Horses for courses

Question 1

What is bias?

Answer 1

Systematic error that distorts results and leads to wrong conclusions. It exists in all studys at any phase of research.

Question 2

What is cross sectional studies?

Answer 2

Descriptive/analytic. Provides snapshot of population through survey that can measures prevalence.

Question 3

Why are cross sectional studies important?

Answer 3

Informing about prevalence of disease and how to plan and allocate health resources

Question 4

What kind of study is a cross sectional study?

Answer 4

Both descriptive and analytical to identify correlations between exposure and outcomes.

Question 5

What are the benefits of cross sectional studies?

Answer 5

Cheap and easy to conduct. It is ethically safe and can measure prevalence for all factors under investigation. It is good for generating hypotheses and descriptive analysis. Data on variables

Question 6

What are the weaknesses of cross sectional studies?

Answer 6

It measures correlation but it is difficult to determine cause-effect relationships. Cannot estimate incidence and susceptible to bias due to recall and selection bias. It is not suitable to study rare diseases with a short duration.

Question 7

What is selection bias?

Answer 7

Participants are systematically different in their characteristics compared with eligible non-participants

Question 8

What is analytic epidemiology?

Answer 8

Quantifies the association between exposures and outcomes to test hypotheses about casual relationship.

Question 9

What are observational studies?

Answer 9

No intervention by investigator. It is an analysis of spontaneously occurring events It is used to explore aetiology (cause)

Question 10

What are the types of Observational studies?

Answer 10

Cohort and case-control and cross sectional

Question 11

What is a cohort study?

Answer 11

Can be retrospective or prospective and uses odds ratio. Compares exposed group with control group to see any health outcomes.

Question 12

What is a cohort study most beneficial for?

Answer 12

Diseases with a long development time.

Question 13

What is case-control?

Answer 13

Compare the exposures once deciding on an outcome.

Question 14

How are cohort diseases framed?

Answer 14

Formulated using a question which covers population (such as children), exposure (such as a disease) and outcome (such as mortality.)

Question 15

What is the weaknesses of cohort study?

Answer 15

Costly and time-consuming due to long-follow up periods which can lead to attrition bias. It is susceptible to selection bias.

Question 16

What are the benefits of cohort studies?

Answer 16

Reduces survival bias and recall bias.
Good for long development time disease
Good for incidence

Question 17

What are case-control studies?

Answer 17

Retrospective and uses relative risk. Compares diseased and healthy group to study exposure.

Question 18

What are the strengths of case control studies?

Answer 18

Efficient in time and money and effective in long term study of diseases, especially rare diseases. Study multiple risk factors at once.

Question 19

What are the weaknesses of case control studies?

Answer 19

Difficult to choose an appropriate control group and can become inefficient if frequency of exposure is low.

Question 20

What type of study is a randomised control trial?

Answer 20

Experimental epidemiology- intervention to establish effectiveness and confirm hypotheses about causal relationships

Question 21

What is a RCT?

Answer 21

Clinical trial to compare outcomes after participants receive an intervention. Best evidence and every participant has an equal chance of being selected.

Question 22

What are the benefits of RCTs?

Answer 22

Establish causation, minimises bias, publishable and comparative.

Question 23

What are the weaknesses of RCT?

Answer 23

Expensive, logistically challenging. Results may not reflect reality. It has ethical limitations where informed consent does not occur, and the context of randomised patients with different backgrounds and support.

Question 24

How to mitigate bias for RCT?

Answer 24

Use pre-existing records, not select people based on outcome, consistently account for the study population, and using double blind or allocation concealment. To mitigate attrition bias using appropriate analyses such as intention

Question 25

What are the types of observational studies?

Answer 25

Descriptive and analytical

Question 26

What is a case report?

Answer 26

A description of a single individual patient case. It is cheap and easy however it lacks temporality and there may be seleciton bias.

Question 27

What is a case series?

Answer 27

A collection of multiple case reports. It is cheap and easy and useful for rare diseases. However, it lacks temporality (long term tracking) and there may be selection bias.