Prognostic Value of Residual Urine Volume, GFR by 24-hour Urine Collection, and eGFR in Patients Receiving Dialysis

Abstract

Background and objectives Residual kidney function can be assessed by simply measuring urine volume, calculating GFR using 24-hour urine collection, or estimating GFR using the proposed equation (eGFR). We aimed to investigate the relative prognostic value of these residual kidney function parameters in patients on dialysis.Design, setting, participants, & measurements Using the database from a nationwide prospective cohort study, we compared differential implications of the residual kidney function indices in 1946 patients on dialysis at 36 dialysis centers in Korea between August 1, 2008 and December 31, 2014. Residual GFR calculated using 24-hour urine collection was determined by an average of renal urea and creatinine clearance on the basis of 24-hour urine collection. eGFR-urea, creatinine and eGFR b 2 -microglobulin were calculated from the equations using serum urea and creatinine and b 2 -microglobulin, respectively. The primary outcome was all-cause death.Results During a mean follow-up of 42 months, 385 (19.8%) patients died. In multivariable Cox analyses, residual urine volume (hazard ratio, 0.96 per 0.1-L/d higher volume; 95% confidence interval, 0.94 to 0.98) and GFR calculated using 24-hour urine collection (hazard ratio, 0.98; 95% confidence interval, 0.95 to 0.99) were independently associated with all-cause mortality. In 1640 patients who had eGFR b 2 -microglobulin data, eGFR b 2 -microglobulin (hazard ratio, 0.98; 95% confidence interval, 0.96 to 0.99) was also significantly associated with all-cause mortality as well as residual urine volume (hazard ratio, 0.96 per 0.1-L/d higher volume; 95% confidence interval, 0.94 to 0.98) and GFR calculated using 24-hour urine collection (hazard ratio, 0.97; 95% confidence interval, 0.95 to 0.99). When each residual kidney function index was added to the base model, only urine volume improved the predictability for all-cause mortality (net reclassification index =0.11, P=0.01; integrated discrimination improvement =0.01, P=0.01).Conclusions Higher residual urine volume was significantly associated with a lower risk of death and exhibited a stronger association with mortality than GFR calculated using 24-hour urine collection and eGFR-urea, creatinine. These results suggest that determining residual urine volume may be beneficial to predict patient survival in patients on dialysis.

Estimating of Residual Kidney Function by Multi-Frequency Bioelectrical Impedance Analysis in Hemodialysis Patients Without Urine Collection

“…Residual urine volume was even more closely associated with adverse outcomes compared with the other RKF indices in a recent study [2]. Rely on our statistical analysis residual urine volume showed good reliability to express mGFR and substantial reliability to express eGFRBIA.…”

“…Today there is no doubt that residual kidney function (RKF) is a pivotal predictor of better clinical outcomes in maintenance hemodialysis (MHD) patients [1-2]. RKF provides a number of clinical benefits including improved clearance of uremic toxins [3] and hemodynamic stability due to requirement in lower ultrafiltration (UF) rate [4] and contributes consequently to health-related quality of life (QoL), lower inflammation, and significantly less EPO use in MHD population [1].…”

Ultrafiltration rate in conventional hemodialysis: Where are the limits and what are the consequences?

“…Lower residual renal function has been associated with higher mortality. 17 Similarly, higher IDWG has also been associated with greater mortality. 18 In addition, lower body weight can be associated with frailty and higher mortality; it is also included in the UFR calculation.…”

“…Patients with higher urine output have lower weight gains and lower UFRs. Lower residual renal function has been associated with higher mortality . Similarly, higher IDWG has also been associated with greater mortality .…”

Gradual initiation of dialysis as a means to reduce cost while providing quality health care

“…The second issue relates to approaches to monitor RKF and when to increase dialysis frequency. We suggest that RKF monitoring could be simplified through the use of daily RUV 10 , instead of more cumbersome methods such as 24 h urea or creatinine clearance. Implementation of incremental haemodialysis will eventually cut the cost of dialysis, at least in the first year of dialysis initiation.…”