Evaluation of an alternative HIV diagnostic algorithm using specimens from seroconversion panels and persons with established HIV infections

Performance evaluation of the CHEMBIO DPP® (dual path platform) HIV-1/2 assay in early and established infections

BACKGROUND

The availability of more accurate point-of-care technology could increase the number of persons aware of their HIV status. The DPP(®) HIV-1/2 assay is the first dual path platform rapid test (RT) approved in the U.S. that also received the Clinical Laboratory Improvement Amendments (CLIA) waiver for use with oral fluid and fingerstick and venous whole blood.

OBJECTIVE

To evaluate the performance of the DPP(®) HIV-1/2 assay with plasma specimens.

STUDY DESIGN

Sensitivity and specificity of the assay were calculated from 696 HIV-1 groups M (B and non-B subtypes) and O and HIV-2 (groups A and B) specimens and 505 HIV-negative specimens, respectively. Analysis of the assay performance in HIV-1 early infections was assessed by estimating the relative sensitivity of the RT before the Western blot (WB) becomes positive using a 50% cumulative frequency analysis and by comparing the reactivity with other Food and Drug Administration (FDA)-approved RTs.

RESULTS

The sensitivity for established infection was 100% for HIV-1 and 100% for HIV-2. The specificity was 100%. The DPP(®) HIV-1/2 assay performs similarly to most antibody-based RT approved by FDA in early HIV-1 infections.

CONCLUSIONS

The DPP(®) technology showed no significant improvement for detecting early infections over other lateral-flow RTs used in the U.S. Without more data on the DPP(®) HIV-1/2 assay, especially from whole blood and oral fluid specimens collected during the early phase of infection, its performance as point-of-care technology remains to be assessed.

Integrating Antiretroviral Strategies for Human Immunodeficiency Virus Prevention: Post- and Pre-Exposure Prophylaxis and Early Treatment

Best practices for integrating HIV testing and antiretroviral interventions for prevention and treatment are suggested based on research evidence and existing normative guidance. The goal is to provide high impact prevention services during periods of substantial risk.

Best practices for integrating human immunodeficiency virus (HIV) testing and antiretroviral interventions for prevention and treatment are suggested based on research evidence and existing normative guidance. The goal is to provide high-impact prevention services during periods of substantial risk. Antiretroviral medications are recommended for postexposure prophylaxis (PEP), pre-exposure prophylaxis (PrEP), and treatment of HIV infection. We reviewed research evidence and current normative guidelines to identify best practices for integrating these high-impact prevention strategies. More sensitive HIV tests used for screening enable earlier diagnosis and treatment of HIV infection, more appropriate counseling, and help limit drug resistance. A fully suppressive PEP regimen should be initiated based on exposure history or physical findings when sensitive diagnostic testing is delayed or not available and antibody tests are negative. Transitions from PEP to PrEP are often warranted because HIV exposure events may continue to occur. This algorithmic approach to integrating PEP, PrEP, and early treatment decisions may increase the uptake of these interventions by a greater number and diversity of knowledgeable healthcare providers.

Independent assessment of candidate HIV incidence assays on specimens in the CEPHIA repository

Objective:

Cross-sectional HIV incidence surveillance, using assays that distinguish ‘recent’ from ‘nonrecent’ infections, has been hampered by inadequate performance and characterization of incidence assays. In this study, the Consortium for the Evaluation and Performance of HIV Incidence Assays presents results of the first independent evaluation of five incidence assays (BED, Limiting Antigen Avidity, Less-sensitive Vitros, Vitros Avidity and BioRad Avidity).

Design:

A large repository of diverse specimens from HIV-positive patients was established, multiple assays were run on 2500 selected specimens, and data were analyzed to estimate assay characteristics relevant for incidence surveillance.

Methods:

The mean duration of recent infection (MDRI, average time ‘recent’ while infected for less than some time cut-off T) was estimated from longitudinal data on seroconverters by regression. The false-recent rate (FRR, probability of testing ‘recent’ when infected for longer than T) was explored by measuring the proportions of ‘recent’ results in various subsets of patients.

Results:

Assays continue to fail to attain the simultaneously large MDRI and small FRR demanded by existing performance guidelines. All assays produce high FRRs amongst virally suppressed patients (>40%), including elite controllers and treated patients.

Conclusions:

Results from this first independent evaluation provide valuable information about the current performance of assays, and suggest the need for further optimization. Variation of ‘recent’/‘nonrecent’ thresholds and the use of multiple antibody-maturation assays, as well as other biomarkers, can now be explored, using the rich data generated by the Consortium for the Evaluation and Performance of HIV Incidence Assays. Consistently high FRRs amongst those virally suppressed suggest that viral load will be a particularly valuable supplementary marker.

Video abstract:

Replacing clinic-based tests with home-use tests may increase HIV prevalence among Seattle men who have sex with men: evidence from a mathematical model

BACKGROUND

Home-use tests have potential to increase HIV testing but may increase the rate of false-negative tests and decrease linkage to HIV care. We sought to estimate the impact of replacing clinic-based testing with home-use tests on HIV prevalence among men who have sex with men (MSM) in Seattle, Washington.

METHODS

We adapted a deterministic, continuous-time model of HIV transmission dynamics parameterized using a 2003 random digit dial study of Seattle MSM. Test performance was based on the OraQuick In-Home HIV Test (OraSure Technologies, Inc, Bethlehem, PA) for home-use tests and, on an average, of antigen-antibody combination assays and nucleic acid amplification tests for clinic-based testing.

RESULTS

Based on observed levels of clinic-based testing, our baseline model predicted an equilibrium HIV prevalence of 18.6%. If all men replaced clinic-based testing with home-use tests, prevalence increased to 27.5% if home-use testing did not impact testing frequency and to 22.4% if home-use testing increased testing frequency 3-fold. Regardless of how much home-use testing increased testing frequency, any replacement of clinic-based testing with home-use testing increased prevalence. These increases in HIV prevalence were mostly caused by the relatively long window period of the currently approved test. If the window period of a home-use test were 2 months instead of 3 months, prevalence would decrease if all MSM replaced clinic-based testing with home-use tests and tested more than 2.6 times more frequently.

