An alternate psoriasis severity outcome measure that includes the product of a physician’s global assessment and body surface area (PGAxBSA) is sensitive to changes in skin manifestations in patients with psoriatic arthritis (PsA) who are treated with certolizumab pegol (CZP) and may be a practical alternative to the Psoriasis Area and Severity Index (PASI), according to the results of an analysis that used data from the double-blind, placebo-controlled RAPID-PsA trial (ClinicalTrials.gov identifier: NCT01087788). The study results were published in The Journal of Rheumatology.
The investigators sought to examine the use of PGAxBSA as an alternative to PASI to evaluate the efficacy of CZP in patients with PsA. Study outcomes assessed whether the results with PGAxBSA and PASI were comparable and whether the outcomes were associated with one another or with the Dermatology Life Quality Index (DLQI).
In CZP-treated patients, both PGAxBSA and PASI exhibited similar sensitivities to treatment between baseline and 24 weeks, with mean improvements of 77.4% and 69.0%, respectively. PGAxBSA and PASI also demonstrated similar improvements with placebo (3.2% vs 6.1%). Achievement of 75% response criterion was obtained in PGAxBSA and PASI was accomplished by similar percentages of patients treated with CZP (59.0% vs 61.4%) and placebo (15.1% vs 15.1%).
Cross tabulations demonstrated significant agreement between achievement of response outcomes in PGAxBSA and PASI (79.6% to 95.2%). Based on Spearman correlations, strong associations were reported between PGAxBSA and PASI at baseline (r=0.78; n=225) and percentage improvement to 24 weeks (r=0.85; n=186). Both outcomes were only moderately associated with DLQI (r=0.41 to 0.50; n=179 to 249).
The investigators concluded that PGAxBSA is sensitive to changes in skin manifestations in CZP-treated patients with PsA. Additional research from prospective studies is warranted in order to further validate the use of this tool.
Walsh JA, Arledge T, Nurminen T, Peterson L, Stark J. PGA×BSA: a measure of psoriasis severity tested in patients with active psoriatic arthritis and treated with certolizumab pegol [published online May 1, 2018]. J Rheumatol. doi:10.3899/jrheum.170244