Evaluation of HIV testing algorithms in Ethiopia: the role of the tie-breaker algorithm and weakly reacting test lines in contributing to a high rate of false positive HIV diagnoses

Molecular epidemiology of hepatitis B virus among HIV co-infected and mono-infected cohorts in Northwest Ethiopia

BACKGROUND

Hepatitis B virus (HBV) infection is a particular concern in human immunodeficiency virus (HIV) infected individuals. In Ethiopia, detailed clinical and virological descriptions of HBV prevailing during HIV co-infection and symptomatic liver disease patients are lacking. The aim of this study was to investigate HBV virological characteristics from Ethiopian HBV/HIV co-infected and HBV mono-infected individuals.

METHODS

A total of 4105 sera from HIV positive individuals, liver disease patients, and blood donors were screened serologically for HBV. The overlapping polymerase/surface genome region of HBV from 180 infected individuals was extracted, amplified, and sequenced for genotypic analysis.

RESULTS

The HBsAg seroprevalence was detected 43% in liver disease patients, 8.4% in blood donors, and 6.7% in HIV/HBV co-infected individuals. The occult HBV prevalence was 3.7% in HIV/HBV co-infected individuals and 2.8% in blood donors with an overall prevalence rate of 3.4%. A phylogenetic analysis showed three HBV genotypes; A (61.1%), D (38.3%) and E (0.6%). Genotype A belongs to subtypes A1 (99.1%) and A9 (0.9%), but genotype D showed heterogeneous subtypes; D2 (63.8%) followed by D4 (21.7%), D1 (8.7%), D3 (4.3%), and D10 (1.4%).

CONCLUSIONS

The HIV/HBV co-infected individuals and blood donors showed lower HBsAg seroprevalence compared to liver diseases patients. Occult HBV prevalence showed no difference between HIV/HBV co-infected and blood donor groups. This study demonstrated predominance distribution of HBV subtypes A1 and D2 in northwest Ethiopia. The observed virological characteristics could contribute for evidence-based management of viral hepatitis in Ethiopia where antiretroviral therapy guidelines do not cater for viral hepatitis screening during HIV co-infection.

Assessment of HIV Rapid Test Kits Inventory Management Practice and Challenges in Public Health Facilities of Addis Ababa, Ethiopia

Background

Many people with undiagnosed HIV live in sub-Saharan Africa and vulnerable laboratory systems undermine testing services.

Methods

A facility-based mixed-approach cross-sectional study was conducted from January 1 to February 1, 2020. A total of 23 health facilities were included in the study which stratified into hospitals and health centers. Six months of bin card records and request and resupply forms (RRFs) were reviewed. Data were collected through physical inventory, observation, and document review. After the data was imported into the MS Excel 2016 spreadsheet, it was analyzed using SPSS | Version 20 | Software. In addition, 12 semi-structured in-depth interviews were conducted and responses were analysed using a thematic approach.

Results

The entire health facility had RRF reports and bin card records while the availability of HIV rapid test kits was 75%. More than half, 38 (55.1%) of the bin card records were updated and the average data accuracy of bin cards was 84.1%. The data quality of the RRF reports was determined accurate 18 (78.3%), complete 15 (65.22%), and on-time 7 (30.3%). Sixteen (69.6%) health facilities experienced at least one stock out with an average daily stock out of 4%. The wastage rate was 0.0083%. Only 9 (39.1%) health facilities have fulfilled acceptable storage conditions.

Conclusion

Most of the health facilities did no longer fulfilled acceptable storage conditions. Similarly, the data quality of most bin card records and RRF reports was poor. This deprived inventory management practice was likely related to supply, staff, and documentation challenges.

HIV-1 diagnosis using dried blood spots from patients in Kinshasa, DRC: a tool to detect misdiagnosis and achieve World Health Organization 2030 targets

INTRODUCTION

Currently, only 54% of the population of the Democratic Republic of the Congo (DRC) know their HIV status. The aim of this study was to detect HIV misdiagnosis from rapid diagnostic tests (RDT) and to evaluate serological immunoassays using dried blood spots (DBS) from patients in Kinshasa, DRC.

METHODS

Between 2016 and 2018, 365 DBS samples were collected from 363 individuals and shipped to Spain. The samples were from people with a new HIV positive (n = 123) or indeterminate (n = 23) result, known HIV-positive patients (n = 157), and a negative control group (n = 62). HIV serology was performed using Elecsys HIV combi PT (Roche), VIDAS HIV Duo Quick (BioMérieux), and Geenius (Bio-Rad). In addition, HIV RNA detection was performed in all samples using the COBAS AmpliPrep/COBAS Taqman HIV-1 Test 2.0 (Roche).

RESULTS

Overall, 272 samples were found to be positive and 93 to be negative for HIV serology. The sensitivity was 100% for both Elecsys and VIDAS techniques, but specificity was slightly higher for the VIDAS test: 100% (96.1-100%) vs 98.9% (94.1-99.9%). Of the 23 indeterminate cases using RDT, only three cases were true-positives with a detectable viral load. Eleven samples out of the 280 classified as positive by RDT corresponded to nine patients who had received a false diagnosis of HIV through RDT (3.9%); six of them had been on antiretroviral therapy for at least 2 years.

CONCLUSIONS

Elecsys HIV combi PT and VIDAS HIV Duo Quick immunoassays showed high sensitivity and specificity when using DBS. RDT-based serological diagnosis can lead to HIV misdiagnosis with personal and social consequences in sub-Saharan Africa.

