PGAxBSA composite versus PASI: Comparison across disease severities and as therapeutic response measure for Cal/BD foam in plaque psoriasis

Background The product of the Physician Global Assessment and body surface area (PGA×BSA) is simpler to use than the Psoriasis Area and Severity Index (PASI), which lacks sensitivity in patients with mild psoriasis. Objective To compare the PGA×BSA versus the modified PASI (mPASI) for assessing disease severity and therapeutic response to calcipotriol/betamethasone dipropionate (Cal/BD) foam. Methods This post hoc analysis evaluated the efficacy of Cal/BD foam in mild, moderate, and severe psoriasis, as assessed by the PGA×BSA and mPASI, using data from 3 randomized controlled trials ( NCT01536886 , NCT01866163 , NCT02132936 ). Spearman correlation and Bland-Altman plots were used to compare the PGA×BSA with the mPASI. Results Proportions of patients receiving Cal/BD foam achieving 75% response for PGA×BSA and mPASI at weeks 1, 2, and 4 were similar and significantly greater than with vehicle (P ≤ .002 at all timepoints); at week 4, mean improvements were 51.0% and 50.7%, respectively. Spearman correlations for mild, moderate, and severe psoriasis were moderate to high between PGA×BSA and mPASI at baseline (r = .51, .72, and .86, respectively; n = 126, 465, and 58, respectively) and high at week 4 (r = .80, .81, and .89, respectively; n = 121, 452, and 58, respectively) (P Limitations Pooled data from different trials were not prespecified for post hoc analysis. Interrater reliability was not assessed. Conclusion Pooled data analysis showed that the PGA×BSA and mPASI correlation was higher with increasing psoriasis severity.