Performance evaluation of the point-of-care INSTI™ HIV-1/2 antibody test in early and established HIV infections

Findings from a novel and scalable community-based HIV testing approach to reduce the time required to complete point-of-care HIV testing in South Africa

BACKGROUND

Mobile HIV testing approaches are a key to reaching the global targets of halting the HIV epidemic by 2030. Importantly, the number of clients reached through mobile HIV testing approaches, need to remain high to maintain the cost-effectiveness of these approaches. Advances in rapid in-vitro tests such as INSTI® HIV-1/HIV-2 (INSTI) which uses flow-through technologies, offer opportunities to reduce the HIV testing time to about one minute. Using data from a routine mobile HTS programme which piloted the use of the INSTI point-of-care (POC) test, we sought to estimate the effect of using a faster test on client testing volumes and the number of people identified to be living with HIV, in comparison with standard of care HIV rapid tests.

METHODS

In November 2019, one out of four mobile HTS teams operating in Ekurhuleni District (South Africa) was randomly selected to pilot the field use of INSTI-POC test as an HIV screening test (i.e., the intervention team). We compared the median number of clients tested for HIV and the number of HIV-positive clients by the intervention team with another mobile HTS team (matched on performance and area of operation) which used the standard of care (SOC) HIV screening test (i.e., SOC team).

RESULTS

From 19 to 20 December 2019, the intervention team tested 7,403 clients, and the SOC team tested 2,426 clients. The intervention team tested a median of 442 (IQR: 288-522) clients/day; SOC team tested a median of 97 (IQR: 40-187) clients/day (p<0.0001). The intervention team tested about 180 more males/day compared to the SOC team, and the median number of adolescents and young adults tested/day by the intervention team were almost four times the number tested by the SOC team. The intervention team identified a higher number of HIV-positive clients compared to the SOC team (142 vs. 88), although the proportion of HIV-positive clients was lower in the intervention team due to the higher number of clients tested.

CONCLUSIONS

This pilot programme provides evidence of high performance and high reach, for men and young people through the use of faster HIV rapid tests, by trained lay counsellors in mobile HTS units.

Multi-volume hemacytometer

Cell counting has become an essential method for monitoring the viability and proliferation of cells. A hemacytometer is the standard device used to measure cell numbers in most laboratories which are typically automated to increase throughput. The principle of both manual and automated hemacytometers is to calculate cell numbers with a fixed volume within a set measurement range (10⁵ ~ 10⁶ cells/ml). If the cell concentration of the unknown sample is outside the range of the hemacytometer, the sample must be prepared again by increasing or decreasing the cell concentration. We have developed a new hemacytometer that has a multi-volume chamber with 4 different depths containing different volumes (0.1, 0.2, 0.4, 0.8 µl respectively). A multi-volume hemacytometer can measure cell concentration with a maximum of 10⁶ cells/ml to a minimum of 5 × 10³ cells/ml. Compared to a typical hemacytometer with a fixed volume of 0.1 µl, the minimum measurable cell concentration of 5 × 10³ cells/ml on the multi-volume hemacytometer is twenty times lower. Additionally, the Multi-Volume Cell Counting model (cell concentration calculation with the slope value of cell number in multi-chambers) showed a wide measurement range (5 × 10³ ~ 1 × 10⁶ cells/ml) while reducing total cell counting numbers by 62.5% compared to a large volume (0.8 µl-chamber) hemacytometer.

Aspects of Point-of-Care Diagnostics for Personalized Health Wellness

Advancements in analytical diagnostic systems for point-of-care (POC) application have gained considerable attention because of their rapid operation at the site required to manage severe diseases, even in a personalized manner. The POC diagnostic devices offer easy operation, fast analytical outcome, and affordable cost, which promote their advanced research and versatile adoptability. Keeping advantages in view, considerable efforts are being made to design and develop smart sensing components such as miniaturized transduction, interdigitated electrodes-based sensing chips, selective detection at low level, portable packaging, and sustainable durability to promote POC diagnostics according to the needs of patient care. Such effective diagnostics systems are in demand, which creates the challenge to make them more efficient in every aspect to generate a desired bio-informatic needed for better health access and management. Keeping advantages and scope in view, this mini review focuses on practical scenarios associated with miniaturized analytical diagnostic devices at POC application for targeted disease diagnostics smartly and efficiently. Moreover, advancements in technologies, such as smartphone-based operation, paper-based sensing assays, and lab-on-a-chip (LOC) which made POC more sensitive, informative, and suitable for major infectious disease diagnosis, are the main focus here. Besides, POC diagnostics based on automated patient sample integration with a sensing platform is continuously improving therapeutics interventions against specific infectious disease. This review also discussed challenges associated with state-of-the-art technology along with future research opportunities to design and develop next generation POC diagnostic systems needed to manage infectious diseases in a personalized manner.