Utilization of Rapid Diagnostic Testing in sub-Saharan Africa: Challenges and Effects on HIV Prevention

The human immunodeficiency virus (HIV) remains a global threat to health. To prevent and control the disease caused by the virus, developed and developing countries continue to invest heavily in research and equipment so as to accurately detect the virus. The utilization of highly sensitive and effective rapid diagnostic tests (RDTs) have the potential to detect HIV in high-burden countries, especially those in sub-Saharan Africa (SSA). Yet, in SSA, challenges associated with HIV-RDT result inaccuracy, HIV misdiagnosis, poor tester capacity, and the improper storage of HIV-RDT kits have negatively impacted the benefits, and threaten to undermine HIV prevention. This paper focuses on the utilization of RDTs in HIV diagnosis in SSA, HIV-RDT challenges, and the effects of HIV-RDT challenges on HIV prevention. Subsequent to reviewing available literature, the authors found that although HIV-RDTs can negatively impact HIV-prevention efforts in SSA due to the likelihood of false positive HIV diagnoses, they generally provide quick results for people in resource poor settings, and do not require them to return to the testing sites to obtain their results. Obtaining accurate rapid HIV results means people who test positive can immediately seek care and take steps to prevent future transmission of the virus.

The use of the GeeniusTM HIV-1/2 Rapid confirmatory test for the enrolment of patients and blood donors in the WHO Universal Test and Treat Strategy in Cameroon, Africa

BACKGROUND AND OBJECTIVE

In the WHO Universal test and treat strategy, false-positive HIV blood donors and patients may be unnecessarily put under antiretroviral treatment and false-negative subjects may be lost to follow-up. This study assessed the false positivity rate of the Cameroonian national HIV screening testing algorithm and the benefit of a confirmation test in the enrolment of patients and donors in the HIV care programme.

METHODS

We included initial HIV reactive blood donors and patients in a cross-sectional study conducted in two Cameroonian hospitals. Samples were retested according to the Cameroon national algorithm for HIV diagnosis. A positive or discordant sample was retested with the Geenius Bio-Rad HIV 1&2 (Bio-Rad, Marnes-la-Coquette, France) for confirmation. The Geenius HIV-1-positive results with 'poor' profiles were retested for RNA as well as the Geenius indeterminate results.

RESULTS

Of the 356 participants, 190/225 (84·4%) patients and 76/131 (58%) blood donors were declared positive with the national algorithm; 257 participants (96·6%) were confirmed HIV-1-positive. The study revealed that about 34/1000 blood donors and patients are false-positive and unnecessarily put on treatment; 89/1000 blood donors and patients declared discordant could have been included immediately in the HIV care programme if confirmatory testing was performed. The second test of the algorithm had a false-negative rate of 3%. Eleven samples (3·1%) were Geenius poor positive and NAT negative.

CONCLUSION

The universal test and treat strategy may identify and refer more individuals to HIV care if a third rapid confirmatory test is performed for discordant cases.

Undiagnosed HIV, hepatitis B, and hepatitis C infections in people with severe psychiatric disorders in Ethiopia

Background

Worldwide, there is limited epidemiologic evidence on the seroprevalence of undiagnosed chronic viral infections including HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) infections among patients with severe psychiatric disorders. To our knowledge, this is the first study to explore and compare undiagnosed seroprevalence rates of HIV, HBV, and HCV infections among patients with severe psychiatric disorders.

Method

In this study, we included a random sample of 309 patients with severe psychiatric disorders selected by systematic sampling technique. We used a structured clinical interview for DSM-IV (SCID) to confirm the diagnosis of severe psychiatric disorders among the participants. Binary and multivariable logistic regression models, adjusting for the potential confounding factors was used to explore the potential determinants of chronic viral infections.

Result

The prevalence estimates of HIV infection among patients with severe psychiatric disorders in this study (3.24%) was roughly 3 times the estimated population prevalence of HIV infection in Ethiopia (1.1%). This study showed that the prevalence rates of HBV and HCV infections among patients with severe psychiatric disorders were 4.85 and 1.29%, respectively. Our results also showed that among patients with chronic viral infections, HIV, HBV and HCV, 76.92, 60, 80, and 75% respectively were undiagnosed. Regarding associated factors, the presence of chronic viral infection was found to be significantly associated with the age of the participants (ranging between 30 and 40 years) after adjusting for the possible confounding factors [AOR = 3.95 (95%CI.18–13.17)].

Conclusion

Even though the prevalence estimates of HIV (3.24%), HBV (4.85%), and HCV (1.29%) infections were high among patients with severe psychiatric disorders, the majority of them remained undiagnosed. HBV was found to be the commonly undiagnosed infection (4 out of 5) followed by HCV (3 out of 4) and HIV (6 out of 10). The present study provided evidence of a significant association between the age of the participant (between 30 and 40 years) and chronic viral infections in patients with severe psychiatric disorders. Increasing the awareness of psychiatry professionals and early screening, as well as interventions of chronic viral infections among patients with severe psychiatric disorders are imperative.

Cost implications of HIV retesting for verification in Africa

INTRODUCTION

HIV misdiagnosis leads to severe individual and public health consequences. Retesting for verification of all HIV-positive cases prior to antiretroviral therapy initiation can reduce HIV misdiagnosis, yet this practice has not been not widely implemented.

METHODS

We evaluated and compared the cost of retesting for verification of HIV seropositivity (retesting) to the cost of antiretroviral treatment (ART) for misdiagnosed cases in the absence of retesting (no retesting), from the perspective of the health care system. We estimated the number of misdiagnosed cases based on a review of misdiagnosis rates, and the number of positives persons needing ART initiation by 2020. We presented the total and per person costs of retesting as compared to no retesting, over a ten-year horizon, across 50 countries in Africa grouped by income level. We conducted univariate sensitivity analysis on all model input parameters, and threshold analysis to evaluate the parameter values where the total costs of retesting and the costs no retesting are equivalent. Cost data were adjusted to 2017 United States Dollars.

