Background: Indoxyl sulfate (IS), a uremic toxin, has cardiovascular as well as uremic toxicity. We evaluated the prognostic value of blood IS level for long-term outcome.
Methods and Results: This study followed 311 patients with coronary artery disease. Plasma IS level and estimated glomerular filtration rate (eGFR) were determined. The endpoint was a major adverse cardiac event (MACE). Median follow-up was 759 days. IS was significantly higher in patients with MACE than in those without (P<0.001). Patients were divided according to quartiles (Q) of plasma IS level (Q1, Q2, Q3, and Q4). On Kaplan-Meier analysis a significantly lower MACE-free rate was obtained for Q4 compared with the other quartiles (P<0.001). In patients with eGFR >= 90, 89-60, 59-30, 29-15, and <15 ml.min(-1).1.73m(-2), the percentage of patients in Q4 was 0%, 13%, 29%, 100%, and 100%, respectively. In patients with eGFR 89-60 ml.min(-1).1.73 m(-2),there was no significant difference in MACE-free rate between Q4 and the other quartiles; in patients with eGFR 59-30 ml.min(-1).1.73m(-2), a significantly lower MACE-free rate was obtained for Q4 compared with the other quartiles (P=0.832 and P=0.015, respectively).
Conclusions: Plasma IS level is a significant predictor of MACE, especially in patients with eGFR 59-30 ml.min(-1).1.73 m(-2).