Multi-centre evaluation of the Determine HIV Combo assay when used for point of care testing in a high risk clinic-based population

Practical Challenges of Point-of-Care Testing

The practical challenges of point-of-care testing (POCT) include analytical performance and quality compared with testing performed in a central laboratory and higher cost per test compared with laboratory-based tests. These challenges can be addressed with new test technology, consensus, and practice guidelines for the use of POCT, instituting a quality management system and data connectivity in the POCT setting, and studies that demonstrate evidence of clinical and economic value of POCT.

2021 European guideline on HIV testing in genito-urinary medicine settings

Testing for HIV is critical for early diagnosis of HIV infection, providing long-term good health for the individual and prevention of onward transmission if antiretroviral treatment is initiated early. The main purpose of the 2021 European Guideline on HIV Testing in Genito-Urinary Settings is to provide advice on testing for HIV infection in individuals aged 16 years and older who present to sexually transmitted infection, genito-urinary or dermato-venereology clinics across Europe. The guideline presents the details of best practice and offers practical guidance to clinicians and laboratories to identify and offer HIV testing to appropriate patient groups.

Development of a Mobile Laboratory for Sudden Onset Disasters

OBJECTIVES

Clinical diagnostics in sudden onset disasters have historically been limited. We set out to design, implement, and evaluate a mobile diagnostic laboratory accompanying a type 2 emergency medical team (EMT) field hospital.

METHODS

Available diagnostic platforms were reviewed and selected against in field need. Platforms included HemoCue301/WBC DIFF, i-STAT, BIOFIRE FILMARRAY multiplex rt-PCR, Olympus BX53 microscopy, ABO/Rh grouping, and specific rapid diagnostic tests. This equipment was trialed in Katherine, Australia, and Dili, Timor-Leste.

RESULTS

During the initial deployment, an evaluation of FilmArray tests was successful using blood culture identification, gastrointestinal, and respiratory panels. HemoCue301 (n = 20) hemoglobin values were compared on Sysmex XN 550 (r = 0.94). HemoCue WBC DIFF had some variation, dependent on the cell, when compared with Sysmex XN 550 (r = 0.88-0.16). i-STAT showed nonsignificant differences against Vitros 250. Further evaluation of FilmArray in Dili, Timor-Leste, diagnosed 117 pathogens on 168 FilmArray pouches, including 25 separate organisms on blood culture and 4 separate cerebrospinal fluid pathogens.

CONCLUSION

This mobile laboratory represents a major advance in sudden onset disaster. Setup of the service was quick (< 24 hr) and transport to site rapid. Future deployment in fragmented health systems after sudden onset disasters with EMT2 will now allow broader diagnostic capability.

Rapid HIV Antigen-Antibody Assays and Detection of Acute HIV Infection in Sub-Saharan Africa

Detection of acute HIV infection is a unique problem that fourth-generation HIV assays were expected to alleviate. In this commentary, we draw attention to the limitations and challenges with use of currently available rapid antigen-antibody (Ag/Ab) combination tests for detection of acute HIV infection in sub-Saharan Africa. Laboratory-based HIV-1 Ag/Ab immunoassays are complex, requiring specialized equipment and handling that are currently not affordable in many settings in Africa. The point-of-care Ag/Ab platform on the other hand is easier to deploy and potentially more accessible in resource-limited settings. However, available fourth-generation HIV-1 rapid diagnostic tests have demonstrated poor performance characteristics in field studies where non-B subtypes of HIV-1 dominate. The potential for point-of-care HIV-1 Ag/Ab diagnostics to significantly improve detection of acute HIV infection remains yet to be realized in sub-Saharan Africa. Assay platforms need to be optimized to identify local circulating subtypes, and optimal algorithms need to be determined.

Comparative multi-assay evaluation of Determine™ HIV-1/2 Ag/Ab Combo rapid diagnostic tests in acute and chronic HIV infection

In resource-limited or point-of-care settings, rapid diagnostic tests (RDTs), that aim to simultaneously detect HIV antibodies and p24 capsid (p24CA) antigen with high sensitivity, can pose important alternatives to screen for early infections. We evaluated the performance of the antibody and antigen components of the old and novel version of the Determine™ HIV-1/2 Ag/Ab Combo RDTs in parallel to quantifications in a fourth-generation antigen/antibody immunoassay (4G-EIA), p24CA antigen immunoassay (p24CA-EIA), immunoblots, and nucleic acid quantification. We included plasma samples of acute, treatment-naïve HIV-1 infections (Fiebig stages I–VI, subtypes A1, B, C, F, CRF02_AG, CRF02_AE, URF) or chronic HIV-1 and HIV-2 infections. The tests’ antigen component was evaluated also for a panel of subtype B HIV-1 transmitted/founder (T/F) viruses, HIV-2 strains and HIV-2 primary isolates. Furthermore, we assessed the analytical sensitivity of the RDTs to detect p24CA using a highly purified HIV-1_NL4-3 p24CA standard. We found that 77% of plasma samples from acutely infected, immunoblot-negative HIV-1 patients in Fiebig stages II–III were identified by the new RDT, while only 25% scored positive in the old RDT. Both RDTs reacted to all samples from chronically HIV-1-infected and acutely HIV-1-infected patients with positive immunoblots. All specimens from chronically infected HIV-2 patients scored positive in the new RDT. Of note, the sensitivity of the RDTs to detect recombinant p24CA from a subtype B virus ranged between 50 and 200 pg/mL, mirrored also by the detection of HIV-1 T/F viruses only at antigen concentrations tenfold higher than suggested by the manufacturer. The RTD failed to recognize any of the HIV-2 viruses tested. Our results indicate that the new version of the Determine™ HIV-1/2 Ag/Ab Combo displays an increased sensitivity to detect HIV-1 p24CA-positive, immunoblot-negative plasma samples compared to the precursor version. The sensitivity of 4G-EIA and p24CA-EIA to detect the major structural HIV antigen, and thus to diagnose acute infections prior to seroconversion, is still superior.

