An event, condition, or characteristic w/o which the dz. would not have occurred.
Cause
What 3 factors do descriptive epidemiology aim to address?
- Agent factors
- Environmental influences
- Host factors
(all interact)
List 3 Agent Factors
- Infection Rate
- Pathogenicity
- Virulence
What are the 8 criteria for identifying cause-effect relationships?
- Strenght of association
- Temporal relationship
- Dose-response relationship
- Biological plausibility
- Consistency
- Elimination
- Reversible associations
- strength of study design
List 3 types of Associations
(association doesn’t = cause)
- Non-statistical (chance)
- Statistical
- Risk Factors
Casual factors can be:
(4)
- necessary & sufficient
- necessary but not sufficient
- sufficient but not necessary
- neither sufficient nor necessary (but contributes)
Reversible associations?
Removal of a factor results in a decr. or incr. frequency of dz.
List the epidemiologic study types in order of strongest to weakest for providing evidence that an association may be causal.
(5)
- Radonmized clinical trials
- Cohort & case-control
- Cross-sectional
- Case series
- Case report
List the 2 measures of strength of association & the tests the are used in
- Relative Risk (RR): cohort
- Odds Ratio (OR): case-control
List 3 factors that impair making causal inferences.
- lengthy time interval btwn “cause” & dz.
- mulitple “causes” leading to same dz.
- causal factor requires other factors for dz. occurrence
What are 3 characteristics of a Cause?
- must precede the event
- can be (+) or (-) in the presence of exposure
- vaccines
- one or multiple casual factors
Causal factors are
- Disease agents
- Environmental influences
- Host factors
(interactive)
Characteristics of Confidence Interval
- includes P value
- same pop. sampled, resulting intervals would bracket the TRUE estimate of the pop. ~95 or 99% of the time
- depends on sample size (larger is better)
What does (+) statistical association possibly indicate?
Causality
What does (-) statistical association possibly indicate?
a protective factor