RESULTS AND DISCUSSION

The estimated number of misdiagnoses, in the absence of retesting was 156,117, 52,720 and 29,884 for lower-income countries (LICs), lower-middle income countries (LMICs), and upper middle-income countries (UMICs), respectively, totaling 240,463 for Africa. Under the retesting scenario, costs per person initially diagnosed were: $40, $21, and $42, for LICs, LMICs, and UMICs, respectively. When retesting for verification is implemented, the savings in unnecessary ART were $125, $43, and $75 per person initially diagnosed, for LICs, LMICs, and UMICs, respectively. Over the ten-year horizon, the total costs under the retesting scenario, over all country income levels, was $475 million, and was $1.192 billion under the no retesting scenario, representing total estimated savings of $717 million in HIV treatment costs averted.

CONCLUSIONS

Results show that to reduce HIV misdiagnosis, countries in Africa should implement the WHO's recommendation of retesting for verification prior to ART initiation, as part of a comprehensive quality assurance program for HIV testing services.

HIV Testing After a First Positive Rapid Diagnostic Test: A Role for Nucleic Acid Testing?

We developed an open-access, Excel-based model simulating currently recommended and alternative algorithms for adult HIV testing as a preliminary investigation of trade-offs between accuracy and costs. Despite higher costs, simpler HIV testing algorithms incorporating point of care nucleic acid testing may improve outcomes and thus merit additional research and field testing.

False-positive HIV diagnoses: lessons from Ugandan and Russian research cohorts

BACKGROUND

Research studies rely on accurate assessment of entry criteria in order to maintain study integrity and participant safety, however, challenges can exist with HIV studies in international settings.

OBJECTIVE

Examine the unexpectedly high proportion of study participants with an undetectable HIV viral load found in Ugandan and Russian research cohorts meeting antiretroviral therapy (ART)-naïve entry criteria.

METHODS

Russian participants with documented HIV and ART-naïve status were recruited between 2012 and 2015 from clinical and non-clinical sites in St. Petersburg. Participants in Uganda were recruited from Mbarara Regional Referral Hospital from 2011 to 2014 with documented HIV infection via rapid diagnostic testing and recorded ART-naïve in the clinic database. HIV viral load testing of baseline samples was performed; the lower limit of detection was 500 copies/mL in Russia and 40 in Uganda. Due to an unexpectedly high proportion of participants with undetectable viremia, additional tests were performed: enzyme-linked immunosorbent assay HIV testing and testing for ART.

RESULTS

In Russia, 16% (58/360) had undetectable viremia; 3% (9/360) re-tested HIV-seronegative and 4% (13/360) tested positive for ART. In Uganda 11% (55/482) had undetectable viremia; 5% (26/482) re-tested HIV-seronegative, while <1% (4/482) tested positive for ART.

CONCLUSIONS

In both Russia & Uganda, undetectable viremia was much higher than would be expected for an HIV-infected ART-naïve cohort. Misclassification of study participants was due to misdiagnosis of HIV with rapid diagnostic testing and inaccurate accounting of ART use. Confirmatory HIV testing could improve accuracy of participants meeting entry criteria for HIV infection as might increased scrutiny of medication use in an ART-naïve cohort.

Misdiagnosis of HIV infection during a South African community-based survey: implications for rapid HIV testing

Introduction: We describe the overall accuracy and performance of a serial rapid HIV testing algorithm used in community-based HIV testing in the context of a population-based household survey conducted in two sub-districts of uMgungundlovu district, KwaZulu-Natal, South Africa, against reference fourth-generation HIV-1/2 antibody and p24 antigen combination immunoassays. We discuss implications of the findings on rapid HIV testing programmes.

Methods: Cross-sectional design: Following enrolment into the survey, questionnaires were administered to eligible and consenting participants in order to obtain demographic and HIV-related data. Peripheral blood samples were collected for HIV-related testing. Participants were offered community-based HIV testing in the home by trained field workers using a serial algorithm with two rapid diagnostic tests (RDTs) in series. In the laboratory, reference HIV testing was conducted using two fourth-generation immunoassays with all positives in the confirmatory test considered true positives. Accuracy, sensitivity, specificity, positive predictive value, negative predictive value and false-positive and false-negative rates were determined.

Results: Of 10,236 individuals enrolled in the survey, 3740 were tested in the home (median age 24 years (interquartile range 19–31 years), 42.1% males and HIV positivity on RDT algorithm 8.0%). From those tested, 3729 (99.7%) had a definitive RDT result as well as a laboratory immunoassay result. The overall accuracy of the RDT when compared to the fourth-generation immunoassays was 98.8% (95% confidence interval (CI) 98.5–99.2). The sensitivity, specificity, positive predictive value and negative predictive value were 91.1% (95% CI 87.5–93.7), 99.9% (95% CI 99.8–100), 99.3% (95% CI 97.4–99.8) and 99.1% (95% CI 98.8–99.4) respectively. The false-positive and false-negative rates were 0.06% (95% CI 0.01–0.24) and 8.9% (95% CI 6.3–12.53). Compared to true positives, false negatives were more likely to be recently infected on limited antigen avidity assay and to report antiretroviral therapy (ART) use.

Conclusions: The overall accuracy of the RDT algorithm was high. However, there were few false positives, and the sensitivity was lower than expected with high false negatives, despite implementation of quality assurance measures. False negatives were associated with recent (early) infection and ART exposure. The RDT algorithm was able to correctly identify the majority of HIV infections in community-based HIV testing. Messaging on the potential for false positives and false negatives should be included in these programmes.

Identification of misdiagnosed HIV clients in an Early Access to ART for All implementation study in Swaziland

Introduction: Rapid diagnostic testing has made HIV diagnosis and subsequent treatment more accessible. However, multiple factors, including improper implementation of testing strategies and clerical errors, have been reported to lead to HIV misdiagnosis. The World Health Organization has recommended HIV retesting prior to antiretroviral therapy (ART) initiation which has become pertinent with scaling up of Early Access to ART for All (EAAA). In this analysis, misdiagnosed clients are identified from a subgroup of clients enrolled in EAAA implementation study in Swaziland.

