title: Prognostic Value of Residual Urine Volume, GFR by 24-hour Urine Collection, and eGFR in Patients Receiving Dialysis.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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 eGFRβ2-microglobulin were calculated from the equations using serum urea and creatinine andβ2-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 eGFRβ2-microglobulin data, eGFRβ2-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.
authors.affiliation: Department of Internal Medicine, CHA Bundang Medical Center, CHA University, Seongnamsi, Korea.
authors.forename: Mi Jung
authors.initials: MJ
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jung Tak
authors.initials: JT
authors.lastname: Park
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Kyoung Sook
authors.initials: KS
authors.lastname: Park
authors.affiliation: Department of Internal Medicine, Myongji Hospital, Seonam University College of Medicine, Goyangsi, Korea.
authors.forename: Young Eun
authors.initials: YE
authors.lastname: Kwon
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hyung Jung
authors.initials: HJ
authors.lastname: Oh
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Tae-Hyun
authors.initials: TH
authors.lastname: Yoo
authors.affiliation: Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea.|Clinical Research Center for End-Stage Renal Disease, Daegu, Korea.
authors.forename: Yong-Lim
authors.initials: YL
authors.lastname: Kim
authors.affiliation: Clinical Research Center for End-Stage Renal Disease, Daegu, Korea.|Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Yon Su
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Clinical Research Center for End-Stage Renal Disease, Daegu, Korea.|Department of Internal Medicine, Catholic University of Korea College of Medicine, Seoul, Korea; and.
authors.forename: Chul Woo
authors.initials: CW
authors.lastname: Yang
authors.affiliation: Clinical Research Center for End-Stage Renal Disease, Daegu, Korea.|Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Nam-Ho
authors.initials: NH
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.|Clinical Research Center for End-Stage Renal Disease, Daegu, Korea.
authors.forename: Shin-Wook
authors.initials: SW
authors.lastname: Kang
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Seung Hyeok
authors.initials: SH
authors.lastname: Han
mesh_terms: D000328:Adult; D000368:Aged; D003404:Creatinine / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000503:physiopathology* / Q000628:therapy* / Q000652:urine; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D006435:Renal Dialysis; D015996:Survival Rate; D014508:Urea / Q000097:blood; D014556:Urine; D001613:beta 2-Microglobulin / Q000097:blood
chemical_list: D001613:beta 2-Microglobulin; D014508:Urea; D003404:Creatinine
keywords: dialysis; end-stage renal disease; glomerular filtration rate; mortality; residual kidney function; urine volume