Which Gay and Bisexual Men Attend Community-Based HIV Testing Services in Australia? An Analysis of Cross-Sectional National Behavioural Surveillance Data

In Australia, HIV testing services have become increasingly available in non-traditional settings such as peer-led, community-based services to expand access and increase uptake of HIV testing among gay and bisexual men (GBM). This study aimed to compare the socio-demographic and behavioural characteristics of GBM whose last HIV test was conducted at a community-based service to GBM whose last test was at a traditional clinical setting. We analysed behavioural surveillance data collected from 5988 participants in seven states and territories in the period 2016-2017. We found that non-HIV-positive GBM who attended community-based services were largely similar to men attending clinic-based settings, particularly in terms of sexual practice and risk of HIV. However, non-HIV-positive GBM who were younger, born in Asia, more socially engaged with other gay men but who had not recently used PrEP were more likely to attend community-based services for their last HIV test. This study points to the successful establishment of community-based HIV testing services in Australia as a way to attract subgroups of GBM at potentially higher risk of HIV.

Challenges of HIV diagnosis and management in the context of pre-exposure prophylaxis (PrEP), post-exposure prophylaxis (PEP), test and start and acute HIV infection: a scoping review

INTRODUCTION

Knowledge of HIV status relies on accurate HIV testing, and is the first step towards access to HIV treatment and prevention programmes. Globally, HIV-status unawareness represents a significant challenge for achieving zero new HIV infections and deaths. In order to enhance knowledge of HIV status, the World Health Organisation (WHO) recommends a testing strategy that includes the use of HIV-specific antibody point-of-care tests (POCT). These POCTs do not detect acute HIV infection, the stage of disease when viral load is highest but HIV antibodies are undetectable. Complicating things further, in the presence of antiretroviral therapy (ART) for pre-exposure prophylaxis (PrEP) or post-exposure prophylaxis (PEP), other currently available testing technologies, such as viral load detection for diagnosis of acute HIV infection, may yield false-negative results. In this scoping review, we evaluate the evidence and discuss alternative HIV testing algorithms that may mitigate diagnostic dilemmas in the setting of increased utilization of ART for immediate treatment and prevention of HIV infection.

DISCUSSION

Missed acute HIV infection prevents people living with HIV (PLHIV) from accessing early treatment, increases likelihood of onward transmission, and allows for inappropriate initiation or continuation of PrEP, which may result in HIV drug resistance. While immediate ART is recommended for all PLHIV, studies have shown that starting ART in the setting of acute HIV infection may result in a delayed or complete absence of development of HIV-specific antibodies, posing a diagnostic challenge that is particularly pertinent to resource-limited, high HIV burden settings where HIV-antibody POCTs are standard of care. Similarly, ART used as PrEP or PEP may supress HIV RNA viral load, complicating current HIV testing algorithms in resource-wealthy settings where viral detection is included. As rollout of PrEP continues, HIV testing algorithms may need to be modified.

CONCLUSIONS

With increasing use of PrEP and ART in acute infection we anticipate diagnostic challenges using currently available HIV testing strategies. Research and surveillance are needed to determine the most appropriate assays and optimal testing algorithms that are accurate, affordable and sustainable.

HIV rapid screening tests and self-tests: Be aware of differences in performance and cautious of vendors

BACKGROUND

Rapid tests for HIV testing are essential tools to achieve the 90-90-90 target of the World Health Organization. Many tests are available, some directly from websites. Evaluation of the performance of rapid tests, under close to real-life usage, is therefore needed to ensure accurate diagnosis in the context of the recommendation for their more widespread use.

METHOD

Nine third- (3G) or fourth-generation (4G) rapid screening tests or self-tests (two bought on websites), were evaluated on an extensive panel of 200 HIV-negative and 312 HIV-positive samples, representative of a wide variety of clinical situations and HIV genetic diversity. A whole blood reconstitution protocol was designed to simulate real-life usage of these tests in community-based and private settings.

FINDINGS

The specificity was high (98.5-100%) and sensitivity excellent (100%) for samples from patients chronically infected with the pandemic strains. The performance for infrequent situations with a major epidemiological and clinical impact, such as infection with divergent viruses or primary infection, was highly variable, depending on the test. One of the two 4G tests allowed detection of additional positive samples from early stages of infection, whereas the second (sold as a 4G test on a website) corresponded in reality to a 3G test.

INTERPRETATION

Our study showed that not all tests are equal for the detection of major HIV variants or early stages of HIV infection; adding the detection of specific p24Ag improved the latter point. This study also showed, for the first time, that buying through web-based vendors can be risky, due to the varying performance of the tests and questionable sales practices. Our results are of particular importance in the context of the increasing use of rapid tests in an "outside laboratory" settings. FUND: Santé Publique France, COREVIH - Normandie, and Rouen University Hospital.

p24 revisited: a landscape review of antigen detection for early HIV diagnosis

: Despite major advances in HIV testing, early detection of infection at the point of care (PoC) remains a key challenge. Although rapid antibody PoC and laboratory-based nucleic acid amplification tests dominate the diagnostics market, the viral capsid protein p24 is recognized as an alternative early virological biomarker of infection. However, the detection of ultra-low levels of p24 at the PoC has proven challenging. Here we review the landscape of p24 diagnostics to identify knowledge gaps and barriers and help shape future research agendas. Five hundred and seventy-four research articles to May 2018 that propose or evaluate diagnostic assays for p24 were identified and reviewed. We give a brief history of diagnostic development, and the utility of p24 as a biomarker in different populations such as infants, the newly infected, those on preexposure prophylaxis and self-testers. We review the performance of commercial p24 assays and consider elements such as immune complex disruption, resource-poor settings, prevalence, and assay antibodies. Emerging and ultrasensitive assays are reviewed and show a number of promising approaches but further translation has been limited. We summarize studies on the health economic benefits of using antigen testing. Finally, we speculate on the future uses of high-performance p24 assays, particularly, if available in self-test format.

No Time to Delay! Fiebig Stages and Referral in Acute HIV infection: Seattle Primary Infection Program Experience

There has been increasing recognition of the importance of diagnosing individuals during the earliest stages of human immunodeficiency virus (HIV) infection. Sera from individuals referred to a primary HIV infection research program were screened using the IgG-sensitive Vironostika HIV-1 Microelisa System, IgG/IgM-sensitive GS HIV-1/HIV-2 Plus O antibody enzyme immunoassay (EIA), or Abbott ARCHITECT HIV antigen (Ag)/antibody (Ab) Combo assay and confirmed by the Bio-Rad Multispot and Western blot. A subset of participants was co-enrolled in a study designed to compare the ability of point-of-care tests to detect early infection. We calculated time within primary infection laboratory stages using actual observed transitions and with an expectation-maximization algorithm. Three hundred and sixty participants contributed data to this analysis. Of 123 persons referred with EIA-negative/RNA-positive test results (Fiebig stage I-II) or for concern for symptoms, 24 (20%) were still in stages I-II, and 99 (80%) were in stages III or later at their screening visit. Participants were estimated to spend a median of 13.5 days in stages I and II, 2.3 days in stage III, and 7.8 days in stage IV. OraQuick performed on oral fluids detected 53% of 17 participants in stage V. The durations of stages we observed are consistent with previous publications. Most persons referred for research no longer had acute infection at their first visit. Programs wishing to identify persons in the very earliest stages of infection need to expedite referrals or develop targeted screening programs.

