title: Validation of the revised Schwartz estimating equation in a predominantly non-CKD population.
abstract: Recently, Schwartz et al. (J Am Soc Nephrol 20:629-637, 2009) used data from the National Institutes of Health-funded Chronic Kidney Disease in Children (CKiD) study to generate new equations for estimating the glomerular filtration rate (eGFR), including an update of the commonly used bedside equation. However, it is unclear if the equation can be generalized to a broader pediatric population. We have used the updated equation on a sample of pediatric patients with less impaired renal function to evaluate the correlation between the new Schwartz equation and measured GFR by iothalamate clearance. We retrospectively analyzed 738 iothalamate clearance tests from 503 patients with a mean serum creatinine of 0.50 mg/dl whose ages ranged from 1 to 16 years. We measured bias, precision, and accuracy and performed a Bland-Altman plot to determine the measure of agreement between the two methods. The mean GFR by iothalamate clearance was 110.6 ml/min/1.73 m(2) and by the new Schwartz estimation 104.7 ml/min/1.73 m(2). The mean difference was 5.84 ml/min/1.73 m(2) (95% CI 4.00-7.67). The newly purposed bedside Schwartz equation therefore demonstrated good agreement with the iothalamate renal clearances in our patient population and appears to be a valid bedside estimating equation for GFR in this sample of children.
authors.affiliation: UNM Pediatrics/ACC-3, MSC10-5590, University of New Mexico, Albuquerque, NM 87131, USA. astaples@salud.unm.edu
authors.forename: Amy
authors.initials: A
authors.lastname: Staples
authors.forename: Robin
authors.initials: R
authors.lastname: LeBlond
authors.forename: Sandra
authors.initials: S
authors.lastname: Watkins
authors.forename: Craig
authors.initials: C
authors.lastname: Wong
authors.forename: John
authors.initials: J
authors.lastname: Brandt
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000097:blood; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007223:Infant; D007483:Iothalamic Acid / Q000378:metabolism; D007676:Kidney Failure, Chronic / Q000503:physiopathology; D008297:Male; D008433:Mathematics; D051436:Renal Insufficiency, Chronic / Q000503:physiopathology*; D012189:Retrospective Studies
chemical_list: D007483:Iothalamic Acid; D003404:Creatinine