A novel method to rapidly calculate the urea clearance index and urea reduction rate based on parameters obtained during hemodialysis

Background: The efficacy of hemodialysis (HD) is closely associated with patient survival time and quality of life. The classical method (CLM) to calculate the urea clearance index (Kt/V) and urea reduction rate (URR) requires multiple blood tests. A novel method that may be used as a noninvasive alternative to CLM is required.

Methods: Based on the urea kinetic model, a new method, named the "assessment method" (ASM), was established to calculate blood urea nitrogen after HD, based on parameters obtained during HD. The consistency of the Kt/V and URR values between the ASM and CLM was evaluated in 41 patients from the China-Japan Friendship Hospital between September 2017 and December 2018.

Results: Forty-one patients (24 males and 17 females; mean age, 55.7 ± 14.2 years) undergoing regular HD in our hospital were randomly selected for this study. The blood flow rate was 244.5 ± 19.6 mL/min and the dialysate flow rate was 500 mL/min. We obtained Kt/V (CLM = 1.40 ± 0.06, ASM = 1.37 ± 0.07) and URR (CLM = 68.6 ± 6.4%, ASM = 67.7 ± 7.2%) values. Paired t-test indicated no significant differences between the ASM- and CLM-derived values. The intraclass correlation coefficients were 0.907 and 0.916 for Kt/V and URR, respectively. Similarly, Bland-Altman plots suggested good concordance between the 2 methods.

Conclusions: The Kt/V and URR values calculated using the ASM and CLM were in significant agreement, and both can be used to effectively assess the adequacy of HD in patients undergoing maintenance HD. The ASM is an effective, rapid, inexpensive, and noninvasive alternative to the CLM for obtaining Kt/V and URR values. The ASM has good potential for clinical application, particularly for patients in areas of low socioeconomic status.