title: Serum Cystatin C Does Not Predict Mortality or Treatment Failure in Peritoneal Dialysis: A Prospective Study.
abstract: ♦
  
  
  BACKGROUND
  Small solute clearance, especially that derived from residual renal function (RRF), is an independent risk factor for death in peritoneal dialysis (PD) patients. Assessment of solute clearance is time-consuming and prone to multiple errors. Cystatin C is a small protein which has been used as a glomerular filtration rate (GFR) marker. We investigated whether serum cystatin C concentrations are related to mortality in patients receiving PD. ♦
  
  
  METHODS
  New and prevalent PD patients (n = 235) underwent assessment of Kt/Vurea, RRF, weekly creatinine clearance (CCr), normalized protein catabolic rate (nPCR) and a peritoneal equilibration test (PET) at intervals. Blood was collected simultaneously for cystatin C measurement. Patients were followed for a median of 1,429 days (range 12 to 2,964 days) until death or study closure. Cause of death was recorded where given. Cox regression was performed to determine whether cystatin C had prognostic value either independently or with adjustment for other factors (age, sex, dialysis modality, diabetic status, cardiovascular comorbidity, Kt/V, CCr, RRF, nPCR or 4 h dialysate to plasma creatinine ratio (4 h D/Pcr) during the PET). The primary outcomes were all-cause mortality and treatment failure. ♦
  
  
  RESULTS
  There were 93 deaths. Increasing age and 4 h D/Pcr ratio, decreased RRF and presence of diabetes were significantly [p < 0.05] negatively associated with survival and treatment failure. Serum cystatin C was not related to either outcome. ♦
  
  
  CONCLUSIONS
  Serum cystatin C concentration does not predict mortality or treatment failure in patients receiving PD.
authors.affiliation: Kent Kidney Care Centre and Clinical Biochemistry, Kent and Canterbury Hospital, Canterbury, Kent, UK.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Delaney
authors.affiliation: Kent Kidney Care Centre and Clinical Biochemistry, Kent and Canterbury Hospital, Canterbury, Kent, UK.
authors.forename: Paul E
authors.initials: PE
authors.lastname: Stevens
authors.affiliation: East Kent Hospitals University NHS Foundation Trust, Kent and Canterbury Hospital, Canterbury, Kent, UK.
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Witham
authors.affiliation: Kent Kidney Care Centre and Clinical Biochemistry, Kent and Canterbury Hospital, Canterbury, Kent, UK.
authors.forename: Caroline
authors.initials: C
authors.lastname: Judge
authors.affiliation: Kent Kidney Care Centre and Clinical Biochemistry, Kent and Canterbury Hospital, Canterbury, Kent, UK.
authors.forename: Gillian L
authors.initials: GL
authors.lastname: Eaglestone
authors.affiliation: East Kent Hospitals University NHS Foundation Trust, Kent and Canterbury Hospital, Canterbury, Kent, UK.
authors.forename: Joanne L
authors.initials: JL
authors.lastname: Carter
authors.affiliation: Statsconsultancy Ltd., Amersham, Bucks, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Bassett
authors.affiliation: East Kent Hospitals University NHS Foundation Trust, Kent and Canterbury Hospital, Canterbury, Kent, UK elamb@nhs.net.
authors.forename: Edmund J
authors.initials: EJ
authors.lastname: Lamb
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D055316:Cystatin C / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis; D011237:Predictive Value of Tests; D011446:Prospective Studies; D051437:Renal Insufficiency / Q000097:blood* / Q000401:mortality / Q000628:therapy*; D017211:Treatment Failure; D055815:Young Adult
chemical_list: D055316:Cystatin C
keywords: Cystatin C; dialysis adequacy; kidney failure; peritoneal dialysis; residual renal function; survival analysis