title: Predictors of Incident ESRD among Patients with Primary Hyperoxaluria Presenting Prior to Kidney Failure.
abstract: OBJECTIVE
  Overproduction of oxalate in patients with primary hyperoxaluria (PH) leads to calcium oxalate deposition in the kidney and ESRD in a substantial number of cases. However, the key determinants for renal outcome remain unclear. Thus, we performed a retrospective analysis to identify predictors for renal outcome among patients with PH participating in the Rare Kidney Stone Consortium (RKSC) PH Registry.
  
  
  METHODS
  We characterized clinical and laboratory features of patients enrolled in the RKSC PH Registry. We assessed correlation between urinary measures and eGFR at diagnosis by Spearman rank correlation and estimated renal survival using the Kaplan-Meier method. We determined factors associated with renal survival by Cox proportional hazard models.
  
  
  RESULTS
  Of 409 patients enrolled in the RKSC Registry as of March 2014, we excluded 112 patients who had ESRD at PH diagnosis from analysis. Among the remaining 297 patients, 65% had PH type 1, 12% had type 2, 13% had type 3, and 11% had unclassified PH. Median (25th, 75th percentile) age at PH diagnosis was 8.1 (4.0, 18.2) years with an eGFR of 73.0 (56.4, 97.5) ml/min per 1.73 m(2) and urinary oxalate excretion rate of 1.64 (1.11, 2.44) mmol/1.73 m(2) per 24 hours. During a median follow-up of 3.9 (1.0, 12.8) years, 59 (20%) patients developed ESRD. Urinary oxalate excretion at diagnosis stratified by quartile was strongly associated with incident ESRD (hazard ratio [HR], 3.4; 95% confidence interval [95% CI], 1.4 to 7.9). During follow-up there was a significant association between urinary oxalate quartile (Q) and incident ESRD (Q4 versus Q1: HR, 3.3; 95% CI, 1.2 to 9.3). This association remained even when adjusted for sex, age, and baseline eGFR (HR, 4.2; 95% CI, 1.6 to 10.8).
  
  
  CONCLUSIONS
  Among patients with PH, higher urinary oxalate excretion is predictive of poor renal outcome.
authors.affiliation: Division of Nephrology and Hypertension.
authors.forename: Fang
authors.initials: F
authors.lastname: Zhao
authors.affiliation: Division of Biostatistics.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Bergstralh
authors.affiliation: Division of Biostatistics.
authors.forename: Ramila A
authors.initials: RA
authors.lastname: Mehta
authors.affiliation: Division of Biostatistics.
authors.forename: Lisa E
authors.initials: LE
authors.lastname: Vaughan
authors.affiliation: Division of Nephrology and Hypertension.
authors.forename: Julie B
authors.initials: JB
authors.lastname: Olson
authors.affiliation: Division of Nephrology and Hypertension.
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Seide
authors.affiliation: Division of Nephrology and Hypertension.
authors.forename: Alicia M
authors.initials: AM
authors.lastname: Meek
authors.affiliation: Division of Nephrology and Hypertension.
authors.forename: Andrea G
authors.initials: AG
authors.lastname: Cogal
authors.affiliation: Division of Nephrology and Hypertension, Department of Laboratory Medicine and Pathology, and.
authors.forename: John C
authors.initials: JC
authors.lastname: Lieske
authors.affiliation: Division of Nephrology and Hypertension, Division of Pediatric Nephrology, Mayo Clinic, Rochester, Minnesota milliner.dawn@mayo.edu.
authors.forename: Dawn S
authors.initials: DS
authors.lastname: Milliner
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D006960:Hyperoxaluria, Primary / Q000150:complications* / Q000503:physiopathology; D007676:Kidney Failure, Chronic / Q000209:etiology*; D008297:Male; D016016:Proportional Hazards Models; D012189:Retrospective Studies
keywords: calcium oxalate; follow-up studies; genetic renal disease; humans; hyperoxaluria, primary; kidney failure, chronic; kidney stones; mineral metabolism; oxalates; registries