Serum protein-bound uraemic toxins and clinical outcomes in haemodialysis patients

BACKGROUND: The protein-bound uraemic toxin p-cresol is associated with immunodeficiency in haemodialysis (HD) patients. We investigated the effect of serum p-cresol, indoxyl sulphate and other variables on clinical outcomes in HD patients during a 20-month follow-up. METHODS: We enrolled 100 stable HD patients from a single medical centre. The primary outcomes were infection-related hospitalization, cardiovascular events and all-cause mortality. Serum total and free p-cresol and indoxyl sulphate levels were measured using ultra-performance liquid chromatography. Biochemical data were collected concurrently. RESULTS: Multivariate logistic regression analysis revealed that infection-related hospitalization correlated with free p-cresol (adjusted odds ratio: 1.70, P = 0.01) and highly sensitive C-reactive protein (hsCRP) (adjusted odds ratio: 2.07, P = 0.01); cardiovascular event was associated with free p-cresol (adjusted odds ratio: 1.78, P = 0.01) and nPCR (adjusted odds ratio: 0.01, P = 0.02); and all-cause mortality was related to albumin (adjusted odds ratio: 0.04, P = 0.01). The Kaplan-Meier method showed that free and total p-cresol were significantly associated with cardiovascular events (log-rank P < 0.01 and log-rank P < 0.01, respectively). Serum free p-cresol seemed to have a trend to correlate with infection-related hospitalization during a 20-month follow-up (log-rank P = 0.05). CONCLUSIONS: Serum free and total p-cresol levels were significantly related to cardiovascular events. In addition, serum free p-cresol and hsCRP levels were also found to be associated with infection-related hospitalization.