CONCLUSIONS

Our model suggests that if home-use HIV tests replace supplement clinic-based testing, HIV prevalence may increase among Seattle MSM, even if home-use tests result in increased testing.

Performance of a parallel diagnostic algorithm for HIV diagnosis in low risk pediatric and obstetric patient populations

BACKGROUND

Little is known about the clinical performance of the 2010 APHL/CDC Western-blot independent HIV testing algorithm in low risk pediatric and obstetric patients.

OBJECTIVE

To evaluate the performance of an alternate Western-blot independent algorithm and the individual algorithm components in diagnosing HIV infections in low risk pediatric and obstetric patients.

STUDY DESIGN

6242 specimens from pediatric and obstetric patients were tested by the Bio-Rad Multispot HIV-1/HIV-2 (MS) and VITROS Anti HIV 1+2 (VITROS) assays. 913 specimens were also tested by the ARCHITECT HIV Ag/Ab Combo assay (ARCHITECT). Discordant specimens were tested by the APTIMA HIV-1 RNA qualitative assay (RNA Qual).

RESULTS

Twenty-eight specimens tested positive for HIV-1 by both MS and VITROS, 4 of these 28 specimens were also tested by and positive by ARCHITECT; all 28 positives identified by the algorithm were positive by viral load analysis. MS identified 164 preliminary positives, which were not confirmed as true positives, representing a specificity of 97.4%. This specificity varied between patient populations (96.1% in the pediatric population and 99.1% in the obstetric population). The specificities of VITROS and ARCHITECT were 99.2% and 99.4% for pediatric patients; 99.7% and 99.8% for obstetric patients, respectively.

CONCLUSION

Our results highlight suboptimal specificity of MS in pediatric patients, and a lower specificity in both pediatric and obstetric patients relative to either VITROS or ARCHITECT. Additionally, parallel testing with both a third and fourth generation EIA in a low risk patient population provides a potential alternative to Western-blot dependent algorithms for confirmation.

Arguments for and against HIV self-testing

Approximately 60% of human immunodeficiency virus (HIV)-infected individuals are unaware of their infection, and stigma and discrimination continue to threaten acceptance of HIV testing services worldwide. Self-testing for HIV has garnered controversy for years and the debate reignited with the approval of a point-of-care test for over-the-counter sale in the US in 2012. Here, we present arguments for and against HIV self-testing. The case in support of HIV self-testing contends that: the modality is highly acceptable, especially among the most at-risk individuals; self-testing empowers users, thus helping to normalize testing; and mutual partner testing has the potential to increase awareness of risk and avert condomless sex between discordant partners. Arguments against HIV self-testing include: cost limits access to those who need testing most; false-negative results, especially during the window period, may lead to false reassurance and could promote sex between discordant partners at the time of highest infectivity; opportunities for counseling, linkage to care, and diagnosis of other sexually transmitted infections may be missed; and self-testing leads to potential for coercion between partners. Research is needed to better define the risks of self-testing, especially as performance of the assays improves, and to delineate the benefits of programs designed to improve access to self-test kits, because this testing modality has numerous potential advantages and drawbacks.

Performance comparison of the 4th generation Bio-Rad Laboratories GS HIV Combo Ag/Ab EIA on the EVOLIS™ automated system versus Abbott ARCHITECT HIV Ag/Ab Combo, Ortho Anti-HIV 1+2 EIA on Vitros ECi and Siemens HIV-1/O/2 enhanced on Advia Centaur

BACKGROUND

A multisite study was conducted to evaluate the performance of the Bio-Rad 4th generation GS HIV Combo Ag/Ab EIA versus Abbott 4th generation ARCHITECT HIV Ag/Ab Combo. The performance of two 3rd generation EIAs, Ortho Diagnostics Anti-HIV 1+2 EIA and Siemens HIV 1/O/2 was also evaluated.

OBJECTIVE

Study objective was comparison of analytical HIV-1 p24 antigen detection, sensitivity in HIV-1 seroconversion panels, specificity in blood donors and two HIV false reactive panels.

STUDY DESIGN

Analytical sensitivity was evaluated with International HIV-1 p24 antigen standards, the AFFSAPS (pg/mL) and WHO 90/636 (IU/mL) standards; sensitivity in acute infection was compared on 55 seroconversion samples, and specificity was evaluated on 1000 negative blood donors and two false reactive panels.

RESULTS

GS HIV Combo Ag/Ab demonstrated better analytical HIV antigen sensitivity compared to ARCHITECT HIV Ag/Ab Combo: 0.41 IU/mL versus 1.2 IU/mL (WHO) and 12.7 pg/mL versus 20.1 pg/mL (AFSSAPS); GS HIV Combo Ag/Ab EIA also demonstrated slightly better specificity compared to ARCHITECT HIV Ag/Ab Combo (100% versus 99.7%). The 4th generation HIV Combo tests detected seroconversion 7-11 days earlier than the 3rd generation HIV antibody only EIAs.

CONCLUSION

Both 4th generation immunoassays demonstrated excellent performance in sensitivity, with the reduction of the serological window period (7-11 days earlier detection than the 3rd generation HIV tests). However, GS HIV Combo Ag/Ab demonstrated improved HIV antigen analytical sensitivity and slightly better specificity when compared to ARCHITECT HIV Ag/Ab Combo assay, with higher positive predictive values (PPV) for low prevalence populations.

Relative accuracy of serum, whole blood, and oral fluid HIV tests among Seattle men who have sex with men

BACKGROUND

Point-of-care (POC) rapid HIV tests have sensitivity during the "window period" comparable only to earliest generation EIAs. To date, it is unclear whether any POC test performs significantly better than others.

OBJECTIVE

Compare abilities of POC tests to detect early infection in real time.

STUDY DESIGN

Men who have sex with men (MSM) were recruited into a prospective, cross-sectional study at two HIV testing sites and a research clinic. Procedures compared four POC tests: one performed on oral fluids and three on fingerstick whole blood specimens. Specimens from participants with negative POC results were tested by EIA and pooled nucleic acid amplification testing (NAAT). McNemar's exact tests compared numbers of HIV-infected participants detected.

