

Do the two quantities used to calculate a ratio need to be related?

Answer 45

No.

Question 46

What is the prerequisite for something to be a proportion?

Answer 46

N needs to be in D.

Question 47

What does the denominator need to be for the measurement need to a rate?

Answer 47

A measure of person time.

Question 48

What does prevalence measure?

Answer 48

The extent of existing cases of a health condition of interest by providing a snapshot of a situation.

Question 49

What is the most common type of prevalence?

Answer 49

Point.

Question 50

What type of prevalence takes into account the entire period of interest?

Answer 50

Period.

Question 51

What is point prevalence often expressed as?

Answer 51

A percentage.

Question 52

What is prevalence good at doing?

Answer 52

Comparing populations.

Question 53

What needs to be stated when stating a point prevalence?

Answer 53

A given time point.

Question 54

What is the equation for point prevalence?

Answer 54

Number of existing cases/ total population.

Question 55

Why would the prevalence of the common cold be calculated as a point prevalence rather than a period prevalence?

Answer 55

The time course is too short.

Question 56

What sort of disease is it hard to find a prevalence of?

Answer 56

Diseases with a high fatality.

Question 57

Why is the prevalence of smoking in diabetics less?

Answer 57

As a diabetic who smokes is more likely to die than a diabetic who does not smoke.

Question 58

What can you not infer from prevalence?

Answer 58

Causation.

Question 59

When will a case be including in period prevalence?

Answer 59

If it became a case before or during the time period.

Question 60

What can a person 'at risk of developing a condition' be described as?

Answer 60

Disease free.

Question 61

What two things does prevalence reflect?

Answer 61

The incidence rate (IR) and the duration of the disease (D).

Question 62

Name three scenarios that will decrease the prevalence of a disease?

Answer 62

1. Occurrence decreases. 2. Cases are cured. 3. Cases die earlier.

Question 63

What can prevalence be used to assess?

Answer 63

The health status of a population.

Question 64

What is cumulative incidence defined as?

Answer 64

Proportion of a population with a new event during a given time period.

Question 65

What does CI measure?

Answer 65

Occurrence of a disease within a population.

Question 66

Why does CI need a timepoint?

Answer 66

As it is cumulative? Ie it will eventually reach 1.

Question 67

What is the equation for CI?

Answer 67

Number of new cases during a given time period/ Number of disease free individuals at the start of the time period.

Question 68

To be included in a CI calculation what must a person have?

Answer 68

The potential to develop the disease.

Question 69

What is CI also known as?

Answer 69

Incidence proportion/ risk.

Question 70

What is the definition of 'Attack Rate'.

Answer 70

Proportion of individuals that develop an infectious disease during an outbreak. (Not a true rate).

Question 71

What is the definition of 'Case Fatality Rate'.

Answer 71

Proportion of cases who die among those who develop the disease. (Not a true rate).

Question 72

CI cannot be estimated from cross sectional studies or surveys. What can?

Answer 72

Prevalence.

Question 73

What is the survival proportion equal to?

Answer 73

1- CI.

Question 74

What is the definition of a competing risk?

Answer 74

An event that removes a subject from being at risk from the outcome of interest.

Question 75

What is the definition of person time?

Answer 75

The sum of the individual time period spent in the cohort by each individual.

Question 76

Is person time a rate?

Answer 76

Yes.

Question 77

What is the definition of incidence rate?

Answer 77

Number of new cases during follow up/ total person time contributed by disease free individuals.

Question 78

How can you minimise competing risk (2 ways)?

Answer 78

1. Look at incidence rate/ person time instead of just CI. | 2. Reduce the time of follow up.

Question 79

How can you work out the average density of CI during a short time period?

Answer 79

C/ NΔT. = CI/ΔT.

Question 80

What does NΔT equal?

Answer 80

Approximate person time during Δt ( a short time interval).

Question 81

Why is the actual person time slightly less than NΔT ?

Answer 81

As some people will develop the disease in this periodn of time despite the short time period.

Question 82

What is the equation for working out odds/ proportion?

Answer 82

Odds = Proportion/ 1- proportion.

Question 83

Why is there more discrepancy between odds and proportions when both get larger?

Answer 83

As proportions can not exceed 1.

Question 84

Presuming that CI (IR) and D are constant over time and that the population is in steady state what can prevalence be defined as?

Answer 84

Prevalence = IR x D.

Question 85

CI can be calculated from the incidence rate by what equation?

Answer 85

CI= 1-e^(-IR x t).

Question 86

What two scales can quantify the strength of an association?

Answer 86

1. Multiplicative. | 2. Additive.

Question 87

What is the definition of a counterfactual?

Answer 87

Potential outcomes that would have been observed under each possible exposure/ treatment value. For some subjects these are outcomes that they would not have experienced.

Question 88

At the start of a study what does each subject have a chance of experiencing?

Answer 88

All counterfactuals.

Question 89

What would need to happen for a causal relationship to actually be determined?

Answer 89

Each individual would need to experience both counterfactuals. This can't happen.

Question 90

What does 'the endpoint of a casual mechanism' define?

Answer 90

An effect.

Question 91

In terms of the Bradford Hill criteria does a small association mean no effect?

Answer 91

No.

Question 92

What are the 9 points in the Bradford Hill criteria?

Answer 92

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

Question 93

What does the Temporality part of the Bradford Hill Criteria state?

Answer 93

Effect must be after cause with the expected time delay.

Question 94

What does the Biological gradient part of the Bradford Hill Criteria state?

Answer 94

Greater exposure should lead to greater incidence. In some cases the presence of a specific factor can trigger an effect.

Question 95

Absolute effects are differences in incidence rates, cumulative incidences and prevalence. All of these have an additive scale. What sort of effects are relatives of these measures and have a multiplicative effect?

Answer 95

Ratios.

Question 96

What sort of measure is a risk difference?

Answer 96

An absolute measure.

Question 97

What is the equation for risk difference?

Answer 97

CID = CI1- CI2.

Question 98

What is the equation for risk ratio?

Answer 98

RR= CI1/CI2.

Question 99

What sort of effect does a odds ratio show?

Answer 99

An individual effect.

Question 100

What is the equation for the odds ratio?

Answer 100

O1/O2.