Case-Control Studies (Lecture 3) Flashcards Preview

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Flashcards in Case-Control Studies (Lecture 3) Deck (17)
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1
Q

Case-Control Studies

A

Observational studies allowing researcher to be a passive observer of natural events occurring in individuals with the disease/condition of interest (cases) who are compared with people who do NOT have the condition of interest (controls); conducted in a retrospective fashion

2
Q

Reasons to select a Case-Control Study

A
  1. Unable to force group allocation; unethical/not feasible
  2. Limited resources such as time, money, and subjects
  3. Disease of interest is rare in occurrence and little is known about its associations/causes
  4. Prospective exposure data is difficult/expensive to obtain and/or very time inappropriate
3
Q

Strengths of Case Control Study

A
  1. Good for assessing multiple exposures of one outcome
  2. Useful when diseases are rare
  3. Useful in determining associations
  4. Less expensive than interventional
  5. Useful when ethical issues limit interventional studies
  6. Useful when disease has a long induction/latent period
4
Q

Weaknesses of Case Control Study

A
  1. Can’t demonstrate causation
  2. Can be impacted by unassessed confounders
  3. Retrospective; can’t control for other exposures or potential changes in amount of study-exposure during study frame
  4. Can be impacted by various biases, most importantly selection and recall/assessment bias
  5. Limited by available data
5
Q

Selection of Cases

A

Defined by the investigator using accurate, medically-reliable, efficient data sources; applied to all study participants objectively, consistently, accurately, and with validity; best criteria are clinically supportable/definable

6
Q

Goal of Control Selection

A

To assess for the presence of an association between exposure and known condition of interest by selecting non-disease individuals from the sample population which produced the cases; controls should represent the baseline risk of exposure in the general/reference population

7
Q

Major determinant in whether a conclusion is valid in case-control studies?

A

The way controls are selected

8
Q

How to select control populations

A

Must be selected irrespective of exposure status; can come from population of the state, community, or neighborhood, from an institution or organization as long as any illnesses in controls are unrelated to the exposure(s) being studied, from relatives/friends/spouse. or from those who participated in the same picnic or convention but did NOT get sick (outbreak sources of controls)

9
Q

Case-Crossover Design

A

Subjects are their own controls during the other times they don’t have the acute change in risk; only case-control study that can attempt to address issue of temporality

10
Q

Nested Case-Control Studies

A

Case-control studies conducted after, or out of, a prospective previous study type (cohort or interventional study); subjects in cohort study, ultimately developing disease/outcome, are defined as cases for the subsequent case-control study to evaluate other exposures

11
Q

Survivor Sampling

A

Sample of non-diseased individuals (survivors) at end of study period

12
Q

Base Sampling

A

Sample of non-diseased individuals at start of study period

13
Q

Risk-Set Sampling

A

Sample of non-diseased individuals during study period at same time when case was diagnosed

14
Q

Selection Bias

A

Related to the way subjects are chosen for study; usually more of a concern for control selection and less of a concern during case-crossover study designs

15
Q

Recall Bias

A

Related to the amount/specificity that cases or controls recall past events differently

16
Q

Individual Matching

A

Matches individuals based on specific patient-based characteristics; useful for controlling confounding characteristics

17
Q

Group Matching

A

Proportion of cases and proportion of controls with identical characteristics are matched (if 41% of cases are males, 41% of controls need to be male); cases must be selected first