Evaluation of SAMBA II: A Qualitative and Semiquantitative HIV Point-of-Care Nucleic Acid Test.

BACKGROUND: Point-of-care (POC) nucleic acid tests (NATs) have potential to diagnose acute HIV infection and monitor persons taking pre-exposure prophylaxis or antiretroviral therapy (ART). POC NATs have not yet been evaluated in the US. METHODS: From June 2018-March 2019, we conducted a cross-sectional evaluation of the Simple Amplification-Based Assay version II (SAMBA II) POC NAT. People with HIV (PWH) and persons testing for HIV were tested with the SAMBA II qualitative (Qual) whole blood (WB) test. From April-September 2019, the Qual test was used on persons who were ART-naive, and SAMBA II Semi-quantitative (Semi-Q) WB was used with ART-experienced PWH. Both were performed on unprocessed venipuncture (VP) and, when indicated by protocol, fingerstick (FS) WB and plasma. SAMBA results were compared with Abbott RealTime HIV-1 polymerase chain reaction results on plasma. We calculated sensitivity, specificity, and concordance between tests. RESULTS: SAMBA was used in 330 visits among 280 participants: 202 (61.2%) visits from PWH, and 128 (38.8%) from HIV-negative persons. Qual test sensitivity with ART-naive participants was 91.4% [32/35, 95% confidence interval (CI): 77.6% to 97.0%] using VP WB and 100% (27/27, 95% CI: 87.5% to 100%) using FS WB. Specificity was 100% using both specimen types. Concordance between the gold standard and Semi-Q at 1000 copies/mL among PWH on ART was 97.7% (86/88, 95% CI: 92.1% to 99.4%) and 100% (30/30, 95% CI: 88.7% to 100%) using VP and FS WB, respectively. CONCLUSIONS: The SAMBA II POC NATs showed high sensitivity, specificity, and concordance with the gold standard assay, indicating its potential use in diagnostics and monitoring. Future work will evaluate POC NAT implementation in the US.

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.

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.

Group Sex Events Among Cisgender Men Who Have Sex With Men: Cross-Sectional and Longitudinal Survey Study to Explore Participation and Risk-Taking Behaviors.

BACKGROUND: Group sex events (GSEs) are common among cisgender men who have sex with men (MSM), pose a unique risk profile for HIV and sexually transmitted disease (STD) transmission, and may be on the rise, in part because of Web-based networking platforms. However, collecting data on GSEs can be challenging, and many gaps exist in our knowledge about GSE participation among MSM. OBJECTIVE: The objective of this study was to develop survey questions addressing aggregate and partner-specific group sex behaviors to measure prevalence of GSEs and associated risks in persons participating in Project Diagnostic Evaluation To Expand Critical Testing Technologies (DETECT), including MSM seeking HIV and STD testing at a public clinic in Seattle, Washington. METHODS: We developed a computer self-assisted survey that included questions about participant demographics, sexual history, and risk behaviors, including group sex, as a part of Project DETECT, a Centers for Disease Control and Prevention-funded study evaluating point-of-care HIV tests. Aggregate and partner-specific questions asked about participation in all GSEs, threesomes, and four-or-more-somes including questions about number and HIV status of sex partners and condom use during the events. To evaluate question performance, we assessed the discrepancies in reporting between the aggregate and partner-specific questions, quantified question refusal rates, and calculated the additional time required to answer the GSE questions. Information about network density (number of partnerships of overlapping duration) was estimated and compared for MSM who did and did not report GSEs. RESULTS: Among 841 visits by 690 MSM who were asked any group sex survey question, participation in a GSE of any type in the past 3 months was reported at 293 visits (293/841, 34.8%). We found that 9.0% (76/841) of MSM in the sample reported ≥1 four-or-more-some in the partner-specific questions but did not report in the aggregate. The proportion of refusals on any given aggregate GSE-related question ranged from 0% (0/273) to 10.6% (15/141) (median 2.6%) and partner-specific questions ranged from 0% (0/143) to 22% (5/23) (median 3.0%), with questions about four-or-more-somes having the highest proportions of refusals. Completing the aggregate group sex questions added 1 to 2 minutes and the partner-specific questions added an additional 2 to 4 minutes per partner to the total survey length. As expected, the partner-specific GSE questions documented higher density of sexual networks that was not captured by asking about total partner counts and overlap of specific partnerships. CONCLUSIONS: We found that the Project DETECT survey was able to obtain nuanced information about GSEs. The question skip patterns and consistency checks were effective, and survey fatigue was minimal. More research is needed on GSEs, and our survey represents a promising data collection tool to help fill gaps in knowledge about the subject.

