Percent reduction in blood urea concentration during dialysis estimates Kt/V in a simple and accurate way

Urea Kt/V is an accurate tool to estimate the adequacy of hemodialysis (HD) therapy; however, the current methods of calculating Kt/V are too complex for routine clinical use and require great care in order to avoid major inaccuracies. As percent reduction in blood urea concentration during dialysis (PRU) is a function of dialyzer urea clearance, length of dialysis, and urea distribution volume of the patient, it might correlate with Kt/V. Thus, analyzing retrospectively data of 78 studies, we found that the following linear regression equation existed between Kt/V values calculated by means of direct dialysis quantification (DDQ) and PRU values: Kt/V = 0.023 x PRU - 0.284 (r = 0.92). Furthermore, a good correlation existed between Kt/V values measured both by means of DDQ and of the classical algorithm (CA) of the urea kinetic model (UKM) (r = 0.98). Then, a prospective study was started in which 145 Kt/V values calculated by means of the above equation were correlated with the corresponding ones computed by means of a modified algorithm (MA) of UKM, perfectly fitting those generated by CA of UKM. Although the relationship was exponential, it was linear in the clinically important range of PRU between 40% and 70%, corresponding to a Kt/V between 0.64 and 1.33. Furthermore, an excellent correlation (r = 0.96) and no statistically significant difference existed in this range between the two series.(ABSTRACT TRUNCATED AT 250 WORDS)