case control study

Question 1

What is the classification of a case control study

Answer 1

A retrospecifive, observational analytic epidemilolgical study

Question 2

How are the groups detemined in a case control study

Answer 2

Groups are selected based on having or not having the outcome of interest

Question 3

What is the measure of association used for a case control study
- why is incidence not valid

Answer 3

Odds ratio - ratio between exposure in casesvs control
Incidence isnt valid as the total number of outcomes is determined in the study

Question 3

When does the odds rratio approximate the relative risk

Answer 3

When the disease is very rare

Question 4

What is index dating and why is it done in case control studys

Answer 4

Determine a group/control at the same time as a new case is added to the case control study
- enables control of potentional confounding at the time point of case developing

Question 5

What are the two methods to select cases for a case control study and which is best

Answer 5

best = incidence cases, selecting a case when they contract outcome
seconadry = prevelent cases, select cases at one time based on prevelance, wont have all contrated at the same time

Question 6

What is the importance of control selection for a case control study

Answer 6

Must be prepresentative of the sorce population with an accurate representation of the odds of exposure
- individuals must be able to become a case
- multiple control per cases can be used to increase statisitical power

Question 7

What are the strength of a case control study

Answer 7

Gain the temporal sequence
Can determine mutiple exposures
good for rare outcomes
cheap and time efficent

Question 8

What are the weaknesses of a case control study

Answer 8

Information bias, recall bias
- outcomes might have skewed reporting of exposure as they want to feel give a reason to their condition
only look at 1 outcome
hard to select appropriate cases