Methods: The subgroup to assess misdiagnosis was identified from enrolled EAAA study clients, who had an undetectable viral load prior to ART initiation between September 1, 2014 and May 31, 2016. One hundred and five of 2533 (4%) clients had an undetectable viral load prior to initiation to ART (pre-ART). The HIV status of clients was confirmed using the Determine HIV 1/2 and Uni-Gold HIV 1/2 rapid tests performed serially as recommended by the national testing algorithm. The status of clients on ART was additionally confirmed by fourth-generation HIV Ag/Ab combo tests, Architect and Genscreen Ultra.

Results: Fourteen of the 105 (13%) clients were false positive (HIV negative) on confirmation testing, of whom five (36%) were still in pre-ART care, while nine (64%) were in ART care. Overall, proportion of false positive was 0.6% (14/2533). The false-positive clients had a median CD4 of 791 cells/ml (interquartile range (IQR): 628, 967) compared to 549 cells/ml (IQR: 387, 791) for true positives (HIV positive) (p = 0.0081) and were nearly 20 years older (p = 0.0008).

Conclusions: Overall 0.6% of all enrolled EAAA clients were misdiagnosed, and 64% of misdiagnosed clients were initiated on ART. With adoption of EAAA guidelines by national governments, ART initiation regardless of immunological criteria, strengthening of proficiency testing and adoption of retesting prior to ART initiation would allow identification of misdiagnosed clients and further reduce potential of initiating misdiagnosed clients on ART.

HIV misdiagnosis in sub-Saharan Africa: performance of diagnostic algorithms at six testing sites

Introduction: We evaluated the diagnostic accuracy of HIV testing algorithms at six programmes in five sub-Saharan African countries.

Methods: In this prospective multisite diagnostic evaluation study (Conakry, Guinea; Kitgum, Uganda; Arua, Uganda; Homa Bay, Kenya; Doula, Cameroun and Baraka, Democratic Republic of Congo), samples from clients (greater than equal to five years of age) testing for HIV were collected and compared to a state-of-the-art algorithm from the AIDS reference laboratory at the Institute of Tropical Medicine, Belgium. The reference algorithm consisted of an enzyme-linked immuno-sorbent assay, a line-immunoassay, a single antigen-enzyme immunoassay and a DNA polymerase chain reaction test.

Results: Between August 2011 and January 2015, over 14,000 clients were tested for HIV at 6 HIV counselling and testing sites. Of those, 2786 (median age: 30; 38.1% males) were included in the study. Sensitivity of the testing algorithms ranged from 89.5% in Arua to 100% in Douala and Conakry, while specificity ranged from 98.3% in Doula to 100% in Conakry. Overall, 24 (0.9%) clients, and as many as 8 per site (1.7%), were misdiagnosed, with 16 false-positive and 8 false-negative results. Six false-negative specimens were retested with the on-site algorithm on the same sample and were found to be positive. Conversely, 13 false-positive specimens were retested: 8 remained false-positive with the on-site algorithm.

Conclusions: The performance of algorithms at several sites failed to meet expectations and thresholds set by the World Health Organization, with unacceptably high rates of false results. Alongside the careful selection of rapid diagnostic tests and the validation of algorithms, strictly observing correct procedures can reduce the risk of false results. In the meantime, to identify false-positive diagnoses at initial testing, patients should be retested upon initiating antiretroviral therapy.

One or two serological assay testing strategy for diagnosis of HBV and HCV infection? The use of predictive modelling

BACKGROUND

Initial serological testing for chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infection is conducted using either rapid diagnostic tests (RDT) or laboratory-based enzyme immunoassays (EIA)s for detection of hepatitis B surface antigen (HBsAg) or antibodies to HCV (anti-HCV), typically on serum or plasma specimens and, for certain RDTs, capillary whole blood. WHO recommends the use of standardized testing strategies - defined as a sequence of one or more assays to maximize testing accuracy while simplifying the testing process and ideally minimizing cost. Our objective was to examine the diagnostic outcomes of a one- versus two-assay serological testing strategy. These data were used to inform recommendations in the 2017 WHO Guidelines on hepatitis B and C testing.

METHODS

Few published studies have compared diagnostic outcomes for one-assay versus two-assay serological testing strategies for HBsAg and anti-HCV. Therefore, the principles of Bayesian statistics were used to conduct a modelling exercise to examine the outcomes of a one-assay versus two-assay testing strategy when applied to a hypothetical population of 10,000 individuals. The resulting model examined the diagnostic outcomes (true and false positive diagnoses; true and false negative diagnoses; positive and negative predictive values as a function of prevalence; and total tests required) for both one-assay and two-assay testing strategies. The performance characteristics assumed for assays used within the testing strategies were informed by WHO prequalification assessment findings and systematic reviews for diagnostic accuracy studies. Each of the presumptive testing strategies (one-assay or two-assay) was modelled at varying prevalences of HBsAg (10%, 2% and 0.4%) and of anti-HCV (40%, 10%, 2% and 0.4%), aimed at representing the range of testing populations typically encountered in WHO Member States. When the two-assay testing strategy was considered, the model assumed the independence of the two assays.

RESULTS

Modeling demonstrated that applying a single assay (HBsAg or anti-HCV), even with high specificity (99%), may result in considerable numbers of false positive diagnoses and low positive predictive values (PPV), particularly in lower prevalence settings. Even at very low prevalences shifting to a two-assay testing strategy would result in a PPV approaching 1.0. When test sensitivity is high (>99%) false negative reactions are rare at all but the highest prevalences; but a two-test strategy might yield more false negative diagnoses. The order in which the tests are used has no impact on the overall accuracy of a two-assay strategy though it may impact the total number of tests needed to complete the diagnostic strategy, incurring added cost and complexity. HBsAg assays may have a low sensitivity (<90%), and result in large numbers of false negative diagnoses, particularly in high prevalence settings, which would be exacerbated in the two-assay testing strategy. In contrast, most anti-HCV assays have high sensitivity and lead to fewer false negative results, both in the one-assay and two-assay testing strategies. At prevalences ≤2% the number of tests needed using a second assay was nearly always small, at <300 per 10,000 individuals tested, making sustainability of a second assay uncertain in such a setting.

