PASI Psoriasis Severity Score Calculator

Erythema Head Induration Head Scaling Head Area Head Erythema Upper Limbs Induration Upper Limbs Scaling Upper Limbs Area Upper Limbs Erythema Trunk Induration Trunk Scaling Trunk Area Trunk Erythema Lower Limbs Induration Lower Limbs Scaling Lower Limbs Area Lower Limbs PASI Psoriasis Severity Score Explanation and Clinical Context PASI is one of the most widely accepted scoring systems to quantify the severity of psoriasis in both clinical care and research. The score integrates three key dimensions that reflect the inflammatory burden which are erythema thickness or induration and scaling. These components are evaluated across four anatomical regions which are head upper limbs trunk and lower limbs.

Each region receives an area score that represents the percentage of skin involved which is then multiplied by weighted coefficients proportional to regional skin surface area. The final PASI value ranges from zero to seventy two with higher scores reflecting more extensive and severe disease. Clinically PASI helps physicians determine baseline severity monitor treatment response and compare therapeutic efficacy in trials.

Although there is no absolute normal value a PASI less than ten is generally associated with mild disease. PASI seventy five PASI ninety and PASI one hundred represent improvement thresholds frequently used in treatment studies indicating reduction in disease burden by seventy five ninety or complete clearance respectively. Overall PASI remains a fundamental and structured tool for objective assessment in psoriasis management.

Reference Fredriksson T Pettersson U. Dermatology. 1978.

PASI original publication.