title: Urine osmolarity and risk of dialysis initiation in a chronic kidney disease cohort--a possible titration target?
abstract: BACKGROUND
  Increasing evidence is linking fluid intake, vasopressin suppression and osmotic control with chronic kidney disease progression. Interestingly, the association between urine volume, urine osmolarity and risk of dialysis initiation has not been studied in chronic kidney disease patients before.
  
  
  OBJECTIVE
  To study the relationship between urine volume, urine osmolarity and the risk of initiating dialysis in chronic kidney disease.
  
  
  METHODS
  In a retrospective cohort analysis of 273 patients with chronic kidney disease stage 1-4 we assessed the association between urine volume, urine osmolarity and the risk of dialysis by a multivariate proportional sub-distribution hazards model for competing risk data according to Fine and Gray. Co-variables were selected via the purposeful selection algorithm.
  
  
  RESULTS
  Dialysis was reached in 105 patients over a median follow-up period of 92 months. After adjustment for age, baseline creatinine clearance, other risk factors and diuretics, a higher risk for initiation of dialysis was found in patients with higher urine osmolarity. The adjusted sub-distribution hazard ratio for initiation of dialysis was 2.04 (95% confidence interval, 1.06 to 3.92) for each doubling of urine osmolarity. After 72 months, the estimated adjusted cumulative incidence probabilities of dialysis were 15%, 24%, and 34% in patients with a baseline urine osmolarity of 315, 510, and 775 mosm/L, respectively.
  
  
  CONCLUSIONS
  We conclude that higher urine osmolarity is associated with a higher risk of initiating dialysis. As urine osmolarity is a potentially modifiable risk factor, it thus deserves further, prospective research as a potential target in chronic kidney disease progression.
authors.affiliation: Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University Vienna, Vienna, Austria.
authors.forename: Max
authors.initials: M
authors.lastname: Plischke
authors.affiliation: Section for Clinical Biometrics, Center of Medical Statistics, Informatics and Intelligent Systems, Medical University of Vienna, Vienna, Austria.
authors.forename: Maria
authors.initials: M
authors.lastname: Kohl
authors.affiliation: INSERM UMRS 1138, Equipe 2, Centre de Recherche des Cordeliers, Paris, France.
authors.forename: Lise
authors.initials: L
authors.lastname: Bankir
authors.affiliation: Division of Cardiology, Pulmonology, and Vascular Medicine, Medical Faculty, University Hospital Düsseldorf, Düsseldorf, Germany.
authors.forename: Sascha
authors.initials: S
authors.lastname: Shayganfar
authors.affiliation: Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University Vienna, Vienna, Austria.
authors.forename: Ammon
authors.initials: A
authors.lastname: Handisurya
authors.affiliation: Section for Clinical Biometrics, Center of Medical Statistics, Informatics and Intelligent Systems, Medical University of Vienna, Vienna, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Heinze
authors.affiliation: Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University Vienna, Vienna, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Haas
mesh_terms: D000328:Adult; D000368:Aged; D003404:Creatinine / Q000652:urine; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D006435:Renal Dialysis; D051436:Renal Insufficiency, Chronic / Q000628:therapy* / Q000652:urine*; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D003404:Creatinine