Related Experiment Video
Updated: Sep 2, 2026
Functional Near-Infrared Spectroscopy Hyperscanning Study in Psychological Counseling
Published on: January 17, 2025
Psychometric validation of the Chinese version of the Scratch Intensity and Impact Scale (SIIS) in patients with
Jian Sun1, Yiru Chang1, Lun He1
1Department of Dermatology and Venereology, The First Affiliated Hospital of Jinzhou Medical University, Jinzhou, Liaoning, China.
Background:
Chronic pruritus poses a substantial burden on patients, leading to physical discomfort, emotional distress, and psychosocial dysfunction. The Scratch Intensity and Impact Scale (SIIS) is a patient-reported outcome (PRO) measure designed to assess both scratching intensity and its effects on health-related quality of life (HRQoL). However, its psychometric properties have not been validated in a Chinese population. This study aimed to culturally adapt and psychometrically validate the SIIS for Chinese patients with chronic pruritus.
Methods:
The original SIIS was translated into Chinese following a standardized forward-backward translation procedure. In a cross-sectional study, 358 adult patients with chronic pruritus were recruited from Northeast China. Construct validity was assessed by randomly splitting the sample for exploratory factor analysis (EFA; n = 179) with oblique rotation and confirmatory factor analysis (CFA; n = 179). Reliability was evaluated through internal consistency (Cronbach's α and McDonald's ω), split-half reliability, and two-week test-retest reliability. Content validity was examined using content validity indices.
Results:
The 13-item Chinese version of the SIIS exhibited a stable two-factor structure, explaining 84.378% of the total variance. Sampling adequacy was confirmed (KMO = 0.948), and Bartlett's test indicated suitability for factor analysis (χ2 = 6798.064, p < 0.001). CFA demonstrated acceptable model fit: chi-square degree of freedom (χ 2/df) = 2.094, root mean square error of approximation (RMSEA) = 0.078, standardized root mean square residual (SRMR) = 0.0188. Comparative Fit Index (CFI) = 0.985, Tucker-Lewis Index (TLI) = 0.981, Normed Fit Index (NFI) = 0.972, and Incremental Fit Index (IFI) = 0.985. Content validity was strong, with a scale-level content validity index (S-CVI) of 0.96 and item-level indices (I-CVI) ranging from 0.83 to 1.00. The scale also showed excellent reliability, including high internal consistency (Cronbach's α = 0.971, McDonald's ω = 0.969), split-half reliability (Spearman-Brown coefficient = 0.904), and strong test-retest stability over 2 weeks (r = 0.958).
Conclusion:
The Chinese version of the SIIS demonstrates strong psychometric properties, confirming its reliability and validity as a PRO instrument for evaluating scratching intensity and HRQoL impact. In this population, it shows promise as a PRO instrument for adult patients with chronic pruritus due to AD or psoriasis in dermatology settings, pending further validation in broader populations.
