2.3 Case Control studies

Question 1

What type of study is Case control studies?

Answer 1

Observational studies

Question 2

What do case control studies allow?

Answer 2

researcher to be a passive observer of natural events occurring in cases who are compared with controls

Question 3

What are case control group assignments based on?

Answer 3

Disease status

Question 4

What are case control studies useful for?

Answer 4

Rare disease or investigating an outbreak

Question 5

What key word tells us that we are dealing with observational studies?

Answer 5

Randomly selected. Not randomized

Question 6

What key word tells us that we are dealing with interventional studies?

Answer 6

Randomized

Question 7

On the epi table, for case controls, what are we looking at?

Answer 7

A+C and B+D

Question 8

What are 3 reasons to use a case control study?

Answer 8

Unable to force group allocation. Limited resources and disease is rare.

Question 9

Case control studies are conducted in a what type of fashion?

Answer 9

Retrospective

Question 10

What are the 5 strengths of case control studies?

Answer 10

1. Good for multiple exposures of one outcome. 2 Usefull for rare diseases. 3 Determines associations (not causation). 4. Good with ethics. 5. Good when disease has a long induction/latent period.

Question 11

What are 5 weaknesses of case control studies?

Answer 11

1. Cant demonstrate causation. 2. confounders. 3. They are retrospective. 4. Have lots of bias. 5. Limited data due to retrospective nature.

Question 12

How are the selection of cases for case control study designs?

Answer 12

want the most detailed criteria possible. So we hope these cases are accurate. Find out how did they find out they were cases. Missclaffication can be a problem. Still an error.

Question 13

What is the recall counterfactual theory?

Answer 13

All else being equal except outcome. Requires exchangeablilty to other determinants of outcome

Question 14

What is the most difficult part with case control studies?

Answer 14

Control selection

Question 15

Why is the control selection the hardest?

Answer 15

The way the controls are selected is a major determinant in whether any conclusion is valid. Internal validity,, selection bias.

Question 16

Where can control groups come from? 3 ways

Answer 16

Population, institutional/organization/provider, spouse/relatives/friends.

Question 17

True or False? An individual can function as both an exposed and unexposed individual in the same study?

Answer 17

True

Question 18

How can a pt be in both the exposed and unexposed group in the same study?

Answer 18

Via outbreak investigation with multiple exposures or case-crossover

Question 19

What are Nested case control studies?

Answer 19

like case control, but nested and comes form another study. Developed as case study after another study.

Question 20

What are three ways Nested case control studies sample from other studies?

Answer 20

Survivor, base and risk set sampling.

Question 21

What is survivor sampling?

Answer 21

Sample of survivors at END of study period

Question 22

What is base sampling?

Answer 22

Sample of non diseased individuals at START of study period

Question 23

What is risk-set sampling?

Answer 23

Sample of non diseased individula DURING study period at same time when case was diagnosed.

Question 24

What is selection bias?

Answer 24

To the way subjects are chosen for study

Question 25

What is recall bias?

Answer 25

pts recall past events differently

Question 26

What is individual matching?

Answer 26

Matches individuals based on specific patient based characterisitcs.

Question 27

What is group matching?

Answer 27

Proportion of cases and proportion of controls with identical characteristics are matched. requires cases be selected first