The Static Physician’s Global Assessment of Genitalia: A Clinical Outcome Measure for the Severity of Genital Psoriasis
August 2017 | Volume 16 | Issue 8 | Original Article | 793 | Copyright © 2017
Joseph F. Merola MD MMSc,a Alison Potts Bleakman PhD,b Alice B. Gottlieb MD PhD,c Alan Menter MD,d April N. Naegeli PhD,b Robert Bissonnette MD MS FAAD FRCPC,e Lyn Guenther MD FRCPC,f John Sullivan MBBS MS,g Kim Meeuwis MD PhD,h Kyoungah See PhD,b and Kristina Callis Duffin MD MSi
aDepartment of Dermatology and Medicine, Division of Rheumatology, Harvard Medical School, Brigham and Women’s Hospital, Boston, MA, USA bEli Lilly and Company, Indianapolis, IN, USA cDepartment of Dermatology, New York Medical College at Metropolitan Hospital, New York, NY, USA dDepartment of Dermatology, Baylor University Medical Center, Dallas, TX, USA eInnovaderm Research, Montreal, QC, Canada fThe Guenther Dermatology Research Centre, London, ON, Canada gDepartment of Medicine, UNSW, Sydney, New South Wales, Australia hDepartment of Dermatology, Radboud University Medical Center, Nijmegen, The Netherlands iDepartment of Dermatology, University of Utah, Salt Lake City, UT, USA
Introduction: Genital psoriasis is a common but frequently overlooked manifestation of psoriasis with a considerable impact on patients’ quality of life. Currently no validated clinical trial outcome measures exist to assess genital psoriasis severity that meet regulatory agency requirements.
Methods: This study describes the development of the static Physician’s Global Assessment of Genitalia (sPGA-G) scale, a clinical outcome measure for the assessment of genital psoriasis severity that accounts for the erythematous clinical presentation of genital psoriasis. The reliability of the sPGA-G was evaluated using scores collected from clinician assessments of photographs of genital psoriasis cases. Scores were collected from 10 academic and clinical experts in genital psoriasis and 95 clinician assessors who participated in either in-person (n=28) or online (n=67) sPGA-G training modules.
Results: The sPGA-G had a high inter-rater reliability (IRR, measured by Kendall’s W) for expert raters (W=0.856, P less than 0.0001), in-person assessors (W=0.822, P less than 0.0001), and online assessors (W=0.678, P less than 0.0001). IRR was also high for all clinical assessors combined, (W=0.714, P less than 0.0001).
Discussion: This study demonstrates that the sPGA-G is an intuitive and reliable clinical outcome measure that specifically measures the severity of genital psoriasis.
J Drugs Dermatol. 2017;16(8):793-799.
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Psoriasis is a chronic immune-mediated skin disorder affecting approxmiately 2% to 3% of adults in the United States and 0.5% to 8.5% globally.1 Questionnaire-based studies estimate that 28.6% to 45.5% of patients with psoriasis are affected by genital psoriasis.2-4 Recent studies involving a physical examination of patients with psoriasis indicate that 38% have current genital involvement and 63% develop genital psoriasis at least once over the course of their disease.5,6 Because of friction, moisture, and maceration in the genital region, genital psoriasis is characterized by thin, symmetrical, and bright red plaques with well-defined edges, generally lacking the characteristic scale and thickness observed on other body areas.3,7 Genital psoriasis also has a considerable impact on patient quality of life by affecting daily activities, social interactions, and sexual health.5,8 Guidelines for the treatment of psoriasis suggest that cases of mild psoriasis with genital involvement may justify classification as moderate or severe disease and may warrant systemic treatment, especially if topical treatments are ineffective.9-12Because genital psoriasis is a high burden5,8 subset of disease that is often overlooked or misdiagnosed,3,7,9,13,14 there is a scientific need for validated outcome measures that meet the requirements of the Food and Drug Administration (FDA) and other regulatory agencies for use in assessing genital psoriasis severity in clinical trials. Few clinical outcome measures exist for the assessment of genital psoriasis, and none are well established or appropriately validated. The Static Physician’s Global Assessment of Genitalia (sPGA-G) scale is a well-defined clinician reported outcome measure developed to evaluate the severity of genital psoriasis. The objective of this study is to describe the sPGA-G scale, the methodology used