Reliability, validity, and the ability to detect change of the Psoriasis Symptom Scale (PSS) in patients with plaque psoriasis. (3rd July 2020)

• Record Type: Journal Article
• Authors: Rentz, Anne M.; Skalicky, Anne M.; Esser, Dirk; Zema, Carla; Becker, Karin; Bodhani, Amit; Revicki, Dennis A.
• Is Part Of: Journal of dermatological treatment. Volume 31:Number 5(2020)
• Page Start: 460
• Page End: 469
• Publication Date: 2020-07-03
• Subjects: Psoriasis -- PRO -- PSS -- symptoms; Skin -- Diseases -- Treatment -- Periodicals; Skin Diseases -- drug therapy -- Periodicals; Skin Diseases -- therapy -- Periodicals; 616.5
• DOI: 10.1080/09546634.2019.1709612
• Languages: English
• ISSNs: 0954-6634

Abstract

Abstract: Introduction: The primary objective of the study was to evaluate the measurement properties of the patient-reported four-item Psoriasis Symptom Scale (PSS). Methods : Analysis of phase-III data on the efficacy of risankizumab to assess psychometric characteristics of the PSS in patients with moderate-to-severe psoriasis. Results: PSS items had a good range of symptom severity coverage. The PSS had good test–retest reliability (ICCs >0.90). Convergent and discriminant validity was indicated by moderate-to-strong correlations between the PSS and Dermatology Life Quality Index (DLQI), PSS pain item and EQ-5D pain/discomfort item at week 12 (0.63), and moderate negative correlation with EQ-Visual Analog Scale score at week 12 (−0.37). Known groups validity demonstrated as mean PSS total scores varied by Psoriasis Area and Severity Index (PASI) and Static Physician's Global Assessment (sPGA) defined groups ( p < .0001). PSS total scores were responsive to changes in PASI score ( p < .0001) and sPGA ( p < .0001). PSS minimal, clinical, and meaningful change is estimated to be 1 to 2 points; a preliminary responder definition is a total change score of 3 to 4 points. Conclusions: The PSS is a short, valid unidimensional measure of psoriasis symptom severity, well suited for use in clinical trials.