False-Reactive Fourth-Generation Human Immunodeficiency Virus Testing in Cancer Patients.

BACKGROUND: The fourth-generation (4th-gen) human immunodeficiency virus (HIV)-1/2 antibody/antigen (Ab/Ag) combination immunoassay currently used for HIV screening offers greater sensitivity than previous assays, but false-reactive results occur in up to 20% of patients. Large-scale observations in cancer patients are lacking. METHODS: We conducted a retrospective study of cancer patients seen at the University of Texas MD Anderson Cancer Center (March 2016-January 2023) who had reactive 4th-gen ARCHITECT HIV-1/2 Ab/Ag combination immunoassay results. We analyzed characteristics of patients with true-reactive and false-reactive results, defined based on Centers for Disease Control and Prevention criteria. RESULTS: A total of 43 637 patients underwent 4th-gen HIV screening, and 293 had reactive 4th-gen HIV test results. Twenty-one patients were excluded because they did not have cancer. Among the remaining 272 patients, 78 (29%) had false-reactive results. None of these patients experienced delays in their cancer treatment, but 26% experienced mental distress. Multivariate logistic regression analysis identified 5 predictors of having false-reactive results: age >60 years (adjusted odds ratio [aOR], 6.983; P < .0001), female sex (aOR, 6.060; P < .0001), race/ethnicity (Black: aOR, 0.274; Hispanic: aOR, 0.236; P = .002), syphilis coinfection (aOR, 0.046; P = .038), and plant alkaloids therapy (aOR, 2.870; P = .013). CONCLUSIONS: False-reactive 4th-gen HIV test results occur in almost one-third of cancer patients. Physicians should be aware of the high rates of false-reactive HIV screening results in this patient population. These findings may have implications for counseling regarding testing, especially among those at low risk for HIV infection.

Repeated false reactive ADVIA centaur® and bio-rad Geenius™ HIV tests in a patient self-administering anabolic steroids.

BACKGROUND: An individual is considered HIV positive when a confirmatory HIV-1/HIV-2 differentiation test returns positive following an initial reactive antigen/antibody combination screen. Falsely reactive HIV screens have been reported in patients with various concomitant infectious and autoimmune conditions. Falsely positive confirmatory HIV differentiation assays are seen less frequently, but have been observed in cases of pregnancy, pulmonary embolism, and malaria. CASE PRESENTATION: A healthy 27 year-old man was referred after a reactive ADVIA Centaur® HIV Ag/Ab screen and positive Bio-Rad Geenius™ HIV 1/2 Confirmatory assay, suggesting HIV-1 infection. The patient's HIV viral load was undetectable prior to initiation of antiretroviral therapy, and remained undetectable on subsequent testing after initiation of antiretroviral therapy. Both Centaur® and Geenius™ tests were repeated and returned reactive. As this patient was believed to be at low risk of acquiring HIV infection, samples were additionally run on Genscreen™ HIV-1 Ag assay and Fujirebio Inno-LIA™ HIV-1/2 score, with both returning non-reactive. For confirmation, the patient's proviral HIV DNA testing was negative, confirming the initial results as being falsely positive. The patient disclosed that he had been using a variety of anabolic steroids before and during the time of HIV testing. DISCUSSION AND CONCLUSIONS: The erroneous diagnosis of HIV can result in decreased quality of life and adverse effects of antiretroviral therapy if initiated, hence the importance of interpreting the results of HIV testing in the context of an individual patient. This reports suggests a potential association between the use of anabolic steroids and falsely-reactive HIV testing.

Intravenous immunoglobulin infusion contributes to a high incidence of false reactive screen results for human T-lymphotropic virus.

Intravenous immunoglobulin (IVIg) has been increasingly used to treat immunodeficiencies and inflammatory disorders. However, IVIg has also been shown to affect a wide range of laboratory testing, including human T-lymphotropic virus (HTLV) screening. Our laboratory frequently observes false reactive HTLV screens from patients receiving IVIg infusions, however the extent of IVIg contribution to the false reactivity has not been extensively investigated. The objective of this study was to explore the prevalence of HTLV-1/2 infection in patients from the Sydney metropolitan area and evaluate the positive predictive value for HTLV screening test in sera from patients with or without IVIg infusions. HTLV screening test results from sera of 3843 patients referred to Central Sydney Immunology Laboratory between June 2006 and May 2021 were retrospectively analysed. Among 72 (1.9%) sera reactive on screening enzyme-linked immunosorbent assay (ELISA), 62 (86.1%) were from patients receiving IVIg infusions, including 60 collected post-IVIg and two collected pre-IVIg infusions. Only two (3.3%) of the 60 post-IVIg sera were positive on confirmatory western blot. In contrast, in non-IVIg sera, five (50.0%) from the 10 screen-reactive sera were positive on western blot. If positive western blot is used as the reference for determining 'true' HTLV infection, we found the positive predictive value of HTLV screening ELISA in sera collected post-IVIg (3.3%) is considerably lower than that in non-IVIg and pre-IVIg sera (41.7%). The vast majority of false reactive screen results (89.2%) in our study cohort were from sera collected post-IVIg infusion. Our study suggests that the high incidence of falsely reactive results in HTLV screening ELISA could be attributed to IVIg infusion. Hence, collection of sera from patients on IVIg should be avoided and screen-reactive results should be interpreted with greater caution, particularly for patients from non-endemic areas.

False reactive HIV-1 diagnostic test results in an individual from Kenya on multiple testing platforms-A case report.

