All three components of the PASI (plaque induration, scaling, and erythema) contributed comparably to the improvement in PASI. Other clinical responses evaluated (Table 2) included the proportion of patients who achieved minimal or clear status by a static Physician Global Assessment (sPGA) and the proportion of patients with a reduction in PASI of at least 50% from baseline (PASI-50) 1 week following the 12-week treatment period. The sPGA is a 6 category scale ranging from "very severe" to "clear" indicating the physician's overall assessment of the psoriasis severity focusing on plaque, scaling and erythema. Treatment success of minimal or clear consisted of none or slight elevation in plaque, none or minimal white color in scaling, and up to moderate definite red coloration in erythema. Across all four studies, the percentage of patients with baseline sPGA classifications of moderate was 48−56%, severe 33−43%, and 3−6% were classified as very severe.