Analysis of Body Regions and Components of PASI Scores During Adalimumab or Methotrexate Treatment for Patients With Moderate-to-Severe Psoriasis

May 2014 | Volume 13 | Issue 5 | Original Article | 554 | Copyright © May 2014

Alexander A. Navarini MD,a Yves Poulin MD,b Alan Menter MD,c Yihua Gu MS,d and Henrique D. Teixeira PhDd

aSt. John's Institute of Dermatology, King’s College, London, UK
bCentre Dermatologique du Québec Metropolitain, Québec, QC, Canada
cBaylor Research Institute, Dallas, TX
dAbbVie Inc., North Chicago, IL

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.

J Drugs Dermatol. 2014;13(5):554-562.

The Psoriasis Area Severity Index (PASI) is the most commonly utilized and extensively validated tool to assess the severity of psoriasis and treatment effect, especially in clinical research.1,2 PASI quantitatively assesses disease activity by means of an overall composite score, based on the amount of involved body surface area (BSA) and the degree of severity of psoriatic lesions as reflected by the 3 key components erythema, induration, and desquamation of psoriatic plaques, weighted by body region (head, trunk, upper and lower extremities).3-5 The extent (percentage) of involvement of each body region is scored from 0 to 6. Calculating these scores yield a possible range of PASI scores from 0 to 72.
The PASI assessment is seldom used in clinical practice, but primarily in clinical trials.6 PASI is also utilized to measure treatment response, compare response between active treatments, standardize the measurement of psoriasis severity,7 and correlate psoriasis severity among patient populations.4 An American Academy of Dermatology consensus group recommends utilizing PASI to determine the extent of disease when evaluating treatment options.8
While PASI has become the most commonly used outcome measure in clinical trials of psoriasis treatment, it has several limitations. The scoring method can be unreliable due to its complex score calculation,4,7,9 the amount of affected BSA is a subjective decision based on estimation,1,9 which prevents this assessment from being completely validated,2,10 and the score can be difficult to interpret due to its non-linearity.2 Additionally, PASI is a less sensitive measurement in patients with low BSA involvement,6 and the amount of improvement in the score does not always correspond to clinical relevance.11 Furthermore, the scoring does not take into account the disproportionate disease burden reflected in the more visible (hands, feet, nails, face) or covered (genitalia and perianal) body regions,1 or the impact on patient quality of life (QoL).12 In the face of the PASI score’s limitations, a number of other psoriasis scoring methods have been developed, but not widely adopted.4,13-20
Although PASI is considered to be reliable for measuring global activity of moderate-to-severe psoriasis,1,2 the score can be misleading. Potentially important response differences may be