Abstract
BackgroundThe BED Capture Enzyme Immunoassay, believed to distinguish recent HIV infections, is being used to estimate HIV incidence, although an important property of the test – how specificity changes with time since infection – has not been not measured.MethodsWe construct hypothetical scenarios for the performance of BED test, consistent with current knowledge, and explore how this could influence errors in BED estimates of incidence using a mathematical model of six African countries. The model is also used to determine the conditions and the sample sizes required for the BED test to reliably detect trends in HIV incidence.ResultsIf the chance of misclassification by BED increases with time since infection, the overall proportion of individuals misclassified could vary widely between countries, over time, and across age-groups, in a manner determined by the historic course of the epidemic and the age-pattern of incidence. Under some circumstances, changes in BED estimates over time can approximately track actual changes in incidence, but large sample sizes (50,000+) will be required for recorded changes to be statistically significant.ConclusionsThe relationship between BED test specificity and time since infection has not been fully measured, but, if it decreases, errors in estimates of incidence could vary by place, time and age-group. This means that post-assay adjustment procedures using parameters from different populations or at different times may not be valid. Further research is urgently needed into the properties of the BED test, and the rate of misclassification in a wide range of populations.
Highlights
To date, HIV prevalence has been the main measure used in monitoring HIV epidemics, but it is neither timely nor interpreted, especially since antiretroviral treatment can increase prevalence without concomitant increases in the spread of the virus [1,2,3,4]
The most widely used of these assays is the BED capture enzyme immunosorbent assay (‘BED test’), in which the optical density varies according to proportion of IgG that is anti-HIV antibody [9]
Recent infections are more frequent in countries that have experienced recent epidemic growth (e.g. Mozambique) and late infections are more frequent following epidemic stabilisation and decline (e.g. Uganda and Kenya)
Summary
HIV prevalence has been the main measure used in monitoring HIV epidemics, but it is neither timely nor interpreted, especially since antiretroviral treatment can increase prevalence without concomitant increases in the spread of the virus [1,2,3,4]. The most widely used of these assays is the BED capture enzyme immunosorbent assay (‘BED test’), in which the optical density varies according to proportion of IgG that is anti-HIV antibody [9]. Assuming that all (or a known proportion of) the detected recent infections have occurred within a period V preceding the survey, the number of incidence infection occurring in the last year can be estimated [10]. The BED Capture Enzyme Immunoassay, believed to distinguish recent HIV infections, is being used to estimate HIV incidence, an important property of the test – how specificity changes with time since infection – has not been not measured
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
