Diagnostic reliability of Architect anti-HCV assay: Experience of a tertiary care hospital in India

Notification and follow-up of blood donors reactive for transfusion-transmitted infections: A narrative review of the literature from India

BACKGROUND AND OBJECTIVES

Notifying blood donors of their reactive status for transfusion-transmitted infections (TTIs) plays a vital role in enabling early diagnosis and management while also preventing these donors from making future donation and transmission of the infectious agent. Given the limited data on donor notification processes in India, a narrative review was conducted to assess the existing notification process and identify areas requiring enhancement.

MATERIALS AND METHODS

We conducted literature searches using PubMed, Google Scholar and Scopus, employing various keywords. The review included data on the year of the study, study design, donor numbers, TTI screening methods, sero-reactive donor confirmation, notification frequency and methods, donor responses, post-test counselling and risk factor assessment.

RESULTS

Out of the 29 identified articles, 16 studies were included in the analysis. Repeat testing for initially reactive results was conducted in nine studies for 24.3% reactive donors. Phone calls were the primary notification method in most studies (8; 50%), with letters sent in cases of no response. Only 12 studies provided data on notified donors, revealing a notification rate of 71.2%. Of all initially reactive donors, 33.3% sought post-test counselling. Data from six studies indicated that 74.3% of responsive donors had identifiable TTI risk factors.

CONCLUSION

Our review revealed significant variability in the notification processes across different studies. To enhance the management of TTI-reactive donor notifications and responses, we recommend the establishment of universal protocols encompassing pre-donation counselling, repeat/confirmatory testing, notification methods and comprehensive follow-up and treatment.

High false discovery rate of the Architect anti-HCV screening test in blood donors in Uganda and evaluation of an algorithm for confirmatory testing

BACKGROUND AND OBJECTIVES

Adequate supplies of donor blood remain a major challenge in sub-Saharan Africa. This is exacerbated by a lack of confirmatory testing for transfusion-transmitted infections by blood transfusion services (BTS), leading to significant blood disposal owing to putatively high seroprevalence rates amongst Ugandan blood donors. We aimed to ascertain the false discovery rate of the Architect anti-hepatitis C virus (HCV) screening assay and categorize screen-reactive samples into three groups: presumed false positive, active and past infection, and develop an algorithm for confirmatory testing.

MATERIALS AND METHODS

A total of 470 screen-reactive HCV blood donations were retested using the Architect anti-HCV assay, an alternative antibody test (SD Biosensor) and a core antigen (cAg) test. signal-to cut-off (S/CO) ratios and pre-analytical factors (centrifugation speed, haemolysis check, time between collection and testing) were recorded. Based on the S/CO ratio evaluation, we propose a testing algorithm to guide supplemental tests.

RESULTS

The false discovery rate of the Architect anti-HCV assay was 0.84 as 395/470 (84%) screen-reactive samples had no evidence of HCV infection (SD Biosensor and cAg negative) (presumed false positive), 38/470 (8.1%) were antigenaemic, and 32/470 (6.8%) had evidence of past infection. The median S/CO ratios of the presumed false-positive and active infection samples were 1.8 and 17.3, respectively. The positive predictive value of HCV positivity in samples with ratios above 12 was 91.8%. On retesting, 104/470 (22.1%) samples became negative.

CONCLUSION

The Architect anti-HCV assay has a very high false discovery rate in Ugandan BTSs, leading to excessive blood disposal. Pre-analytical factors likely contribute to this. An introduction of confirmatory testing using an algorithm based on S/CO ratio evaluation could limit unnecessary blood wastage and donor deferral.

Prescreening with a Rapid Diagnostic Test Followed by a Confirmatory Qualitative Nucleic Acid Test Can Simplify Hepatitis C Diagnosis

Asymptomatic hepatitis C virus (HCV) infection without treatment is associated with chronic liver diseases including hepatocellular carcinoma. A major obstacle to hepatitis C diagnosis leading to antiviral treatment in some developing countries is the complicated HCV testing required before treatment. To simplify an HCV test-to-treat strategy, which could lead to timely diagnosis and treatment at the point-of-care, we evaluated the performance of four anti-HCV rapid diagnostic tests (RDTs) (Abon, Blue Cross, Healgen, and SD Bioline). They yielded comparable sensitivity (80-83%), specificity (99-100%), and accuracy (90-91.5%). When we field-tested Abon in 4,769 residents of an HCV-endemic province in Thailand, 306 seropositive individuals (6.4%) were identified. In comparison, laboratory test using an automated commercial chemiluminescent microparticle immunoassay (Abbott ARCHITECT) identified slightly more seropositives (327% or 6.9%). Field implementation suggests that Abon was sensitive (88.7%), specific (99.6%), and accurate (98.9%). Furthermore, 82% (250/306) of Abon-positive samples had detectable HCV RNA as determined by nucleic acid test (Roche cobas). The same 250 samples out of 327 reactive in Abbott immunoassay also had detectable HCV RNA (mean RNA level: log 6.28 IU/mL, range: log 3.06- 7.78 IU/mL). The use of RDT followed by qualitative nucleic acid test can cost-effectively identify the majority of HCV seropositive individuals with active infection, which will obviate the need for expensive viral load quantification tests when simplifying HCV diagnosis for the test-to-treat program at the point-of-care.

Evaluation of dried blood spot testing using the Abbott Alinity i

BACKGROUND

The West of Scotland Specialist Virology Centre currently uses the Abbott Architect for DBS serology. The new Abbott Alinity i will replace the Architect in our laboratory. In this study, mock and stored patient DBS samples were tested on both platforms and results compared.