Time Until Emergence of HIV Test Reactivity Following Infection With HIV-1: Implications for Interpreting Test Results and Retesting After Exposure.

BACKGROUND: Understanding the period of time between an exposure resulting in infection with human immunodeficiency virus (HIV) and when a test can reliably detect the presence of that infection, that is, the test window period, may benefit testing programs and clinicians in counseling patients about when the clinician and the patient can be confident a suspected exposure did not result in HIV infection. METHODS: We evaluated the intervals between reactivity of the Aptima HIV-1 RNA test (Aptima) and 20 US Food and Drug Administration-approved HIV immunoassays using 222 longitudinally collected plasma specimens from HIV-1 seroconverters from the United States. Using interval-censored survival and binomial regression approaches a multi-model framework was implemented to estimate the relative emergence of test reactivity, referred to here as an inter-test reactivity interval (ITRI). We then combined ITRI results with simulated data for the eclipse period, the time between exposure and detection of HIV virus by Aptima, to estimate the window period for each test. RESULTS: The estimated ITRIs were shorter with each new class of HIV tests, ranging from 5.9 to 24.8 days. The 99th percentiles of the window period probability distribution ranged from 44 days for laboratory screening tests that detect both antigen and antibody to 65 days for the Western blot test. CONCLUSIONS: Our directly comparable estimates of the emergence of reactivity for 20 immunoassays are valuable to testing providers for interpreting negative HIV test results obtained shortly after exposure, and for counseling individuals on when to retest after an exposure.

Acute infections, cost and time to reporting of HIV test results in three U.S. State Public Health Laboratories.

OBJECTIVE: In three U.S. State Public Health Laboratories (PHLs) using a fourth-generation immunoassay (IA), an HIV-1/HIV-2 differentiation antibody IA and a nucleic acid test (NAT), we characterized the yield and time to reporting of acute infections, and cost per positive specimen. METHODS: Routine HIV testing data were collected from July 1, 2012-June 30, 2013 for Massachusetts and Maryland PHLs, and from November 27, 2012-June 30, 2013 for Michigan PHL. Massachusetts and Michigan used fourth-generation and differentiation IAs with NAT conducted by a referral laboratory. In Maryland, fourth-generation IA repeatedly reactive specimens were followed by a Western blot (WB), and those with negative or indeterminate results were tested with a differentiation IA and HIV-1 NAT, and if positive by NAT, confirmed by a different HIV-1 NAT. Specimens from WB-positive persons at risk for HIV-2 were tested with a differentiation IA and, if positive, with an HIV-2 WB and/or differential HIV-1/HIV-2 proviral DNA polymerase chain reaction. RESULTS: Among 7914 specimens from Massachusetts PHL, 6069 from Michigan PHL, and 36,266 from Maryland PHL, 0.10%, 0.02% and 0.05% acute infections were identified, respectively. Massachusetts and Maryland PHLs each had 1 HIV-2 positive specimen. The median time from specimen receipt to laboratory reporting of results for acute infections at Massachusetts, Michigan and Maryland PHLs was 8, 11, and 7 days respectively. The laboratory cost per HIV positive specimen was $336 (Massachusetts), $263 (Michigan) and $210 (Maryland). CONCLUSIONS: Acute and established infections were found by PHLs using fourth-generation IA in conjunction with antibody tests and NAT. Time to reporting of acute HIV test results to clients was suboptimal, and needs to be streamlined to expedite treatment and interrupt transmission.