Human anti-HIV IgM detection by the OraQuick ADVANCE® Rapid HIV 1/2 Antibody Test

The Centers for Disease Control and Prevention (CDC) and many public health jurisdictions continue to advocate for the most sensitive rapid HIV test that is available. Currently, the recommendation is to utilize tests that can detect HIV infection biomarkers within 30 days of infection, when initial immune responses are mounted. The infected patient's IgM response is often used to detect acute infection within a 20-25 days window after infection. This requirement applies to lab-based testing with automated analyzers and rapid, point of care (POC) testing used for screening in a non-clinical setting. A recent study has demonstrated that POC tests using a Protein A-based detection system can detect samples with predominantly HIV-1 IgM reactivity (Moshgabadi et al., 2015). The OraQuick ADVANCE® Rapid HIV-1/2 Antibody Test (OraQuick ADVANCE®) also uses Protein A as the detection protein in the antibody-binding colloidal gold conjugate, so it is expected that the OraQuick ADVANCE® Test will also detect samples with predominantly IgM reactivity. This report definitively demonstrates that the OraQuick ADVANCE® Test can detect IgM antibodies during an acute infection window period of approximately 20-25 days after infection, and is therefore suitable for use in testing environments requiring adherence to current CDC recommendations.

Selecting an HIV Test: A Narrative Review for Clinicians and Researchers

Given the many options available, selecting an HIV test for a particular clinical or research setting can be daunting. Making an informed decision requires an assessment of the likelihood of acute infection in the test population and an understanding of key aspects of the tests themselves. The ability of individual tests to reliably detect HIV infection depends on the target(s) being detected, when they can be expected to be present after infection, and the concentration of stable target in test specimens, all of which are explained by the virologic and serologic events after infection. The purpose of this article is to review the timeline of HIV infection, nomenclature, and characteristics of different tests; compare point-of-care and laboratory-based tests; discuss the impact of different specimens on test performance; and provide practical advice to help clinicians and researchers new to the field select a test that best suits their needs.

Clinical and public health implications of acute and early HIV detection and treatment: a scoping review

INTRODUCTION

The unchanged global HIV incidence may be related to ignoring acute HIV infection (AHI). This scoping review examines diagnostic, clinical, and public health implications of identifying and treating persons with AHI.

METHODS

We searched PubMed, in addition to hand-review of key journals identifying research pertaining to AHI detection and treatment. We focused on the relative contribution of AHI to transmission and the diagnostic, clinical, and public health implications. We prioritized research from low- and middle-income countries (LMICs) published in the last fifteen years.

RESULTS AND DISCUSSION

Extensive AHI research and limited routine AHI detection and treatment have begun in LMIC. Diagnostic challenges include ease-of-use, suitability for application and distribution in LMIC, and throughput for high-volume testing. Risk score algorithms have been used in LMIC to screen for AHI among individuals with behavioural and clinical characteristics more often associated with AHI. However, algorithms have not been implemented outside research settings. From a clinical perspective, there are substantial immunological and virological benefits to identifying and treating persons with AHI - evading the irreversible damage to host immune systems and seeding of viral reservoirs that occurs during untreated acute infection. The therapeutic benefits require rapid initiation of antiretrovirals, a logistical challenge in the absence of point-of-care testing. From a public health perspective, AHI diagnosis and treatment is critical to: decrease transmission via viral load reduction and behavioural interventions; improve pre-exposure prophylaxis outcomes by avoiding treatment initiation for HIV-seronegative persons with AHI; and, enhance partner services via notification for persons recently exposed or likely transmitting.

CONCLUSIONS

There are undeniable clinical and public health benefits to AHI detection and treatment, but also substantial diagnostic and logistical barriers to implementation and scale-up. Effective early ART initiation may be critical for HIV eradication efforts, but widespread use in LMIC requires simple and accurate diagnostic tools. Implementation research is critical to facilitate sustainable integration of AHI detection and treatment into existing health systems and will be essential for prospective evaluation of testing algorithms, point-of-care diagnostics, and efficacious and effective first-line regimens.

Performance evaluation of the FDA-approved Determine™ HIV-1/2 Ag/Ab Combo assay using plasma and whole blood specimens

BACKGROUND

The Determine™ HIV-1/2 Ag/Ab Combo (DC) rapid test can identify HIV-1 infection earlier than rapid antibody-only tests in plasma specimens.

OBJECTIVES

We compared the performance of DC with a laboratory-based antigen/antibody (Ag/Ab) combo assay in plasma and evaluated antigen reactivity in whole blood specimens.

STUDY DESIGN

We tested by DC 508 plasma specimens collected in a prospective study and 107 sequential plasma and simulated whole blood specimens from 20 seroconversion panels. Previous results using the ARCHITECT (ARC) Ag/Ab combo assay were compared to DC results. In seroconversion panels, the days from the first HIV1 RNA-positive test to first DC-reactive in plasma and whole blood was compared. McNemar's and Wilcoxon signed rank tests were used for statistical analysis.

RESULTS

Of 415 HIV-positive samples, ARC detected 396 (95.4%) and DC 337 (81.2%) (p<0.0001). DC was reactive in 50.0% of ARC-reactive/MS-negative, 78.6% of ARC-reactive/MS-indeterminate, and 99.6% of ARC-reactive/MS-HIV-1-positive or -undifferentiated specimens. DC antigen reactivity was higher among ARC-reactive/MS-negative than MS-indeterminate samples. In 20 HIV-1 seroconversion panels, there was a significant difference between DC reactivity in plasma (91.1%) and whole blood (56.4%) (p<0.0001). DC with whole blood showed a significant delay in reactivity compared to plasma (p=0.008).

CONCLUSIONS

In plasma, DC was significantly less sensitive than an instrumented laboratory-based Ag/Ab combo assay. DC in plasma was significantly more sensitive compared to whole blood in early HIV-1 infections. With the U.S. laboratory-based diagnostic algorithm, DC as the first step would likely miss a high proportion of HIV-1 infections in early stages of seroconversion.