CONCLUSIONS

A key public health objective of an effective testing strategy is to identify all individuals who would benefit from treatment. Therefore, a strategy that prioritizes a high NPV (minimal false negatives) may be acceptable even if the PPV is suboptimal (some false positives) as the implementation of such a public health programme must also take account of other factors such as costs, feasibility, impact on testing uptake and linkage to care, and consequences of a false-positive test. This rationale informed the development of the WHO Viral Hepatitis Testing Guidelines, with a conditional recommendation for a one-assay serological testing strategy in most testing settings and populations (≥0.4% prevalence in population tested). A one-test strategy results in few failures to diagnose infection and, although it is associated under most assumptions with a sub-optimal PPV, benefits include greater simplicity, easier implementation, lower costs and better feasibility, uptake and linkage to care. Furthermore, prior to antiviral therapy all those diagnosed either HBsAg or anti-HCV positive will require confirmation of viræmia, preventing unnecessary treatment of those who may be false positive on serology. For HBsAg, in low-prevalence settings (≤0.4%), a second recommendation was made to consider a two-assay testing strategy, using a confirmatory neutralization step or a second different HBsAg assay.

Rapid Diagnostic Testing of Hospitalized Malawian Children Reveals Opportunities for Improved HIV Diagnosis and Treatment

Recent World Health Organization (WHO) guidelines recommend antiretroviral therapy (ART) for all HIV-infected people; previously CD4+ T lymphocyte quantification (CD4 count) or clinical staging determined eligibility for children ≥ 5 years old in low- and middle-income countries. We examined positive predictive value (PPV) of a rapid diagnostic test (RDT) algorithm and ART eligibility for hospitalized children with newly diagnosed HIV infection. We enrolled 363 hospitalized Malawian children age 2 months to 16 years with two serial positive HIV RDT from 2013 to 2015. Children aged ≤ 18 months whose nucleic acid testing was negative or unavailable were later excluded from the analysis (N = 16). If RNA PCR was undetectable, human immunodeficiency virus (HIV) enzyme immunoassay (EIA) and western blot (WB) were performed. Those with negative or discordant EIA and WB were considered HIV negative and excluded from further analysis (N = 6). ART eligibility was assessed using age, CD4 count, and clinical HIV stage. Among 150 patients with HIV RNA PCR results, 15 had undetectable HIV RNA. Of those, EIA and WB were positive in nine patients and negative or discordant in six patients. PPV of serial RDT was 90% versus RNA PCR alone and 96% versus combined RNA PCR, EIA, and WB. Of all patients aged ≥ 5 years, 8.9% were ineligible for ART under previous WHO guidelines. Improved HIV testing algorithms are needed for accurate diagnosis of HIV infection in children as prevalence of pediatric HIV declines. Universal treatment will significantly increase the numbers of older children who qualify for ART.

Towards more accurate HIV testing in sub-Saharan Africa: a multi-site evaluation of HIV RDTs and risk factors for false positives

Introduction: Although individual HIV rapid diagnostic tests (RDTs) show good performance in evaluations conducted by WHO, reports from several African countries highlight potentially significant performance issues. Despite widespread use of RDTs for HIV diagnosis in resource-constrained settings, there has been no systematic, head-to-head evaluation of their accuracy with specimens from diverse settings across sub-Saharan Africa. We conducted a standardized, centralized evaluation of eight HIV RDTs and two simple confirmatory assays at a WHO collaborating centre for evaluation of HIV diagnostics using specimens from six sites in five sub-Saharan African countries.

Methods: Specimens were transported to the Institute of Tropical Medicine (ITM), Antwerp, Belgium for testing. The tests were evaluated by comparing their results to a state-of-the-art reference algorithm to estimate sensitivity, specificity and predictive values.

Results: 2785 samples collected from August 2011 to January 2015 were tested at ITM. All RDTs showed very high sensitivity, from 98.8% for First Response HIV Card Test 1–2.0 to 100% for Determine HIV 1/2, Genie Fast, SD Bioline HIV 1/2 3.0 and INSTI HIV-1/HIV-2 Antibody Test kit. Specificity ranged from 90.4% for First Response to 99.7% for HIV 1/2 STAT-PAK with wide variation based on the geographical origin of specimens. Multivariate analysis showed several factors were associated with false-positive results, including gender, provider-initiated testing and the geographical origin of specimens. For simple confirmatory assays, the total sensitivity and specificity was 100% and 98.8% for ImmunoComb II HIV 12 CombFirm (ImmunoComb) and 99.7% and 98.4% for Geenius HIV 1/2 with indeterminate rates of 8.9% and 9.4%.

Conclusions: In this first systematic head-to-head evaluation of the most widely used RDTs, individual RDTs performed more poorly than in the WHO evaluations: only one test met the recommended thresholds for RDTs of ≥99% sensitivity and ≥98% specificity. By performing all tests in a centralized setting, we show that these differences in performance cannot be attributed to study procedure, end-user variation, storage conditions, or other methodological factors. These results highlight the existence of geographical and population differences in individual HIV RDT performance and underscore the challenges of designing locally validated algorithms that meet the latest WHO-recommended thresholds.

Misdiagnosed HIV infection in pregnant women initiating universal ART in South Africa

INTRODUCTION

Rapid diagnostic tests (RDTs) are the primary diagnostic tools for HIV used in resource-constrained settings. Without a proper confirmation algorithm, there is concern that false-positive (FP) RDTs could result in misdiagnosis of HIV infection and inappropriate antiretroviral treatment (ART) initiation, but programmatic data on FP are few.

METHODS

We examined the accuracy of RDT diagnosis among HIV-infected pregnant women attending public sector antenatal services in Cape Town, South Africa. We describe the proportion of women found to have started on ART erroneously due to FP RDT results based on pre-ART viral load (VL) testing and enzyme-linked immunosorbent assay (ELISA).