Acute Infections, Cost per Infection and Turnaround Time in Three United States Hospital Laboratories Using Fourth-Generation Antigen-Antibody Human Immunodeficiency Virus Immunoassays.

Background. To improve clinical and public health outcomes through early human immunodeficiency virus (HIV) detection, fourth-generation antigen/antibody immunoassay (4IA) and supplemental testing results must be returned rapidly. Methods. We examined HIV testing data at Harborview Medical Center (HMC), Massachusetts General Hospital (MGH), and the Medical University of South Carolina (MUSC), which used 4IA and supplemental antibody and nucleic acid tests (NATs). At MGH and MUSC, HIV-1 Western blot (WB) and HIV-2 testing were conducted at a reference laboratory. We compared time from specimen collection to laboratory result for established (positive WB) and acute infections (reactive 4IA, negative/indeterminate WB, detectable NAT), and we calculated testing cost per positive-test result. Results. From 3731 (MUSC) to 19 774 (MGH) tests were conducted; 0.01% (MGH) to 0.05% (HMC) were acute infections. Each laboratory had reactive 4IA, WB-negative, or indeterminate specimens without NAT (ie, potential acute infections). Time to result was 1.5 (HMC) to 5.2 days (MGH) for acute and 1.0 (HMC) to 5.2 days (MGH) for established infections. Costs were $1054 (MGH) to $1521 (MUSC). Conclusions. Conducting supplemental testing in-house lowered turnaround times, which may be further reduced with rapid HIV-1/HIV-2 differentiation tests. Hospitals may benefit from quantitative NATs not requiring physician orders, so all potential acute infections receive NAT.

Nucleic acid testing by public health referral laboratories for public health laboratories using the U.S. HIV diagnostic testing algorithm.

BACKGROUND: Many public health laboratories adopting the U.S. HIV laboratory testing algorithm do not have a nucleic acid test (NAT), which is needed when the third- or fourth-generation HIV screening immunoassay is reactive and the antibody-based supplemental test is non-reactive or indeterminate. OBJECTIVES: Among public health laboratories utilizing public health referral laboratories for NAT conducted as part of the algorithm, we evaluated the percentage of screening immunoassays needing NAT, the number of specimens not meeting APTIMA (NAT) specifications, time to APTIMA result, the proportion of acute infections (i.e., reactive APTIMA) among total infections, and screening immunoassay specificity. STUDY DESIGN: From August 2012 to April 2013, 22 laboratories enrolled to receive free APTIMA (NAT) at New York or Florida public health referral laboratories. Data were analyzed for testing conducted until June 2013. RESULTS: Submitting laboratories conducted a median of 4778 screening immunoassays; 0-1.3% (median 0.2%) needed NAT. Of 140 specimens received, 9 (6.4%) did not meet NAT specifications. The median time from specimen collection to reporting the 11 reactive NAT results was ten days, including six days from receipt in the submitting laboratory to shipment to the referral laboratory. Acute infections ranged from 0 to 12.5% (median 0%) of total infections. Third- and fourth-generation immunoassays met package insert specificity values. CONCLUSIONS: Public health referral laboratories provide a feasible option for conducting NAT. Reducing the time from specimen collection to submission of specimens for NAT is an important step toward maximizing the public health impact of identifying acute infections.

Evaluation of supplemental testing with the Multispot HIV-1/HIV-2 Rapid Test and APTIMA HIV-1 RNA Qualitative Assay to resolve specimens with indeterminate or negative HIV-1 Western blots.

