Reconciling HIV incidence results from two assays employed in the serological testing algorithm for recent HIV seroconversion (STARHS)

Development of an international external quality assurance program for HIV-1 incidence using the Limiting Antigen Avidity assay

Laboratory assays for identifying recent HIV-1 infections are widely used for estimating incidence in cross-sectional population-level surveys in global HIV-1surveillance. Adequate assay and laboratory performance are required to ensure accurate incidence estimates. The NIAID-supported External Quality Assurance Program Oversight Laboratory (EQAPOL) established a proficiency testing program for the most widely-used incidence assay, the HIV-1 Limiting Antigen Avidity EIA (LAg), with US Centers for Disease Control and Prevention (CDC)-approved kits manufactured by Sedia Biosciences Corporation and Maxim Biomedical. The objective of this program is to monitor the performance of participating laboratories. Four rounds of blinded external proficiency (EP) panels were distributed to up to twenty testing sites (7 North American, 5 African, 4 Asian, 2 South American and 2 European). These panels consisted of ten plasma samples: three blinded well-characterized HIV-1-seropositive samples that were included as replicates and an HIV-negative control. The seropositive samples spanned the dynamic range of the assay and are categorized as either recent or long-term infection. Participating sites performed the assay according to manufacturers’ instructions and completed an online survey to gather information on kit manufacturer, lot of kit used, laboratory procedures and the experience of technicians. On average, fifteen sites participated in each round of testing, with an average of four sites testing with only the Maxim assay, seven testing with only the Sedia assay and five sites utilizing both assays. Overall, the Sedia and Maxim assays yielded similar infection status categorization across the laboratories; however, for most of the nine HIV+ samples tested, there were significant differences in the optical density readouts, ODn (N = 8) and OD (N = 7), between LAg kit manufacturers (p < 0.05 based on mixed effects models. The EQAPOL LAg program is important for monitoring laboratory performance as well as detecting variations between manufacturers of HIV-1incidence assays.

Standardization and monitoring of laboratory performance and quality assurance by use of the less-sensitive HIV incidence assay: seven years of results

BACKGROUND

The Performance Evaluation Program for HIV-1 incidence tests provided quality assurance services to laboratories conducting the serological testing algorithm for recent HIV seroconversion by use of a modified less-sensitive version of the Vironostika HIV-1 MicroElisa System assay. We report on the performance of the assay using proficiency testing and quality control materials tested from 2001 to 2008.

METHODS

Two sets of 5 blinded serum panels using common calibration and quality control materials were tested. The mean, standard deviation, and coefficient of variation were calculated. Results were analyzed for misclassifications: false recent HIV infection errors (long-term infection classified as HIV infection less than 1 year), false long-term infection errors (HIV infection less than 1 year classified as long-term infection), and differences in standardized optical density means and variances over time.

RESULTS

The false recent error rate was 1.26% (n = 2219). The false long-term error rate was 0.25% (n = 1618). No significant trends were observed for misclassification rates by year, and no significant trend in the standardized optical density over 7 years was observed.

CONCLUSIONS

Laboratories using the less-sensitive Vironostika HIV-1 assay produced consistent results by use of a common calibrator and quality control materials.

Nomenclature and definitions for emergency department human immunodeficiency virus (HIV) testing: report from the 2007 conference of the National Emergency Department HIV Testing Consortium

Early diagnosis of persons infected with human immunodeficiency virus (HIV) through diagnostic testing and screening is a critical priority for individual and public health. Emergency departments (EDs) have an important role in this effort. As EDs gain experience in HIV testing, it is increasingly apparent that implementing testing is conceptually and operationally complex. A wide variety of HIV testing practice and research models have emerged, each reflecting adaptations to site-specific factors and the needs of local populations. The diversity and complexity inherent in nascent ED HIV testing practice and research are associated with the risk that findings will not be described according to a common lexicon. This article presents a comprehensive set of terms and definitions that can be used to describe ED-based HIV testing programs, developed by consensus opinion from the inaugural meeting of the National ED HIV Testing Consortium. These definitions are designed to facilitate discussion, increase comparability of future reports, and potentially accelerate wider implementation of ED HIV testing.

