PASI severidade psoríase
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The PASI calculator is a medical tool that assesses psoriasis severity based on four criteria: erythema (E), induration (I), desquamation (D), affected area (A), and a correction factor. Each criterion is scored from 0 to 4, and the formula 0.1·(E+I+D)·A·factor generates a unique index. This helps dermatologists track treatment effectiveness and adjust therapies.
The affected area (A) is divided into four body regions (head, legs, trunk, and arms), each with its own scale. Higher values indicate greater disease extent. The correction factor adjusts the index for atypical cases. It is crucial that diagnoses are performed by professionals, as psoriasis can resemble other skin conditions.
Use this tool after medical consultations to monitor changes over time. It is not intended for self-diagnosis. Keep records of scores for the dermatologist to analyze trends. The formula is widely used in clinical trials and chronic disease monitoring.
Frequently asked questions
What does the PASI index measure?
It measures the severity of psoriasis based on erythema, induration, desquamation, and affected area. Higher values indicate worsening disease.
How is the affected area calculated?
The area is divided into four body regions (head, legs, trunk, arms), each with a 0-6 scale based on the extent in each region.
Who should use this calculator?
It is intended only for dermatologists, as it requires objective lesion assessment and clinical expertise for accurate interpretation.
Does a high result mean severe psoriasis?
Yes. Indices above 10 are generally classified as moderate/severe, but the final diagnosis depends on the professional evaluating all symptoms.
What is the correction factor used for?
It adjusts the calculation in atypical cases, such as when psoriasis affects less than 1% of the body or when other factors influence the condition.