Definition and calculation of relative risk

Definition and calculation of relative risk - Risk Rundown

• Relative Risk (RR): Compares the risk of developing a disease in the exposed group versus the unexposed group. It's the ratio of incidence in the exposed to incidence in the unexposed.

• Calculation Formula:

  • The risk of disease in the exposed group is $a/(a+b)$.
  • The risk of disease in the unexposed group is $c/(c+d)$.
  • $RR = [a/(a+b)] / [c/(c+d)]$

• Interpretation:

  • RR > 1: Exposure increases the risk of disease.
  • RR < 1: Exposure decreases the risk of disease (protective).
  • RR = 1: No association between exposure and disease.

⭐ Relative risk is the primary measure of association in cohort studies, as these studies track incidence over time.

High‑Yield Points - ⚡ Biggest Takeaways

• Relative Risk (RR) is the ratio of the incidence of an outcome in the exposed group to the incidence in the unexposed group.
• It is the preferred measure of association for cohort studies and randomized controlled trials (RCTs).
• The formula is [a/(a+b)] / [c/(c+d)].
• RR = 1 indicates no association between the exposure and the outcome.
• RR > 1 suggests an increased risk of the outcome in the exposed group.
• RR < 1 implies a decreased risk (protective effect) from the exposure.