Reliability and validity of the Persian version of 5-D itching scale among patients with chronic kidney disease

Abstract

Background: Hemodialysis is considered a major therapeutic method for patients with chronic kidney disease. Pruritus is a common complaint of hemodialysis patients. The 5-D pruritus scale is amongst the most common tools to evaluate several dimensions of itch. Psychometric properties of the 5-D scale have not been evaluated in Persian speaking population with hemodialysis; hence, the objective of this study was to assess reliability and validity of the Persian version of the scale. Methods: Ninety hemodialysis patients (men: 50, women: 40, mean age: 54.4 years) participated in this cross-sectional study. The final Persian version of 5-D scale was given to the participants. Tests Compared: One-third of the participants completed the scale twice within 3–7 days apart to evaluate test- retest reliability. Other psychometric properties including internal consistency, absolute reliability, convergent, discriminative and construct validity, floor/ceiling effects were also evaluated. Results: The Persian 5-D scale has strong test-retest reliability (ICC= 0.98) and internal consistency (Cronbach’s alpha= 0.99). Standard error of measurement and minimal detectable change were 0.33 and 0.91, respectively. Regarding convergent validity, the scale had moderate correlation with numeric rating scale (r =0.67) and quality of life questionnaire related to itch (r = 0.59). Exploratory factor analysis revealed two factors within the scale. No floor or ceiling effect was found for the scale. Conclusion: The Persian version of 5-D the itching scale is a brief instrument with acceptable reliability and validity. Therefore, the scale could be used by experts, nurses, and other health service providers to evaluate pruritus among Persian speaking hemodialysis patients.