title: Economic evaluation of a hypothetical screening assay for alloimmunization risk among transfused patients with sickle cell disease.
abstract: BACKGROUND
  Prophylactic antigen-matching can reduce alloimmunization rates among chronically transfused patients with sickle cell disease (SCD), but this matching increases costs and may only benefit 30% of patients. We assessed the clinical and financial value of a potential assay for alloimmunization risk that would allow for targeted antigen-matching.
  
  
  METHODS
  A Markov-based model evaluated direct medical costs and alloimmunization events over 10 to 20 years among transfused (simple or exchange) patients with SCD. Four matching strategies were evaluated: prospective matching (for all patients), history-based matching (only for patients with prior alloimmunization), perfectly informed matching (assay with 100% sensitivity, 100% specificity), and imperfectly informed matching (reduced accuracy). Under all matching protocols, matching included C, E, K, and any additional alloantibodies present. A hospital perspective was adopted, with costs (2012US$) and events discounted (3%).
  
  
  RESULTS
  Perfectly informed antigen-matching using a $1000 assay is expected to save $82,334 per patient over 10 years, compared to prospective matching. Perfectly informed antigen-matching is more costly than history-based matching, but reduces alloimmunization events by 45.6% over 10 years. Averting each alloimmunization event using this strategy would cost an additional $10,934 per patient. Imperfectly informed antigen-matching using an assay with 75% specificity and 75% sensitivity is less costly than prospective matching, but increases alloimmunization events. Compared to history-based matching, imperfectly informed matching would decrease alloimmunization events by 32.61%, at an additional cost of $147,915 per patient over 10 years. Cost-effectiveness of informed antigen-matching is largely driven by assay specificity.
  
  
  CONCLUSIONS
  A sufficiently specific assay to inform antigen-matching may be cost-effective in reducing alloimmunization among transfused patients with SCD.
authors.affiliation: Department of Pathology, Johns Hopkins University, Baltimore, Maryland.
authors.forename: Seema
authors.initials: S
authors.lastname: Kacker
authors.forename: Paul M
authors.initials: PM
authors.lastname: Ness
authors.forename: William J
authors.initials: WJ
authors.lastname: Savage
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Frick
authors.forename: R Sue
authors.initials: RS
authors.lastname: Shirey
authors.forename: Karen E
authors.initials: KE
authors.lastname: King
authors.forename: Aaron A R
authors.initials: AA
authors.lastname: Tobian
mesh_terms: D000755:Anemia, Sickle Cell / Q000191:economics / Q000276:immunology / Q000628:therapy*; D001782:Blood Donors; D001789:Blood Group Antigens / Q000276:immunology*; D001787:Blood Group Incompatibility / Q000191:economics / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D001788:Blood Grouping and Crossmatching / Q000191:economics*; D001803:Blood Transfusion / Q000191:economics; D003362:Cost-Benefit Analysis; D003365:Costs and Cost Analysis; D003661:Decision Support Techniques; D046148:Donor Selection / Q000191:economics*; D005102:Health Expenditures; D006801:Humans; D007518:Isoantibodies / Q000097:blood*; D008390:Markov Chains; D008499:Medical Records / Q000191:economics; D018803:Models, Economic; D012306:Risk; D012680:Sensitivity and Specificity; D065227:Transfusion Reaction; D014481:United States
chemical_list: D001789:Blood Group Antigens; D007518:Isoantibodies