RESULTS

Between February 2010 and May 2013, 104 men tested HIV-positive during 2479 visits. Eighty-two participants had concordant reactive POC results, 3 participants had concordant non-reactive POC tests but reactive EIAs, and 8 participants had acute infection. Of 12 participants with discordant POC results, OraQuick ADVANCE Rapid HIV-1/2 Antibody Test performed on oral fluids identified fewer infections than OraQuick performed on fingerstick (p = .005), Uni-Gold Recombigen HIV test (p = .01), and determine HIV-1/2 Ag/Ab combo (p = .005).

CONCLUSIONS

These data confirm that oral fluid POC testing detects fewer infections than other methods and is best reserved for circumstances precluding fingerstick or venipuncture. Regardless of specimen type, POC tests failed to identify many HIV-infected MSM in Seattle. In populations with high HIV incidence, the currently approved POC antibody tests are inadequate unless supplemented with p24 antigen tests or NAAT.

Costs and outcomes of laboratory diagnostic algorithms for the detection of HIV

BACKGROUND

An alternative HIV testing algorithm, designed to improve the detection of acute and early infections and differentiate between HIV-1 and HIV-2 antibodies, has been developed by the Centers for Disease Control and Prevention and the Association of Public Health Laboratories. While it promises greater sensitivity, it also raises concerns about costs.

OBJECTIVE

We sought to compare the most commonly used algorithm which was developed in 1989, a third-generation (3G) immunoassay (IA) and Western blot confirmatory test, to a newer algorithm. The new algorithm includes either a 3G or a fourth-generation (4G) initial IA, followed by confirmatory testing with a HIV-1/HIV-2 differentiation IA and, if needed, a nucleic acid amplification test (NAT).

STUDY DESIGN

We conducted an analysis of HIV testing costs from the perspective of the laboratory, and classified costs according to IA testing volume. We developed a decision analytic model, populated with cost data from 17 laboratories and published assay performance data, to compare the cost-effectiveness of the testing algorithms for a cohort of 30,000 specimens with a 1% HIV prevalence and 0.1% acute HIV infection prevalence.

RESULTS

Costs were lower in high-volume laboratories regardless of testing algorithm. For specimens confirmed positive for HIV antibody, the alternative algorithm (IA, Multispot) was less costly than the current algorithm (IA, WB); however, there was wide variation in reported testing costs. For our cohort, the alternative algorithm initiated with a 3G IA and 4G IA identified 15 and 25 more HIV infections, respectively, than the 1989 algorithm. In medium-volume laboratories, the 1989 algorithm was more costly and less effective than the alternative algorithm with a 3G IA; in high-volume laboratories, the alternative algorithm with 3G IA costs $162 more per infection detected. The alternative algorithm with 4G instead of 3G incurred an additional cost of $14,400 and $4865 in medium- and high-volume labs, respectively.

DISCUSSION

HIV testing costs varied with IA testing volumes. The additional cost of 4G over 3G IA might be justified by the additional cases of HIV detected and transmissions averted due to earlier detection.

CONCLUSION

The alternative HIV testing algorithm compares favorably to the 1989 algorithm in terms of cost and effectiveness.

Evaluation in a clinical setting of the performances of a new rapid confirmatory assay for HIV1/2 serodiagnosis

BACKGROUND AND OBJECTIVES

The performances of the new Geenius rapid confirmatory test (Bio-Rad) were evaluated with emphasis towards identifying acute infection (AHI) and discriminating HIV-1/2 in a clinical setting

STUDY DESIGN

Serum samples from individuals attending the L. Spallanzani Institute in Rome, Italy, for HIV diagnosis (one year retrospective collection), repeatedly reactive at 4th generation HIV-1/2 screening assays, confirmed with HIV-1 and HIV-2 Western blot (New LAV I and II Bio-Rad), were retested with Geenius.

RESULTS

Of 6,200 samples, 406 resulted repeatedly reactive at screening, including samples from clinically confirmed AHI. New LAV I identified 378 HIV-1-positive samples. Of these, Geenius found 377 HIV-1-positive and one unclassified HIV-positive. New LAV I classified as indeterminate 18 samples, including 14 from AHI. Among these 14, Geenius results were: 12 positive, 1 indeterminate and 1 negative. Of the remaining, 2 resulted Geenius negative (false-positive screening results) and 2 HIV-2. Ten samples were New LAV I-negative (5 AHI). Geenius results were: 1 (AHI) positive and 9 negative. Geenius detected 110 additional positive samples with no p31 reactivity with respect to New LAV I, with an almost similar prevalence of low avidity samples. Geenius confirmed 3 out of 4 HIV-2 infections identified by New LAV II (one coinfected with HIV-1), while rated as HIV-1 the remaining sample, classified as coinfection by New LAV I and II.

CONCLUSIONS

Geenius allows fast, sensitive and accurate confirmation of HIV serodiagnosis, including AHI and HIV-2 infections. The high sensitivity, in particular towards AHI, could avoid additional sampling and molecular tests.

Clinical application evaluation of two fourth-generation human immunodeficiency virus (HIV) screening assays in West China Hospital

BACKGROUND

Fourth-generation human immunodeficiency virus (HIV) screening assays have been used in many laboratories. The Elecsys® HIV combi PT assay is a new kind of fourth-generation HIV screening assay developed to allow earlier detection of seroconversion.

METHODS

A total of 271,845 routine specimens were detected using the Elecsys® HIV combi assay and Elecsys® HIV combi PT assay from September 2010 to December 2012 in a large university hospital. Repeatedly, reactive screening samples were confirmed according to recommended confirmatory algorithms.

RESULTS

The false-positive rate and positive predictive value (PPV) of two assays are 0.08 and 78.35%, respectively, for the Elecsys® HIV combi assay and 0.07 and 82.21% for the Elecsys® HIV combi PT assay. Ninety-four percent cases with cutoff index ratio <15.0 were false-positive. When we set the specificity as 95.0 and 99.0%, PPV could increase to 98.7, 99.6, 98.8, and 99.7%, and sensitivity reduced to 99.2, 98.4, 98.5, and 96.8% for the Elecsys® HIV combi assay and the Elecsys® HIV combi PT assay, respectively.

