PASI is a combination of the intensity of psoriasis, assessed by the erythema (reddening), induration (plaque thickness) and desquamation (scaling) on of the lesions rated on a a scale from 0 (no symptoms) to 4 (very marked), together with the percentage of the area affected, rated on a scale from 0 (0%) to 6 (100%). PASI scoring is performed at four body areas, the head, arms, trunk, and legs. The total PASI score ranges from 0 to 72. The higher the total score, the more severe the disease. Change from baseline was calculated as the value at baseline minus the value at each subsequent time point. A negative change represents improvement.