The prognostic value of URR equals that of Kt/V for all-cause mortality in Taiwan after 10-year follow-up

Kt/V and URR (urea reduction ratio) measurements represent dialysis adequacy. Single-pool Kt/V is theoretically a superior method and is recommended by the Kidney Disease Outcomes Quality Initiative guidelines. However, the prognostic value of URR compared with Kt/V for all-cause mortality is unknown. The effect modifiers and cut-off values of the two parameters have not been compared. We investigated 2615 incident hemodialysis patients with URR of 72% and Kt/V (Daugirdas) of 1.6. The average patient age was 59 years, 50.7% were female, and 1113 (40.2%) died within 10 years. URR and Kt/V were both positively associated with nutrition factors and female sex and negatively associated with body weight and heart failure. In Cox regression mod-els for all-cause mortality, the hazard ratios (HRs) of high URR groups (65–70%, 70–75%, and > 75%) and the URR < 65% group were 0.748 (0.623–0.898), 0.693 (0.578–0.829), and 0.640 (0.519–0.788), respectively. The HRs of high Kt/V groups (Kt/V 1.2–1.4, 1.4–1.7, and > 1.7) and the Kt/V < 1.2 group were 0.711 (0.580–0.873), 0.656 (0.540–0.799), and 0.623 (0.498–0.779), respec-tively. In subgroup analysis, Kt/V was not associated with all-cause mortality in women. The prognostic value of URR for all-cause mortality is as great as that of Kt/V. URR > 70% and Kt/V > 1.4 were associated with a higher survival rate. Kt/V may have weaker prognostic value for women.