II. Definition
- Relative Risk
- Ratio of probability of an event in an exposed group to that in an unexposed group
III. Evaluation
- Calculation
- Relative Risk = P(disease I exposure) / P(disease I No exposure)
- Example
- Exposure to Substance X
- Disease Y Contracted in 25
- Disease Y NOT Contracted in 75
- NO Exposure to Substance X
- Disease Y Contracted in 10
- Disease Y NOT Contracted in 190
- Probabilities
- P(disease | exposure) = 25 / (25 + 75) = 0.25
- P(disease | No exposure) = 10 / (10 + 190) = 0.05
- Conclusion
- Relative Risk = P(disease I exposure) / P(disease I No exposure) = 0.25/0.05 = 5
- Patients exposed to Substance X are 5 times more likely to develop disease Y
- Exposure to Substance X
IV. Resources
- Wikipedia
- Smart Health Choices
V. References
- Desai (2014) Clinical Decision Making, AMIA’s CIBRC Online Course