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30 Cards in this Set
 Front
 Back
Disease Association

present when exposure occurs together with the outcome more often than chance
association ≠ causation 

Incidence of Disease Among Exposed Cases

= a / (a + b)
a = cases of dz in exposed cases b = cases of no dz in exposed cases 

Incidence of Disease Among Unexposed Cases

= c / (c + d)
c = cases of dz in unexposed cases d = cases of no dz in unexposed cases 

Absolute Risk

1) incidence of dz in exposed pop'n
= a / (a + b) 2) incidence of dz in total pop'n = (a + c) / (a + b + c + d) * does not indicate if exposure is associated with INCREASED risk of disease 

Risk Difference

dz risk in exposed  dz risk in unexposed
= [a/(a+b)] / [c/(c+d)] how much greater on an abs scale is the freq of dz in one group compared to other 

Relative Risk Ratio

dz risk in exposed / dz risk in unexposed
= [a/(a+b)] / [c/(c+d)] how much more LIKELY one group will develop dz releative to other * can't assess incidence using relative risk 

Cumulative Incidence Ratio (Risk Ratio)

cumulative incidence for exposed / cumulative incidence for unexposed


Incidence Density Rate (Rate Ratio)

incidence density of exposed / incidence density of unexposed


Prevalence Ratio

disease prevalence for exposed / disease prevalence for unexposed


Risk

probability of developing an outcome over a specified period of time
* based on a proportion  numerator: number of times outcome occurs during the study  denominator: total number of times outcme could have occurred * cannot estimate risk directly from casecontrol study 

Odds that Case was Exposed

= a/c


Odds that Control was Exposed

= b/d


Odds Ratio

odds that a case was exposed / odds that a control was exposed
= (a * d) / (b * c) 

Interpreting Magnitude and Direction of RR and OR

1) RR = 1, OR = 1
 no association 2) RR > 1, OR > 1  exposed group has more dz than unexposed  regarded as risk factor 3) RR < 1, OR < 1  exposed group has less dz than unexposed  protective factor 

RR vs OR

* RR estimates association btw exposure and dz in exposed relative to unexposed
* OR is the ratio of the odds that cases were exposed relative to the odds that controls were exposed 

Disease Association

present when exposure occurs together with the outcome more often than chance
association ≠ causation 

Incidence of Disease Among Exposed Cases

= a / (a + b)
a = cases of dz in exposed cases b = cases of no dz in exposed cases 

Incidence of Disease Among Unexposed Cases

= c / (c + d)
c = cases of dz in unexposed cases d = cases of no dz in unexposed cases 

Absolute Risk

1) incidence of dz in exposed pop'n
= a / (a + b) 2) incidence of dz in total pop'n = (a + c) / (a + b + c + d) * does not indicate if exposure is associated with INCREASED risk of disease 

Risk Difference

dz risk in exposed  dz risk in unexposed
= [a/(a+b)] / [c/(c+d)] how much greater on an abs scale is the freq of dz in one group compared to other 

Relative Risk Ratio

dz risk in exposed / dz risk in unexposed
= [a/(a+b)] / [c/(c+d)] how much more LIKELY one group will develop dz releative to other * can't assess incidence using relative risk 

Cumulative Incidence Ratio (Risk Ratio)

cumulative incidence for exposed / cumulative incidence for unexposed


Incidence Density Rate (Rate Ratio)

incidence density of exposed / incidence density of unexposed


Prevalence Ratio

disease prevalence for exposed / disease prevalence for unexposed


Risk

probability of developing an outcome over a specified period of time
* based on a proportion  numerator: number of times outcome occurs during the study  denominator: total number of times outcme could have occurred * cannot estimate risk directly from casecontrol study 

Odds that Case was Exposed

= a/c


Odds that Control was Exposed

= b/d


Odds Ratio

odds that a case was exposed / odds that a control was exposed
= (a * d) / (b * c) 

Interpreting Magnitude and Direction of RR and OR

1) RR = 1, OR = 1
 no association 2) RR > 1, OR > 1  exposed group has more dz than unexposed  regarded as risk factor 3) RR < 1, OR < 1  exposed group has less dz than unexposed  protective factor 

RR vs OR

* RR estimates association btw exposure and dz in exposed relative to unexposed
* OR is the ratio of the odds that cases were exposed relative to the odds that controls were exposed 