Association between Dietary Fiber Intake and Uremic Pruritus in Patients with CKD

Background: Uremic pruritus is one of the common symptoms of chronic kidney disease (CKD). Previous studies suggest that mild-inflammation may be one of the causes. The role of dietary fiber in reducing inflammatory factors has become increasingly recognized. It is not clear whether the level of intake of dietary fiber is related to the itchiness in CKD patients. Methods: This was a cross-sectional study that included patients with CKD stages 1-5 and excluded those who used hormones and immunosuppressants within 3 months and suffered from other skin diseases. The level of itchiness was assessed by visual analog scale (VAS). Patients were classified as pruritus group(VAS ＞0) and non-pruritus group(VAS = 0). Dietary fiber intake was recorded using a 3-day dietary survey method. The differences in intake of total dietary fiber, vegetable dietary fiber, and cereal dietary fiber were compared between different groups. Results: A total of 151 patients were included in this study, with a median age of 49.00 (37.00, 58.00) years and a median eGFR of 28.07 (8.27, 77.00) ml/min/1.73m2. A total of 42 (27.81%) patients had pruritus, the mean itch VAS score was 5.28±0.35. Compared to patients without pruritus, CKD patients with pruritus were older [53.50(45.75, 61.00) years vs 47.00(34.00 56.00) years, P=0.003], lower glomerular filtration rate [9.87 (5.23, 37.35) ml/min/1.73m2 vs 36.15 (12.04, 83.98) ml/min/1.73m2, P <0.001], blood potassium [4.37(3.89,4.82) mmol/L vs 4.07(3.70,4.43) mmol/L, P =0.018], and had higher eosinophil levels [0.22(0.13,0.40) x 10^9/L vs 0.16(0.08,0.26) x 10^9/L, P=0.007]. For dietary fiber intake, pruritic patients consumed less vegetable dietary fiber than non-pruritic patients [3.55(2.20,5.03) g/day vs 4.40 (2.55,6.40) g/day, P=0.011], but there was no difference in terms of grain dietary fiber [2.55(1.78,3.33) g/day vs 2.30(1.50. 3.20) g/day, P=0.419]. In unadjusted logistic regression, lower vegetable dietary fiber was associated with a higher risk of itching (OR:0.819, 95% CI: 0.695-0.965, P=0.017). However, after adjusting for age, serum creatinine, and blood potassium, vegetable dietary fiber was not associated with the risk of itching (P=0.059). Conclusion: Patients with pruritus in CKD consumed less vegetable dietary fiber than those without pruritus. Low levels of vegetable dietary fiber intake may be associated with uremic pruritus.