RESULTS

We analysed 952 consecutively enrolled pregnant women diagnosed as HIV infected based on two RDTs per local guideline and found 4.5% (43/952) of pre-ART VL results to be <50 copies/ml. After excluding 6 women who had detectable virus on subsequent VL measurements, ELISA was performed on the 37 remaining women. Of these, 3/952 (0.3%) HIV RDT diagnoses were found to be FP. We estimate that using ELISA to confirm all positive RDTs would cost $1110 (uncertainty interval $381-$5382) to identify one patient erroneously initiated on ART, while it costs $3912 for a lifetime of antiretrovirals with VL monitoring for one person.

CONCLUSIONS

Compared to the cost of confirming the RDT-based diagnoses, the cost of HIV misdiagnosis is high. While testing programmes based on RDT should strive for constant quality improvement, where resources permit, laboratory confirmation algorithms can play an important role in strengthening the quality of HIV diagnosis in the era of universal ART.

To err is human, to correct is public health: a systematic review examining poor quality testing and misdiagnosis of HIV status

INTRODUCTION

In accordance with global testing and treatment targets, many countries are seeking ways to reach the "90-90-90" goals, starting with diagnosing 90% of all people with HIV. Quality HIV testing services are needed to enable people with HIV to be diagnosed and linked to treatment as early as possible. It is essential that opportunities to reach people with undiagnosed HIV are not missed, diagnoses are correct and HIV-negative individuals are not inadvertently initiated on life-long treatment. We conducted this systematic review to assess the magnitude of misdiagnosis and to describe poor HIV testing practices using rapid diagnostic tests.

METHODS

We systematically searched peer-reviewed articles, abstracts and grey literature published from 1 January 1990 to 19 April 2017. Studies were included if they used at least two rapid diagnostic tests and reported on HIV misdiagnosis, factors related to potential misdiagnosis or described quality issues and errors related to HIV testing.

RESULTS

Sixty-four studies were included in this review. A small proportion of false positive (median 3.1%, interquartile range (IQR): 0.4-5.2%) and false negative (median: 0.4%, IQR: 0-3.9%) diagnoses were identified. Suboptimal testing strategies were the most common factor in studies reporting misdiagnoses, particularly false positive diagnoses due to using a "tiebreaker" test to resolve discrepant test results. A substantial proportion of false negative diagnoses were related to retesting among people on antiretroviral therapy. Conclusions HIV testing errors and poor practices, particularly those resulting in false positive or false negative diagnoses, do occur but are preventable. Efforts to accelerate HIV diagnosis and linkage to treatment should be complemented by efforts to improve the quality of HIV testing services and strengthen the quality management systems, particularly the use of validated testing algorithms and strategies, retesting people diagnosed with HIV before initiating treatment and providing clear messages to people with HIV on treatment on the risk of a "false negative" test result.

Designing HIV Testing Algorithms Based on 2015 WHO Guidelines Using Data from Six Sites in Sub-Saharan Africa

Our objective was to evaluate the performance of HIV testing algorithms based on WHO recommendations, using data from specimens collected at six HIV testing and counseling sites in sub-Saharan Africa (Conakry, Guinea; Kitgum and Arua, Uganda; Homa Bay, Kenya; Douala, Cameroon; Baraka, Democratic Republic of Congo). A total of 2,780 samples, including 1,306 HIV-positive samples, were included in the analysis. HIV testing algorithms were designed using Determine as a first test. Second and third rapid diagnostic tests (RDTs) were selected based on site-specific performance, adhering where possible to the WHO-recommended minimum requirements of ≥99% sensitivity and specificity. The threshold for specificity was reduced to 98% or 96% if necessary. We also simulated algorithms consisting of one RDT followed by a simple confirmatory assay. The positive predictive values (PPV) of the simulated algorithms ranged from 75.8% to 100% using strategies recommended for high-prevalence settings, 98.7% to 100% using strategies recommended for low-prevalence settings, and 98.1% to 100% using a rapid test followed by a simple confirmatory assay. Although we were able to design algorithms that met the recommended PPV of ≥99% in five of six sites using the applicable high-prevalence strategy, options were often very limited due to suboptimal performance of individual RDTs and to shared falsely reactive results. These results underscore the impact of the sequence of HIV tests and of shared false-reactivity data on algorithm performance. Where it is not possible to identify tests that meet WHO-recommended specifications, the low-prevalence strategy may be more suitable.

Self-reported HIV-positive status but subsequent HIV-negative test result using rapid diagnostic testing algorithms among seven sub-Saharan African military populations

HIV rapid diagnostic tests (RDTs) combined in an algorithm are the current standard for HIV diagnosis in many sub-Saharan African countries, and extensive laboratory testing has confirmed HIV RDTs have excellent sensitivity and specificity. However, false-positive RDT algorithm results have been reported due to a variety of factors, such as suboptimal quality assurance procedures and inaccurate interpretation of results. We conducted HIV serosurveys in seven sub-Saharan African military populations and recorded the frequency of personnel self-reporting HIV positivity, but subsequently testing HIV-negative during the serosurvey. The frequency of individuals who reported they were HIV-positive but subsequently tested HIV-negative using RDT algorithms ranged from 3.3 to 91.1%, suggesting significant rates of prior false-positive HIV RDT algorithm results, which should be confirmed using biological testing across time in future studies. Simple measures could substantially reduce false-positive results, such as greater adherence to quality assurance guidelines and prevalence-specific HIV testing algorithms as described in the World Health Organization’s HIV testing guidelines. Other measures to improve RDT algorithm specificity include classifying individuals with weakly positive test lines as HIV indeterminate and retesting. While expansion of HIV testing in resource-limited countries is critical to identifying HIV-infected individuals for appropriate care and treatment, careful attention to potential causes of false HIV-positive results are needed to prevent the significant medical, psychological, and fiscal costs resulting from individuals receiving a false-positive HIV diagnosis.