CONCLUSIONS

The Elecsys® HIV combi PT assay shows a better performance in specificity than the Elecsys® HIV combi assay. Most weakly reactive results were false-positive, this means it still need to be improved and it will need laboratory personnel to communicate with the clinical doctor and patients more properly about the result of the assay.

Updated US Public Health Service guidelines for the management of occupational exposures to human immunodeficiency virus and recommendations for postexposure prophylaxis

This report updates US Public Health Service recommendations for the management of healthcare personnel (HCP) who experience occupational exposure to blood and/or other body fluids that might contain human immunodeficiency virus (HIV). Although the principles of exposure management remain unchanged, recommended HIV postexposure prophylaxis (PEP) regimens and the duration of HIV follow-up testing for exposed personnel have been updated. This report emphasizes the importance of primary prevention strategies, the prompt reporting and management of occupational exposures, adherence to recommended HIV PEP regimens when indicated for an exposure, expert consultation in management of exposures, follow-up of exposed HCP to improve adherence to PEP, and careful monitoring for adverse events related to treatment, as well as for virologic, immunologic, and serologic signs of infection. To ensure timely postexposure management and administration of HIV PEP, clinicians should consider occupational exposures as urgent medical concerns, and institutions should take steps to ensure that staff are aware of both the importance of and the institutional mechanisms available for reporting and seeking care for such exposures. The following is a summary of recommendations: (1) PEP is recommended when occupational exposures to HIV occur; (2) the HIV status of the exposure source patient should be determined, if possible, to guide need for HIV PEP; (3) PEP medication regimens should be started as soon as possible after occupational exposure to HIV, and they should be continued for a 4-week duration; (4) new recommendation-PEP medication regimens should contain 3 (or more) antiretroviral drugs (listed in Appendix A ) for all occupational exposures to HIV; (5) expert consultation is recommended for any occupational exposures to HIV and at a minimum for situations described in Box 1 ; (6) close follow-up for exposed personnel ( Box 2 ) should be provided that includes counseling, baseline and follow-up HIV testing, and monitoring for drug toxicity; follow-up appointments should begin within 72 hours of an HIV exposure; and (7) new recommendation-if a newer fourth-generation combination HIV p24 antigen-HIV antibody test is utilized for follow-up HIV testing of exposed HCP, HIV testing may be concluded 4 months after exposure ( Box 2 ); if a newer testing platform is not available, follow-up HIV testing is typically concluded 6 months after an HIV exposure.

A multisite study of the prevalence of HIV with rapid testing in mental health settings

OBJECTIVES

We estimated HIV prevalence and risk factors among persons receiving mental health treatment in Philadelphia, Pennsylvania, and Baltimore, Maryland, January 2009 to August 2011.

METHODS

We used a multisite, cross-sectional design stratified by clinical setting. We tested 1061 individuals for HIV in university-based inpatient psychiatric units (n = 287), intensive case-management programs (n = 273), and community mental health centers (n = 501).

RESULTS

Fifty-one individuals (4.8%) were HIV-infected. Confirmed positive HIV tests were 5.9% (95% confidence interval [CI] = 3.7%, 9.4%) for inpatient units, 5.1% (95% CI = 3.1%, 8.5%) for intensive case-management programs, and 4.0% (95% CI = 2.6%, 6.1%) for community mental health centers. Characteristics associated with HIV included Black race, homosexual or bisexual identity, and HCV infection.

CONCLUSIONS

HIV prevalence for individuals receiving mental health services was about 4 times as high as in the general population. We found a positive association between psychiatric symptom severity and HIV infection, indicating that engaging persons with mental illness in appropriate mental health treatment may be important to HIV prevention. These findings reinforce recommendations for routine HIV testing in all clinical settings to ensure that HIV-infected persons receiving mental health services are identified and referred to timely infectious disease care.

Establishing benchmarks and metrics for disruptive technologies, inappropriate and obsolete tests in the clinical laboratory

Benchmarks and metrics related to laboratory test utilization are based on evidence-based medical literature that may suffer from a positive publication bias. Guidelines are only as good as the data reviewed to create them. Disruptive technologies require time for appropriate use to be established before utilization review will be meaningful. Metrics include monitoring the use of obsolete tests and the inappropriate use of lab tests. Test utilization by clients in a hospital outreach program can be used to monitor the impact of new clients on lab workload. A multi-disciplinary laboratory utilization committee is the most effective tool for modifying bad habits, and reviewing and approving new tests for the lab formulary or by sending them out to a reference lab.

Performance of the Alere Determine™ HIV-1/2 Ag/Ab Combo Rapid Test with specimens from HIV-1 seroconverters from the US and HIV-2 infected individuals from Ivory Coast

BACKGROUND

FDA-approved HIV Antigen/Antibody combo (4th generation) immunoassays (IAs) can identify HIV-1 infections before the Western blot (WB) becomes positive. In the US, increased detection of acute HIV infections has been facilitated by using 4th generation IAs, but there is no FDA-approved 4th generation rapid test (RT). The Alere Determine™ HIV-1/2 Ag/Ab Combo (Determine Combo) RT detects and distinguishes HIV p24 Antigen (Ag) from Antibody (Ab) to HIV-1+HIV-2 and thus has the potential to improve diagnosis of acute HIV infection.

OBJECTIVE

To evaluate the ability of Determine Combo RT to detect acute/early HIV-1 infections and HIV-2 antibody in well-characterized plasma specimens.

STUDY DESIGN

In HIV-1 seroconverters from the US, Determine Combo reactivity was evaluated by performing the 50% cumulative frequency analysis and by comparing with 3rd and 4th generation IAs' reactivity. HIV-2 plasma specimens from Ivory Coast were tested with Determine Combo.

RESULTS

The 50% cumulative frequency analysis in 17 seroconverters placed Determine Combo (Ag+/Ab-, Ag+Ab+, Ag-/Ab+) and Ab-component reactivity at 15.5 and 7 days before WB positivity, respectively. In 26 seroconverters, Determine Combo was reactive in 99.0% and 92.5% of 3rd and 4th generation IAs-reactive specimens, respectively. All HIV-2 plasma specimens were Ab-reactive/Ag-non-reactive by Determine Combo.

