Utility of a Single Itch-Related Question and the Skindex-10 Questionnaire for Assessing Pruritus and Predicting Health-Related Quality of Life in Patients Receiving Hemodialysis

Rationale & Objective: Chronic kidney disease-associated pruritus has been linked with poorer mental and physical health-related quality of life (HR-QOL) in patients receiving hemodialysis. We used the Skindex-10 questionnaire and a single itch-related question to evaluate their prediction of HR-QOL.

Study Design: Prospective, international cohort.

Setting & Participants: We analyzed data from 4,940 patients receiving hemodialysis from 17 countries enrolled in phase 5 (2013) of the Dialysis Outcomes and Practice Patterns Study.

Predictors: The responses to the 10 questions of Skindex-10 (0-6 scale) pertaining to itchiness in the past week were summed to create a summary score (range, 0-60). Concurrently, a single question from the Kidney Disease Quality of Life 36-item survey asked "during the past 4 weeks, to what extent were you bothered by itchy skin?" with 5 responses, ranging from "not at all" to "extremely" bothered.

Outcomes: Physical component summary (PCS) and mental component summary (MCS) scores of HR-QOL.

Analytical Approach: We used separate linear regression models to evaluate the predictive power, based on R values, for 3 models: 1 for each predictor and 1 with both predictors.

Results: The correlation between the single itch-related question and the Skindex-10 score was 0.72. A 10-point higher Skindex-10 score was associated with a 1.2-point lower PCS score (95% CI, -1.4 to -0.9) and a 1.5-point lower MCS score (95% CI, -1.7 to -1.3) . The R value for PCS was 0.065 when the single question was used and only 0.033 when Skindex-10 was used as the predictor; the R value for MCS was 0.056 for the single question versus 0.052 for Skindex-10.

Limitations: Measurement bias and translation issues in the questionnaires.

Conclusions: The single question about the extent to which the patients were bothered by itchy skin was highly correlated with the Skindex-10 score and at least as predictive of key HR-QOL measures. In daily clinical practice, using 1 simple question about the extent to which patients are bothered by itchy skin can be a feasible and efficient method for the routine assessment of pruritus.