Could HIV-1 RNA Testing be an Option as the Second Step in the HIV Diagnostic Algorithm?

BACKGROUND

There is benefit to early HIV-1 diagnosis and treatment, but there is no Food and Drug Administration-approved quantitative assay with a diagnostic claim. We compared the performance of the Hologic Aptima HIV-1 Quant (APT-Quant) and Aptima HIV-1 Qual (APT-Qual) assays for diagnostic use and the performance of a diagnostic algorithm consisting of Bio-Rad BioPlex 2200 HIV Ag-Ab assay (BPC) followed by APT-Quant (2-test) compared with BPC followed by Geenius HIV-1/2 supplemental assay (Geenius) with reflex to APT-Qual (3-test).

METHODS

Five hundred twenty-four plasma, which included 419 longitudinal specimens from HIV-1 seroconverters (78 were after initiating antiretroviral therapy [ART]) and 105 from ART-naive persons with established HIV-1 infections, were used to evaluate APT-Quant performance for diagnostic use. Specimens from 200 HIV-negative persons were used to measure specificity. For the algorithm comparison, BPC-reactive specimens were evaluated with the 2-test or 3-test algorithm. McNemar's test was used to compare performance.

RESULTS

The APT-Quant detected more samples early in infection compared with APT-Qual. The APT-Quant specificity was 99.8%. Before ART initiation, the algorithms performed similarly among samples from different stages of infection. After ART initiation, the 3-test algorithm performed significantly better (P = 0.0233).

CONCLUSIONS

The APT-Quant has excellent performance for diagnostic use. The 2-test algorithm works well in ART-naive samples, but its performance decreases after the IgG response is elicited and with ART-induced suppressed viremia. Providing confirmation and viral load assay with 1 test result could be advantageous for patient care. However, additional factors and challenges associated with the implementation of this 2-test algorithm, such as cost, specimen type, and collection need further evaluation.

Performance evaluation of the MedMira reveal G4 LAB S/P and POC HIV antibody rapid screening tests using plasma and whole blood specimens

BACKGROUND

The Reveal G4 antibody rapid test is FDA-approved for HIV-1 detection using the versions LAB S/P and POC in CLIA-moderate complexity settings with serum/plasma and whole blood, respectively. The same Reveal tests are CE-marked for HIV-1 and HIV-2 detection in laboratory and point-of-care (POC) settings.

OBJECTIVE

We compared the performance of G4 LAB S/P with plasma and POC with whole blood (blood) for detecting early and established HIV-1/HIV-2 infections.

STUDY DESIGN

Matched well-characterized plasma and simulated blood were used to evaluate: sensitivity in 104 HIV-1 and 55 HIV-2 established infections, specificity in 49 HIV-negative, and reactivity in early HIV-1 infection in a performance panel (n=38) and 18 plasma panels from seroconverters (SCs, n=183). Median number of days after first RNA-positive was calculated for 13 SCs. Impact of viral suppression (VS) was evaluated in 3 SCs receiving early antiretroviral therapy (ART).

RESULTS

Sensitivity was 100 % for HIV-1 and 98.18 % for HIV-2, while specificity was 100 %. All 38 plasma and blood become reactive by Fiebig stage V. Of 18 SCs, 10 had similar reactivity in plasma/blood, 7 showed delayed reactivity in blood, and 1 was nonreactive in plasma/blood. The median days for a G4-reactive after first RNApositive was 13 for plasma and 14 for blood. Long-term VS had no impact on G4 reactivity.