STUDY DESIGN

Mock DBS were made from whole blood where patient results were known (38 negative samples and 141 positive samples; 39 HIV Antigen/Antibody (Ag/Ab), 35 HCV IgG antibody (HCVG), 34 HBV core IgG (HBCG) and 33 HBsAg). Mock DBS were tested on both Abbott platforms. Stored patient DBS samples (132 negative and 263 positive: 9 HIVAg/Ab, 10 HBsAg, 52 HBCG and 60 HCVG) previously tested on the Architect were retested on the Alinity i.

RESULTS

Mock DBS showed good correlation between the Architect and Alinity i for the HIV Ag/Ab,HBCG and HCVG assays. A poorer correlation occurred with HBsAg, the Alinity i reported HBsAg positives at a lower value compared to the Architect. The coefficient of variation for intra-assay variation was 1.69 % (HIVAg/Ab), 3.25 % (HCVG), 1.68 % (HBsAg) and 1.95 % (HBCG). The sensitivity and specificity was determined based on results from the mock and patient samples. At S/Co cut-off 1.0 both HIV and HBsAg had a sensitivity of 100 %. A cut-off 0.8 gave a sensitivity of 95.83 % (95 % CI 89.67%-98.85%) for HCVG and 0.3 gave a sensitivity of 98.8 % (CI 93.69%-99.97%) for HBCG.

DISCUSSION

The alinity i compared well against the architect and can be used to test DBS samples.

Differential reactivity of anti-hepatitis C virus screening assays in patients with waning antibodies

Hepatitis C virus (HCV) leads to persistent infection. Viral clearance can be obtained through pharmacological treatment or spontaneously. After viral clearance, anti-HCV antibodies (Abs) slowly decline and finally disappear. Subjects with a resolved HCV infection are reactive to anti-HCV screening assays for a long time. These subjects pose a diagnostic challenge, and therefore, a more accurate interpretation of laboratory tests is needed for cases with resolved HCV infection. However, the performances of anti-HCV screening assays against declining anti-HCV Abs have not been assessed. Here we evaluated 1509 samples with different screening assays. Screening assays provided discrepant results in patients with waning Abs. The identification of signal-to-cut-off values indicative of waning Abs for each anti-HCV assay could avoid unnecessary confirmatory tests and reduce the impact of misdiagnosis.

Screening haemodialysis patients for hepatitis C in Vietnam: The inconsistency between common hepatitis C virus serological and virological tests

Selecting the appropriate screening method and interval for the early detection of hepatitis C virus (HCV) infection in low-resourced haemodialysis settings is a challenge. The challenge occurs when patients are classified as HCV-RNA positive but negative to HCV-core antigen (HCV-coreAg), anti-HCV and genotyping tests. We aim to clarify the inconsistency between HCV-RNA, HCV-coreAg, anti-HCV and HCV genotyping tests in haemodialysis patients and determine the reliability of HCV-coreAg as a routine two-monthly screening strategy. Haemodialysis patients were tested every 2 months between 2012 and 2014 at the largest district haemodialysis unit in Ho Chi Minh City, Vietnam, for aminotransferases, anti-HCV antibodies, HCV-coreAg, HCV-RNA and HCV genotype. HCV-coreAg and anti-HCV results were tested against HCV-RNA for sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV). All 201 patients participated in the study. The HCV-coreAg test performed better than the anti-HCV test for sensitivity (100% vs 31%), NPV (100% vs 90%) and accuracy (100% vs 90%). The HCV-coreAg and anti-HCV tests performed no differently for specificity (100% and 98%, respectively) or PPV (100% and 73%, respectively). Kappa values for HCV-coreAg and anti-HCV tests were 1 and 0.39, respectively. Early detection of HCV for the purpose of infection prevention requires a high level of sensitivity and HCV-coreAg performed better in our chronic haemodialysis population as a two-monthly screening method than routine anti-HCV testing. HCV-coreAg test is less labour-intensive with a higher level of accuracy in patients with low viral loads making it cost effective for low-resourced settings. Repeating genotyping may be required in HCV-coreAg positive patients with a low viral load.

Diagnostic reliability of Architect anti-HCV assay: Experience of a tertiary care hospital in India

BACKGROUND & AIMS

Anti-HCV assays are prone to false positive results. Thus, accurate detection of HCV infection is critical for the timely therapeutic management. This study ascertained the reliability of Architect anti-HCV assay (Abbott) and to estimate the agreement of this assay with Ortho HCV 3.0 ELISA Test System with Enhanced SAVe (Ortho), HCV Tri-dot (Tri-dot) and HCV-PCR in a tertiary care setting.

METHODS

A total of 78 788 consecutive sera were routinely screened for anti-HCV antibodies using Architect. All repeatedly reactive anti-HCV sera (n=1000) and anti-HCV negative sera (n=300) were tested in Ortho and in Tri-dot assays. Representative proportions of sera (n=500) with various signal-to-cut-off (S/Co) ratio were also compared with HCV-PCR.

RESULTS

When Architect was compared with Ortho, Tri-dot, and HCV-PCR, the level of agreement as assessed by kappa were .26, .16, and .27 respectively. Using Latent class analysis (LCA), we found that sensitivity and specificity were 100% and 36.1% for Architect, 93.8% and 100% for Ortho and 63.8% and 100% for Tri-dot respectively. The median S/CO ratio of Architect and Ortho anti-HCV assays were significantly different between HCV-PCR positive and negative results (P<.0001). Furthermore, Architect S/CO ratio of >8 showed higher accuracy indices in both anti-HCV assays.

CONCLUSIONS

Architect can be used as a screening assay because of its high sensitivity, high throughput, and short turnaround time. However, S/Co ratios of ≥1 to <8 in Architect necessitates HCV PCR to identify current infection and or EIA to distinguish true positivity from false biological positivity.