BACKGROUND: The use of Western blot (WB) as a supplemental test after reactive sensitive initial assays can lead to inconclusive or misclassified HIV test results, delaying diagnosis. OBJECTIVE: To determine the proportion of specimens reactive by immunoassay (IA) but indeterminate or negative by WB that could be resolved by alternative supplemental tests recommended under a new HIV diagnostic testing algorithm. STUDY DESIGN: Remnant HIV diagnostic specimens that were reactive on 3rd generation HIV-1/2 IA and either negative or indeterminate by HIV-1 WB from 11 health departments were tested with the Bio-Rad Multispot HIV-1/HIV-2 Rapid Test (Multispot) and the Gen-Probe APTIMA HIV-1 RNA Qualitative Assay (APTIMA). RESULTS: According to the new testing algorithm, 512 (89.8%) specimens were HIV-negative, 55 (9.6%) were HIV-1 positive (including 19 [3.3%] that were acute HIV-1 and 9 [1.6%] that were positive for HIV-1 by Multispot but APTIMA-negative), 2 (0.4%) were HIV-2 positive, and 1 (0.2%) was HIV-positive, type undifferentiated. 47 (21.4%) of the 220 WB-indeterminate and 8 (2.3%) of the 350 WB-negative specimens were HIV-1 positive. CONCLUSION: Applying the new HIV diagnostic algorithm retrospectively to WB-negative and indeterminate specimens, the HIV infection status could be established for nearly all of the specimens. IA-reactive HIV-infected persons with WB-negative results had been previously misclassified as uninfected, and HIV diagnosis was delayed for those with WB-indeterminate specimens. These findings underscore the limitations of the WB to confirm HIV infection after reactive results from contemporary 3rd or 4th generation IAs that can detect HIV antibodies several weeks sooner than the WB.

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.

HIV screening practices and hospital characteristics in the US, 2009-2010.

OBJECTIVES: The Centers for Disease Control and Prevention recommends HIV screening in U.S. health-care settings unless providers document a yield of undiagnosed HIV infections of <1 per 1,000 population. However, implementation of this guidance has not been widespread and little is known of the characteristics of hospitals with screening practices in place. We assessed how screening practices vary with hospital characteristics. METHODS: We used a national hospital survey of HIV testing practices, linked to HIV prevalence for the county, parish, borough, or city where the hospital was located, to assess HIV screening of some or all patients by hospitals. We used multivariate logistic regression analysis to assess the association between screening practices and hospital characteristics that were significantly associated with screening in bivariate analyses. RESULTS: Of 376 hospitals in areas of prevalence ≥0.1%, only 25 (6.6%) reported screening all patients for HIV and 131 (34.8%) reported screening some or all patients. Among 638 hospitals included, screening some or all patients was significantly (p<0.05) more common at teaching hospitals, hospitals with higher numbers of annual admissions, and hospitals with a high proportion of Medicaid admissions. In multivariable analysis, screening some or all patients was independently associated with admitting more than 15% of Medicaid patients and receiving resources or reimbursement for screening tests. CONCLUSION: We found that few hospitals surveyed reported screening some or all patients, and failure to screen is common across all types of hospitals in all regions of the country. Expanded reimbursement for screening may increase compliance with the recommendations.

HIV screening practices in U.S. hospitals, 2009-2010.

OBJECTIVE: A 2004 national survey of hospitals showed that 23.4% of hospitals screened for HIV in at least one department, most frequently in labor and delivery departments. However, less than 2% of these hospitals screened patients in inpatient units, urgent care clinics, or emergency departments. In 2006, the Centers for Disease Control and Prevention (CDC) recommended HIV screening for all individuals 13-64 years of age in health-care settings. We determined the frequency of hospital adoption of these CDC recommendations. METHODS: We surveyed hospital infection-control personnel at a randomly selected sample of U.S. general medical and surgical hospitals in 2009-2010. RESULTS: Of the 1,476 hospitals selected for the survey, 754 (51.1%) responded to the survey; of those responding, 703 (93.2%) offered HIV tests for patients at the hospital and 206 (27.3%) screened for HIV in at least one department. Screening was most common in larger hospitals (45.7%), hospitals in large metropolitan areas (50.5%), and teaching hospitals (44.4%); it was least common in public hospitals (19.1%). By department, screening was most common in labor and delivery departments (34.6%) and substance abuse clinics (20.7%); it was least common in emergency departments (11.9%), inpatient units (9.6%), and psychiatry/mental health departments (9.4%). More than half of hospitals were not considering implementing CDC's recommendations within the next 12 months. CONCLUSIONS: Since 2004, HIV screening in hospitals increased overall and by department. However, the majority of U.S. hospitals have not adopted the CDC recommendations.

