title: Improved HIV-1 incidence estimates using the BED capture enzyme immunoassay.
abstract: OBJECTIVE
  To validate the BED capture enzyme immunoassay for HIV-1 subtype C and to derive adjustments facilitating estimation of HIV-1 incidence from cross-sectional surveys.
  
  
  METHODS
  Laboratory analysis of archived plasma samples collected in Zimbabwe.
  
  
  METHODS
  Serial plasma samples from 85 women who seroconverted to HIV-1 during the postpartum year were assayed by BED and used to estimate the window period between seroconversion and the attainment of a specified BED absorbance. HIV-1 incidences for the year prior to recruitment and for the postpartum year were calculated by applying the BED technique to HIV-1-positive samples collected at baseline and at 12 months.
  
  
  RESULTS
  The mean window for an absorbance cut-off of 0.8 was 187 days. Among women who were HIV-1 positive at baseline and retested at 12 months, a proportion (epsilon) 5.2% (142/2749) had a BED absorbance < 0.8 at 12 months and were falsely identified as recent seroconverters. Consequently, the estimated BED annual incidence at 12 months postpartum (7.6%) was 2.2 times the contemporary prospective estimate. BED incidence adjusted for epsilon was 3.5% [95% confidence interval (CI), 2.6-4.5], close to the 3.4% estimated prospectively. Adjusted BED incidence at baseline was 6.0% (95% CI, 5.2-6.9) and, like the prospective estimates, declined with maternal age. Unadjusted BED incidence estimates were largely independent of age; the pooled estimate was 58% higher than adjusted incidence.
  
  
  CONCLUSIONS
  The BED method can be used in an African setting, but further estimates of epsilon and of the window period are required, using large samples in a variety of circumstances, before its general utility can be gauged.
authors.affiliation: ZVITAMBO Project, Harare, Zimbabwe.
authors.forename: John W
authors.initials: JW
authors.lastname: Hargrove
authors.forename: Jean H
authors.initials: JH
authors.lastname: Humphrey
authors.forename: Kuda
authors.initials: K
authors.lastname: Mutasa
authors.forename: Bharat S
authors.initials: BS
authors.lastname: Parekh
authors.forename: J Steve
authors.initials: JS
authors.lastname: McDougal
authors.forename: Robert
authors.initials: R
authors.lastname: Ntozini
authors.forename: Henry
authors.initials: H
authors.lastname: Chidawanyika
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Moulton
authors.forename: Brian
authors.initials: B
authors.lastname: Ward
authors.forename: Kusum
authors.initials: K
authors.lastname: Nathoo
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Iliff
authors.forename: Ekkehard
authors.initials: E
authors.lastname: Kopp
mesh_terms: D015492:AIDS Serodiagnosis / Q000379:methods*; D004812:Epidemiologic Methods; D005260:Female; D015658:HIV Infections / Q000453:epidemiology*; D015497:HIV-1; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods; D007074:Immunoglobulin G / Q000097:blood; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*; D015030:Zimbabwe / Q000453:epidemiology
chemical_list: D007074:Immunoglobulin G