CONCLUSIONS

Based on previous results with the same seroconversion panels, combined Ag/Ab reactivity of the Determine Combo appears between FDA-approved 4th and 3rd generation laboratory IAs. These data indicate that this RT could detect HIV-1 infection earlier than other RTs and it performs well in HIV-2 specimens.

Evaluation of the CDC proposed laboratory HIV testing algorithm among men who have sex with men (MSM) from five US metropolitan statistical areas using specimens collected in 2011

BACKGROUND

Until recently most testing algorithms in the United States (US) utilized Western blot (WB) as the supplemental test. CDC has proposed an algorithm for HIV diagnosis which includes an initial screen with a Combo Antigen/Antibody 4th generation-immunoassay (IA), followed by an HIV-1/2 discriminatory IA of initially reactive-IA specimens. Discordant results in the proposed algorithm are resolved by nucleic acid-amplification testing (NAAT).

OBJECTIVES

Evaluate the results obtained with the CDC proposed laboratory-based algorithm using specimens from men who have sex with men (MSM) obtained in five metropolitan statistical areas (MSAs).

STUDY DESIGN

Specimens from 992 MSM from five MSAs participating in the CDC's National HIV Behavioral Surveillance System in 2011 were tested at local facilities and CDC. The five MSAs utilized algorithms of various screening assays and specimen types, and WB as the supplemental test. At the CDC, serum/plasma specimens were screened with 4th generation-IA and the Multispot HIV-1/HIV-2 discriminatory assay was used as the supplemental test. NAAT was used to resolve discordant results and to further identify acute HIV infections from all screened-non-reactive missed by the proposed algorithm. Performance of the proposed algorithm was compared to site-specific WB-based algorithms.

RESULTS

The proposed algorithm detected 254 infections. The WB-based algorithms detected 19 fewer infections; 4 by oral fluid (OF) rapid testing and 15 by WB supplemental testing (12 OF and 3 blood). One acute infection was identified by NAAT from all screened-non-reactive specimens.

CONCLUSIONS

The proposed algorithm identified more infections than the WB-based algorithms in a high-risk MSM population. OF testing was associated with most of the discordant results between algorithms. HIV testing with the proposed algorithm can increase diagnosis of infected individuals, including early infections.

Comparative evaluation of the Bio-Rad Geenius HIV-1/2 Confirmatory Assay and the Bio-Rad Multispot HIV-1/2 Rapid Test as an alternative differentiation assay for CLSI M53 algorithm-I

INTRODUCTION

The CLSI-M53-A, Criteria for Laboratory Testing and Diagnosis of Human Immunodeficiency Virus (HIV) Infection; Approved Guideline includes an algorithm in which samples that are reactive on a 4th generation EIA screen proceed to a supplemental assay that is able to confirm and differentiate between antibodies to HIV-1 and HIV-2. The recently CE-marked Bio-Rad Geenius HIV-1/2 Confirmatory Assay was evaluated as an alternative to the FDA-approved Bio-Rad Multispot HIV-1/HIV-2 Rapid Test which has been previously validated for use in this new algorithm.

METHODS

This study used reference samples submitted to the Canadian - NLHRS and samples from commercial sources. Data was tabulated in 2×2 tables for statistical analysis; sensitivity, specificity, predictive values, kappa and likelihood ratios.

RESULTS

The overall performance of the Geenius and Multispot was very high; sensitivity (100%, 100%), specificity (96.3%, 99.1%), positive (45.3, 181) and negative (0, 0) likelihood ratios respectively, high kappa (0.96) and low bias index (0.0068). The ability to differentiate HIV-1 (99.2%, 100%) and HIV-2 (98.1%, 98.1%) Ab was also very high.

CONCLUSION

The Bio-Rad Geenius HIV-1/2 Confirmatory Assay is a suitable alternative to the validated Multispot for use in the second stage of CLSI M53 algorithm-I. The Geenius has additional features including traceability and sample and cassette barcoding that improve the quality management/assurance of HIV testing. It is anticipated that the CLSI M53 guideline and assays such as the Geenius will reduce the number of indeterminate test results previously associated with the HIV-1 WB and improve the ability to differentiate HIV-2 infections.

Performance of the new HIV-1/2 diagnostic algorithm in Florida's public health testing population: a review of the first five months of utilization

OBJECTIVE

The Centers for Disease Control and Prevention and the Association of Public Health Laboratories have proposed a new HIV-1/2 Diagnostic Algorithm: a fourth-generation HIV-1/2 Ag/Ab immunoassay (IA) followed, when repeatedly reactive, by an HIV-1/HIV-2 antibody differentiation test, and if that is non-reactive, HIV-1 nucleic acid amplification testing (NAT). The objective of the study was to evaluate performance of the new algorithm after five months of utilization in our high volume, high HIV-1 seroprevalence public health population.

METHODS

Algorithm sensitivity and specificity was evaluated on 51,953 prospective serum or plasma specimens from individuals self-referring for HIV serostatus determination. Specimens were tested on the day of receipt or maintained at 4°C until the next testing opportunity. If the initial HIV-1/2 Ag/Ab IA (Abbott Combo) was nonreactive, a negative lab interpretation report would follow. If the initial IA was reactive, repeat screening in duplicate was immediately performed. Repeatedly reactive specimens were tested with an HIV-1/HIV-2 differentiation assay (Multispot [MS] HIV-1/HIV-2 Rapid Test) on the same or next workday. If the Abbott Combo-MS assays were discordant, HIV-1 NAT (APTIMA(®) HIV-1 RNA) was performed. In addition to the algorithm performance, we also evaluated the laboratory "specimen receipt to reporting" turnaround time (TAT).

RESULTS

The sensitivity and specificity of the new HIV Diagnostic Algorithm with serum and plasma specimens over the initial 5 month period was 100% (922/922) and 99.99% (51,030/51,031), respectively. Two algorithm-defined acute HIV-1 infections (AHI) were detected. In addition only 3 of the 992 MS secondary tests performed were interpreted as HIV-1 Indeterminate (HIV-1 recombinant gp41 reactivity only). Of these, 2 were HIV-1 NAT reactive, defined in-house as an early HIV infection (EHI) and one was HIV-1 NAT nonreactive, indicating a false positive initial screening result. Laboratory TAT for reporting concordant reactive Abbott Combo-MS results in ≤ 2 workdays was 96%, compared to 22% for reporting concordant reactive 3rd generation IA-Western blot results.

