title: Refining the risk estimate for transfusion-transmission of occult hepatitis B virus.
abstract: OBJECTIVE
  We previously published a model to estimate the residual risk (RR) for occult hepatitis B infection (OBI) in the absence of universal anti-HBc testing. To incorporate new information on the epidemiology of OBI, we describe model refinements and estimate a more accurate HBV RR due to OBI in Australia.
  
  
  METHODS
  In our original model, the OBI risk, p(OBI), was defined by the rate of 'non-detection' by the HBV DNA screening test in use, p(NAT non-detection), and the average infectivity of blood components from OBI donors, p(transmission). We revised the model by integrating three refinements: that donations with anti-HBs levels of >10 IU/l, or donations solely for manufactured plasma products, be excluded from the risk calculation, and an updated estimate of p(transmission).
  
  
  RESULTS
  Refining our OBI RR model resulted in a more than 10-fold reduction in the reported RR risk to recipients from OBI in our donor population. Based on the use of a common data set, the mean OBI RR risk decreased from 1 in 374 354 donations (95% CI: 1 in 191 940-1 072 681) to 1 in 3 984 033 (95% CI: 1 in 1 146 188-65 268 257) for the refined model.
  
  
  CONCLUSIONS
  Our model refinements provide a more realistic measure of the HBV RR in the donor population. Unlike the previous model, the new model demonstrates that the risk of HBV due to OBI in the Australian blood donor population is negligible, and further potentially cost-ineffective risk management strategies are not currently warranted.
authors: Australian Red Cross Blood Service, Perth, WA, Australia.
authors: C R
authors: CR
authors: Seed
authors: Australian Red Cross Blood Service, Melbourne, Vic., Australia.
authors: P
authors: P
authors: Kiely
authors: Australian Red Cross Blood Service, Perth, WA, Australia.
authors: V C
authors: VC
authors: Hoad
authors: Australian Red Cross Blood Service, Perth, WA, Australia.
authors: A J
authors: AJ
authors: Keller
mesh_terms: D001782:Blood Donors; D001803:Blood Transfusion; D004279:DNA, Viral / Q000097:blood; D006509:Hepatitis B / Q000453:epidemiology / Q000635:transmission* / Q000821:virology; D006510:Hepatitis B Antibodies / Q000097:blood; D006512:Hepatitis B Core Antigens / Q000276:immunology; D006515:Hepatitis B virus / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D008962:Models, Theoretical; D020411:Oligonucleotide Array Sequence Analysis; D012306:Risk
chemical_list: D004279:DNA, Viral; D006510:Hepatitis B Antibodies; D006512:Hepatitis B Core Antigens
keywords: blood donation testing; nucleic acid testing testing; residual risk estimation