Performance of serological and molecular tests within acute HIV infection

BACKGROUND

Early diagnosis of acute HIV infection can be challenging and is critical in regards to early therapeutic decision making.

OBJECTIVES

To evaluate the performance of different HIV tests in detecting early infections.

STUDY DESIGN

A total of 83 leftover specimens of 61 study participants who seroconverted were used in this sub-study. 35 HIV RNA positive but still seronegative specimens (acute infections) were used for analysis of the sensitivity of the different assays in detecting early infections and 42 HIV RNA and antibody negative specimens were used for specificity analysis.

RESULTS

Four (11%) specimens out of 35 acute infections were reactive with the Enzygnost^® Anti-HIV 1/2 Plus and 12/35 (34%) with the Vironostika^® HIV Ag/Ab. 16 (46%) specimens were confirmed as acute by the INNOTEST^® HIV antigen mAb Antigen test. Only three (9%), 10 (29%) and 9 (27%) specimens were reactive with the Determine HIV-1/2 Ag/Ab Combo, SD Bioline HIV Ag/Ab Combo test and the HIV Combo test, respectively. The specificity of the different tests were 100%, 95%, 100%, 93%, 100% and 93% for Enzygnost^® Anti-HIV 1/2 Plus, Vironostika^® HIV Ag/Ab, INNO-Test HIV antigen mAb, Determine HIV-1/2 Ag/Ab Combo, SD Bioline HIV Ag/Ab Combo test and HIV Combo test respectively.

CONCLUSION

RNA test, 4th generation ELISA and Single Ag test are the most sensitive tests for detection of an acute infection. As an alternative, the HIV Combo test is generally slightly more sensitive compared to its previous version, but the SD Bioline HIV Ag/Ab Combo tests has the best performance compared to the other simple rapid tests (SRTs) but none of them are precise in detecting Ag in the determination of acute infections.

Improving the Quality of Diagnostic Studies Evaluating Point of Care Tests for Acute HIV Infections: Problems and Recommendations

The diagnosis of acute human immunodeficiency virus (HIV) infection (AHI) plays a unique role in preventing the spread of HIV and ending the epidemic. Acutely infected individuals are thought to contribute substantially to forward transmissions of HIV; however, diagnosing AHI in resource-limited settings has proven to be a challenge. While fourth generation antigen-antibody combination assays have been successful in high-resource settings, rapid point of care (POC) versions of these assays have yet to demonstrate high sensitivity to detect AHI. Newer RNA/DNA based POC technologies are being validated, but the challenge to understand the additional value of these devices depends on the quality of study evaluations, in particular choice of study designs and case mix of included populations. In this commentary, we aimed to review the quality of studies evaluating a new fourth generation rapid test for detecting AHI, to identify general methodological limitations and biases in diagnostic accuracy studies, and to recommend strategies for avoiding them in future evaluations. The new studies that were evaluated continued to report the same weaknesses and biases that were seen in previous evaluations of fourth generation rapid tests. We recommend that investigators design future studies carefully, keeping in mind how diagnostic performance may be influenced by prevalence, population, patient case mixes, and reference standards. Care must be taken to avoid biases specific to diagnostic accuracy studies (spectrum, verification, incorporation and reference standard biases). To improve on quality, reporting checklists and guidelines such as Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) and Standards for Reporting Diagnostic accuracy studies (STARD) should be reviewed prior to conducting studies.

Multi-centre field evaluation of the performance of the Trinity Biotech Uni-Gold HIV 1/2 rapid test as a first-line screening assay for gay and bisexual men compared with 4th generation laboratory immunoassays

BACKGROUND

The Trinity Biotech Uni-Gold HIV test (Uni-Gold) is often used as a supplementary rapid test in testing algorithms.

OBJECTIVE

To evaluate the operational performance of the Uni-Gold as a first-line screening test among gay and bisexual men (GBM) in a setting where 4th generation HIV laboratory assays are routinely used.

STUDY DESIGN

We compared the performance of Uni-Gold with conventional HIV serology conducted in parallel among GBM attending 22 testing sites. Sensitivity was calculated separately for acute and established infection, defined using 4th generation screening Ag/Ab immunoassay (EIA) and Western blot results. Previous HIV testing history and results of supplementary 3rd generation HIV Ab EIA, and p24 antigen EIA were used to further characterise cases of acute infection.

RESULTS

Of 10,793 specimens tested with Uni-Gold and conventional serology, 94 (0.90%, 95%CI:0.70-1.07) were confirmed as HIV-positive by conventional serology, and 37 (39.4%) were classified as acute infection. Uni-Gold sensitivity was 81.9% overall (77/94, 95%CI:72.6-89.1); 56.8% for acute infection (21/37, 95%CI:39.5-72.9) and 98.2% for established infection (56/57, 95%CI:90.6-100.0). Of 17 false non-reactive Uni-Gold results, 16 were acute infections, and of these seven were p24 antigen reactive but antibody negative. Uni-Gold specificity was 99.9% (10,692/10,699, 95%CI:99.9-100.0), PPV was 91.7% (95%CI:83.6-96.6) and NPV was 99.8% (95%CI:99.7-99.9), respectively.

CONCLUSIONS

In this population, Uni-Gold had good specificity and sensitivity was high for established infections when compared to 4th generation laboratory assays, however sensitivity was lower in acute infections. Where rapid tests are used in populations with a high proportion of acute infections, additional testing strategies are needed to detect acute infections.

Providing HIV results via SMS one day after testing: more popular than rapid point-of-care tests

An inner Sydney sexual health service introduced the option to gay and bisexual men of receiving a negative HIV result by SMS to mobile phone one business day after venipuncture (rapid SMS). Men could also choose one of the other options: a point-of-care-test (POCT), by phone, or in-person (clinicians could also require in-person). We followed-up patients choosing the rapid SMS method to ascertain their satisfaction. During 12 months, 473 men had 591 HIV tests. Of these tests, 5.4% were POCTs, 9.1% were in-person, 24% were by phone, and 62% were rapid SMS. HIV POCTs declined from being 22% of result methods in the pre-study period to 5.4% during the rapid SMS intervention period (odds ratio 0.20, 95% CI 0.13-0.32, P < 0.0001). Phone/in-person results declined from 78% to 33% (odds ratio 0.14, 95% CI 0.10-0.20, P < 0.0001). SMS was sent by the next business day in 95% of cases; 96% of men were satisfied; and 95% would choose this method for their next test. Of 77 men who previously had an HIV POCT, 56 (73%) elected a rapid SMS result rather than having another POCT. The higher accuracy of conventional serology was commonly expressed as the reason for choosing rapid SMS for results.