CONCLUSIONS

In our public health testing population, results from the new HIV Diagnostic Algorithm exceeded those of the 3rd generation IA-WB algorithm with respect to HIV-1 sensitivity. The identification of two algorithm-defined AHIs provided the opportunity to inform these individuals of their HIV status and link them to medical care earlier than the scheduled posttest counseling appointment.

Performance of an alternative HIV diagnostic algorithm using the ARCHITECT HIV Ag/Ab Combo assay and potential utility of sample-to-cutoff ratio to discriminate primary from established infection

BACKGROUND

The ARCHITECT HIV Ag/Ab Combo assay has a wide dynamic range for determining the sample-to-cutoff ratio (S/CO) values compared to other diagnostic HIV antibody assays.

OBJECTIVES

Determine the performance of an HIV testing algorithm that uses the ARCHITECT combo assay in the clinical setting and explore the utility of the signal-to-cutoff (S/CO) ratio to predict acute HIV-1 infection status.

STUDY DESIGN

A retrospective analysis of clinical samples from a hospital and referral population screened for HIV-1 infection between May 2011 and March 2013. Repeatedly reactive samples were tested using the Multispot HIV-1/HIV-2 rapid test and depending on that result, confirmatory orthogonal testing used the Western blot (WB) for HIV-1, Immunoblot for HIV-2 and nucleic acid amplification testing (NAAT) for HIV RNA.

RESULTS

A total of 21,317 test results were evaluated of which 509 were ARCHITECT repeatedly reactive; of these, 422 were Multispot-reactive only for HIV-1 (413 WB-positive; 9 indeterminate), 4 were Multispot-reactive for both HIV-1 and HIV-2 (one HIV-2 immunoblot-positive with 17 HIV-2 RNA copies/mL) and 83 were Multispot-non-reactive of which 15 were HIV-1 RNA positive and represented acute HIV-1 infection. There was an association among the ARCHITECT S/CO (median; IQR) values for antibody-negative (0.14; 0.11-0.16), acute infection (33; 2.1-76) and established HIV-1 infection (794; 494-1,029) (Kruskal-Wallis, p<0.0001).

CONCLUSIONS

The ARCHITECT combo assay with Multispot confirmation and reserved use of HIV-1 WB, HIV-2 Immunoblot and HIV NAAT for Multispot dual HIV-1/2 infection, and NAAT alone for Multispot-negative specimens, had a suitable test performance for detecting acute and established HIV infection.

Simple estimation of incident HIV infection rates in notification cohorts based on window periods of algorithms for evaluation of line-immunoassay result patterns

Background

Tests for recent infections (TRIs) are important for HIV surveillance. We have shown that a patient's antibody pattern in a confirmatory line immunoassay (Inno-Lia) also yields information on time since infection. We have published algorithms which, with a certain sensitivity and specificity, distinguish between incident (< = 12 months) and older infection. In order to use these algorithms like other TRIs, i.e., based on their windows, we now determined their window periods.

Methods

We classified Inno-Lia results of 527 treatment-naïve patients with HIV-1 infection < = 12 months according to incidence by 25 algorithms. The time after which all infections were ruled older, i.e. the algorithm's window, was determined by linear regression of the proportion ruled incident in dependence of time since infection. Window-based incident infection rates (IIR) were determined utilizing the relationship ‘Prevalence  =  Incidence x Duration’ in four annual cohorts of HIV-1 notifications. Results were compared to performance-based IIR also derived from Inno-Lia results, but utilizing the relationship ‘incident  =  true incident + false incident’ and also to the IIR derived from the BED incidence assay.

Results

Window periods varied between 45.8 and 130.1 days and correlated well with the algorithms' diagnostic sensitivity (R² = 0.962; P<0.0001). Among the 25 algorithms, the mean window-based IIR among the 748 notifications of 2005/06 was 0.457 compared to 0.453 obtained for performance-based IIR with a model not correcting for selection bias. Evaluation of BED results using a window of 153 days yielded an IIR of 0.669. Window-based IIR and performance-based IIR increased by 22.4% and respectively 30.6% in 2008, while 2009 and 2010 showed a return to baseline for both methods.

Conclusions

IIR estimations by window- and performance-based evaluations of Inno-Lia algorithm results were similar and can be used together to assess IIR changes between annual HIV notification cohorts.

Would CLSI M53-A have helped in the diagnosis of HIV in Canada? Results of the performance of Canadian laboratories participating in a recent NLHRS proficiency testing panel containing HIV-1 antigen positive (antibody negative) and HIV-2 samples

INTRODUCTION

The Clinical and Laboratory Standards Institute recently published M53-A, Criteria for Laboratory Testing and Diagnosis of Human Immunodeficiency Virus (HIV) Infection; Approved Guideline (2011), which includes a state of the art algorithm for identifying HIV-1 acute and HIV-2 infections. To assess the ability of Canadian laboratories to detect these sample types and the impact of M53-A, the National Laboratory for HIV Reference Services distributed a special proficiency testing panel.

METHODS

HIVS425-2012Nov22 was sent to 42 laboratories across Canada. It contained one HIV negative sample (B), two HIV-1 positive samples (A and E), one HIV-2 positive sample (C) and one HIV-1/2 antibody negative-HIV-1 antigen positive sample (D). Data was collected and analyzed using DigitalPT; a standardized on-line tool.

RESULTS

Forty-one laboratories returned results. Sample B (HIV negative) was identified by 95% of laboratories (39/41) and samples A and E (HIV-1 positive) by 98% (40/41). No laboratory identified sample C as HIV-2 positive, although 85% (35/41) detected reactivity prompting a referral for further testing. The remaining laboratories identified sample C as HIV-1 positive (4), indeterminate (1) or gave no final status (1). Sample D (HIV antibody negative-antigen positive) was correctly identified by two laboratories as HIV-1 antigen positive while 78% (32/41) detected reactivity, recommending further testing. One laboratory did not provide a final status. Alarmingly, six laboratories called this sample HIV negative.

