title: Stochastic model for estimating the risk of transfusion-transmitted hepatitis B in Vietnam.
abstract: OBJECTIVE
  Transfusion-transmitted hepatitis B virus (HBV) infection may originate from hepatitis B surface antigen (HBsAg) false-negative blood donors, HBsAg negative and anti-HBc positive blood donors and blood donors with both tests negative. HBV DNA may be present in all these cases and blood may be infectious. The aim of the study was to estimate the risk of transfusion-transmitted HBV in Vietnam using a stochastic Monte Carlo model.
  
  
  METHODS
  A cross-sectional study of HBV prevalence in 1200 potential blood donors in rural Vietnam is used as basis for the Monte Carlo model together with expert panel estimates of occult hepatitis B infection (OBI) prevalence in blood donors.
  
  
  RESULTS
  With 1 000 000 blood donors running in the model, the potential OBI ranged from 658 to 747 blood units per million at 5 percentile and from 1342 to 2507 blood units per million at 95 percentile resulting in the risk of post-transfusion hepatitis ranging from 66 to 250 blood units per million assuming that risk of post-transfusion from potential OBI is 10%. Using the manufacturer's HBsAg sensitivity, the mean rate of blood units per million donations having false-negative HBsAg results was 298 (5-95 percentile: 14-893). When the test sensitivity was set lower, false-negative tests was observed at a mean of 1087 per million (5-95 percentile: 762-3220). The fraction of potential OBI donors increased with the increasing age in both genders.
  
  
  CONCLUSIONS
  Current HBsAg screening in Vietnam is insufficient in eliminating the risk of transfusion-transmitted HBV infection. The major risk factors are HBsAg false-negative results and OBI. Increased test sensitivity and locally validated HBsAg assays are recommended.
authors.affiliation: Quang Tri Provincial Preventive Medicine Centre, Quang Tri Health Service, Dong Ha, Vietnam; Department of Clinical Medicine, Faculty of Health Sciences, University of Tromsø
authors.forename: L
authors.initials: L
authors.lastname: Viet
authors.forename: A
authors.initials: A
authors.lastname: Husebekk
authors.forename: H
authors.initials: H
authors.lastname: Husum
authors.forename: E
authors.initials: E
authors.lastname: Skjerve
mesh_terms: D000293:Adolescent; D000328:Adult; D001782:Blood Donors; D001803:Blood Transfusion; D005260:Female; D006509:Hepatitis B / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission*; D006515:Hepatitis B virus; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D013269:Stochastic Processes; D014744:Vietnam / Q000453:epidemiology
keywords: Monte Carlo simulation model; Occult hepatitis B; Vietnam; antibody to hepatitis B core antigen (anti-HBc); hepatitis B surface antigen (HBsAg); transfusion-transmitted hepatitis B