Comparative evaluation of Aptima HIV-1 Qualitative RNA assay performance using plasma and serum specimens from persons with established HIV-1 infection.

BACKGROUND: Blood specimens for HIV testing are frequently collected using serum collection tubes. The Aptima HIV-1 RNA Qualitative test, originally approved for diagnostic use as a supplemental test for use with plasma, is now approved for use with serum, and may be used in new laboratory-based HIV testing algorithms which detect acute and established HIV infections. OBJECTIVES: To compare the sensitivity of Aptima using serum and plasma specimens from persons with established HIV infection. STUDY DESIGN: Parallel serum and plasma specimens were collected from 325 persons with established HIV-1 infection who had positive immunoassay (IA) and Western blot (WB) results. Samples with negative Aptima results were considered false-negative and were subjected to repeat testing. Aptima sensitivity for serum and plasma was calculated relative to IA and WB, and compared using the McNemar test. RESULTS: The sensitivity of Aptima using serum (97.23%, 95% confidence interval [CI] 94.81-98.73) was similar to that using plasma (97.54%, 95% [CI] 95.21-98.93) p=1.00. Five of ten specimens initially false-negative on either serum or plasma were reactive on repeat testing. No specimens initially classified as false-negative on both matrices were reactive on both matrices on repeat testing. CONCLUSIONS: In specimens from persons with established infections, Aptima performed with similar sensitivity when used with serum or plasma. Using serum for immunoassay screening and supplemental testing may provide added convenience for laboratories.

Performance of an alternative laboratory-based algorithm for diagnosis of HIV infection utilizing a third generation immunoassay, a rapid HIV-1/HIV-2 differentiation test and a DNA or RNA-based nucleic acid amplification test in persons with established HIV-1 infection and blood donors.

BACKGROUND: The HIV-1 Western blot (WB) and immunofluorescence assay used to confirm HIV infections are less sensitive during seroconversion than immunoassays (IAs) used for screening. An alternative diagnostic algorithm has been proposed to detect early HIV-1 infection and differentiate HIV-1 from HIV-2. OBJECTIVES: We evaluated the performance of an algorithm with a third generation IA that when reactive was followed by a rapid test (Multispot) that differentiates HIV-1 from HIV-2. Multispot-reactive specimens were considered HIV-infected. Multispot-negative specimens were tested with a nucleic acid amplification test (NAAT) for resolution. STUDY DESIGN: WB-positive specimens [serum (n=2202), plasma (n=1109) and peripheral blood mononuclear cells (PBMCs) (n=1065)] were obtained from HIV-infected persons not taking antiretrovirals. HIV-uninfected specimens [plasma (n=1517) and PBMCs (n=1508)] with negative IA and NAAT results were obtained from blood donors. Specimens were tested with third generation IAs (Abbott rDNA, ADVIA Centaur, GS HIV1-2 Plus O, Ortho VITROS) in singlet, Multispot, and NAAT (APTIMA (RNA) and AMPLICOR (DNA)). We calculated algorithm sensitivity and specificity and the proportion of IA-reactive specimens requiring NAAT. RESULTS: Algorithm sensitivity was 99.95% with APTIMA and 100% with AMPLICOR. One WB-positive specimen reactive by all IAs and AMPLICOR was negative by Multispot and APTIMA. Algorithm specificity was 100% using APTIMA or AMPLICOR as NAAT. From 0.10% (Abbott) to 2.43% (VITROS) of IA-reactive specimens required NAAT. CONCLUSIONS: The proposed algorithm performs with high sensitivity and specificity in specimens from persons with established HIV infection and uninfected blood donors and appears to be a good alternative to the current algorithm.