CONCLUSIONS

Overall reactivity in early HIV-1 infections is delayed by one day in blood compared to plasma. If FDA-approved for POC settings, the G4 POC is a fast sensitive screening tool for HIV-1/HIV-2-specific IgG even during VS.

Performance evaluation of four point-of-care HIV tests using unprocessed specimens

BACKGROUND

The performance of recently approved point-of-care (POC) HIV tests should be assessed using unprocessed specimens.

OBJECTIVE

To evaluate the sensitivity and specificity of four POC HIV tests using whole blood (WB) and two using oral fluid (OF) among persons recruited from health clinics in Seattle, Washington, during September 2015-September 2017.

STUDY DESIGN

Participants were tested with the POC tests, additional plasma and serum were collected for laboratory testing, and participant- reported use of antiretroviral therapy (ART) or pre-exposure prophylaxis (PrEP) was recorded. Participants testing negative on all tests could reenroll every 90 days. Specimens from persons previously diagnosed with HIV infection as well as from those who were newly diagnosed during the study were included in the sensitivity estimate. Sensitivity and specificity were calculated based on HIV status determined by laboratory testing.

RESULTS

Of 1,256 visits, 179 were from persons with HIV infection; 120 of these were taking ART. Among 1,077 visits from participants not diagnosed with HIV, PrEP use was reported at 155 (14.4%) visits. Sensitivity was similar among POC WB tests (95.53%-97.21%; p>0.05). Among participants on ART, sensitivity was lower for the same test performed on OF compared to WB (p<0.003). Specificity was high for all tests (99.44%- 100.00%); we did not detect specificity differences with PrEP use.

CONCLUSIONS

These POC tests displayed relatively high sensitivity and specificity using unprocessed specimens, suggesting their effectiveness in identifying HIV infections whenever laboratory-based testing is not feasible. Nonetheless, clients with recent risk should retest to rule out the possibility of a false-negative result.

Prospective Evaluation of HIV Testing Technologies in a Clinical Setting: Protocol for Project DETECT

BACKGROUND

HIV testing guidelines provided by the Centers for Disease Control and Prevention (CDC) are continually changing to reflect advancements in new testing technology. Evaluation of existing and new point-of-care (POC) HIV tests is crucial to inform testing guidelines and provide information to clinicians and other HIV test providers. Characterizing the performance of POC HIV tests using unprocessed specimens can provide estimates for the window period of detection, or the time from HIV acquisition to test positivity, which allows clinicians and other HIV providers to select the appropriate POC HIV tests for persons who may be recently infected with HIV.

OBJECTIVE

This paper describes the protocols and procedures used to evaluate the performance of the newest POC tests and determine their sensitivity during early HIV infection.

METHODS

Project DETECT is a CDC-funded study that is evaluating POC HIV test performance. Part 1 is a cross-sectional, retrospective study comparing behavioral characteristics and HIV prevalence of the overall population of the Public Health-Seattle & King County (PHSKC) Sexually Transmitted Disease (STD) Clinic to Project DETECT participants enrolled in part 2. Part 2 is a cross-sectional, prospective study evaluating POC HIV tests in real time using unprocessed whole blood and oral fluid specimens. A POC nucleic acid test (NAT) was added to the panel of HIV tests in June 2018. Part 3 is a longitudinal, prospective study evaluating seroconversion sensitivity of POC HIV tests through serial follow-up testing. For comparison, HIV-1 RNA and HIV-1/HIV-2 antigen/antibody tests are also performed for participants enrolled in part 2 or 3. A behavioral survey that collects information about demographics, history of HIV testing, STD history, symptoms of acute HIV infection, substance use, sexual behaviors in the aggregate and with recent partners, and use of pre-exposure prophylaxis and antiretroviral therapy is completed at each part 2 or 3 visit.

RESULTS

Between September 2015 and March 2019, there were 14,990 Project DETECT-eligible visits (part 1) to the PHSKC STD Clinic resulting in 1819 part 2 Project DETECT study visits. The longitudinal study within Project DETECT (part 3) enrolled 27 participants with discordant POC test results from their part 2 visit, and 10 (37%) were followed until they had fully seroconverted with concordant positive POC test results. Behavioral survey data and HIV test results, sensitivity, and specificity will be presented elsewhere.

