Evaluation of the Physician Global Assessment and Body Surface Area Composite Tool for Assessing Psoriasis Response to Apremilast Therapy: Results from ESTEEM 1 and ESTEEM 2
February 2017 | Volume 16 | Issue 2 | Original Article | 147 | Copyright © February 2017
Kristina C. Duffin MD MS,a Kim A. Papp MD PhD,b Jerry Bagel MD,c Eugenia Levi PharmD BCPS,d Rongdean Chen PhD,d and Alice B. Gottlieb MD PhDe
aUniversity of Utah, Salt Lake City, UT bProbity Medical Research and K Papp Clinical Research, Waterloo, ON, Canada cPsoriasis Treatment Center of Central New Jersey, East Windsor, NJ dCelgene Corporation, Summit, NJ eTufts University School of Medicine, Boston, MA
Abstract
BACKGROUND: The Physician Global Assessment and Body Surface Area (PGAxBSA) composite tool is a simple, effective alternative for measuring psoriasis severity.
OBJECTIVE: To evaluate the product of PGAxBSA as a sensitive alternative to the Psoriasis Area and Severity Index (PASI) for assessing disease severity and therapeutic response with data collected from the phase 3 ESTEEM 1 and 2 trials.
METHODS: This post hoc analysis included 836 patients randomized to apremilast 30 mg BID at baseline (ESTEEM 1, n=562; ESTEEM 2, n=274). Spearman correlation coefficients were used to compare PGAxBSA, PASI, and the Dermatology Life Quality Index (DLQI). Concordance between PGAxBSA and PASI was evaluated for 50%/75%/90% improvement from baseline at week 16.
RESULTS: In ESTEEM 1 and 2, PGAxBSA and PASI exhibited significant positive correlations for measuring disease severity at baseline (r≥0.757) and week 16 (r≥0.807). At week 16, ≥79% concordance was observed between PGAxBSA and PASI for 75% and 90% improvement from baseline; greater concordance (>88.0%) was observed using 50% improvement from baseline. At week 16, PGAxBSA and PASI were moderately correlated with DLQI.
Limitations: Analysis was limited to patients with baseline BSA ≥10% and static PGA ≥3.
CONCLUSIONS: In patients with moderate to severe psoriasis, PGAxBSA is correlated with PASI and sensitive to therapeutic response.
J Drugs Dermatol. 2017;16(2):147-153.
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INTRODUCTION
The assessment of psoriasis disease activity in a consistent and clinically meaningful way is critically important for clinicians and clinical research. The Psoriasis Area and Severity Index (PASI), the Physician Global Assessment (PGA), and the percentage of body surface area (BSA) involvement are commonly used to assess psoriasis disease activity in clinical trials.1,2 The PASI is a composite tool that combines the assessment of disease severity and BSA involvement into a single score ranging from 0 (no disease) to 72 (maximum disease).3 The PASI score is derived from a complex multistep formula that is weighted based on the total BSA of each region. Static PGA rating scales assess erythema, desquamation, and induration characteristics of psoriatic plaques using 5- to 8-point scales that are less complex than PASI4; however, most PGA tools do not account for BSA involvement and thus do not include a key aspect of disease severity (Table 1).1,2 For example, a patient with severe disease characterized by 32% BSA and sPGA of 4 at baseline may resolve with treatment to a single scaly red raised lesion that covers 0.25% of body area (Figure 1). The PGA score would remain unchanged based on the nature of the plaque characteristics alone, suggesting no clinical improvement in disease severity. Similarly, the percentage of BSA involvement is easily estimated, but does not evaluate the intensity of the psoriatic lesion and is subject to high inter observer variability.1,4 Thus, as stand-alone instruments, the static PGA and BSA do not consistently provide global assessment of psoriasis disease activity (Table 1).4 A psoriasis severity measurement tool using the product of the static PGA and the percentage of BSA involvement, the Physician Global Assessment and Body Surface Area (PGAxBSA composite tool; also known as s-MAPA), accounting for both extent and severity of psoriasis disease activity, has been developed to provide a simple global assessment of psoriasis disease activity and has been examined as an alternative to the PASI.5 When the PGA is multiplied by the BSA, the resulting score provides an accurate global assessment of disease severity that can be done relatively quickly (Figure 2). In a study using data