Implications of and perspectives on HIV surveillance using a serological method to measure recent HIV infections in newly diagnosed individuals: results from a pilot study in Berlin, Germany, in 2005-2007

OBJECTIVES

This cross-sectional study was designed to pilot the analysis of clinical data, knowledge about and attitudes towards HIV/AIDS, and prevention and risk behaviour in persons recently infected with HIV.

METHODS

Blood samples and demographic, laboratory, clinical and behavioural data were collected from patients with newly diagnosed HIV infections. The BED IgG-capture ELISA (BED-CEIA) was used to determine the recency of infection.

RESULTS

Recent HIV infections contributed 54% [95% confidence interval (CI) 45; 64%] of infections in men who have sex with men (MSM) and 16% (95% CI 0; 39%) of infections in patients with other transmission risks (P=0.041). Recently infected MSM were characterized by younger age and higher viral load as compared with MSM who had longstanding infections (P=0.011 and 0.005, respectively). Symptoms during primary infection and patients' assumptions with regard to time of infection were significantly correlated with test results indicating whether or not the HIV infection was recently acquired (P<0.001).

CONCLUSIONS

Cross-sectional surveillance of recent HIV infections proved to be relevant to the identification of current risks for acquiring HIV infection. The high proportion of recent HIV infections in MSM and the even higher proportion in MSM younger than 30 years indicate ongoing HIV transmission in this group. The method will be used in future national HIV surveillance in Germany.

Comparison of methods to detect recent HIV type 1 infection in cross-sectionally collected specimens from a cohort of female sex workers in the Dominican Republic

Interest in estimating HIV-1 incidence using specimens obtained as part of cross-sectional surveys has led to the development of new methods to detect recent HIV-1 infection through the testing of a single anti-HIV-positive specimen. These assays are based on quantitative and qualitative differences in anti-HIV-1 antibodies between recent and long-standing infections. An ongoing vaccine preparedness study enrolled female sex workers in the Dominican Republic. Specimens from women found to be HIV positive at baseline were tested for recent HIV-1 infection using the detuned assay, avidity index, and BED-CEIA assay. An unweighted kappa statistic in pairwise comparisons was used to estimate the correlation of recent HIV-1 infection detection by the three methods. Nineteen (3.9%) of 482 women were positive for HIV-1 infection. The incidence of HIV infection was 1.4% [95% confidence interval (CI): 0.2, 5.3], 0.9%(95% CI: 0.1, 4.4), and 1.0%(95% CI: 0.1, 4.4) using detuned assay, avidity index, and BED-CEIA techniques, respectively. The overall agreement between both detuned assay and avidity index and detuned assay and BED-CEIA was 94%(kappa = 0.8, 95% CI; 0.3, 1.0). The correlation was highest between BED-CEIA and avidity index methods (100%; kappa = 1.0). All three methods performed similarly in detecting recent HIV-1 infection in this region dominated by clade B HIV-1 infection. Although incidence estimates were slightly higher using the detuned assay method, they were not significantly different. These assays may be of value in both clinical research and practice. The utility of individual assays for recent infection detection will depend upon operating characteristics, HIV-1 subtype limitations, and selection of appropriate assay cutoff values.

Comparison of HIV type 1 incidence observed during longitudinal follow-up with incidence estimated by cross-sectional analysis using the BED capture enzyme immunoassay