CONCLUSIONS

Studies such as Project DETECT are critical for evaluating POC HIV test devices as well as describing characteristics of persons at risk for HIV acquisition in the United States. HIV tests in development, including POC NATs, will provide new opportunities for HIV testing programs.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR1-10.2196/16332.

Field performance of the INSTI HIV-1/-2 antibody test in two South African antenatal clinics

This was a prospective study that assessed field performance of the INSTI HIV-1/-2 antibody test (INSTI test) in two antenatal clinics in South Africa (SA). INSTI test was evaluated against rapid tests used at these clinics, and pooled nucleic acid amplification testing (NAAT) performed for individuals with negative rapid tests. Three hundred and eighty-six pregnant women were enrolled; 334 (86.5%) with negative results on the screening rapid test, and 52 (13.5%; 95% confidence interval [CI]: 10.2-17.3%) with positive results on screening and confirmatory rapid tests. INSTI test yielded the same results as other rapid tests in all participants, thus showing a 100% sensitivity (95% CI: 93.2-100.0%) and specificity (95% CI: 98.9-100.0%). Pooled NAAT was performed for 290 participants who had negative rapid tests, and yielded negative results in all pools. These data show excellent field performance of the INSTI test, and highlight that this test can be implementedat SA clinics.

HIV Diagnostics: Current Recommendations and Opportunities for Improvement

Profound changes in technology have revolutionized laboratory testing for human immunodeficiency virus (HIV) since the first laboratory enzyme immunoassays that detected only immunoglobulin G (IgG) antibodies. Instrumented fourth-generation random-access chemiluminescent assays are now recommended for initial screening because they become reactive in as little as 2 weeks after infection. Using HIV-1 RNA viral load assays after a reactive initial test could confirm infection and provide useful clinical information. Early initiation of antiretroviral therapy and use of preexposure prophylaxis can alter the evolution of biomarkers and assay reactivity, leading to ambiguous test results.

Field evaluation of a dual rapid Human Immunodeficiency Virus and treponemal syphilis rapid test in community-based clinics in Los Angeles and New York

INTRODUCTION

Dual human immunodeficiency virus/syphilis rapid diagnostic devices can play an important role in prevention efforts. The field performance of the INSTI Multiplex HIV-1/HIV-2/Syphilis Antibody Test (Multiplex) was evaluated.

METHODS

Fingerstick whole blood was tested using the rapid test. A fourth-generation HIV laboratory assay and treponemal-specific laboratory assays were used as reference. Rapid plasma reagin (RPR) was used to stratify treponemal results. Sensitivity and specificity were calculated.

RESULTS

Overall, 274 patients participated. Sensitivity of the Multiplex for detection of HIV was 98.8% (95% CI, 93.4-100%), and specificity was 100% (95% CI, 98.1-100%). Sensitivity for detection of syphilis antibodies was 56.8% (95% CI, 44.7-68.2%), and specificity was 98.5% (95% CI, 95.7-99.7%). Sensitivity for treponemal antibodies improved with increasing RPR and was 100% (95% CI, 78.2-100%) among samples with RPR titers ≥1:8.

CONCLUSIONS

The Multiplex showed excellent performance for detection of HIV antibodies and increasing sensitivity for detection of treponemal antibody with increasing RPR titer.

Results of offering oral rapid HIV screening within a dental school clinic

To broaden the availability of human immunodeficiency virus (HIV) testing, we offered rapid HIV screening tests to 811 patients attending a dental school for routine dental hygiene care. Study design is a prospective cross-sectional study. The 319 (39.3%) agreeing to test, self-identified as: Hispanic (34.4%), White (25.8%), African American (13.1%), Asian (8.3%), Native American/Pacific Islander (0.9%), more than one race/ethnicity (1.1%) or declining to state (16.5%). Over 35% (n = 113) were first time HIV test takers, with another 2.2% (n = 7) unaware of their testing history. Approximately 60% of the decliners choose "just don't want test today" as the reason. Following a strictly structured algorithm, four possible undiagnosed infections were initially identified, with one completing the algorithm to case confirmation. In conclusion, the confirmed incidence rate finding of HIV seropositivity of 0.31% found through initial screening at the dental clinic, compared with the 0.018% incidence rate of HIV with confirmed diagnosis in Los Angeles County, indicates that a rapid HIV screening test offered in a dental school clinic can potentially play an important role in discovering undiagnosed HIV individuals.

