Background: The PASI score, the most common outcome measure in clinical trials of psoriasis treatment, is a non-linear scale that does not allow reliable assessment of subtle variations of its components (erythema, induration, and desquamation).
Objective: Highlight treatment response patterns potentially hidden by PASI score's compounded weighted-average calculation.
Methods: Patients with moderate-to-severe psoriasis enrolled in the phase-3, 16-week, randomized CHAMPION study, and received adalimumab, methotrexate, or placebo. PASI scores were assessed post hoc for improvement, by body region and component.
Results: At Week 16, a significantly greater percentage of adalimumab-treated patients vs methotrexate- and placebo-treated patients, achieved PASI 75, PASI 90 and PASI 100 response in each body region and component. 55.7% of adalimumab-treated patients reached PASI 100 response in the head and neck region vs 16.7% overall. Two key components of PASI, induration and desquamation, were affected by treatment more than erythema, the third component. Adalimumab was particularly effective in complete resolution of induration (44.9% of patients) vs methotrexate (10.9%). For all PASI body regions and components, mean percent improvement in score at Weeks 2, 4, 8, 12, and 16 was significantly greater (P<0.05) for adalimumab treatment vs methotrexate or placebo.
Conclusion: Adalimumab therapy resulted in complete resolution of individual body regions in at least 30.6% up to 55.7% of patients in CHAMPION. This was more than twice that of methotrexate and placebo. PASI improvement by body region is a novel and an important patient-relevant outcome worthy of reporting in future studies.