CONCLUSION

Although there is a high quality of HIV testing across Canada, introduction of the M53-A guideline would further improve the ability of laboratories to diagnose HIV-1 acute and HIV-2 infection.

Use of rapid HIV assays as supplemental tests in specimens with repeatedly reactive screening immunoassay results not confirmed by HIV-1 Western blot

BACKGROUND

An alternate HIV testing algorithm has been proposed which includes a fourth-generation immunoassay followed by an HIV-1/HIV-2 antibody differentiation supplemental test for reactive specimens and a nucleic acid test (NAT) for specimens with discordant results.

OBJECTIVE

To evaluate the performance of five rapid tests (Alere Clearview, Bio-Rad Multispot, OraSure OraQuick, MedMira Reveal, and Trinity Biotech Unigold) as the supplemental antibody assay in the algorithm.

STUDY DESIGN

A total of 3273 serum and plasma specimens that were third-generation immunoassay repeatedly reactive and Western blot (WB) negative or indeterminate were tested with rapid tests and NAT. Specimens were classified by NAT: (1) HIV-1 infected (NAT-reactive; n=184, 5.6%), (2) HIV-status unknown (NAT nonreactive; n=3078, 94.2%) or by Multispot, (3) HIV-2 positive (n=5), and (4) HIV-1 and HIV-2 positive (n=6). Excluding HIV-2 positive specimens, we calculated the proportion of reactive rapid tests among specimens with reactive and nonreactive NAT.

RESULTS

The proportion of infected specimens with reactive rapid test results and negative or indeterminate WB ranged from 30.4% (56) to 47.8% (88) depending on the rapid test. From 1% to 2% of NAT-negative specimens had reactive rapid test results.

CONCLUSIONS

In these diagnostically challenging specimens, all rapid tests identified infections that were missed by the Western blot, but only Multispot could differentiate HIV-1 from HIV-2. Regardless of which rapid test is used as a supplemental test in the alternative algorithm, false-positive algorithm results (i.e., reactive screening and rapid test in uninfected person) may occur, which will need to be resolved during the baseline medical evaluation.

Current assays for HIV-1 diagnostics and antiretroviral therapy monitoring: challenges and possibilities

In 2011, there were over 34 million people living with HIV infections, placing a heavy burden on public health sectors. HIV infection is a lifelong threat that cannot be prevented by vaccination or cured by antiretroviral drugs. The infected patients rely on daily antiretroviral therapy to suppress HIV viral replication. Hence, it is important to diagnose HIV infections as early as possible and to monitor the efficacy of antiretroviral therapy every 3–6 months. Different immunoassays detecting HIV antigens and antibodies have been modified to offer better sensitivity and more rapid diagnosis. Several clinical and virological parameters, including CD4+ cell counts, viral load and drug resistance mutations, are also used for treatment monitoring. Many molecular assay optimizations are now being utilized to improve patient care. This review will focus on the most updated HIV diagnostic assays, as well as discussing the upcoming possibilities of other advanced technologies.

Performance of a fourth-generation HIV screening assay and an alternative HIV diagnostic testing algorithm

OBJECTIVE

We evaluated the performance of the GS fourth-generation antigen/antibody assay and compared Centers for Disease Control and Prevention's (CDC's) proposed alternative algorithm [repeatedly reactive fourth-generation immunoassay followed by an HIV-1/HIV-2 differentiation immunoassay and, if needed, nucleic acid test (NAT)] with the current algorithm (repeatedly reactive third-generation immunoassay followed by HIV-1 western blot).

DESIGN

A convenience sample of the following four specimen sets was acquired: 10 014 from insurance applicants, 493 known western blot-positive, 20 known western blot-indeterminate specimens, and 230 specimens from 26 HIV-1 seroconverters.

METHODS

Specimens were tested with the GS third-generation and fourth-generation immunoassays, the Multispot HIV-1/HIV-2 differentiation immunoassay, NAT, and western blot. We applied the two algorithms using these results.

RESULTS

Among insurance specimens, 13 (0.13%) specimens were immunoassay repeatedly reactive: two were HIV-positive (repeatedly reactive by third-generation and fourth-generation immunoassays, and western blot and Multispot positive); two third-generation repeatedly reactive and nine fourth-generation repeatedly reactive specimens were false-positive. Third-generation and fourth-generation specificities were 99.98% [95% confidence interval (CI) 99.93-100%] and 99.91% (95% CI 99.84-99.96%), respectively.All HIV-1 western blot-positive specimens were repeatedly reactive by third-generation and fourth-generation immunoassays. By Multispot, 491 (99.6%) were HIV-1-positive and two (0.4%) were HIV-2-positive.Only eight (40%) western blot-indeterminate specimens were fourth-generation repeatedly reactive: six were Multispot and NAT-negative and two were Multispot HIV-1-positive but NAT-negative.The alternative algorithm correctly classified as positive 102 seroconverter specimens with the third-generation immunoassay and 130 with the fourth-generation immunoassay compared with 56 using the western blot with either immunoassay.

CONCLUSION

The alternative testing algorithm improved early infection sensitivity and identified HIV-2 infections. Two potential false-positive algorithm results occurred with western blot-indeterminate specimens.

ARCHITECT® HIV Ag/Ab Combo assay: correlation of HIV-1 p24 antigen sensitivity and RNA viral load using genetically diverse virus isolates

BACKGROUND

HIV antigen/antibody (Ag/Ab) combination assays represent a significant advancement in assays used for diagnosing HIV infection based on their ability to detect acute and chronic infections. During acute HIV infection (AHI), detection depends on assay sensitivity for p24 Ag.

OBJECTIVE

To directly compare the Ag sensitivity of the ARCHITECT(®) HIV Ag/Ab Combo assay to RNA viral load using cell culture supernatants of virus isolates. HIV-1 isolates allow correlation in the total absence of an antibody response to infection and across genetically diverse HIV-1 group M strains.

