title: Semi-quantitative immunochromatographic test for prostate specific antigen in whole blood: tossing the coin to predict prostate cancer?
abstract: OBJECTIVE
  A strip test for the semi-quantitative determination of prostate specific antigen (PSA) based on whole blood was evaluated by the Working Group on Laboratory Diagnostics of the German Urological Association.
  
  
  METHODS
  In 301 men (156 volunteers and 145 referred patients, mean ages 57 years and 64 years) handling and capability of the strip test to predict PSA serum concentrations (Access Hybritech, Beckman Coulter, Inc., Fullerton, CA, USA) relative to a cutoff of 4 micro g/l were investigated. For patients, the strip test was performed by investigators, volunteers accomplished it according to leaflet instructions. Each test result was interpreted by both, the patient/volunteer and an investigator.
  
  
  RESULTS
  24% of the volunteers required assistance with test performance. The overall agreement between Access PSA (range 0.1-29.7) and strip test was 76% (read by participants) and 79% (read by investigators). Within the PSA ranges 0.1-3, 3.1-5 and 5.1-10, participants yielded agreement rates of 89%, 40% and 56%, respectively. Studying the 2.1-10 PSA range most relevant for prostate cancer screening, agreement rate (53%), sensitivity (50%) and specificity (67%) were barely superior to random chance. Volunteers alone (PSA range 0.1-11.3 micro g/l) yielded a specificity of 92%, however, all PSA values above the cutoff (n=8) went unrecognized and all positive strip tests (n=12) were incorrect (sensitivity 0%, positive predictive value 0%).
  
  
  CONCLUSIONS
  Test handling and interpretation was difficult. The rate of false strip test results is disappointing even for PSA ranges remote from the cutoff. In its present form the strip test fails to meet the clinical requirements and its launch to the market was therefore discontinued.
authors.affiliation: Department of Urology, University of Münster, Albert-Schweitzer Str. 33, D-48129, Münster, Germany. oberpen@uni-muenster.de
authors.forename: Frank
authors.initials: F
authors.lastname: Oberpenning
authors.forename: Stefan
authors.initials: S
authors.lastname: Hetzel
authors.forename: Christoph
authors.initials: C
authors.lastname: Weining
authors.forename: Burkhard
authors.initials: B
authors.lastname: Brandt
authors.forename: Gabriela
authors.initials: G
authors.lastname: De Angelis
authors.forename: Achim
authors.initials: A
authors.lastname: Heinecke
authors.forename: Michael
authors.initials: M
authors.lastname: Lein
authors.forename: Paolo
authors.initials: P
authors.lastname: Fornara
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Schmid
authors.forename: Lothar
authors.initials: L
authors.lastname: Hertle
authors.forename: Axel
authors.initials: A
authors.lastname: Semjonow
mesh_terms: D003951:Diagnostic Errors; D006801:Humans; D007118:Immunoassay; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000175:diagnosis*; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity
chemical_list: D011933:Reagent Kits, Diagnostic; D017430:Prostate-Specific Antigen