Comparison of clinical outcome between twice-weekly and thrice-weekly hemodialysis in patients with residual kidney function

Residual kidney function (RKF) contributes to improved survival in hemodialysis (HD) patients. However, it is not clear whether RKF allows a comparable survival rate in patients undergoing twiceweekly HD compared with thrice-weekly HD. We enrolled 685 patients from a prospective multicenter observational cohort. RKF and HD adequacy was monitored regularly over 3-year follow-up. Patients with RKF were divided into groups undergoing twice-weekly HD (n=113) or thrice-weekly HD (n=137). Patients without RKF undergoing thrice-weekly HD (n=435) were included as controls. Fluid balance and dialysis-associated characteristics were followed and clinical outcomes evaluated using all-cause mortality and cardiovascular events (CVE). In patients with RKF, baseline and follow-up RKF were signifi-cantly higher in patients undergoing twice-weekly HD than in those undergoing thrice-weekly HD. Total Kt/V urea (dialysis plus residual renal) in patients with RKF undergoing twice-weekly HD was greater than or equal to those in patients with or without RKF undergoing thriceweekly HD. Compared with patients with RKF undergoing thriceweekly HD, patients with RKF undergoing twice-weekly HD had no fluid excess, but their normalized protein catabolic rate became lower since 24-month follow up. In multivariable analyses, patients with RKF undergoing twice-weekly HD had a noninferior risk of mortality (hazard ratio [HR], 0.83; 95% confidence interval [95% CI], 0.34-2.01, P=0.68) and of CVE (HR, 0.60; 95% CI, 0.28-1.29, P=0.19) compared with patients without RKF undergoing thrice-weekly HD. However, this group showed an independent association with a greater risk of mortality compared with patients with RKF undergoing thriceweekly HD (HR, 4.20; 95% CI, 1.02-17.32, P=0.04). In conclusion, patients withRKF undergoing twice-weeklyHDhad an increased risk ofmortality comparedwith those undergoing thrice-weekly HD.Decisions about twice-weeklyHDshould consider not onlyRKF, but also other risk factors such as normalized protein catabolic rate.