title: Agreement among measurements and estimations of glomerular filtration in children with cancer.
abstract: BACKGROUND
  Glomerular filtration is an important route of elimination for many types of chemotherapy. Accurate estimation of glomerular filtration at the bedside is essential in the management of children with cancer. Bedside formulae for the estimation of glomerular filtration have not been validated in children with cancer. We investigated the accuracy of three formulae (the original Schwartz, Counahan-Barratt, and revised Schwartz equations) against measurement of the glomerular filtration rate (GFR) in a cohort of children with cancer.
  
  
  METHODS
  This was a retrospective review of existing data from a single institution. The electronic medical record was queried for subjects meeting inclusion criteria during a 3.5 year time frame. Bland-Altman analyses were used to assess agreement among current formulae and estimating the GFR compared to the measured, or index GFR. Logistic regression was performed to identify potential variables with an effect on the estimation of GFR.
  
  
  RESULTS
  None of the three estimation formulae provided a reliable estimate of the index GFR. The mean difference was lowest between the revised Schwartz and the index GFR compared to the other two formulae and the index GFR. For the original Schwartz equation, age and prior receipt of chemotherapy were significant predictors of under- and overestimation. For the revised Schwartz equation, one age group (6-12 years) and a diagnosis of neuroblastoma actively receiving chemotherapy were positive risk factors for overestimation of the GFR.
  
  
  CONCLUSIONS
  Currently available estimation formulae for GFR may not be appropriate for children with cancer.
authors.affiliation: Department of Pharmacy, Texas Children's Hospital, Houston, Texas.
authors.forename: M Brooke
authors.initials: MB
authors.lastname: Bernhardt
authors.forename: Brady S
authors.initials: BS
authors.lastname: Moffett
authors.forename: Michael
authors.initials: M
authors.lastname: Johnson
authors.forename: Vincent H
authors.initials: VH
authors.lastname: Tam
authors.forename: Patrick
authors.initials: P
authors.lastname: Thompson
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Garey
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy; D011379:Prognosis; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012044:Regression Analysis; D012189:Retrospective Studies; D016284:Technetium Tc 99m Pentetate
chemical_list: D019275:Radiopharmaceuticals; D016284:Technetium Tc 99m Pentetate
keywords: late effects; long term survival; nephrology; outcomes research; pediatric oncology