Comparison of alternative interpretive criteria for the HIV-1 Western blot and results of the Multispot HIV-1/HIV-2 Rapid Test for classifying HIV-1 and HIV-2 infections.

BACKGROUND: HIV-1 Western blot (WB) may be positive in specimens from persons with HIV-2 infection due to cross-reactive antibodies. HIV-1 and HIV-2 infections may be identified using assays designed to differentiate HIV-1 and HIV-2 antibody reactivity. OBJECTIVES: To evaluate the ability of the current CDC WB criteria, alternative more stringent HIV-1 WB criteria (2 env plus one gag or pol band) and the Multispot HIV-1/HIV-2 Rapid Test to accurately differentiate HIV-1 and HIV-2 infections. STUDY DESIGN: Two panels were used to determine the ability of each method to properly classify HIV-1 and HIV-2 infections: an HIV-2 panel (n=114) determined to be HIV-2 antibody-positive by both Multispot and by a validated HIV-2 WB, and 2135 HIV-1/HIV-2 immunoassay repeatedly reactive (IA-RR) specimens from the New York State Department of Health Laboratory (NYS). RESULTS: By CDC WB criteria, 53 (46.5%) HIV-2 panel specimens were HIV-1 WB positive, 60 (52.6%) were indeterminate, and 1 (0.9%) was negative; the alternative WB criteria re-classified 75.5% of the positives as indeterminate. Among 2135 NYS IA-RR specimens, the alternative WB criteria increased the proportion of indeterminates by 0.8%. Only 6 (0.3%) of the NYS specimens were determined to be HIV-2 infections; all 6 were classified either as HIV-1 positive or indeterminate by both WB criteria, but were classified as HIV-2 (n=4) or HIV-1/2 undifferentiated (n=2) by Multispot. CONCLUSIONS: The alternative WB criteria classified most of the HIV-2 specimens that were HIV-1 positive by CDC criteria as indeterminate, but also slightly increased the proportion of HIV-1 specimens classified as indeterminate. The WB indeterminate specimens would require further testing or follow-up to resolve the infection status, whereas Multispot directly distinguished HIV-1 from HIV-2.

Evaluation of pooling strategies for acute HIV-1 infection screening using nucleic acid amplification testing.

A 128-member specimen pooling scheme for acute HIV infection (AHI) detection was evaluated using 21 AHI specimens (range, 1,520 to 500,000 copies/ml) previously identified by RNA testing of 16-member plasma pools. HIV-1 RNA was detectable in 128-member pools for all 21 specimens; however, one pool created from a specimen with 1,827 copies/ml was nonreactive in one of three replicates.

Performance of the Aptima HIV-1 RNA qualitative assay with 16- and 32-member specimen pools.

The Aptima HIV-1 RNA qualitative assay tested with a WHO-approved HIV type 1 RNA standard in 16- and 32-member pools detected 100% of the pools (1,070 and 2,130 HIV-1 RNA copies/ml/pool, respectively), thus exceeding the FDA-required lower limit of detection. The Aptima test can be used to screen for acute-phase HIV infection.

Rapid human immunodeficiency virus test quality assurance practices and outcomes among testing sites affiliated with 17 public health departments.

Rapid human immunodeficiency virus testing is often conducted in nonclinical settings by staff with limited training, so quality assurance (QA) monitoring is critical to ensure accuracy of test results. Rapid tests (n = 86,749) were generally conducted according to manufacturers' instructions, but ongoing testing competency assessments and on-site QA monitoring were not uniformly conducted.

Repeat confirmatory testing for persons with discordant whole blood and oral fluid rapid HIV test results: findings from post marketing surveillance.

