G2‐PASE: A Novel, Rapid, and Reliable Measure of Plaque Psoriasis Severity

ABSTRACT Background The Psoriasis Area and Severity Index (PASI), a composite measure of plaque psoriasis disease severity, is commonly used to determine treatment eligibility and response, but is time consuming for every‐day clinical use. The Gulliver‐Gestalt‐Psoriasis Area Severity Estimate (G2‐PASE) was developed to approximate PASI scores using Physician Global Assessment (PGA) and body surface area (BSA) measures. Objectives To determine the reliability and validity of G2‐PASE compared to PASI using data from a multi‐center, Canadian cohort of patients with plaque psoriasis. Methods Canadian patients with a history of moderate to severe plaque psoriasis enrolled in the first cohort of the Psoriasis Longitudinal Assessment and Registry (PSOLAR 1; a global, prospective, longitudinal, disease‐based registry) were included. The G2‐PASE for each patient was calculated by applying baseline PGA and BSA values available from PSOLAR patient data at enrollment. The correlation and reliability of G2‐PASE compared to PASI for each patient at enrollment was then assessed. A similar analysis was conducted to test the reproducibility of results previously published by a participating PSOLAR clinical trial site. Results Of the 1896 Canadian patients in PSOLAR 1, 1803 had PASI data and were included in this analysis. The average baseline PASI score was 5.52 (SD 6.44, range 0.00–64.30), and the mean calculated G2‐PASE score was 8.37 (SD 7.51, range 0.00–45.00). The Pearson's correlation coefficient was 0.83 ( p < 0.0001), indicating very strong and significant correlation between PASI and G2‐PASE scores. The standardized Cronbach coefficient alpha was 0.91. Results from the Canadian PSOLAR cohort are similar to those of patients enrolled at the New Lab Clinical Research Inc. site and complement findings previously reported from this site. Conclusions This study validates G2‐PASE as a reliable measure of plaque psoriasis severity when compared to PASI among a large cohort of patients with predominantly moderate to severe disease.