3.8 Collection and use of epidemiological data Flashcards
1
Q
Describe a cross-sectional study
A
- Snapshot of a population at single point in time
- Simultaneously collect data on exposure and outcome
2
Q
What are cross-sectional studies used for?
A
Estimate prevalence of condition or characteristic
3
Q
What are the advantages of a cross-sectional study?
A
- Quick and cheep
- Can study multiple outcomes and exposures
4
Q
What are the disadvantages of a cross-sectional study?
A
- Can’t establish causality - no temporal aspect
- Prone to bias e.g. recall, selection
- Not helpful for rare outcomes
5
Q
How are the results of a cross-sectional study given?
A
- Prevelence or odds ratio
- Descriptive associations, not causal
6
Q
Describe a case-control stufy?
A
- Retrospective
- Compares people with outcome to without
- Look for exposure retrosepctively
7
Q
What are the advantages of case-control study?
A
- Good for rare outcomes or long latency of disease
- Smaller sample size
- Can look for multiple exposure
8
Q
What are the disadvantages of case-control studies?
A
- Recall bias
- Control selection difficult
- Cannot calculate incidence or relative risk
9
Q
How are results of case-control studies presented?
A
Odds ratio - approximates relative risk for rare diseases
Inferred temporal relationship but not confirmed
10
Q
What is a cohort study?
A
- Observational - participants grouped by exposure and then followed over time
- Can be prospective or retrospective
11
Q
What are the advantages of a cohort study?
A
- Establish temporal relationship
- Study multiple outcomes from a single exposure
- Directly measures incidence and relative risk - risk ratio
12
Q
What are the disadvantage of cohort studies?
A
- Expensive and time-consuming
- Bad for rare outcomes
- Loss to follow-up - bias
13
Q
How are cohort study results summarised?
A
Relative risk and Hazard ratio
14
Q
A
