1. What is Relative Risk Reduction?

Relative Risk Reduction (RRR) is a measure of the proportional reduction in risk between the control group and experimental group in clinical trials. It expresses how much the treatment reduces the risk of an event relative to the control group.

2. How Does the Calculator Work?

The calculator uses the RRR formula:

Where:

• \( RRR \) — Relative Risk Reduction (%)
• \( CER \) — Control Event Rate (proportion of events in control group)
• \( EER \) — Experimental Event Rate (proportion of events in treatment group)

Explanation: RRR shows the percentage reduction in risk achieved by the intervention compared to the control. A higher RRR indicates greater treatment effectiveness.

3. Importance of RRR Calculation

Details: RRR is crucial for understanding treatment efficacy in clinical trials, helping healthcare providers and patients make informed decisions about interventions. It provides a clear measure of how much a treatment can reduce the risk of adverse outcomes.

4. Using the Calculator

Tips: Enter CER and EER as proportions between 0 and 1 (e.g., 0.15 for 15%). CER must be greater than EER for meaningful RRR calculation. Both values must be valid proportions.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between RRR and ARR?
A: RRR shows proportional risk reduction, while ARR (Absolute Risk Reduction) shows the actual difference in risk between groups. RRR is often larger and can be more impressive.

Q2: When is RRR most useful?
A: RRR is particularly useful when baseline risks are high, as it shows the proportional benefit of treatment regardless of the absolute risk level.

Q3: What are the limitations of RRR?
A: RRR can be misleading when baseline risks are low, as small absolute differences can appear as large percentage reductions. Always consider ARR and NNT alongside RRR.

Q4: Can RRR be negative?
A: Yes, if EER > CER, RRR will be negative, indicating the treatment actually increases risk rather than reducing it.

Q5: How should RRR be interpreted in clinical practice?
A: RRR should be interpreted in context with baseline risk. A large RRR may have little clinical impact if the baseline risk is very low.