title: Cost-effectiveness of quantitative hepatitis B virus surface antigen testing in pregnancy in predicting vertical transmission risk.
abstract: Vertical transmission of hepatitis B virus (HBV) can occur despite immunoprophylaxis in mothers with high HBV DNA levels (>5-7 log10IU/ml). Quantitative hepatitis B surface antigen (qHBsAg) testing could be used as a surrogate marker to identify high viral load carriers, but there is limited data in pregnancy. We conducted a prospective observational study to determine the cost-effectiveness and utility of qHBsAg as a valid surrogate marker of HBV DNA.
  
  
  
  Pregnant patients with chronic hepatitis B were recruited from a tertiary referral centre. HBV DNA levels and qHBsAg were assessed in the second to third trimester. Statistical analysis was performed by Spearman's rank correlation and student's t-test. The cost-effectiveness of qHBsAg as compared to HBV DNA testing was calculated.
  
  
  
  Ninety nine women with 103 pregnancies, median age 32 years, 65% Asian, 23% African and 12% other [Hispanic, Caucasian] were enrolled. Overall, 23% (23/99) were HBV e Ag (HBeAg)-positive. A significant correlation between qHBsAg and HBV DNA levels was noted in HBeAg-positive patients (r = 0.79, P < 0.05) but not in HBeAg-negative patients (r = 0.17, P = 0.06). In receiver operating characteristic analysis, the optimal qHBsAg cut-off values for predicting maternal viraemia associated with immunoprophylaxis failure (i.e., HBV DNA ≥7 log10IU/ml) was 4.3 log10IU/ml (accuracy 98.7%, sensitivity 94.7%, specificity 94.4%) (95% CI, 97-100%, P < 0.05). Use of HBV DNA as compared to qHBsAg costs approximately $20 000 more per infection prevented.
  
  
  
  In resource poor regions, qHBsAg could be used as a more cost-effective marker for high maternal viraemia, and indicate when anti-HBV nucleos/tide analogue therapy should be used to prevent HBV immunoprophylaxis failure.
authors.affiliation: Department of Medicine, University of Calgary, Calgary, AB, Canada.
authors.forename: Golasa
authors.initials: G
authors.lastname: Samadi Kochaksaraei
authors.affiliation: Department of Medicine, University of Calgary, Calgary, AB, Canada.
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Congly
authors.affiliation: Department of Medicine, University of Calgary, Calgary, AB, Canada.
authors.forename: Trudy
authors.initials: T
authors.lastname: Matwiy
authors.affiliation: Department of Medicine, University of Calgary, Calgary, AB, Canada.
authors.forename: Eliana
authors.initials: E
authors.lastname: Castillo
authors.affiliation: Department of Pediatrics, Alberta Children's Hospital, University of Calgary, Calgary, AB, Canada.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Martin
authors.affiliation: Provincial Laboratory for Public Health (ProvLab), University of Alberta Hospital, Edmonton, AB, Canada.|Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, Canada.
authors.forename: Carmen L
authors.initials: CL
authors.lastname: Charlton
authors.affiliation: Department of Medicine, University of Calgary, Calgary, AB, Canada. cscoffin@ucalgary.ca.
authors.forename: Carla S
authors.initials: CS
authors.lastname: Coffin
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D002170:Canada; D003362:Cost-Benefit Analysis; D004279:DNA, Viral / Q000097:blood; D005260:Female; D006509:Hepatitis B / Q000175:diagnosis*; D006514:Hepatitis B Surface Antigens / Q000097:blood*; D006515:Hepatitis B virus; D006801:Humans; D018445:Infectious Disease Transmission, Vertical / Q000517:prevention & control; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis* / Q000821:virology; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D019562:Viral Load; D014766:Viremia / Q000175:diagnosis*
chemical_list: D015415:Biomarkers; D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens
keywords: chronic hepatitis B; cost-effectiveness; perinatal transmission; quantitative hepatitis B surface antigen