METHODS

Thirty-five HIV-1 isolates comprising subtypes A-D, F and G, CRF01_AE, CRF02_AG, and unique recombinant forms were evaluated. Cell-free culture supernatant for each isolate was diluted to four levels and tested in the HIV Combo assay to determine a signal to cutoff ratio and the RealTime(®) HIV-1 assay to quantify RNA. The RNA copies/mL at the HIV Combo assay cutoff was determined.

RESULTS

The median RNA copies/mL at the HIV Combo assay cutoff was 57,900 for individual virus isolates (range 26,440-102,400). A single plot of all the data gave a value of 58,500RNA copies/mL. An analysis of data published for acute HIV infection in human subjects gave a similar result; HIV Combo detected 97% of AHIs with RNA copies/mL > 30,700.

CONCLUSIONS

Based on analysis of virus isolates, the ARCHITECT HIV Combo assay can detect p24 Ag when RNA is above approximately 58,000copies/mL. The correlation of viral load and Ag sensitivity was consistent across genetically diverse HIV-1 group M strains.

The INSTI HIV-1/HIV-2 antibody test: a review

INTRODUCTION

Rapid HIV tests have been widely adopted globally as an important component of HIV prevention and control programs. The INSTI™ HIV-1/HIV-2 antibody test is a second-generation HIV antibody test, available in most countries for use from whole blood, serum, and plasma.

AREAS COVERED

Available data on kit characteristics and current performance data on the INSTI™ HIV-1/HIV-2 antibody test are presented together with six other rapid point-of-care tests (RPOCTs) for HIV antibody. Few published data are available providing direct comparisons of INSTI™ with other RPOCTs for HIV antibody and standard laboratory-based HIV-1/HIV-2 antibody assays. Existing data showed that INSTI™ has comparable performance to other RPOCTs but detected seroconversion later than standard laboratory-based assays.

EXPERT OPINION

The good performance of INSTI HIV-1/HIV-2 antibody test, its ease of use, the rapid availability of results (< 5 min), and the lack of specialized equipment required to use the kit make this kit a useful addition to the global market. The unique antigen and flow through technology contained in the kit make it a strong addition to HIV RPOCTs and to rapid/rapid algorithms used in many resource-limited settings.

High HIV incidence and prevalence and associated factors among young MSM, 2008

OBJECTIVE

To estimate HIV prevalence, annual HIV incidence density, and factors associated with HIV infection among young MSM in the United States.

DESIGN

The 2008 National HIV Behavioral Surveillance System (NHBS), a cross-sectional survey conducted in 21 US cities.

METHODS

NHBS respondents included in the analysis were MSM aged 18-24 with a valid HIV test who reported at least one male sex partner in the past year. We calculated HIV prevalence and estimated annual incidence density (number of HIV infections/total number of person-years at risk). Generalized estimating equations were used to determine factors associated with testing positive for HIV.

RESULTS

Of 1889 young MSM, 198 (10%) had a positive HIV test; of these, 136 (69%) did not report previously testing HIV positive when interviewed. Estimated annual HIV incidence density was 2.9%; incidence was highest for blacks. Among young MSM who did not report being HIV infected, factors associated with testing HIV positive included black race; less than high school education; using both alcohol and drugs before or during last sex; having an HIV test more than 12 months ago; and reporting a visit to a medical provider in the past year.

CONCLUSION

HIV prevalence and estimated incidence density for young MSM were high. Individual risk behaviors did not fully explain HIV risk, emphasizing the need to address sociodemographic and structural-level factors in public health interventions targeted toward young MSM.

Use of a multifaceted approach to analyze HIV incidence in a cohort study of women in the United States: HIV Prevention Trials Network 064 Study

BACKGROUND

Reliable methods for estimating the incidence of human immunodeficiency virus (HIV) infection are needed to monitor the epidemic, identify at-risk populations, and evaluate HIV prevention strategies. We used a multifaceted approach to estimate HIV incidence in the HIV Prevention Trials Network (HPTN) 064 study.

METHODS

The HPTN 064 study enrolled 2067 HIV-seronegative women and 32 HIV-seropositive women with no prior HIV infection diagnosis. Women were followed for up to 12 months. HIV incidence estimates were based on (1) detection of acute HIV infection, (2) documentation of HIV seroconversion, and (3) detection of recent HIV infection, using a multiassay algorithm (MAA).

RESULTS

Two women had acute HIV infection at enrollment, 4 seroconverted, and 2 were identified as recently infected at enrollment using the MAA. The annual HIV incidence estimate based on acute infection at enrollment (2.52% [95% confidence interval {CI}, .17%-9.33%], using a 14-day window period) was higher than the estimate based on seroconversion (0.24% [95% CI, .07%-.62%]; P = .027). Incidence estimates obtained using the MAA at enrollment and at the end of study were 0.25% (95% CI, .03%-.93%) and 0.13% (95% CI, .006%-.76%), respectively.

CONCLUSIONS

We detected a high frequency of acute infection at enrollment. Cross-sectional HIV incidence estimates obtained using the MAA were similar to the longitudinal estimate based on HIV seroconversion.

CLINICAL TRIALS REGISTRATION

NCT00995176.

HIV testing in developing countries: what is required?

HIV diagnostic and follow up testing are usually done in laboratory settings. However, in developing countries there is a need to decentralize testing as the majority of the population lives in rural settings. In developing countries stringent quality assurance (QA) practices, which include appropriate training, development of standard operating procedures, maintenance of operator proficiency, routine use of quality control (QC) specimens, standardized data management, equipment calibration and maintenance, and biohazard safety with proper disinfection/disposal procedures are not routinely followed to ensure reliability of results and a safe work environment. The introduction of point-of-care testing technologies involving the use of non-laboratorians in routine testing has further increased the complexity of QA. Therefore, a careful approach towards improvement of laboratories that encourages best practices, coupled with incentives, and review of government policies in point-of-care testing is needed to improve quality of testing as decentralization takes place. Development of a functional laboratory tiered network that facilitates communication, referral, training and problem solving could further enhance confidence in laboratory testing. There is also a need for special considerations in implementing a step-wise approach towards quality improvement, strengthening of the supply chain management, human capacity development, infrastructure upgrade, and strong public private partnerships to ensure long term sustainability of these efforts.