Matched Case Control Sstudies, Case crossover studies, Nested Case Control studies

Question 1

Performing and interpretation

Answer 1

Any of these studies could be performed using a population-type design.

They should be interpreted as if they were descriptive and analytic depending on the specific design, the quality of data and taking into account data are grouped .

Question 2

Nested case control study; type of study, population

Answer 2

• It is a normal case control study
• Population from where cases and controls are derived
– Not a hospital, nor a city or country
– It is within an ongoing cohort study

Question 3

Sampling of controls in nested cases control study

Answer 3

– Incident (incidence density)
• Incident cases
• Non cases at that same time

– Prevalent (cumulative density)
• Case cohort study
• Cases during a period
• Non cases as controls

Question 4

Advantages nested case control study

Answer 4

– New exposures that were not thought off at the beginning of Cohort Study
– Biological samples can be studied this way
– Some results available before ending cohort study

Question 5

Matched case control studies

Answer 5

In the 2-2 table each nº = 2 persons

Question 6

Advantages matched case control studies

Answer 6

– Counterfactual comparison (each person is paired to a very similar person)
– Efficient (less people needed)
– Needs specific Analysis

Question 7

Disadvantages matched case control studies

Answer 7

No effect of matching variables (you’ll never know the effect of making up the pairs)

Question 8

Case cross over studies

Answer 8

Compare the exposure of the case with the exposure of that same person x time before

(All are cases)

Question 9

When do we use case cross over studies

Answer 9

• Outcomes with sudden onset
• Occurs short after exposure
• Exposure is brief and intermittent

– Alcohol consumption-heart attack
– Sex-STIs
– Mobile use-traffic accident
– Cannabis-psychotic reactions

Question 10

Advantages case cross over studies

Answer 10

Counterfactual matching
• Age, sex, genetic susceptibility

Question 11

Disadvantages case cross over studies

Answer 11

– Assumes exposure is not cumulative
– Assumes there is no preclinical phase that affects exposure (couple argument before leaving home?)