title: A computer-based model to assess costs associated with the use of factor VIII and factor IX one-stage and chromogenic activity assays.
abstract: BACKGROUND
  Measurement of coagulation factor factor VIII (FVIII) and factor IX (FIX) activity can be associated with a high level of variability using one-stage assays based on activated partial thromboplastin time (APTT). Chromogenic assays show less variability, but are less commonly used in clinical laboratories. In addition, one-stage assay accuracy using certain reagent and instrument combinations is compromised by some modified recombinant factor concentrates. Reluctance among some in the hematology laboratory community to adopt the use of chromogenic assays may be partly attributable to lack of familiarity and perceived higher associated costs.
  
  
  OBJECTIVE
  To identify and characterize key cost parameters associated with one-stage APTT and chromogenic assays for FVIII and FIX activity using a computer-based cost analysis model.
  
  
  METHODS
  A cost model for FVIII and FIX chromogenic assays relative to APTT assays was generated using assumptions derived from interviews with hematologists and laboratory scientists, common clinical laboratory practise, manufacturer list prices and assay kit configurations.
  
  
  RESULTS
  Key factors that contribute to costs are factor-deficient plasma and kit reagents for one-stage and chromogenic assays, respectively. The stability of chromogenic assay kit reagents also limits the cost efficiency compared with APTT testing. Costs for chromogenic assays might be reduced by 50-75% using batch testing, aliquoting and freezing of kit reagents.
  
  
  CONCLUSIONS
  Both batch testing and aliquoting of chromogenic kit reagents might improve cost efficiency for FVIII and FIX chromogenic assays, but would require validation. Laboratory validation and regulatory approval as well as education and training in the use of chromogenic assays might facilitate wider adoption by clinical laboratories.
authors.affiliation: Royal Hallamshire Hospital, Sheffield, UK.
authors.forename: S
authors.initials: S
authors.lastname: Kitchen
authors.affiliation: Cambridge Consultants Limited, Cambridge, UK.
authors.forename: J
authors.initials: J
authors.lastname: Blakemore
authors.affiliation: Blood Center of Wisconsin, Milwaukee, WI, USA.
authors.forename: K D
authors.initials: KD
authors.lastname: Friedman
authors.affiliation: Barts Health NHS Trust, London, UK.
authors.forename: D P
authors.initials: DP
authors.lastname: Hart
authors.affiliation: Children's Hospital Los Angeles, Los Angeles, CA, USA.|University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
authors.forename: R H
authors.initials: RH
authors.lastname: Ko
authors.affiliation: Addenbrooke's Hospital, Cambridge University Hospital NHS Foundation Trust, Cambridge, UK.
authors.forename: D
authors.initials: D
authors.lastname: Perry
authors.affiliation: Barts Health NHS Trust, London, UK.
authors.forename: S
authors.initials: S
authors.lastname: Platton
authors.affiliation: Children's Hospital Los Angeles, Los Angeles, CA, USA.
authors.forename: D
authors.initials: D
authors.lastname: Tan-Castillo
authors.affiliation: Children's Hospital Los Angeles, Los Angeles, CA, USA.|University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
authors.forename: G
authors.initials: G
authors.lastname: Young
authors.affiliation: Addenbrooke's Hospital, Cambridge University Hospital NHS Foundation Trust, Cambridge, UK.
authors.forename: R J
authors.initials: RJ
authors.lastname: Luddington
mesh_terms: D001780:Blood Coagulation Tests / Q000191:economics / Q000379:methods*; D002138:Calibration; D002863:Chromogenic Compounds; D003029:Coagulants / Q000191:economics / Q000627:therapeutic use*; D003198:Computer Simulation; D003365:Costs and Cost Analysis; D005164:Factor IX / Q000191:economics / Q000627:therapeutic use*; D005169:Factor VIII / Q000191:economics / Q000627:therapeutic use*; D006467:Hemophilia A / Q000188:drug therapy; D002836:Hemophilia B / Q000188:drug therapy; D006801:Humans; D007202:Indicators and Reagents; D010314:Partial Thromboplastin Time; D012015:Reference Standards; D012016:Reference Values; D015203:Reproducibility of Results
chemical_list: D002863:Chromogenic Compounds; D003029:Coagulants; D007202:Indicators and Reagents; C078147:F8 protein, human; D005169:Factor VIII; D005164:Factor IX
keywords: blood coagulation disorders; blood coagulation tests; factor IX; factor VIII; hemophilia