title: A multicenter study demonstrating discordant results from electronic prostate-specific antigen biochemical failure calculation systems.
abstract: OBJECTIVE
  To evaluate the interobserver variation of four electronic biochemical failure (bF) calculators using three bF definitions.
  
  
  METHODS
  The data of 1200 men were analyzed using the electronic bF calculators of four institutions. Three bF definitions were examined for their concordance of bF identification across the centers: the American Society for Therapeutic Radiology and Oncology consensus definition (ACD), the lowest prostate-specific antigen (PSA) level to date plus 2 ng/mL (L2), and a threshold of 3 ng/mL (T3).
  
  
  RESULTS
  Unanimous agreement regarding bF status using the ACD, L2, and T3 definitions occurred in 87.3%, 96.4%, and 92.7% of cases, respectively. Using the ACD, 63% of the variation was from one institution, which allowed the bF status to be reversed if a PSA decline was seen after bF (PSA "bounce"). A total of 270 men had an ACD bF time variation of >2 months across the calculators, and the 5-year freedom from bF rate was 49.8-60.9%. The L2 definition had a 20.5% rate of calculated bF times; which varied by >2 months (median, 6.4; range, 2.1-75.6) and a corresponding 5-year freedom from bF rate of 55.9-61.0%. The T3 definition had a 2.0% range in the 5-year freedom from bF. Fifteen definition interpretation variations were identified.
  
  
  CONCLUSIONS
  Reported bF results vary not only because of bF definition differences, but because of variations in how those definitions are written into computer-based calculators, with multiple interpretations most prevalent for the ACD. An algorithm to avoid misinterpretations is proposed for the L2 definition. A verification system to guarantee consistent electronic bF results requires development.
authors.affiliation: Peter MacCallum Cancer Centre and University of Melbourne, Melbourne, Australia. scott.williams@petermac.org
authors.forename: Scott G
authors.initials: SG
authors.lastname: Williams
authors.forename: Tom
authors.initials: T
authors.lastname: Pickles
authors.forename: Larry
authors.initials: L
authors.lastname: Kestin
authors.forename: Louis
authors.initials: L
authors.lastname: Potters
authors.forename: Paul
authors.initials: P
authors.lastname: Fearn
authors.forename: Ryan
authors.initials: R
authors.lastname: Smith
authors.forename: Gary
authors.initials: G
authors.lastname: Pratt
mesh_terms: D016208:Databases, Factual / Q000592:standards; D006801:Humans; D008297:Male; D015588:Observer Variation; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000532:radiotherapy*; D018787:Radiation Oncology / Q000592:standards; D012016:Reference Values; D015203:Reproducibility of Results; D013997:Time Factors
chemical_list: D017430:Prostate-Specific Antigen