Cornerstones of epidemiology

Question 1

What are descriptive studies?

Answer 1

Describe the distribution of factors in relation to the person, the place and the time

Question 2

What types of data are descriptive, give examples?

Answer 2

• routine (births and deaths)
• survey (Health survey for England)
• performance management

Question 3

What are some examples of study designs and what are they used for?

Answer 3

• to assess accuracy of diagnostic tests, cross sectional studies used
• to assess prognosis of disease, cohort study
• to assess pop healthcare needs, ecological studies
• to assess causes and risk factors, use non randomised
• for treatment efficacy, use randomised

Question 4

What is routine data?

Answer 4

Collected and recorded systematically, without any research questions in mind, simply for administrative reasons

Question 5

What are some types of routine data?

Answer 5

• health outcome data from hospitals for example
• Exposure and health determinant data e.g air pollution
• Disease prevention data e.g. screening
• Demographic data e.g. cenus
• geographical data e.g. location of GPs
• Health services e.g. bed counts
• Births
• Deaths

Question 6

What are some advantages of routine data?

Answer 6

• cheap
• already collected
• standardised collection
• comprehensive
• wide range of things recorded
• available for many years

Question 7

What are some disadvantages of routine data?

Answer 7

• many not answer the question
• not every case may be included
• variation in quality
• validity is variable
• coding may change e.g. ICD9/ICD10
• must be interpreted carefully

Question 8

What are examples of health outcome data?

Answer 8

• mortality
• cancer
• infectious disease
• pregnancy termination
• congenital abnormalities
• hospital episode statistic
• GP data
• road accidents

Question 9

What are cross sectional studies used for?

Answer 9

used by healthcare providers for correct allocation of resources and prevention planning
Allows hypothesis development , however cannot establish cause and effect

Question 10

How is mortality measured and where can data be obtained from?

Answer 10

Death certificates - local registrar of births and death, office of national stats and produced in tables regularly

Question 11

Where can cancer registrations be obtained and what can they be used for?

Answer 11

• voluntary notification to local registry
• death certificates
• useful for survival info
• useful to determine trends and prevalence

Question 12

Where are infectious disease notifications obtained?

Answer 12

• doctors

Question 13

What is QOF?

Answer 13

Quality and outcomes framework - component of GMC for GPs
They:
- reward 
- help fund improvements
Data is collected in a database

Question 14

What are administrative hospital admissions data used for?

Answer 14

To classify treatment

Question 15

What is a finished consultant episode?

Answer 15

time spent under care of a consultant

Question 16

What is an admission?

Answer 16

stay in hospital, so 1+ episodes and/or hospital transfers

Question 17

Where can controls be obtained for a case-control study?

Answer 17

must be representative

• neighbourhood
• friends
• family
• hospital
• GP

Question 18

Advantages of case control study

Answer 18

• good for rare disease
• quick
• cost effective
• investigate many exposures

Question 19

Disadvantages of case control study

Answer 19

• selection bias
• recall bias
• uncertain of when exposure occurred
• bad for rare exposures
• cannot calculate incidence

Question 20

What is a case control study?

Answer 20

Comparing odds of being exposed among case and control

Question 21

What is the procedure for a case control study?

Answer 21

• select control and cases
• obtain info
• compare those exposed in either

Question 22

What is a cohort study?

Answer 22

A group of people with something in common - they are free of the outcome and over time development is observed (usually prospective)

Question 23

What is a prospective cohort study?

Answer 23

Compare disease rates in exposed and unexposed. Watch over time

Question 24

What is a retrospective cohort study?

Answer 24

Done with routine data, look at relationship between exposure and outcome

Question 25

What are advantages of cohort studies?

Answer 25

• multiple outcomes observed
• follow through natural development of disease
• good to look at risks related to rare exposures
• incidence calculated
• minimize recall bias in prospective

Question 26

Disadvantages of cohort studies?

Answer 26

• inefficient for rare diseases
• prospective is time consuming and expensive
• loss to follow up introduces bias
• generalisability affected by healthy worker/volunteer effect

Question 27

What is standardised mortality ratio?

Answer 27

It is a ratio between the observed
number of deaths in an study population and the number of deaths that would be expected (accounting for age and often sex)

Question 28

How is standardised mortality ratio calculated?

Answer 28

number of observed deaths/ number of expected deaths if experienced the same age specific rates as standard population

Question 29

What are age standardised death rates?

Answer 29

Measuring death rates standardised for different ages

Question 30

Why is mortality rate and finding the cause of death important?

Answer 30

Important to assess how good the healthcare system is