title: Comparison between creatinine-based equations for estimating total creatinine clearance in peritoneal dialysis: a multicentre study.
abstract: BACKGROUND
  It is crucial to assess the adequacy of peritoneal dialysis (PD) because of its influence on patient outcome. Collecting dialysate and urine for 24 h can be rather troublesome, so a simple and inexpensive alternative method for rapidly evaluating adequacy in PD would be very useful. Our study aimed to assess the performance of 12 different creatinine (Cr)-based equations commonly used to estimate GFR in predicting total Cr clearance (totCrCL) in PD.
  
  
  METHODS
  Four Italian dialysis centres enrolled 355 PD patients with 2916 fluid collections. To rank the equations, their accuracy (median absolute percentage error, MAPE), precision (root mean square error, RMSE), agreement (k statistics), sensitivity and specificity (area under ROC curves, AUC, where x = 1 - specificity and y = sensitivity) were calculated with reference to the measured totCrCL.
  
  
  RESULTS
  The Gates, Virga and 4-MDRD equations showed the best global performance as concerns accuracy (MAPE = 14.1, 16.3, 15.9% respectively), precision (RMSE = 13.2, 13.3, 13.4), agreement (k = 0.425, 0.440, 0.375), sensitivity and specificity (AUC = 0.825, 0.826, 0.820), while the Cockcroft-Gault formula revealed a rather poor reliability.
  
  
  CONCLUSIONS
  Fluid collection remains the gold standard for assessing PD adequacy. Our study ascertained how 12 Cr-based equations performed in estimating totCrCL in PD patients with a view to enabling the most accurate and precise among them to be chosen for use in approximately assessing totCrCL.
authors.affiliation: Nephrology and Dialysis Unit, Provincial Hospital, Camposampiero, Padova, Italy. virgolino14@libero.it
authors.forename: Giovambattista
authors.initials: G
authors.lastname: Virga
authors.forename: Vincenzo
authors.initials: V
authors.lastname: La Milia
authors.forename: Roberto
authors.initials: R
authors.lastname: Russo
authors.forename: Luciana
authors.initials: L
authors.lastname: Bonfante
authors.forename: Marilena
authors.initials: M
authors.lastname: Cara
authors.forename: Maurizio
authors.initials: M
authors.lastname: Nordio
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D003404:Creatinine / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D010530:Peritoneal Dialysis; D010531:Peritoneal Dialysis, Continuous Ambulatory; D012372:ROC Curve; D012680:Sensitivity and Specificity
chemical_list: D003404:Creatinine