1. What is Population Attributable Risk?

Definition: PAR measures the disease burden in a population attributable to a specific exposure.

Purpose: It helps epidemiologists and public health professionals understand how much disease could be prevented by eliminating a risk factor.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( PAR \) — Population Attributable Risk (dimensionless)
• \( P_e \) — Proportion of population exposed (0-1)
• \( I_e \) — Incidence in exposed group (0-1)
• \( I_u \) — Incidence in unexposed group (0-1)

Explanation: The difference in incidence rates between exposed and unexposed groups is multiplied by the proportion of the population exposed.

3. Importance of PAR Calculation

Details: PAR helps prioritize public health interventions by quantifying the potential impact of removing a risk factor from the entire population.

4. Using the Calculator

Tips: Enter values between 0 and 1 for all parameters. Incidence rates should be expressed as proportions (e.g., 0.05 for 5%).

5. Frequently Asked Questions (FAQ)

Q1: What does a PAR of 0.15 mean?
A: It means 15% of disease cases in the population could be prevented by eliminating the exposure.

Q2: How is PAR different from attributable risk?
A: Attributable risk (I_e - I_u) measures individual risk difference, while PAR considers the population exposure proportion.

Q3: Can PAR be negative?
A: No, if calculated as negative, it suggests the exposure might be protective rather than harmful.

Q4: What are typical sources for these parameters?
A: Epidemiological studies, cohort studies, or randomized controlled trials provide these values.

Q5: How precise should my inputs be?
A: Use 2-4 decimal places for accuracy, especially for small incidence rates.