Measuring And Describing Disease

Question 1

What is the literal translation of epidemiology?

Answer 1

The study of that which is upon the people.

Question 2

What is the meaning of ‘endemic’?

Answer 2

Diseases that reside within a population

Question 3

What is the meaning of ‘epidemic’?

Answer 3

Diseases that befall a population

Question 4

What is the definition of epidemiology?

Answer 4

The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.

Put simply, how often diseases occur in different groups of people and why

Question 5

Who is known as the father of modern epidemiology?

Answer 5

John Snow

Question 6

What is primary prevention?

Answer 6

Primary (before onset): the prevention of disease through the control of exposure to risk factors, e.g. reducing salt in your diet reduces the risk of developing hypertension

Question 7

What is secondary prevention?

Answer 7

Secondary (slows progression): the application of available measures to detect early departures from health and to introduce appropriate treatment and interventions, e.g. providing anti hypertensive drugs to control hypertension

Question 8

What is tertiary prevention?

Answer 8

Tertiary (enables return to functioning after insult): the application of measures to reduce or eliminate long-term impairments and disabilities, minimising suffering caused by existing departures from good health and to promote the patient’s adjustments to their condition.

Question 9

What is the correct epidemiological definition of odds?

Answer 9

The ratio of the probability (P) of an event to the probability of its complement (1-P). (P/1-P)

Question 10

What is the epidemiological definition of prevalence?

Answer 10

The proportion of individuals in a population who have the attribute at a specific timepoint

Question 11

What does prevalence reflect?

Answer 11

Both the occurrence and duration of a disease

Question 12

What is a limitation of prevalence?

Answer 12

Prevalence provides no information on new cases of a disease

Question 13

What is the epidemiological definition of cumulative incidence?

Answer 13

The proportion of the population with a new event during a given time period.

Question 14

How do you calculate cumulative incidence?

Answer 14

Number of new cases during period of interest/number of disease-free individuals at the start of this time period

Question 15

What is cumulative incidence also referred to as?

Answer 15

Incidence proportion
Risk

Question 16

What are the limitations of cumulative incidence?

Answer 16

• Survey requires a follow-up stage
• There may be competing risk, e.g. risk of death due to injuries so you wouldn’t know if that individual may have developed the disease
• Also people may enter/leave study population and there could be loss of follow-ups

Question 17

What is person-time?

Answer 17

A measure of the time participants spend in the study

Question 18

How is incidence rate calculated?

Answer 18

Number of new cases during follow-up period/total person time by disease free individuals

Question 19

How is rate expressed?

Answer 19

Can only be expressed as new cases per unit of person time

Question 20

What are the strengths of incidence rate?

Answer 20

• Accounts for the time of follow-up and the time when the new event occurred
• Suitable for studies when participates enter and leave at different times and when there are competing risks
• Can be used cumulative incidence is problematic or cannot be properly defined

Question 21

What are the two types of standardisation and Howard the results presented?

Answer 21

Direct - this gives a comparable incidence, e.g. 120 strokes per 100,000 per year
Indirect - this gives a ratio out of 100 (or sometimes 1.0)

Question 22

What type of standard population do we use in Europe?

Answer 22

European Standard Population

Question 23

What do you need to check before comparing data between to areas?

Answer 23

Whether the data is standardised and what is has been standardised for, if so

Question 24

What is data termed as before standardisation?

Answer 24

Crude data

Question 25

What are the different types of variation?

Answer 25

Unwarranted variation - suggests a particular setting is dangerous
Explained variation
Statistical artefact - how well data is recorded

Question 26

How is the standardised mortality ratio and how is it interpreted?

Answer 26

It is calculated by dividing the observed count by the expected count.
An SMR of 1.65 (or 165) suggests there were 65% more deaths than expected.

Question 27

What does SHMI stand for?

Answer 27

Standardised Hospital Mortality Indicators - identify hospitals that report a higher than expected mortality

Question 28

When is indirect comparison used?

Answer 28

Usually used when we only have high-level data about outcomes and we can’t make a direct comparison.

Question 29

What is the different between granular and aggregated data?

Answer 29

Granular - individual level
Aggregated - high-level (top level) data