Epidemiology Study Design

Question 1

List 6 types of study designs.

Answer 1

1. Cohort studies
2. Case-control
3. Randomised Controlled Trial
4. Cross-sectional study
5. Intervention study
6. Ecological study

Question 2

What is a cohort study?

Answer 2

• Pick people
• Split into exposed and unexposed
• See if each group have disease or not
• Measures relative risk

Question 3

What is a case-control study?

Answer 3

• Pick people
• Split them into disease or not
• Find out if each group exposed of not
• Uses odds ratio

Question 4

What is a RCT?

Answer 4

• Pick people
• Randomise control and treatment group

Question 5

What is a cross-sectional study?

Answer 5

•Pick people at one point in time to find out prevalence

Question 6

What is ecological study?

Answer 6

•Geographical

–Compares between populations

•Longitudinal

–Compares over time

•Eg Investigators find a high level of correlation between levels of socioeconomic deprivation and cardiovascular mortality across electoral wards in the UK.

Question 7

What is an interventional study?

Answer 7

An interventional study is one in which the participants receive some kind of intervention, such as a new medicine, in order to evaluate it.

Eg- In the medicines development process, medicines are evaluated through interventional studies known as clinical trials

Question 8

What is odds ratio?

Answer 8

OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure

OR>1 associated with disease

OR<1 protective factor

OR=1 no association

Question 9

List 5 things to consider when doing a systematic review.

Answer 9

1. Formulate a good research question
2. Define the strategy you intend to use in order to answer the research question
3. Assess the quality of included studies using standardised criteria
4. Decide beforehand how you intend to analyse your results
5. Decide how you will test whether your results are valid

Question 10

Define blinding in a study.

Answer 10

A study done in such a way that the patients or subjects do not know what treatment they are receiving to ensure that the results are not affected by a placebo effect.

Question 11

Explain the differences between experimental and observational studies.

Answer 11

The main difference between observational study and experiments is in the way the observation is done.

1. In an experimental study, investigators apply treatments to experimental units and then proceed to observe the effect of the treatments on the experimental units. In an observational study, investigators observe subjects and measure variables of interest without assigning treatments to the subjects.
2. There is human intervention in experiments whereas there is no human intervention in observational study.
3. Eg of experimental study: RCT.

Eg of observational study: cohort study, case-control study, cross-sectional study