Improved HIV-1 incidence estimates using the BED capture enzyme immunoassay.
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.
Hargrove
John W
JW
ZVITAMBO Project, Harare, Zimbabwe.
Humphrey
Jean H
JH
Mutasa
Kuda
K
Parekh
Bharat S
BS
McDougal
J Steve
JS
Ntozini
Robert
R
Chidawanyika
Henry
H
Moulton
Lawrence H
LH
Ward
Brian
B
Nathoo
Kusum
K
Iliff
Peter J
PJ
Kopp
Ekkehard
E
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
D007074:Immunoglobulin G