Mean Urea Reduction Ratio among Patients Undergoing Hemodialysis at a Tertiary Care Centre: A Descriptive Cross-sectional Study

ABSTRACT Introduction: Chronic kidney disease is a major cause of mortality with a prevalence of 6%. Over the past half-century, hemodialysis has been the most preferred modality of treatment for sustaining the life of patients with end-stage kidney disease. Despite hemodialysis being freely available, achieving adequacy in hemodialysis is a challenging task. Inadequate dialysis is responsible for the high mortality. This study aimed to find out the mean value of the urea reduction ratio among patients undergoing hemodialysis at a tertiary care centre. Methods: This was a descriptive cross-sectional study conducted from 15 January 2023 to 15 April 2023. Ethical approval was taken from Institutional Review Committee (Reference number: UCMS/IRC/044/23). Patients aged >18 years, undergoing maintenance hemodialysis and giving informed and written consent were included in the study. Urea reduction rate and single-pool Kt/V were estimated. Convenience sampling method was used. Results: Among 100 patients, the mean urea reduction ratio among the study population was 25.24±15.59%. Males represented 62 (62%) of the study population. The mean age was 47.9±14.74 years. Hypertension and Diabetes mellitus was found to be the leading cause of end-stage kidney disease with 61 (61%) and 27 (27%) respectively. The mean value of spKT/V was 0.73±0.162. Conclusions: The mean urea reduction ratio was found to be lower than the other studies done in similar settings.


INTRODUCTION
Chronic kidney disease (CKD) is an emerging disease with a prevalence of 6% in Nepal. 1 Over the past halfcentury, there has been a remarkable achievement in hemodialysis (HD) as a modality for renal replacement therapy. 2 Beginning from the initiation of hemodialysis at Bir Hospital in 1987, 3 Government of Nepal has been providing free hemodialysis since 2016. 4 According to Renal Physicians Association and the National Kidney Foundation's disease outcomes quality initiative, dialysis adequacy is estimated by calculating urea reduction ratio (URR) and/or KT/V where (K: clearance of urea, T: duration of dialysis, V: distribution of urea). 5 Due to logistics and financial constraints, most hemodialysis centres are providing twice-a-week hemodialysis and reusing dialysers which may affect the quality of hemodialysis. 6,7 It is imperative to know the quality of HD provided at individual centres. Hence, we designed this study to estimate URR and single pool KT/V in patients undergoing HD.
This study aimed to find out the mean value of the urea reduction ratio among patients undergoing hemodialysis at a tertiary care centre. Here, the minimum required sample size was 71. However, 100 sample size was taken. The measurement of blood urea before and after dialysis was done and the calculation of URR and spKT/V was done using the formulas mentioned below:

Single-Pool Index (spKt/V)
Parameters spKt/V and URR are connected mathematically as follows: Where ln stands for natural logarithm.
Several studies have shown that if the rate of KT/V reaches 1.2 or URR is more than 65%, this is effective in improving dialysis patients' prognosis. 5 The available demographic, clinical and laboratory parameters were recorded as per the proforma. Data were entered and analyzed using IBM SPSS Statistics version 17.0.

DISCUSSION
This study highlighted the importance of estimation of URR and calculating spKT/V in patients undergoing hemodialysis. In our study of 100 hemodialysis patients, males were more in number 62 (62%) than females 38 (38%), which was similar to a study done in Chitwan, Nepal. 9 The mean age of patients in our study was 47.9±14.7 years which was similar to other studies. 10 The commonest cause of end-stage kidney disease (ESKD) in our study was hypertension 61 (61%) followed by type 2 diabetes mellitus 27 (27%) and chronic glomerulonephritis 6 (6%) whereas in another study it was found that diabetic nephropathy followed by hypertension were common causes of ESKD. 11,12 On the contrary, another study found chronic glomerulonephritis to be the most common cause followed by diabetic nephropathy. 13 Mean Hemoglobin level in our study population was found to be 8.11±1.83 gm/dl which was similar to the study done at a centre in Kathmandu. 14 The mean calcium level in the study population was found to be 8.06±0.43 mg/dl which is similar to findings in a retrospective study conducted at KIST Medical College Teaching Hospital. 15 Similar results were also observed in a study from Bir Hospital. 16 Hypocalcaemia is a part of abnormal mineral metabolism in CKD and evident from stage 4 CKD. 17 20 Various factors are accountable for lower URR and spKt/V. The average time of dialysis treatment received by patients could be actually less than the prescribed treatment time. The length of each hemodialysis session and low-flux membranes used for HD could be a justifiable reason for such discrepancies in various studies. Patients could not reach the dialysis unit at the scheduled time or had to leave before the completion of the prescribed time due to transportation and scheduled timing issues. Hence considering these factors for lower values of URR and spKt/V, it is necessary to take measures to improve the quality of dialysis.
Limitations such as confounding factors for Kt/V were not collected in this study which includes albumin, ferritin, residual renal function, and other comorbidities of the study population.

CONCLUSIONS
The mean urea reduction ratio was found to be lower than the other studies done in similar settings.