PGA×BSA: A Measure of Psoriasis Severity Tested in Patients with Active Psoriatic Arthritis and Treated with...

The product of physician's global assessment and body surface area (PGA×BSA) to assess psoriasis severity has previously been investigated in patients with psoriasis, with the aim of assessing PGA×BSA as an alternative to the time-consuming Psoriasis Area and Severity Index (PASI). Here, we investigate PGA×BSA as an alternative to PASI in patients with psoriatic arthritis (PsA).

Analyses used data from the double-blind, placebo-controlled, RAPID-PsA trial (NCT01087788) that investigated the efficacy of certolizumab pegol (CZP) in patients with PsA. Outcomes assessed whether the PGA×BSA and PASI results were comparable, and whether these outcomes correlated with one another or with the Dermatology Life Quality Index (DLQI).

For CZP-treated patients, both PGA×BSA and PASI demonstrated similar sensitivities to treatment between baseline and Week 24, with mean improvements of 77.4% and 69.0%, respectively. Similar improvements were also seen with placebo (PGA×BSA: 3.2%, PASI: 6.1%). Achievement of 75% response criterion in PGA×BSA and PASI was attained by similar proportions of patients with CZP (PGA×BSA75: 59.0%, PASI75: 61.4%) and placebo (PGA × BSA75: 15.1%, PASI75: 15.1%). Cross tabulations showed high concordance between achievement of response outcomes in PGA×BSA and PASI (79.6-95.2%). Spearman correlations revealed strong correlations between PGA×BSA and PASI at baseline (r = 0.78; n = 225) and percentage improvement to Week 24 (r = 0.85; n = 186). Both outcomes were only moderately correlated with DLQI (r = 0.41-0.50; n = 179-249).

PGA×BSA is sensitive to changes in skin manifestations in patients with PsA treated with CZP. Further, PGA×BSA correlates strongly with PASI, and achievement of 75% improvement was similar for PGA×BSA and PASI.