Comparison between different methods of calculating Kt/V as the marker of adequacy of dialysis

Objectives: To compare different methods of calculating adequacy of hemodialysis in terms of Kt/V.

Methods: This was an observational, quantitative study undertaken after the approval of Internal Review Board at the Hemodialysis Unit of Nephrology department, Mayo Hospital, Lahore from 1st December 2018 to 30th June 2019. Sixty hemodynamically stable patients of end stage renal disease undergoing hemodialysis for more than three months with age 18 to 70 years were included in the study by convenience non probability sampling. Critically ill patients with multiple co-morbidities like sepsis (i.e. total leukocyte count >11000 or <4000 x 109/L), ischemic heart disease, pace- makers, malignancies, cirrhosis etc were excluded. Patients who were not adherent to dialysis prescription or hemodynamically unstable were also excluded. One way ANOVA and Pearson’s correlation were used to find correlation between three methods of measuring Kt/V.

Results: Mean ultrafiltration was 2.1+ 0.76 liter/session. Pre dialysis weight was 64.7 +14.7 kgs, mean post dialysis weight was 62.5 + 14.7 kgs. For every patient blood flow rate was 300 ml/m and dialysis flow rate was 500 ml/min. The mean values of Kt/V measured by Daugirdas formula was 1.35 ± 0.33, mean online clearance monitoring (OCM) value was 1.17 ± 0.29 and by normogram was 1.36 ± 0.33. There was positive significant correlation between values of Daugirdas formula, Normogram and online clearance monitoring (OCM) i.e. r = 0.897 (p-value < 0.001) measured by Pearson’s correlation and one way-ANOVA.

Conclusion: Online clearance monitoring can be used for measuring adequacy of hemodialysis, but OCM slightly underestimates Kt/V as compared to Daugirdas formula and Normogram.