Sensitivity of HIV rapid tests compared with fourth-generation enzyme immunoassays or HIV RNA tests

OBJECTIVE

Determine the sensitivity of HIV rapid tests compared with fourth-generation enzyme immunoassays (EIA) or nucleic acid amplification tests (NAAT) in clinical settings.

DESIGN

Systematic review and meta-analysis.

METHODS

Medline, PubMed, Embase, Cochrane Controlled Trials Register, Cochrane reviews and Cumulative Index to Nursing and Allied Health Literature were searched until 14 July 2015 for studies of adults comparing point-of-care HIV rapid tests to fourth-generation HIV EIA antibody/p24 antigen or HIV NAAT.

RESULTS

From 953 titles, 18 studies were included, involving 110 122 HIV rapid test results. Compared with EIA, the estimated sensitivity (random effects) of HIV rapid tests was 94.5% [95% confidence interval (CI): 87.4-97.7]. Compared with NAAT, the sensitivity of HIV rapid tests was 93.7% (95% CI: 88.7-96.5). The sensitivity of HIV rapid tests in high-income countries was 85.7% (95% CI: 81.9-88.9) and in low-income countries was 97.7% (95% CI: 95.2-98.9) compared with either EIA or NAAT (P < 0.01 for difference between settings). Proportions of antibody negative acute infections were 13.6 (95% CI: 10.1-18.0) and 4.7% (95% CI: 2.8-7.7) in studies from high-income and low-income countries, respectively (P < 0.01).

CONCLUSION

In clinical settings, HIV rapid tests were less sensitive in high-income countries compared with low-income countries, missing about one in seven infections, possibly because of the larger proportion of acute infections in targeted populations. This suggests that in high-income countries, HIV rapid tests should be used in combination with fourth-generation EIA or NAAT tests, except in special circumstances. Prospective Registration of Systematic Reviews registration number CRD42015020154.Supplementary video link: http://links.lww.com/QAD/A924.

Incorporating Acute HIV Screening into Routine HIV Testing at Sexually Transmitted Infection Clinics, and HIV Testing and Counseling Centers in Lilongwe, Malawi

Background and Objectives:

Integrating acute HIV-infection (AHI) testing into clinical settings is critical to prevent transmission, and realize potential treatment-as-prevention benefits. We evaluated acceptability of AHI testing and compared AHI prevalence at sexually transmitted infection (STI) clinics and HIV testing and counseling (HTC) clinics in Lilongwe, Malawi.

Methods:

We conducted HIV RNA testing for HIV-seronegative patients visiting STI and HTC clinics. AHI was defined as positive RNA and negative/discordant rapid antibody tests. We evaluated demographic, behavioral, and transmission-risk differences between STI and HTC patients and assessed performance of a risk-score for targeted screening.

Results:

Nearly two-thirds (62.8%, 9280/14,755) of eligible patients consented to AHI testing. We identified 59 persons with AHI (prevalence = 0.64%)–a 0.9% case-identification increase. Prevalence was higher at STI [1.03% (44/4255)] than at HTC clinics [0.3% (15/5025), P < 0.01], accounting for 2.3% of new diagnoses vs 0.3% at HTC clinic. Median viral load (VL) was 758,050 copies per milliliter; 25% (15/59) had VL ≥10,000,000 copies per milliliter. Median VL was higher at STI (1,000,000 copies/mL) compared with HTC (153,125 copies/mL, P = 0.2). Among persons with AHI, those tested at STI clinics were more likely to report genital sores compared with those tested at HTC clinics (54.6% vs 6.7%, P < 0.01). The risk score algorithm performed well in identifying persons with AHI at HTC clinics (sensitivity = 73%, specificity = 89%).

Conclusions:

The majority of patients consented to AHI testing. AHI prevalence was substantially higher in STI clinics than HTC clinics. Remarkably high VLs and concomitant genital scores demonstrate the potential for transmission. Universal AHI screening at STI clinics, and targeted screening at HTC centers, should be considered.

Evaluation of a Rapid Point of Care Test for Detecting Acute and Established HIV Infection, and Examining the Role of Study Quality on Diagnostic Accuracy: A Bayesian Meta-Analysis

Introduction

Fourth generation (Ag/Ab combination) point of care HIV tests like the FDA-approved Determine HIV1/2 Ag/Ab Combo test offer the promise of timely detection of acute HIV infection, relevant in the context of HIV control. However, a synthesis of their performance has not yet been done. In this meta-analysis we not only assessed device performance but also evaluated the role of study quality on diagnostic accuracy.

Methods

Two independent reviewers searched seven databases, including conferences and bibliographies, and independently extracted data from 17 studies. Study quality was assessed with QUADAS-2. Data on sensitivity and specificity (overall, antigen, and antibody) were pooled using a Bayesian hierarchical random effects meta-analysis model. Subgroups were analyzed by blood samples (serum/plasma vs. whole blood) and study designs (case-control vs. cross-sectional).

Results

The overall specificity of the Determine Combo test was 99.1%, 95% credible interval (CrI) [97.3–99.8]. The overall pooled sensitivity for the device was at 88.5%, 95% [80.1–93.4]. When the components of the test were analyzed separately, the pooled specificities were 99.7%, 95% CrI [96.8–100] and 99.6%, 95% CrI [99.0–99.8], for the antigen and antibody components, respectively. Pooled sensitivity of the antibody component was 97.3%, 95% CrI [60.7–99.9], and pooled sensitivity for the antigen component was found to be 12.3%, 95% (CrI) [1.1–44.2]. No significant differences were found between subgroups by blood sample or study design. However, it was noted that many studies restricted their study sample to p24 antigen or RNA positive specimens, which may have led to underestimation of overall test performance. Detection bias, selection (spectrum) bias, incorporation bias, and verification bias impaired study quality.

Conclusions

Although the specificity of all test components was high, antigenic sensitivity will merit from an improvement. Besides the accuracy of the device itself, study quality, also impacts the performance of the test. These factors must be kept in mind in future evaluations of an improved device, relevant for global scale up and implementation.