Performance and usability evaluation of the INSTI HIV self-test in Kenya for qualitative detection of antibodies to HIV

BACKGROUND

HIV testing is often undermined by lack of confidentiality, stigma, shortage of counselors and long distances to testing centers. Self-testing has the potential to circumvent these constraints.

OBJECTIVE

To determine the performance and usability characteristics of the INSTI® HIV-1/HIV-2 Self-Test.

METHODS

The performance evaluation was a cross sectional study and the usability a mixed methods study. For method comparison, Bioelisa HIV-1+2 Ag/Ab test was used as the reference test. When the test results were discrepant, results from Alere Determine™ HIV-1/2 and First Response HIV-1-2 Antibody tests were used for confirmation of status.

RESULTS

Sensitivity of the INSTI HIV Self-Test was 98.99% (95% CI 96.05-99.75%), and specificity 98.15% (95% CI 95.63-99.23%). The concordance was therefore 97.27%. A total of 354 participants took part in the usability study. Of those, 343 (98.00%) found instructions for use easy to follow, 330 (94.29%) found the finger prick device easy to use, 303 (86.57%) were confident while performing the test, 342 (97.71%) felt result interpretation was easy, while 304 (86.86%) declared results within the recommended five minutes. Three hundred and forty two (342, 97.71%) were willing to use the test again while 344 (98.29%) would recommend the kit to a sexual partner. None of the 350 participants quit the process at any stage. Three hundred and eighteen (318, 91.12%) participants felt the test needed no further improvement. All 91 lay users correctly identified cartridges that showed positive, negative and invalid results. Only 31 (34.07%) participants correctly identified weak positive dummy test results.

CONCLUSION

The excellent performance and usability characteristics of INSTI HIV-1/HIV-2 self-test make the kit a viable option for HIV self-testing. To improve the identification of weak positive results, the manufacturer should indicate on the IFU that even a faint test spot should be interpreted as positive.

Sensitivity of the STAT-VIEW rapid self-test and implications for use during acute HIV infection

OBJECTIVES

HIV testing is an important step towards diminishing incident infections. Rapid self-tests whose use is becoming more common in France could help increase access to testing, yet could fail to diagnose HIV during acute HIV infection (AHI). The aim of the present study was to evaluate HIV-detection sensitivity of a commonly used rapid self-test (STAT-VIEW HIV1/2), compared with another point-of-care rapid test (INSTI), among patients presenting with AHI.

METHODS

Individuals tested at Saint-Antoine Hospital (Paris, France) with negative or indeterminate western blot (WB) results and detectable HIV-RNA were included. Rapid tests were performed retrospectively on stored serum. Patients with and without reactive rapid tests were compared, while probability of having a reactive test was modelled across infection duration using logistic regression.

RESULTS

Of the 40 patients with AHI, 23 (57.5%) had a reactive STAT-VIEW rapid test. Patients with non-reactive versus reactive tests had a significantly shorter median time since infection (p=0.01), time since onset of symptoms (p=0.009), higher proportion with Fiebig stage III versus IV (p=0.003), negative WB results (p=0.007), higher HIV-RNA levels (p=0.001) and lower CD4+ and CD8+ cell count (p=0.03, p<0.001, respectively). When examining sensitivity over the course of AHI duration, the probability of HIV detection was 75.5% at 5 weeks from HIV transmission. The INSTI provided similar results with respect to proportion of reactive tests (62.5%), determinants for non-reactive test and probability of HIV detection at 5 weeks of infection (85.0%).

CONCLUSIONS

Over half of AHI patients had reactive serology using the STAT-VIEW rapid self-test when performed on serum samples. Considering that detection sensitivity increased substantially over infection time, individuals should not rely on a negative result to accurately exclude HIV infection within at least 5 weeks of potential HIV exposure. Notwithstanding strong recommendations against rapid test use during AHI, some utility in detecting HIV is observed 5-12 weeks after transmission.