BACKGROUND: Rapid diagnostic tests (RDT) are routinely used in screening for HIV infection. More complex diagnostic algorithms incorporating fourth-generation screening and confirmatory HIV-1/HIV-2 differentiation immunoassays (IA) may be used to confirm HIV infection. Co-infections and autoimmune diseases may lead to falsely reactive HIV diagnostic test results. CASE PRESENTATION: A Kenyan man with asymptomatic schistosomiasis and low risk factors for HIV infection demonstrated an inconsistent and discordant pattern of reactivity on HIV RDT, repeated reactivity on fourth-generation IA and positive at a single time-point for HIV-1 on the Geenius HIV1/HIV2 confirmatory assay during the course of a prospective cohort study with HIV repeat testing. The individual initiated antiretroviral therapy following HIV diagnosis. However, his bi-annual behavioral questionnaire suggested low-risk factors for infection. Supplementary confirmatory serologic and nucleic acid tests were performed and gave discordant results. The participant was determined to be HIV uninfected using cell-associated HIV-1 DNA/RNA testing and antiretroviral therapy was discontinued. DISCUSSION AND CONCLUSIONS: Sole reliance on diagnostic test results may result in misdiagnosis of HIV infection, social harm and potential antiretroviral induced drug toxicity. Interpretation of HIV test results should incorporate multiple parameters.

Re-reading of OraQuick HIV-1/2 rapid antibody test results: quality assurance implications for HIV self-testing programmes.

INTRODUCTION: Scale-up of HIV self-testing (HIVST) will play a key role in meeting the United Nation's 90-90-90 targets. Delayed re-reading of used HIVST devices has been used by early implementation studies to validate the performance of self-test kits and to estimate HIV positivity among self-testers. We investigated the stability of results on used devices under controlled conditions to assess its potential as a quality assurance approach for HIVST scale-up. METHODS: 444 OraQuick® HIV-1/2 rapid antibody tests were conducted using commercial plasma from two HIV-positive donors and HIV-negative plasma (high-reactive n = 148, weak-reactive n = 148 and non-reactive n = 148) and incubated them for six months under four conditions (combinations of high and low temperatures and humidity). Devices were re-read daily for one week, weekly for one subsequent month and then once a month by independent readers unaware of the previous results. We used multistage transition models to investigate rates of change in device results, and between storage conditions. RESULTS AND DISCUSSION: There was a high incidence of device instability. Forty-three (29%) of 148 initially non-reactive results became false weak-reactive results. These changes were observed across all incubation conditions, the earliest on Day 4 (n = 9 kits). No initially HIV-reactive results changed to a non-reactive result. There were no significant associations between storage conditions and hazard of results transition. We observed substantial statistical agreement between independent re-readers over time (agreement range: 0.74 to 0.96). CONCLUSIONS: Delayed re-reading of used OraQuick® HIV-1/2 rapid antibody tests is not currently a valid methodological approach to quality assurance and monitoring as we observed a high incidence (29%) of true non-reactive tests changing to false weak-reactive and therefore its use may overestimate true HIV positivity.

Heterophilic interference in specimens yielding false-reactive results on the Abbott 4th generation ARCHITECT HIV Ag/Ab Combo assay.

BACKGROUND: False-reactivity in HIV-negative specimens has been detected in HIV fourth-generation antigen/antibody or 'combo' assays which are able to detect both anti-HIV-1/HIV-2 antibodies and HIV-1 antigen. OBJECTIVES: We sought to characterize these specimens and determine the effect of heterophilic interference. STUDY DESIGN: Specimens previously testing as false-reactive on the Abbott ARCHITECT HIV Ag/Ab combo assay and re-tested on a different (Siemens ADVIA Centaur HIV Ag/Ab) assay. A subset of these specimens were also pre-treated with heterophilic blocking agents and re-tested on the Abbott assay. RESULTS: Here we report that 95% (252/264) of clinical specimens that were repeatedly reactive on the Abbott ARCHITECT HIV Ag/Ab combo assay (S/Co range, 0.94-678) were negative when re-tested on a different fourth generation HIV combo assay (Siemens ADVIA Centaur HIV Ag/Ab). All 264 samples were subsequently confirmed to be HIV negative. On a small subset (57) of specimens with available volume, pre-treatment with two different reagents (HBT; Heterophilic Blocking Tube, NABT; Non-Specific Blocking Tube) designed to block heterophilic antibody interference either eliminated (HBT) or reduced (NABT) the false reactivity when re-tested on the ARCHITECT HIV Ag/Ab combo assay. CONCLUSIONS: Our results suggest that the Abbott ARCHITECT HIV Ag/Ab combo assay can be prone to heterophilic antibody interference.

Specificity of two HIV screening tests detecting simultaneously HIV-1 p24 antigen and antibodies to HIV-1 and -2.

This study aimed at assessing the specificity of the Elecsys® HIV combi PT in comparison to the ARCHITECT® HIV Ag/Ab Combo. With both of these assays, 3997 unselected sera from patients of a tertiary health care centre in Basel, Switzerland, were screened for HIV. Reactive sera were reanalysed on the VIDAS® HIV Duo Ultra to identify false-reactive specimens prior to confirmation by quantitative PCR and line immunoassay. The Elecsys® compared to the ARCHITECT® shows a similar specificity (99.7% versus 99.8%) but a slightly lower positive predictive value (71.8% versus 80%). Samples tested with a cut-off index (COI) between 0.91 and 4.85 (cut-off <0.9) with the Elecsys® and with a signal to cut-off index (S/CO) between 1.09 and 12.49 (cut-off <1.0) with the ARCHITECT® were false-reactive. There was no false-reactive result with the VIDAS®. Of the false-reactive samples, 66.7% could be related to patient-specific underlying conditions. The HIV two-tiered diagnostic algorithm proposed in this work improved the positive predictive values of the Elecsys® or ARCHITECT® to 100% when the results of the VIDAS® were included. Values just above the cut-off are highly suspicious to be false-reactive and high COI or S/CO ratios are associated with true positivity.