Performance of Determine Combo and other point-of-care HIV tests among Seattle MSM

BACKGROUND AND OBJECTIVE

The rapid test study was a real-time comparison of point-of-care (POC) HIV tests to determine their abilities to detect early HIV infection.

STUDY DESIGN

Men and transgender persons reporting sex with men in the prior year were recruited at the Public Health-Seattle & King County STD Clinic, Gay City Health Project, and University of Washington Primary Infection Clinic. Study tests included the OraQuick ADVANCE Rapid HIV-1/2 Antibody Test performed on oral fluids and tests performed on fingerstick whole blood specimens including OraQuick, Uni-Gold Recombigen HIV test, Determine HIV-1/2 Ag/Ab Combo, and INSTI HIV-1 Rapid Antibody Test. Specimens from subjects with negative results were sent for EIA and nucleic acid amplification testing. McNemar's exact tests compared the numbers of HIV-infected subjects detected.

RESULTS

Between February 2010 and August 2014, there were 3438 study visits. Twenty-four subjects had discordant POC results with at least one reactive and one non-reactive test, including one subject with a reactive Determine p24 antigen. OraQuick performed on oral fluids identified fewer persons compared to all fingerstick tests. OraQuick performed on fingerstick whole blood detected fewer persons compared to the Determine Combo antibody component (p=.008) and Combo overall (p=.004), and there was a trend when compared to INSTI (p=.06). The Determine Combo specificity was 98.99%.

CONCLUSIONS

As reported by others, Determine Combo underperforms compared to laboratory-based testing, but it did detect one acute infection. If these results are validated, the specificity of Determine Combo may limit its usefulness in populations with lower HIV incidence.

Updating the management of sexually transmitted infections

The control of sexually transmitted infections relies on case-finding and treatment of sexual contacts to prevent further transmission. Screening for infections should be tailored to the demographic and sexual risk of the individual. For most sexually transmitted infections, screening is performed on self-collected, non-invasive samples using highly sensitive molecular assays. These are quick and inexpensive. Shorter courses of antivirals for genital herpes are now recommended. New chemoprophylactic strategies for preventing HIV transmission have emerged, including treatment to prevent transmission and the use of antiretrovirals for pre-exposure prophylaxis.

Field accuracy of fourth-generation rapid diagnostic tests for acute HIV-1: a systematic review

INTRODUCTION

Fourth-generation HIV-1 rapid diagnostic tests (RDTs) detect HIV-1 p24 antigen to screen for acute HIV-1. However, diagnostic accuracy during clinical use may be suboptimal.

METHODS

Clinical sensitivity and specificity of fourth-generation RDTs for acute HIV-1 were collated from field evaluation studies in adults identified by a systematic literature search.

RESULTS

Four studies with 17 381 participants from Australia, Swaziland, the United Kingdom and Malawi were identified. All reported 0% sensitivity of the HIV-1 p24 component for acute HIV-1 diagnosis; 26 acute infections were missed. Specificity ranged from 98.3 to 99.9%.

CONCLUSION

Fourth-generation RDTs are currently unsuitable for the detection of acute HIV-1.

The HIV treatment cascade in acutely infected people: informing global guidelines

PURPOSE OF REVIEW

Acute and early HIV (AHI) is a pivotal time during HIV infection, yet there remain major shortfalls in diagnosis, linkage to care, and antiretroviral therapy (ART) initiation during AHI. We introduce an AHI-specific cascade, review recent evidence pertaining to the unique challenges of AHI, and discuss strategies for improving individual and public health outcomes.

RECENT FINDINGS

Presentation during AHI is common. Expanding use of fourth-generation testing and pooled nucleic acid amplification testing has led to improved AHI detection in resource-wealthy settings. Technologies capable of AHI diagnosis are rare in resource-limited settings; further development of point-of-care devices and utilization of targeted screening is needed. Rapid ART initiation during AHI limits reservoir seeding, preserves immunity, and prevents transmission. Reporting of AHI cascade outcomes is limited, but new evidence suggests that impressive rates of diagnosis, linkage to care, rapid ART initiation, and viral suppression can be achieved.

SUMMARY

With advancements in AHI diagnostics and strong evidence for the therapeutic and prevention benefits of ART initiated during AHI, improving AHI cascade outcomes is both crucial and feasible. HIV guidelines should recommend diagnostic algorithms capable of detecting AHI and prescribe rapid, universal ART initiation during AHI.

Barriers to HIV testing and characteristics associated with never testing among gay and bisexual men attending sexual health clinics in Sydney

INTRODUCTION

HIV diagnoses among gay and bisexual men have increased over the past decade in Australia. HIV point-of-care testing (POCT) was introduced in Australia in 2011 as a strategy to increase HIV testing by making the testing process more convenient. We surveyed gay and bisexual men undergoing POCT to assess barriers to HIV testing and characteristics associated with not having previously tested for HIV (never testing).

METHODS

During 2011 and 2012, gay and bisexual men who were undergoing POCT at four Sydney sexual health clinics self-completed questionnaires assessing testing history and psychological and structural barriers to HIV testing. Bivariate and multivariate logistic regression was used to assess associations between patient characteristics and never testing.

RESULTS

Of 1093 participants, 981 (89.9%) reported ever testing for HIV and 110 (10.1%) never testing. At least one barrier to testing was reported by 1046 men (95.7%), with only 47 men (4.3%) not reporting any barrier to testing. The most commonly reported barriers to testing were annoyance at having to return for results (30.2%), not having done anything risky (29.6%), stress in waiting for results (28.4%), being afraid of testing positive (27.5%) and having tested recently (23.2%). Never testing was independently associated with being non-gay-identified (adjusted odds ratio [AOR]: 1.9; 95% confidence interval [CI]: 1.1-3.2), being aged less than 25 years (AOR: 2.4; 95% CI: 1.6-3.8), living in a suburb with few gay couples (AOR: 1.9; 95% CI: 1.2-3.0), being afraid of testing HIV-positive (AOR: 1.6; 95% CI: 1.0-2.4), not knowing where to test (AOR: 3.8; 95% CI: 1.3-11.2) and reporting one or no sexual partners in the last six months (AOR: 2.7; 95% CI: 1.2-6.2).

CONCLUSIONS

Barriers to HIV testing were commonly reported among the clinic-based gay and bisexual men in this study. Our findings suggest further health promotion and prevention strategies are needed to address the knowledge, attitudes and behavioural factors associated with never testing.