The accuracy of HIV rapid testing in integrated bio-behavioral surveys of men who have sex with men across 5 Provinces in South Africa

We describe the accuracy of serial rapid HIV testing among men who have sex with men (MSM) in South Africa and discuss the implications for HIV testing and prevention.This was a cross-sectional survey conducted at five stand-alone facilities from five provinces.Demographic, behavioral, and clinical data were collected. Dried blood spots were obtained for HIV-related testing. Participants were offered rapid HIV testing using 2 rapid diagnostic tests (RDTs) in series. In the laboratory, reference HIV testing was conducted using a third-generation enzyme immunoassay (EIA) and a fourth-generation EIA as confirmatory. Accuracy, sensitivity, specificity, positive predictive value, negative predictive value, false-positive, and false-negative rates were determined.Between August 2015 and July 2016, 2503 participants were enrolled. Of these, 2343 were tested by RDT on site with a further 2137 (91.2%) having definitive results on both RDT and EIA. Sensitivity, specificity, positive predictive value, negative predictive value, false-positive rates, and false-negative rates were 92.6% [95% confidence interval (95% CI) 89.6-94.8], 99.4% (95% CI 98.9-99.7), 97.4% (95% CI 95.2-98.6), 98.3% (95% CI 97.6-98.8), 0.6% (95% CI 0.3-1.1), and 7.4% (95% CI 5.2-10.4), respectively. False negatives were similar to true positives with respect to virological profiles.Overall accuracy of the RDT algorithm was high, but sensitivity was lower than expected. Post-HIV test counseling should include discussions of possible false-negative results and the need for retesting among HIV negatives.

Human immunodeficiency virus: Diagnostic approach

First descriptions of acquired immunodeficiency syndrome appeared in 1981. Four years later the causative agent was cultured which lead to development and production of tests that helped healthcare providers to identify persons living with HIV. Currently, diagnosis of HIV is performed with fourth generation immunoassays (those that detect p24 antigen together with IgM and IgG antibodies to HIV-1 and -2) which if positive need to be followed by an assay that can differentiate between HIV-1 and HIV-2 viruses. The Western blot is no longer used to confirm HIV infections per CDC guidelines. In case there is a positive fourth generation assay but negative differentiation assay, nucleic acid testing for HIV-1 should be performed. This algorithm allows for detection of acute infections. Alternatively, the World Health Organization has algorithms that use rapid testing for diagnosis of HIV infections. This review will describe the evolution of tests and diagnostic algorithms from the 1980s to the current state. Special situations regarding diagnosis will also be discussed.

Initial Accuracy of HIV Rapid Test Kits Stored in Suboptimal Conditions and Validity of Delayed Reading of Oral Fluid Tests

Objectives

To evaluate the effect of storing commonly used rapid diagnostic tests above manufacturer-recommended temperature (at 37°C), and the accuracy of delayed reading of oral fluid kits with relevance to HIV self-testing programmes.

Design

A quality assurance study of OraQuick (OraSure), Determine HIV 1/2^™ (Alere) and Uni-Gold^™ (Recombigen^®).

Methods

Consecutive adults (≥18y) attending Ndirande Health Centre in urban Blantyre, Malawi in January to April 2012 underwent HIV testing with two of each of the three rapid diagnostic test kits stored for 28 days at either 18°C (optimally-stored) or at 37°C (pre-incubated). Used OraQuick test kits were stored in a laboratory for delayed day 1 and subsequent monthly re-reading was undertaken for one year.

Results

Of 378 individuals who underwent parallel testing, 5 (1.3%) were dropped from the final analysis due to discordant or missing reference standard results (optimally-stored Determine and Uni-Gold). Compared to the diagnostic reference standard, OraQuick had a sensitivity of 97.2% (95% CI: 93.6–99.6). There were 7 false negative results among all test kits stored at 37°C and three false negatives among optimally stored kits. Excellent agreement between pre-incubated tests and optimally-stored tests with Kappa values of 1.00 for Determine and Uni-Gold; and 0.97 (95% CI: 0.95; 1.00) for OraQuick were observed. There was high visual stability on re-reading of OraQuick, with only 1/375 pre-incubated and 1/371 optimally-stored OraQuick kits changing from the initial result over 12 months.

Conclusion

Erroneous results observed during HIV testing in low income settings are likely to be due to factors other than suboptimal storage conditions. Re-reading returned OraQuick kits may offer a convenient and accurate quality assurance approach, including in HIV self-testing programmes.

Accuracy in HIV Rapid Testing among Laboratory and Non-laboratory Personnel in Zambia: Observations from the National HIV Proficiency Testing System

Background

Despite rapid task-shifting and scale-up of HIV testing services in high HIV prevalence countries, studies evaluating accuracy remain limited. This study aimed to assess overall accuracy level and factors associated with accuracy in HIV rapid testing in Zambia.

Methods

Accuracy was investigated among rural and urban HIV testing sites participating in two annual national HIV proficiency testing (PT) exercises conducted in 2009 (n = 282 sites) and 2010 (n = 488 sites). Testers included lay counselors, nurses, laboratory personnel and others. PT panels of five dry tube specimens (DTS) were issued to testing sites by the national reference laboratory (NRL). Site accuracy level was assessed by comparison of reported results to the expected results. Non-parametric rank tests and multiple linear regression models were used to assess variation in accuracy between PT cycles and between tester groups, and to examine factors associated with accuracy respectively.

Results

Overall accuracy level was 93.1% (95% CI: 91.2–94.9) in 2009 and 96.9% (95% CI: 96.1–97.8) in 2010. Differences in accuracy were seen between the tester groups in 2009 with laboratory personnel being more accurate than non-laboratory personnel, while in 2010 no differences were seen. In both PT exercises, lay counselors and nurses had more difficulties interpreting results, with more occurrences of false-negative, false-positive and indeterminate results. Having received the standard HIV rapid testing training and adherence to the national HIV testing algorithm were positively associated with accuracy.

