Development of the Psoriasis Symptoms Scale (PSS) in patients with moderate-to-severe psoriasis: qualitative and quantitative analyses. (3rd July 2020)

• Record Type: Journal Article
• Authors: Armstrong, April W.; Edson-Heredia, Emily; Naegeli, April N.; Burge, Russel; Poon, Jiat-Ling; Anatchkova, Milena; Sun, Luna; Zhu, Baojin; Wyrwich, Kathleen W.
• Is Part Of: Journal of dermatological treatment. Volume 31:Number 5(2020)
• Page Start: 452
• Page End: 459
• Publication Date: 2020-07-03
• Subjects: Psoriasis -- patient-reported outcomes -- symptoms -- signs -- Psoriasis Symptoms Scale; Skin -- Diseases -- Treatment -- Periodicals; Skin Diseases -- drug therapy -- Periodicals; Skin Diseases -- therapy -- Periodicals; 616.5
• DOI: 10.1080/09546634.2019.1623370
• Languages: English
• ISSNs: 0954-6634

Abstract

Abstract: Background: Psoriasis is a chronic inflammatory skin disease. Objective: To establish content validity and assess psychometric properties of the Psoriasis Symptoms Scale (PSS) in patients with moderate-to-severe psoriasis (Ps). Methods: The PSS is an eight-item patient-completed questionnaire assessing symptoms (itch, pain, stinging, burning), signs (redness, scaling, cracking), and discomfort. Content validity was established during interviews of patients ( n = 14) with Ps. PSS Symptoms and Signs domain scores were evaluated for reliability, construct validity, and responsiveness using data from a clinical study (NCT02899988) in Ps ( n = 205). Results: Patients confirmed content validity; the PSS was understandable and relevant. Cronbach's alphas were 0.84 (Symptoms) and 0.86 (Signs), demonstrating internal consistency reliability. Test–retest reliability was confirmed in patients before receiving study drug (intraclass coefficient: 0.82 [Symptoms]; 0.81 [Signs]). Convergent and discriminant validity were demonstrated at baseline and Week 16 by large (≥0.50) correlations between PSS Symptoms and Signs domain scores and Dermatology Life Quality Index total and symptoms and feelings domain scores, and small (<0.30) correlations with Short Form-36 Mental Component Summary score, respectively. Symptoms and Signs scores responded to clinical changes ( p < .001). Conclusions: The PSS Symptoms and Signs domains are valid and reliable assessments of patient-reported symptoms and signs, useful for assessing treatment efficacy.