BACKGROUND: Reactive oral fluid and whole blood rapid HIV tests must be followed with a confirmatory test (Western blot (WB), immunofluorescent assay (IFA) or approved nucleic acid amplification test (NAAT)). When the confirmatory result is negative or indeterminate (i.e. discordant with rapid result), repeat confirmatory testing should be conducted using a follow-up specimen. Previous reports have not described whether repeat testing adequately resolves the HIV-infection status of persons with discordant results. METHODOLOGY: Post-marketing surveillance was conducted in 368 testing sites affiliated with 14 state and 2 city health departments from August 11, 2004 to June 30, 2005 and one health department through December 31, 2005. For persons with discordant results, data were collected on demographics, risk behaviors, HIV test results and specimen types. Persons with repeat confirmatory results were classified as HIV-infected or uninfected. Regression models were created to assess risk factors for not having repeat testing. PRINCIPAL FINDINGS: Of 167,371 rapid tests conducted, 2589 (1.6%) were reactive: of these, 2417 (93%) had positive WB/IFA, 172 (7%) had negative or indeterminate WB/IFA. Of 89/172 (52%) persons with a repeat confirmatory test: 17 (19%) were HIV-infected, including 3 with indeterminate WB and positive NAAT; 72 (81%) were uninfected, including 12 with repeat indeterminate WB. Factors associated with HIV-infection included having an initial indeterminate WB/IFA (vs. negative) (p<0.001) and having an initial oral fluid WB (vs. serum) (p<0.001). Persons who had male-female sex (vs. male-male sex) were at increased risk for not having a repeat test [adjusted OR 2.6, 95% CI (1.3, 4.9)]. CONCLUSIONS: Though only half of persons with discordant results had repeat confirmatory testing, of those who did, nearly one in five were HIV-infected. These findings underscore the need for rapid HIV testing programs to increase repeat confirmatory testing for persons with discordant results. Because of the lower sensitivity of oral fluid WBs, confirmatory testing following a reactive rapid test should be conducted using serum or plasma, when possible.

Post-marketing surveillance of OraQuick whole blood and oral fluid rapid HIV testing.

OBJECTIVE: Post-marketing surveillance was conducted to monitor the performance of the OraQuick Advance rapid HIV-1/2 antibody test (OraQuick) on whole blood and oral fluid. DESIGN: Surveillance of routinely collected data on clients tested with OraQuick in 368 testing sites affiliated with 17 state and city health departments between 11 August 2004 and 30 June 2005. METHODS: For whole blood and oral fluid, we report the median (range) health department OraQuick specificity and positive predictive value (PPV), and the number of clients with discordant results (e.g. who had a reactive rapid test not confirmed positive by Western blot or indirect immunofluorescence). At one site with lower than expected oral-fluid specificity, we evaluated whether device expiration, manufacturing lot, operator practices, or device-storage or testing-area temperatures were associated with false-positive tests. RESULTS: During the surveillance period, 135 724 whole blood and 26 066 oral fluid rapid tests were conducted. The median health department whole blood OraQuick specificity was 99.98% (range: 99.73-100%) and PPV was 99.24% (range: 66.67-100%); the median oral fluid specificity was 99.89% (range: 99.44-100%) and PPV was 90.00% (range: 50.00-100%). A total of 124 discordant results were reported from 68 (0.05%) whole blood and 56 (0.22%) oral fluid rapid tests. The oral fluid specificity at the site with excess oral fluid false-positive tests was 98.7% (95% confidence interval: 98.18-99.11%). The increase in false-positive tests at that site was not associated with any specific device characteristic, operator procedure or temperature condition. CONCLUSION: The specificity of OraQuick performed on whole blood and oral fluid during post-marketing surveillance was compatible with the manufacturer's claim within the package insert. However, one site experienced lower than expected oral fluid specificity. Sites that observe that the specificity of OraQuick is lower than the range indicated in the package insert should notify the manufacturer and evaluate quality assurance procedures.