1. What Is Absolute Risk Reduction From Hazard Ratio?

Absolute Risk Reduction (ARR) approximates the difference in risk between treatment and control groups when derived from Hazard Ratio (HR) in survival analysis. This conversion provides an estimate of the absolute benefit of an intervention.

2. How Does The Calculator Work?

The calculator uses the simplified approximation formula:

Where:

• \( ARR \) — Absolute Risk Reduction (proportion)
• \( HR \) — Hazard Ratio

Explanation: This approximation works best for binary outcomes and provides a quick estimate of absolute risk reduction from relative risk measures.

3. Importance Of ARR Calculation

Details: While Hazard Ratio provides relative risk information, Absolute Risk Reduction gives the actual difference in risk, which is often more clinically meaningful for decision-making and patient communication.

4. Using The Calculator

Tips: Enter the Hazard Ratio value. The calculator will compute the approximate Absolute Risk Reduction as both a proportion and percentage.

5. Frequently Asked Questions (FAQ)

Q1: When is this approximation valid?
A: This approximation works best for binary outcomes in survival analysis and when event rates are not extremely low.

Q2: What's the difference between ARR and HR?
A: HR is a relative measure (ratio of hazards), while ARR is an absolute measure (difference in risk proportions).

Q3: Can this be used for continuous outcomes?
A: No, this approximation is specifically for binary outcomes in time-to-event analyses.

Q4: What are typical HR values in clinical studies?
A: HR values typically range from 0.5 to 2.0, with values below 1 indicating treatment benefit.

Q5: How accurate is this approximation?
A: It provides a reasonable estimate but may not be precise for all scenarios, especially with very low baseline risks.