title: Psychometric properties of the Itch Numeric Rating Scale in patients with moderate-to-severe plaque psoriasis.
abstract: BACKGROUND
  Itching is a profoundly distressing symptom for many patients with psoriasis, but it has not been rigorously studied using validated tools for this condition.
  
  
  OBJECTIVE
  This study investigated the psychometric properties of the Itch Numeric Rating Scale (Itch NRS), a single-item patient-reported outcome (PRO) measuring the worst itching severity due to psoriasis in the past 24 h.
  
  
  METHODS
  Using disease-specific clinician-rated and PRO data from one phase II and three phase III randomized clinical studies of subjects with moderate-to-severe plaque psoriasis, the Itch NRS was evaluated for test-retest reliability, construct validity and responsiveness. A responder definition was explored using anchor- and distribution-based methods.
  
  
  RESULTS
  Test-retest reliability analyses supported the reproducibility of the measure (intraclass correlation coefficient range 0·71-0·74). To support the construct validity of the Itch NRS, large cross-sectional correlations with the Dermatology Life Quality Index (DLQI) Symptoms and Feelings domain (r ≥ 0·60 at baseline and r ≥ 0·80 at week 12) supported a priori hypotheses, while large correlations (r ≥ 0·71) between changes in Itch NRS scores and changes in DLQI Symptoms and Feelings domain scores from baseline to week 12 established responsiveness. A 4-point change was optimal for demonstrating a level of clinically meaningful improvement in itch severity after 12 weeks of treatment, which corresponds with marked clinical improvements in plaque psoriasis.
  
  
  CONCLUSIONS
  The Itch NRS demonstrated sufficient reliability, validity and responsiveness, and appropriate interpretation standards for evaluating change over time in itch severity among patients with moderate-to-severe plaque psoriasis when validated using clinical trial data for this condition.
authors: Massachusetts General Hospital and Harvard Medical School, Boston, MA, U.S.A.
authors: A B
authors: AB
authors: Kimball
authors: Eli Lilly and Company, Indianapolis, IN, U.S.A.
authors: A N
authors: AN
authors: Naegeli
authors: Eli Lilly and Company, Indianapolis, IN, U.S.A.
authors: E
authors: E
authors: Edson-Heredia
authors: Eli Lilly and Company, Indianapolis, IN, U.S.A.
authors: C-Y
authors: CY
authors: Lin
authors: Eli Lilly and Company, Indianapolis, IN, U.S.A.
authors: C
authors: C
authors: Gaich
authors: Eli Lilly and Company, Indianapolis, IN, U.S.A.
authors: E
authors: E
authors: Nikaï
authors: Evidera, Inc., Bethesda, MD, U.S.A.
authors: K
authors: K
authors: Wyrwich
authors: Temple University, Philadelphia, PA, U.S.A.
authors: G
authors: G
authors: Yosipovitch
mesh_terms: D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use; D001384:Azetidines / Q000627:therapeutic use; D003879:Dermatologic Agents / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000071066:Patient Reported Outcome Measures; D011537:Pruritus / Q000175:diagnosis* / Q000209:etiology; D011565:Psoriasis / Q000150:complications* / Q000188:drug therapy; D011594:Psychometrics; D011687:Purines; D011720:Pyrazoles; D011788:Quality of Life; D012720:Severity of Illness Index; D013449:Sulfonamides / Q000627:therapeutic use; D011795:Surveys and Questionnaires
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D001384:Azetidines; D003879:Dermatologic Agents; D011687:Purines; D011720:Pyrazoles; D013449:Sulfonamides; C549079:ixekizumab; C000596027:baricitinib