title: Renal parenchymal area and risk of ESRD in boys with posterior urethral valves.
abstract: OBJECTIVE
  Approximately 20% of boys with posterior urethral valves develop ESRD; however, few factors associated with the risk of ESRD have been identified. The objective of this study was to determine if renal parenchymal area, defined as the area of the kidney minus the area of the pelvicaliceal system on first postnatal ultrasound, is associated with the risk of ESRD in infants with posterior urethral valves.
  
  
  METHODS
  A retrospective cohort of boys who were diagnosed with posterior urethral valves at less than 6 months of age between 1988 and 2011 and followed for at least 1 year at a free-standing children's hospital was assembled. Cox proportional hazard regression and Kaplan-Meier analysis were used to estimate the association between renal parenchymal area and time to ESRD. Cox models were adjusted for age at presentation, minimum creatinine 1 month after bladder decompression, and vesicoureteral reflux.
  
  
  RESULTS
  Sixty patients were followed for 393 person-years. Eight patients developed ESRD. Median renal parenchymal area was 15.9 cm(2) (interquartile range=13.0-21.6 cm(2)). Each 1-cm(2) increase in renal parenchymal area was associated with a lower risk of ESRD (hazard ratio, 0.64; 95% confidence interval, 0.42 to 0.98). The rate of time to ESRD was 10 times higher in boys with renal parenchymal area<12.4 cm(2) than boys with renal parenchymal area≥12.4 cm(2) (P<0.001). Renal parenchymal area could best discriminate children at risk for ESRD when the minimum creatinine in the first 1 month after bladder decompression was between 0.8 and 1.1 mg/dl.
  
  
  CONCLUSIONS
  In boys with posterior urethral valves presenting during the first 6 months of life, lower renal parenchymal area is associated with an increased risk of ESRD during childhood. The predictive ability of renal parenchymal area, which is available at time of diagnosis, should be validated in a larger, prospectively-enrolled cohort.
authors: Perelman School of Medicine, and, ‡Department of Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, †Department of Pediatrics, Division of Nephrology, and, §Department of Surgery, Division of Pediatric Urology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors: Jose E
authors: JE
authors: Pulido
authors: Susan L
authors: SL
authors: Furth
authors: Stephen A
authors: SA
authors: Zderic
authors: Douglas A
authors: DA
authors: Canning
authors: Gregory E
authors: GE
authors: Tasian
mesh_terms: D015415:Biomarkers / Q000097:blood; D002675:Child, Preschool; D003404:Creatinine / Q000097:blood; D018450:Disease Progression; D018572:Disease-Free Survival; D005919:Glomerular Filtration Rate; D006776:Hospitals, Pediatric; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053208:Kaplan-Meier Estimate; D007668:Kidney / Q000000981:diagnostic imaging* / Q000503:physiopathology; D007676:Kidney Failure, Chronic / Q000097:blood / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy; D008297:Male; D015999:Multivariate Analysis; D015143:Philadelphia; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D013997:Time Factors; D014463:Ultrasonography; D014521:Urethra / Q000002:abnormalities*; D014552:Urinary Tract Infections / Q000209:etiology; D014718:Vesico-Ureteral Reflux / Q000209:etiology
chemical_list: D015415:Biomarkers; D003404:Creatinine