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15 Cards in this Set
- Front
- Back
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Epidemiological activities |
1) surveillance and screening 2) studies on causation, therapy, prognosis 3) modelling |
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Observational Study Types |
-case series -cross-sectional studies -cohort studies -case control studies |
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Experimental Study Types |
-randomized, controlled clinical trial |
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Case Report (< or = 10 subjects) |
-selected due to same disease or treatment -no comparison group -can be useful for very rare diseases, unique circumstances (that's it) -very weak evidence |
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Case Series (> or = 10 subjects) |
-help refine diagnostic criteria, provide data about prognosis -indicates frequency of a particular clinical sign -description of ways the same disease manifests itself in a group of animals -no comparison group -can report rare diseases, complications; BUT descriptions may be atypical -report new, emerging diseases; BUT description may be atypical -early reporters of new developments; BUT the intervention described may not have actually helped |
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Cross Sectional Studies |
-used to generate hypotheses about causation -begin with a population of animals whose status you don't know, find out which has the disease and who doesn't, ask what is different btwn the groups and whether it is assoc. w. outcome of interest -measuring what fraction of each group has the exposure of interest -quick and easy -do not cope well with rare diseases -have no way of knowing whether exposure occurred before or after outcome of interest -have a comparison group -measured by ODDS RATIO |
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Cohort Studies |
-test hypotheses about causation -follow population that already had exposure of interest to see if they develop outcome of interest -can take years for outcome of interest to appear -lost to follow-up -do not cope well with rare diseases -know the exposure occurs before the outcome--good for est. causation -have a comparison group -measured by RELATIVE RISK |
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Case-Control Studies |
-used to test hypotheses about causation -find all the cases in a population, find 2-3 controls for each case in the same population, determine what fraction of each group was exposed to risk factor of interest -quick and easy -cope well with rare diseases--start out by collecting cases, don't need to wait for them to occur -no way to know whether exposure occurred before or after outcome of interest -have a comparison group -measured by ODDS RATIO |
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outcome of interest |
-an event like disease onset, the occurrence of complications (incl. death), or remission or cure |
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exposure |
-something the investigator thinks causes the outcome of interest aka "risk factor" |
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probability |
-probability of an event occurring is the fraction of times you expect to see the event in many trials -range between 1 and 0 |
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odds |
-the probability that the event will occur divided by the probability that it will not occur -range between 0 and infinity -probability=0.5, odds=1 -as probability incr. 0.5-->1, odds, incr from 1-->infinity |
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odds ratio |
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effect |
-the difference in disease (aka OUTCOME) occurrence btwn 2 groups which differ with respect to a particular exposure |
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risk factor |
-if a disease is more common among animals with a certain characteristic (the "exposure") than among those without it, there is an association btwn the characteristic and the disease ("outcome") -if the characteristic ("exposure") is present prior to the disease, the characteristic is called a risk factor for the disease ("outcome") |