The BED capture enzyme immunoassay (BED CEIA) for recent infection was developed for the estimation of HIV-1 incidence in a population from a single cross-sectional survey. To evaluate performance, we applied the assay to specimen sets obtained from a longitudinal cohort study, the AIDSVAX B/B vaccine trial, in which there was an independent and conventional measure of observed incidence. The BED CEIA was performed on specimens obtained during follow-up for seroconversion conducted every 6 months for 3 years. There was excellent agreement between the observed and BED-estimated incidence for all the intervals. The cumulative, annualized incidence observed in the cohort was 3.10 new infections per 100 person-years (95% CI, 2.57-3.63). The corresponding BED-estimated incidence was 2.91 (2.30-3.53). We also estimated the effect of varied prevalence on a fixed incidence. Because some specimens from persons with longer-term infection are classified as recent by the assay, this can inflate the incidence estimate. We quantify this effect and discuss potential mitigation by excluding certain specimens on clinical grounds, by relying on trend differences rather than absolute incidence estimates, by secondary confirmatory testing, or by analytic adjustments for misclassification. Cross-sectional HIV incidence estimation circumvents many of the drawbacks associated with longitudinal cohort studies, but there are test-specific limitations that should be considered in the design of population surveys.

HIV seroincidence estimates among at-risk populations in Buenos Aires and Montevideo: use of the serologic testing algorithm for recent HIV seroconversion

Using the serological testing algorithm for recent HIV seroconversion, we estimated annualized incidences (per 100 person-years) of HIV-1 infection in different at-risk groups in Buenos Aires and Montevideo, during a 5-year period between 1998 and 2003. HIV-positive serum samples from 9 serosurveys conducted among men who have sex with men, patients attending clinics for a sexually transmitted infections consult (STIs), female commercial sex workers, injecting drug users (IDUs), noninjecting cocaine users (NICUs), asymptomatic women screened for HIV infection, and patients with tuberculosis were used. HIV incidences were as follows: 6.7 for men who have sex with men, 2.0 for STIs, 1.3 for female commercial sex workers, 0.0 for Argentinean IDUs, 10.3 for Uruguayan IDUs, 3.1 for Argentinean NICUs, 4.4 for Uruguayan NICUs, and 2.4 for patients with tuberculosis. Among asymptomatic women screened for HIV infection, incidence rose from 0.4 in 1998 to 4.6 in 1999 and to a high of 10.2 in the year 2000. Unexpectedly, high HIV incidences were detected among at-risk groups in Buenos Aires and Montevideo. This pattern shows an emerging HIV epidemic among heterosexuals stemming from core HIV-infected at-risk groups. There is an urgent need for development and implementation of specific prevention strategies to address this burgeoning epidemic.

Advances in laboratory testing for HIV

In 2004, the diagnosis of established human immunodeficiency virus (HIV) infection can be made with close to 100% assurity. The extraordinarily engineered performances of HIV-screening assays are unprecedented. The well-established confirmatory tests performed by well-versed laboratories using criteria that are well understood in order to interpret the results of these tests give highly accurate outcomes of diagnostic testing strategies. Furthermore, the ability to monitor the progress of the infection and the viral pathogenesis is possible through the use of tests that quantify viral load or the peripheral CD4+ T-cells and other lymphocyte sub-type levels. Newer laboratory testing mechanisms, such as assessment of reverse transcriptase activity and sophisticated cell staining and flow cytometric analyses, have been used to map disease processes and progress on a research level and may be used in future to fine-tune therapy and to follow disease progression in even greater detail. Regulation of all HIV tests is of the highest level in Australia. In-house tests will be expected to conform to the levels specified for commercially produced tests.

Surveillance for HIV-1 incidence using tests for recent infection in resource-constrained countries

Over the past few years, several assays have been developed for the purpose of estimating HIV-1 incidence from cross-sectional population surveys. The tests detect features of the evolving virological or immunological response to HIV-1 infection that distinguish recent from established infection. Surveillance programmes that collect specimens from population surveys for HIV-1 prevalence can apply some of these tests to the same specimen sets to estimate incidence. We describe these tests and discuss the principle and strategy for implementation of a testing programme for recent infection in surveillance settings. Test-specific prerequisites, such as calibration, validation, and quality assurance, and other test-specific performance characteristics that may influence interpretation, epidemiological considerations that may guide application, and practical operational considerations for implementation in surveillance settings are considered. When properly and judiciously applied, the capacity to estimate incidence from existing programmes that conduct surveillance for prevalent HIV-1 infection will enhance the capacity for more precise and timely analysis of the dynamics of the epidemic and the effectiveness of public health interventions.