Sensitivity of a rapid point of care assay for early HIV antibody detection is enhanced by its ability to detect HIV gp41 IgM antibodies

BACKGROUND

Anti-HIV-1 IgM antibody is an important immunoassay target for early HIV antibody detection.

OBJECTIVES

The objective of this study is to determine if the early HIV antibody sensitivity of the 60s INSTI test is due to detection of anti-HIV-1 IgM in addition to IgG.

STUDY DESIGN

To demonstrate HIV gp41 IgM antibody capture by the INSTI HIV-1 gp41 recombinant antigen, an HIV-IgM ELISA was conducted with commercial HIV-1 seroconversion samples. To demonstrate that the INSTI dye-labelled Protein A-based colour developer (CD) has affinity to human IgM, commercial preparations of purified human immunoglobulins (IgM, IgD, IgA, IgE, and IgG) were blotted onto nitrocellulose (NC) and probed with the CD to observe spot development. To determine that INSTI is able to detect anti-HIV-1 IgM antibody, early seroconversion samples, were tested for reduced INSTI test spot intensity following IgM removal.

RESULTS

The gp41-based HIV-IgM ELISA results for 6 early seroconversion samples that were INSTI positive determined that the assay signal was due to anti-HIV-1 IgM antibody capture by the immobilised gp41 antigen. The dye-labelled Protein-A used in the INSTI CD produced distinct spots for purified IgM, IgA, and IgG blotted on the NC membrane. Following IgM removal from 21HIV-1 positive seroconversion samples with known or undetermined anti-HIV-1 IgM levels that were western blot negative or indeterminate, all samples had significantly reduced INSTI test spot intensity.

CONCLUSIONS

The INSTI HIV-1/HIV-2 Antibody Test is shown to detect anti-HIV-1 IgM antibodies in early HIV infection which enhances its utility in early HIV diagnosis.

How can we better identify early HIV infections?

PURPOSE OF REVIEW

Detection of early HIV infections (EHIs), including acute HIV infection (AHI), is important for individual health, prevention of HIV transmission, and measurement of HIV incidence. We describe markers of EHI, diagnostic strategies for detecting these markers, and ways to incorporate these strategies into diagnostic and HIV incidence algorithms.

RECENT FINDINGS

For individual diagnosis in the USA and Europe, laboratory-based diagnostic algorithms increasingly incorporate fourth-generation HIV antigen tests, allowing for earlier detection. In some sub-Saharan African settings, symptom-based screening is being explored to identify subsets of persons at high risk for AHI. Point-of-care diagnostics designed for AHI detection are in the pipeline and, if validated, represent an opportunity for real-time AHI diagnosis. At the population level, multiassay algorithms are promising new strategies for estimating HIV incidence on the basis of several assays applied to cross-sectional samples. These algorithms can be developed to optimize performance, in addition to cost and logistical considerations.

SUMMARY

There are important recent advances in detection of EHIs at the individual and population levels. Applying optimal combinations of tests in diagnostic and HIV incidence algorithms is urgently needed to support the multiple goals derived from enhanced detection and discrimination of EHIs.

Public health implications of molecular point-of-care testing for chlamydia and gonorrhoea in remote primary care services in Australia: a qualitative study

OBJECTIVES

With accurate molecular tests now available for diagnosis of chlamydia and gonorrhoea (Chlamydia trachomatis (CT)/Neisseria gonorrhoeae (NG)) at the point-of-care (POC), we aimed to explore the public health implications (benefits and barriers) of their integration into remote primary care in Australia.

METHODS

Qualitative interviews were conducted with a purposively selected group of 18 key informants reflecting sexual health, primary care, remote Aboriginal health and laboratory expertise.

RESULTS

Participants believed that POC testing may decrease community prevalence of sexually transmitted infections (STIs), and associated morbidity by reducing the time to treatment and infectious period and expediting partner notification. Also, POC testing could improve acceptability of STI testing, increase testing coverage and result in more targeted prescribing, thereby minimising the risk of antibiotic resistance. Conversely, some felt the immediacy of diagnosis could deter certain young people from being tested. Participants also noted that POC testing may reduce the completeness of communicable disease surveillance data given the current dependence on reporting from pathology laboratories. Others expressed concern about the need to maintain and improve the flow of NG antibiotic sensitivity data, already compromised by the shift to nucleic acid-based testing. This is particularly relevant to remote areas where culture viability is problematic.

CONCLUSIONS

Results indicate a high level of support from clinicians and public health practitioners for wider access to CT/NG POC tests citing potential benefits, including earlier, more accurate treatment decisions and reductions in ongoing transmission. However, the data also highlight the need for new systems to avoid adverse impact on disease surveillance.

TRIAL REGISTRATION NUMBER

Australian and New Zealand Clinical Trials Registry: ACTRN12613000808741.

Rapid HIV Testing Is Highly Acceptable and Preferred among High-Risk Gay And Bisexual Men after Implementation in Sydney Sexual Health Clinics

BACKGROUND

Rapid HIV testing (RHT) is well established in many countries, but it is new in Australia. We assessed the acceptability of RHT and its associations among gay, bisexual and other men who have sex with men (GBM) after implementation of RHT in Sydney sexual health clinics.

METHODS

GBM were invited to complete an acceptability questionnaire before and after provision of the result of finger-prick blood RHT, comparing their experience of RHT with conventional HIV testing (CHT) involving venipuncture. Logistic regression was used to assess associations between patient characteristics and the preference for RHT over CHT next time they tested for HIV.

RESULTS

Of 1061 GBM who received non-reactive RHT results, 59% found RHT less stressful than CHT and 34% reported no difference, and 61% found RHT more comfortable than CHT and 26% reported no difference. Nearly all men were satisfied with RHT result delivery (99%) and the RHT process overall (99%). Most men (79%) preferred RHT for their next HIV test and this preference was stronger in men who were aged 35-44 years (adjusted odds ratio [AOR] 2.49, p<0.01), reported they would test more often if RHT was available (AOR 1.66, p=0.01), found returning for results annoying (AOR 1.67, p=0.01), and found RHT less stressful (AOR 2.37, p<0.01) and more comfortable (AOR 1.62, p=0.02) than CHT. Men concerned about the reliability of RHT were less than half as likely to prefer RHT for their next HIV test (AOR 0.44, p<0.01).

CONCLUSIONS

Most GBM preferred RHT to CHT next time and this preference was associated with finding RHT more convenient, more comfortable and less stressful than CHT. These findings suggest that in a clinic setting RHT should be considered to improve the patient experience and may potentially increase uptake and frequency of HIV testing.

