3. OUTLINE
Definition of case control.
Checklist.
Study design.
Advantages of case control study.
Disadvantages of case control study.
Summary.
References.
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4. .
Compare patient with and without disease to
determine how they may differ and ton what
they are exposed to.
Collect data on exposure retrospectively.
An observational study because on
intervention is attempted and no attempt is
made to alter the course of disease.
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5. DEFINITION
Case control studies start with a disease and
work backward to find association between
exposure and the disease.
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6. CASECONTROLCHECKLIST
KEY COMPONENTS
Study base
All people in study I f developed the disease
• Case definition:
Clear definition
Controls
Random sample of those without disease
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9. ADVANTAGES
Good for latency cases
Less time taken
Multiple risk factor
Less costly
Exposed data
Small sample size
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10. ADVANTAGES
Small sample size
Generate hypothesis for future study
Multiple exposures
No follow up
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11. DISADVANTAGES
Study for limited outcome
Poor choice of study of rare exposure
Difficult to find suitable control group
Methodological error
Difficult to keep record
Prone to bias
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12. EXAMPLE:1
The average risk of human immuno deficiency virus
(HIV) infection after percutaneous HIV infected blood
is 0.3 percent, but he factors that influence this risk not
well understood. We conducted a study consisting of
health care workers with occupational, percutaneous
exposure to HIV infected blood. There were patients
were those who became, seropositive after exposure to
HIV, as reported by national surveillance system in
France, Italy, & the United States. The controls were
health care workers in a prospective surveillance
project who were exposed to HIV but did not
seroconvert.
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13. EXAMPLE:2
Obesity is a major factor for Cardiovascular
Diseases (CVS) but the most predictive measure for
different ethinic population is not clear. It is aimed to
assess whether obesity is stronger indicator of
Myocardial Infraction than BMI. A study of acute
Myocardial Infraction with 27098 participants in
different countries (12461 cases & 14637 controls). To
assess relation between BMI & Myocardial Infraction
for each group.
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14. SUMMARY:
1) Control study is a study that works, backwards, beginning
with health endpoint outcome and then hunting back for
possible causes that might caused the outcomes.
2)Things to keep in mind.
Potential bias
Recall
Selection
3) Defining control groups
Who are appropiate & controls in your study.
A study should be statistically powered.
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