Background: High-quality patient-reported outcome (PRO) measures for dialysis patients with chronic pruritus are urgently needed. However, no known, well-validated multidimensional tools have been investigated to measure pruritus symptoms in dialysis patients., Objectives: To examine the psychometric properties of a multidimensional tool of chronic pruritus, the Uraemic Pruritus in Dialysis patients (UP-Dial) 14-item scale, by comparing haemodialysis and peritoneal dialysis modality., Methods: This validation study used data from the Thai Renal Outcomes Research-Uraemic Pruritus, a prospective, multicentre, longitudinal study. Data for this study were collected from 1 February 2019 to 31 May 2022. The adult sample of 226 haemodialysis and 327 peritoneal dialysis patients fulfilled the criteria of chronic pruritus based on the International Forum for the Study of Itch. Psychometric properties of the UP-Dial included validity and reliability, as measured across haemodialysis and peritoneal dialysis patients. Patients completed a set of anchor-based measurement tools, including global itching, Dermatology Life Quality Index (DLQI), EuroQoL-5 dimension-5 level (EQ-5D-5L), Kidney Disease Quality of Life-36 (KDQOL-36), Pittsburgh Sleep Quality Index (PSQI), global fatigue, Somatic Symptom Scale-8 (SSS-8) and Patient Health Questionnaire-9 (PHQ-9)., Results: From the patient's perspective, face validity was satisfactory for both dialysis samples. Psychometric analyses of the UP-Dial for each dialysis sample had good convergent validity. Spearman rho correlations indicate a positively strong correlation (0.73-0.74) with global itching, a positively moderate correlation (0.33-0.58) with DLQI, PSQI, global fatigue, SSS-8 and PHQ-9, and a negatively moderate correlation (-0.39 to -0.58) with EQ-5D-5L and KDQOL-36. The discriminant validity was satisfactory with a group of moderate and severe burden of pruritus for both dialysis samples. For scale reliability, the UP-Dial revealed excellent internal consistency (Cronbach's α = 0.89 and McDonald's ω = 0.90) and reproducibility (intraclass correlation 0.84-0.85) for both dialysis samples. Regarding psychometric properties, no statistically significant differences between dialysis samples were observed (all P > 0.05)., Conclusions: The findings reaffirm good measurement properties of the UP-Dial 14-item scale in haemodialysis and peritoneal dialysis patients with chronic pruritus. These suggest a transferability of the UP-Dial as a PRO measure in clinical trial and practice settings., Competing Interests: Conflicts of interest M.M.S. is an advisor/consultant for AstraZeneca, Bayer, GlaxoSmithKline (GSK) and Otsuka. J.A.B. is a consultant and has received research grants from Allakos, Amgen, AstraZeneca, Celldex, Escient, Genentech, GlaxoSmithKline (GSK), Jasper, Novartis and Sanofi Regeneron; has a leadership or fiduciary role in the American Academy of Allergy, Asthma & Immunology (president); Hereditary Angioedema Association (member activities board); Interasma (vice president); and the World Allergy Organization (board of directors). J.C.S. is an advisor/consultant for AbbVie, Leo Pharma, Novartis, Pfizer, Sanofi-Genzyme, Trevi, UCB and Vifor; is a speaker for AbbVie, Almirall, Eli-Lilly, Janssen-Cilag, Leo Pharma, Novartis, Pfizer and Sanofi-Genzyme; is an investigator (principal investigator in clinical trials) for AbbVie, Almirall, Amgen, AnaptysBio, BMS, Boehringer Ingelheim, Celtrion, Galapagos, Galderma, Helm AG, Incyte, InfraRX, Janssen-Cilag, Kliniksa, Leo Pharma, Medimmune, Menlo Therapeutics, Merck, Novartis, Pfizer, Regeneron, Teva, Trevi and UCB; and has a leadership or fiduciary role in the Polish Dermatological Society (president). The other authors declare that they have no relevant conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of British Association of Dermatologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)