1. What is the PASI Score?

The Psoriasis Area and Severity Index (PASI) is the gold standard tool for measuring the severity of psoriasis. It combines assessments of lesion severity and affected area into a single score ranging from 0 to 72.

2. How Does the Calculator Work?

The calculator uses the PASI equation:

Where:

• E - Erythema (redness) score (0-4)
• I - Induration (thickness) score (0-4)
• D - Desquamation (scaling) score (0-4)
• A - Area affected (0-6 scale)
• Subscripts H (head), U (upper limbs), T (trunk), L (lower limbs)

Explanation: The equation weights different body areas according to their proportion of total body surface area.

3. Importance of PASI Calculation

Details: PASI score is crucial for assessing psoriasis severity, monitoring treatment response, and determining eligibility for systemic therapies or clinical trials.

4. Using the Calculator

Tips: For each body region, score the three severity parameters (0-4) and the area affected (0-6). All values must be within their specified ranges.

5. Frequently Asked Questions (FAQ)

Q1: How do I score the severity parameters?
A: 0=none, 1=slight, 2=moderate, 3=severe, 4=very severe. Assess the most severe plaque in each region.

Q2: How is area scored?
A: 0=0%, 1=1-9%, 2=10-29%, 3=30-49%, 4=50-69%, 5=70-89%, 6=90-100% of body region affected.

Q3: What is a clinically significant PASI improvement?
A: PASI 75 (75% improvement from baseline) is often used as a treatment efficacy benchmark.

Q4: Are there limitations to PASI?
A: PASI doesn't assess quality of life or nail/special area involvement. It can be subjective in mild cases.

Q5: What PASI score indicates severe psoriasis?
A: Typically PASI >10 indicates moderate-severe disease, though clinical judgment is also important.