Validation of the Psoriasis Symptom Inventory (PSI), a patient-reported outcome measure to assess psoriasis symptom severity

Donald M. Bushnell*, Mona L. Martin, Kelly Mccarrier, Kenneth Gordon, Chiun Fang Chiou, Xingyue Huang, Brian Ortmeier, Gregory Kricorian

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

Background: The objective of this study was to evaluate the measurement properties of the Psoriasis Symptom Inventory (PSI), an eight-item patient-reported outcome measure for assessing severity of plaque psoriasis symptoms. Methods: In this prospective, randomized study using data from adults with moderate-to-severe plaque psoriasis, patients completed the PSI, Dermatology Life Quality Index (DLQI), SF-36v2 Acute, and Patient Global Assessment (PtGA). PSI construct validity was assessed using Spearman rank correlations between PSI and DLQI and SF-36; test-retest reliability and sensitivity to change were evaluated using PtGA as an anchor. Daily 24-h and weekly 7-day PSI versions were evaluated. Results: Eight US sites enrolled 143 patients; 139 (97.2%) completed the study. All symptoms (itch, redness, scaling, burning, cracking, stinging, flaking, and pain) were reported across all response options (not at all severe, mild, moderate, severe, very severe). Test-retest reliability was acceptable (intraclass correlation coefficients range = 0.70-0.80). A priori hypotheses of convergent and discriminant validity were confirmed by correlations of PSI with DLQI items and SF-36 domains. The PSI demonstrated good construct validity and was sensitive to within-subject change (p < 0.0001). Conclusions: The PSI is brief, valid, reproducible, and responsive to change and has the potential to be a useful PRO measure in psoriasis clinical trials.

Original languageEnglish (US)
Pages (from-to)356-360
Number of pages5
JournalJournal of Dermatological Treatment
Volume24
Issue number5
DOIs
StatePublished - Oct 2013

Funding

Declaration of interest: This study was funded by Amgen Inc. DMB, MLM, and KM are employees of Health Research Associates, which received funding for this study. KG has received honoraria from and served as a consultant to Abbott Laboratories, Amgen, Janssen Novartis, Pfizer, Merck, and Lilly and has received grants from Abbott, Amgen, Janssen, Lilly, and Celgene. C-FC and XH are past employees and shareholders of Amgen Inc. BO and GK are employees and shareholders of Amgen Inc. Julia R. Gage, PhD, provided writing support on behalf of Amgen Inc. Jon Nilsen, PhD (Amgen Inc.) provided editorial assistance.

Keywords

  • Daily diary
  • Patient-reported outcome
  • Plaque psoriasis
  • Psychometric properties
  • Symptom

ASJC Scopus subject areas

  • Dermatology

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