1. Review – Key Chapters Chapter 2 Chapter 3 Chapter 5 Chapter 6

2. Review – Final Incidence and Prevalence Cumulative incidence
Incidence Rate
Age standardization
Risk difference (attributable risk in exposed)
Risk ratio
Population attributable risk
Attributable proportion
In exposed
Total population

3. Review – Final Odds Ratio Confounding Effect Modification
Sensitivity – Specificity
Positive predictive value
Negative predictive value
Criteria for causality

4. Among the Exposed Attributable Risk, rate/risk difference (RD)
RD= Re – Ru
Excess risk of death associated with the exposure among those exposed
the number of cases that would be eliminated if the exposure was eliminated among those exposed
Public health impact of the exposure among exposed
Attributable Proportion among the exposed, Etiologic Fraction
APe=[(Re-Ru)/Re] X 100
The proportion of disease among the exposed that would be eliminated if the exposure were eliminated

5. Among the Total Population
Population Attributable Risk (PAR) or
Population rate/risk difference (PRD)
PRD= Rt – Ru=RD X Pe
Excess risk of death associated with the exposure in the total population
the number of cases that would be eliminated if the exposure was eliminated in the total population
Public health impact of the exposure in the total population
Attributable Proportion in the total population
APt=[(Rt-Ru)/Rt] X 100
The proportion of disease in the total population that would be eliminated if the exposure were eliminated

6. Measures of Association
Risk Ratio = [a/(a + b)] / [c/(c + d)] = [prevalence or incidence of outcome for the exposed group] divided by [prevalence or incidence of the outcome for the unexposed group]
Risk Difference = [a/(a + b)] - [c/(c + d)] = [prevalence or incidence of outcome for the exposed group] minus [prevalence or incidence of the outcome for the unexposed group]

7. Measures of Association
Attributable Proportion among Exposed=Etiologic Fraction =
(Re-Ru)/Re= [a/(a + b)] - [c/(c + d)] / [a/(a + b)] = Proportion of the prevalence or incidence of the outcome for the exposed group that can be attributed to the exposure.
Population Attributable Proportion = Rt-Ru/Rt=[(a + c) / (a + b + c + d)] - [c/(c + d)] / [(a + c) / (a + b + c + d)] = Proportion of the total prevalence or incidence that can be attributed to the exposure.

8. Suitable Test Disease Status (Truth) Yes No Total Positive a b a + b
Yes No
Total
Positive a b
a + b
Negative c d
c + d
a + c
b + d
a + b + c+ d
Screening Test Result
Sensitivity - enables you to pick up the cases of disease -- a / a + c = those that test positive / all with disease
Specificity - enables you to pick out the no diseased people -- d / b + d = those that test negative / all without disease
Valid test has high sensitivity and specificity

9. Suitable Test Disease Status (Truth) Yes No Total Positive a b a + b
Yes No
Total
Positive a b
a + b
Negative c d
c + d
a + c
b + d
a + b + c+ d
Screening Test Result