Uremic pruritus, dialysis adequacy, and metabolic profiles in hemodialysis patients: a prospective 5-year cohort study

Abstract

Background: Uremic pruritus is a common and intractable symptom in patients on chronic hemodialysis, but factors associated with the severity of pruritus remain unclear. This study aimed to explore the associations of metabolic factors and dialysis adequacy with the aggravation of pruritus.

Methods: We conducted a 5-year prospective cohort study on patients with maintenance hemodialysis. A visual analogue scale (VAS) was used to assess the intensity of pruritus. Patient demographic and clinical characteristics, laboratory parameters, dialysis adequacy (assessed by Kt/V), and pruritus intensity were recorded at baseline and follow-up. Change score analysis of the difference score of VAS between baseline and follow-up was performed using multiple linear regression models. The optimal threshold of Kt/V, which is associated with the aggravation of uremic pruritus, was determined by generalized additive models and receiver operating characteristic analysis.

Results: A total of 111 patients completed the study. Linear regression analysis showed that lower Kt/V and use of low-flux dialyzer were significantly associated with the aggravation of pruritus after adjusting for the baseline pruritus intensity and a variety of confounding factors. The optimal threshold value of Kt/V for pruritus was 1.5 suggested by both generalized additive models and receiver operating characteristic analysis.

Conclusions: Hemodialysis with the target of Kt/V ≥1.5 and use of high-flux dialyzer may reduce the intensity of pruritus in patients on chronic hemodialysis. Further clinical trials are required to determine the optimal dialysis dose and regimen for uremic pruritus.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1. Histogram and density plot of visual analogue scale (VAS) scores.

(A) Frequency distribution of pruritus VAS scores at baseline in the study participants. (B) Frequency distribution of pruritus VAS scores at follow-up in the study participants. The density of vertical axis represents the percentage of study participants.

Figure 2. Histogram and density plot of visual analogue scale (VAS) change scores.

Frequency distribution of pruritus VAS change scores in the study participants. The density of vertical axis represents the percentage of study participants. The VAS change score = VAS score at follow-up − VAS score at baseline.

Figure 3. Identifying the appropriate threshold of baseline Kt/V by the generalized additive models (GAM) plot.

(A) The GAM plot adjusted for the important covariates at baseline only (gender, Kt/V, use of high-flux dialyzer, pruritus intensity, hematocrit, creatinine, uric acid, fasting glucose, total bilirubin, and Ca×P).(B) The GAM plot adjusted for the important covariates at baseline (Kt/V, pruritus intensity, AST, and Ca×P) and the change scores of the covariates (uric acid, fasting glucose, and AST). The solid red lines show nonlinearity of multivariable-adjusted relation between baseline Kt/V and change score of pruritus (with 95% confidence intervals shown in black dotted lines). Pruritus intensity was assessed by visual analog scale scores. The little vertical bars (i.e., rugs) on the horizontal axis of the GAM plots display the distribution of individual observations. Both GAM plots identified the value around 1.5 to be the appropriate threshold of baseline Kt/V for uremic pruritus, which indicated start of the aggravation of pruritus intensity began at Kt/V