Effect of testing experience and profession on provider acceptability of rapid HIV testing after implementation in public sexual health clinics in Sydney

OBJECTIVES

Rapid HIV testing (RHT) is well established in many countries, but it is new in Australia since a policy change in 2011. We assessed service provider acceptability of RHT before and after its implementation in four Sydney public sexual health clinics.

METHODS

Service providers were surveyed immediately after training in RHT and again 6-12 months later. Differences in mean scores between survey rounds were assessed via t-tests, with stratification by profession and the number of tests performed.

RESULTS

RHT was rated as highly acceptable among staff at baseline and acceptability scores improved between survey rounds. Belief in being sufficiently skilled and experienced to perform RHT (P = 0.004) and confidence in the delivery of nonreactive results increased (P = 0.007), while the belief that RHT was disruptive declined (P = 0.001). Acceptability was higher for staff who had performed a greater number of tests regarding comfort with their role in RHT (P = 0.004) and belief that patients were satisfied with RHT (P = 0.007). Compared with nurses, doctors had a stronger preference for a faster rapid test (P = 0.027) and were more likely to agree that RHT interfered with consultations (P = 0.014).

CONCLUSIONS

Differences in responses between professions may reflect differences in staff roles, the type of patients seen by staff and the model of testing used, all of which may affect the number of tests performed by staff. These findings may inform planning for how best to implement RHT in clinical services.

Generation of a recombinant Gag virus-like-particle panel for the evaluation of p24 antigen detection by diagnostic HIV tests

Background

Detection of HIV-1 p24 antigen permits early identification of primary HIV infection and timely intervention to limit further spread of the infection. Principally, HIV screening should equally detect all viral variants, but reagents for a standardised test evaluation are limited. Therefore, we aimed to create an inexhaustible panel of diverse HIV-1 p24 antigens.

Methods

We generated a panel of 43 recombinantly expressed virus-like particles (VLPs), containing the structural Gag proteins of HIV-1 subtypes A-H and circulating recombinant forms (CRF) CRF01_AE, CRF02_AG, CRF12_BF, CRF20_BG and group O. Eleven 4^th generation antigen/antibody tests and five antigen-only tests were evaluated for their ability to detect VLPs diluted in human plasma to p24 concentrations equivalent to 50, 10 and 2 IU/ml of the WHO p24 standard. Three tests were also evaluated for their ability to detect p24 after heat-denaturation for immune-complex disruption, a pre-requisite for ultrasensitive p24 detection.

Results

Our VLP panel exhibited an average intra-clade p24 diversity of 6.7%. Among the 4^th generation tests, the Abbott Architect and Siemens Enzygnost Integral 4 had the highest sensitivity of 97.7% and 93%, respectively. Alere Determine Combo and BioRad Access were least sensitive with 10.1% and 40.3%, respectively. Antigen-only tests were slightly more sensitive than combination tests. Almost all tests detected the WHO HIV-1 p24 standard at a concentration of 2 IU/ml, but their ability to detect this input for different subtypes varied greatly. Heat-treatment lowered overall detectability of HIV-1 p24 in two of the three tests, but only few VLPs had a more than 3-fold loss in p24 detection.

Conclusions

The HIV-1 Gag subtype panel has a broad diversity and proved useful for a standardised evaluation of the detection limit and breadth of subtype detection of p24 antigen-detecting tests. Several tests exhibited problems, particularly with non-B subtypes.

Point-of-care diagnostics, a major opportunity for change in traditional diagnostic approaches: potential and limitations

'Point-of-care' (POC) diagnostics are a powerful emerging healthcare approach. They can rapidly provide statistically significant results, are simple to use, do not require specialized equipment and are cost-effective. For these reasons, they have the potential to play a major role in revolutionizing the diagnosis, initiation and monitoring of treatment of major global diseases. This review focuses on antibody-based POC devices that target four major global diseases: cardiovascular diseases, prostate cancer, HIV infection and tuberculosis. The key statistics and pathology of each disease is described in detail, followed by an in-depth discussion on emerging POC devices that target each disease, highlighting their potential and limitations.

A novel time-limited pop-up HIV testing service for gay men in Sydney, Australia, attracts high-risk men

Background HIV diagnoses have been increasing steadily in Australia and are concentrated among gay, bisexual and other men who have sex with men (GBM). HIV testing is a key control strategy, and in 2013, a novel time-limited pop-up community HIV testing service (Pop-up) was introduced to raise awareness and increase testing options for GBM. The Pop-up service offered rapid HIV tests only. We compared uptake and outcomes of the Pop-up service to an established clinical model [a fast-track screening service in a sexual health clinic offering rapid and/or conventional HIV tests and sexually transmissible infection (STI) tests].

METHODS

Service delivery data was collated and analysed from the HIV Pop-up (25 November to 1 December 2013) and the fast-track HIV/STI screening service (Xpress) in a sexual health clinic immediately before the Pop-up (1 August to 22 November 2013). A comparison of all the HIV tests and results, tests per hour and characteristics of new clients (demographics, risk behaviour, testing history) was conducted using χ(2), Poisson distribution and Ranksum tests.

RESULTS

At the Pop-up service, 182 GBM had a rapid HIV test conducted over the 5-day period (average: seven HIV tests per hour) and no HIV tests were reactive (0%, 95% confidence interval: 0-1.8%). At the Xpress service, 1075 asymptomatic GBM had at least one STI test and 957 GMB had a HIV test (rapid or conventional) conducted over the 3-month period (average: four HIV tests per hour), with two positive HIV tests (0.2%, 95% confidence interval: 0.02-0.7) and 151 positive STI tests (14%, 95% confidence interval: 12-16.2). Compared with new patients at the Xpress service, GBM attending the Pop-up service were older (median of 39 vs 29 years, P<0.01); more likely to report ≥5 sexual partners in the past 3 months (P=0.02); more likely to reside in 'Gay Sydney' (P<0.01); and more likely to be tested for HIV (P<0.01).

CONCLUSIONS

Time-limited Pop-up community HIV testing is feasible and reached high-risk GBM, but compared with a clinic-based model, it only reached a smaller proportion of GBM who test infrequently or who have never been tested and are unaware of their HIV status. No STI testing was conducted through the Pop-up service, which allowed a higher throughput of HIV tests; however, a significant number of STIs may have been missed.