Conclusion

The study showed an improvement in tester group and overall accuracy from the first PT exercise to the next. Average number of incorrect test results per 1000 tests performed was reduced from 69 to 31. Further improvement is needed, however, and the national HIV proficiency testing system seems to be an important tool in this regard, which should be continued and needs to be urgently strengthened.

Accounting for False Positive HIV Tests: Is Visceral Leishmaniasis Responsible?

BACKGROUND

Co-infection with HIV and visceral leishmaniasis is an important consideration in treatment of either disease in endemic areas. Diagnosis of HIV in resource-limited settings relies on rapid diagnostic tests used together in an algorithm. A limitation of the HIV diagnostic algorithm is that it is vulnerable to falsely positive reactions due to cross reactivity. It has been postulated that visceral leishmaniasis (VL) infection can increase this risk of false positive HIV results. This cross sectional study compared the risk of false positive HIV results in VL patients with non-VL individuals.

METHODOLOGY/PRINCIPAL FINDINGS

Participants were recruited from 2 sites in Ethiopia. The Ethiopian algorithm of a tiebreaker using 3 rapid diagnostic tests (RDTs) was used to test for HIV. The gold standard test was the Western Blot, with indeterminate results resolved by PCR testing. Every RDT screen positive individual was included for testing with the gold standard along with 10% of all negatives. The final analysis included 89 VL and 405 non-VL patients. HIV prevalence was found to be 12.8% (47/ 367) in the VL group compared to 7.9% (200/2526) in the non-VL group. The RDT algorithm in the VL group yielded 47 positives, 4 false positives, and 38 negatives. The same algorithm for those without VL had 200 positives, 14 false positives, and 191 negatives. Specificity and positive predictive value for the group with VL was less than the non-VL group; however, the difference was not found to be significant (p = 0.52 and p = 0.76, respectively).

CONCLUSION

The test algorithm yielded a high number of HIV false positive results. However, we were unable to demonstrate a significant difference between groups with and without VL disease. This suggests that the presence of endemic visceral leishmaniasis alone cannot account for the high number of false positive HIV results in our study.

Magnitude of HIV and syphilis seroprevalence among pregnant women in Gondar, Northwest Ethiopia: a cross-sectional study

Background

Human immunodeficiency virus (HIV) and syphilis are major public health problems in sub-Saharan Africa, causing numerous adverse pregnancy outcomes. The aim of study was to assess the magnitude of HIV and syphilis seroprevalence among pregnant women at University of Gondar Teaching Hospital.

Method

The study was conducted between March and May, 2012. Sociodemographic data were collected through face-to-face interview. HIV1/2 was tested following current national HIV1/2 testing algorithm. Syphilis infection was also tested using the rapid plasm reagin test for screening and Treponema pallidum hemagglutination as a confirmatory test. Both bivariate and multivariate analysis were used to identify factors associated with HIV and syphilis seroprevalence from selected sociodemographic variables.

Results

Of 300 women, 31 (10.33%), eleven (3.7%), and three (1%) were seroreactive for HIV, syphilis, and HIV–syphilis coinfection, respectively. High seroprevalence of HIV was found in women ages 25–30 years (13.4%), and women whose husbands attended primary school (19.7%). Syphilis was high in women occupationally housewives (15.2%) and whose husbands were illiterate (11.5%). HIV was associated with husband illiteracy (AOR [adjusted odds ratio] of 4.13, 95% CI [confidence interval] [1.01, 16.95]) and primary educational level of husbands (AOR [95% CI] =3.83 [1.50, 9.90]), whereas syphilis was associated with illiteracy of husband (AOR [95% CI] =7.25 [1.74, 30.30]).

Conclusion

Seroprevalence of HIV and syphilis was high. Low husband educational status was a risk factor for HIV and syphilis. Therefore, substantial efforts have to be made to reinforce prevention strategies and to screen as early as possible to prevent mother-to-child and further horizontal transmission.

Dilution testing using rapid diagnostic tests in a HIV diagnostic algorithm: a novel alternative for confirmation testing in resource limited settings

BACKGROUND

Current WHO testing guidelines for resource limited settings diagnose HIV on the basis of screening tests without a confirmation test due to cost constraints. This leads to a potential risk of false positive HIV diagnosis. In this paper, we evaluate the dilution test, a novel method for confirmation testing, which is simple, rapid, and low cost. The principle of the dilution test is to alter the sensitivity of a rapid diagnostic test (RDT) by dilution of the sample, in order to screen out the cross reacting antibodies responsible for falsely positive RDT results.

METHODS

Participants were recruited from two testing centres in Ethiopia where a tiebreaker algorithm using 3 different RDTs in series is used to diagnose HIV. All samples positive on the initial screening RDT and every 10th negative sample underwent testing with the gold standard and dilution test. Dilution testing was performed using Determine™ rapid diagnostic test at 6 different dilutions. Results were compared to the gold standard of Western Blot; where Western Blot was indeterminate, PCR testing determined the final result.

RESULTS

2895 samples were recruited to the study. 247 were positive for a prevalence of 8.5 % (247/2895). A total of 495 samples underwent dilution testing. The RDT diagnostic algorithm misclassified 18 samples as positive. Dilution at the level of 1/160 was able to correctly identify all these 18 false positives, but at a cost of a single false negative result (sensitivity 99.6 %, 95 % CI 97.8-100; specificity 100 %, 95 % CI: 98.5-100). Concordance between the gold standard and the 1/160 dilution strength was 99.8 %.

CONCLUSION

This study provides proof of concept for a new, low cost method of confirming HIV diagnosis in resource-limited settings. It has potential for use as a supplementary test in a confirmatory algorithm, whereby double positive RDT results undergo dilution testing, with positive results confirming HIV infection. Negative results require nucleic acid testing to rule out false negative results due to seroconversion or misclassification by the lower sensitivity dilution test. Further research is needed to determine if these results can be replicated in other settings.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01716299 .