New direct-acting antivirals for patients with chronic HCV infection: can we monitor treatment using an HCV core antigen assay?

Diagnostic performance of hepatitis C virus core antigen testing for detecting hepatitis C in people living with hepatitis B: a systematic review and meta-analysis

BACKGROUND

The current diagnostic strategy for hepatitis C virus (HCV) infection involves a two-step approach: antibody HCV screening followed by confirmatory nucleic acid testing. This study aimed to evaluate the diagnostic performance of the Abbott ARCHITECT HCV Ag assay in serum/plasma samples as a potential one-step alternative for diagnosing active HCV infection in people living with hepatitis B virus (PLWHB) through a systematic review and meta-analysis.

METHODS

A systematic review and meta-analysis were conducted following PRISMA-DTA guidelines. This protocol was registered on PROSPERO (CRD42023402093). A comprehensive search of electronic databases identified studies published up to 1 November 2024, comparing the ARCHITECT HCV Ag assay to an HCV-RNA reference standard. Sensitivity, specificity, and likelihood ratios were pooled using a random-effects model within the MIDAS module of Stata software. Study quality was assessed using QUADAS-2. Heterogeneity was evaluated using the Q statistic, quantified using the I², and further explored through meta-regression.

RESULTS

Ten studies (n = 494 participants) met inclusion criteria. The Abbott ARCHITECT HCV Ag assay demonstrated high sensitivity [91%, 95% confidence interval (CI): 76-97%] and specificity (99%, 95% CI: 99-100%). The positive likelihood ratio (PLR) was 81.20 (95% CI: 12.34-534.36), and the negative likelihood ratio (NLR) was 0.09 (95% CI: 0.03-0.27). The area under the summary receiver operating characteristic curve (AUC-SROC) was 99% (95% CI 98-100%). In regions with high HCV prevalence (≥ 10%), the test accurately confirmed active HCV infection in over 90% of cases. However, confirmatory testing remains necessary in low-prevalence settings (≤ 5%). The assay demonstrated an excellent ability to identify individuals without HCV infection, with a low false-negative rate (≤ 2%) regardless of HCV prevalence. Heterogeneity analysis revealed moderate to substantial variation in test performance (I² = 72.09% for sensitivity, 35.47% for PLR, and 78.33% for NLR). QUADAS-2 applicability concerns predicted heterogeneity, but differences were likely insignificant due to minimal variations and limited studies.

CONCLUSIONS

The Abbott ARCHITECT HCV Ag assay exhibited promising accuracy in detecting active HCV infection among PLWHB. This test might help diagnose active HCV infection in high-prevalence scenarios (≥ 10%) but needs further confirmation in low-prevalence settings (≤ 5%).

Hepatitis C Virus-Core Antigen: Implications in Diagnostic, Treatment Monitoring and Clinical Outcomes

The hepatitis C virus (HCV) infection, a global health concern, can lead to chronic liver disease. The HCV core antigen (HCVcAg), a viral protein essential for replication, offers a cost-effective alternative to HCV RNA testing, particularly in resource-limited settings. This review explores the significance of HCVcAg, a key protein in the hepatitis C virus, examining its structure, function, and role in the viral life cycle. It also evaluates its clinical use in diagnosis and treatment monitoring, comparing its performance to the standard HCV RNA assay using data from PubMed and Google Scholar. HCVcAg assays show high pooled sensitivity (93.5%) and pooled specificity (99.2%) compared to HCV RNA assays, correlating closely (r = 0.87) with HCV RNA levels. Hence, HCVcAg testing offers a cost-effective way to diagnose active HCV infections and monitor treatment, especially in resource-limited settings, but its sensitivity can vary and standardization is needed. HCVcAg also predicts liver disease progression and assesses liver damage risk, aiding patient management. It helps to identify patients at risk for fibrosis or carcinoma, making it vital in hepatitis C care. HCVcAg testing can expand access to HCV care, simplify management, and contribute to global elimination strategies, especially in low- and middle-income countries.

Diagnostic performance of hepatitis C core antigen assay to identify active infections: A systematic review and meta-analysis

Hepatitis C virus (HCV) core antigen (HCVcAg) assay is an alternative for diagnosing HCV infection in a single step. This meta-analysis aimed to evaluate the Abbott ARCHITECT HCV Ag assay's diagnostic performance (validity and utility) for diagnosing active hepatitis C. PubMed, EMBASE, Scopus, Web of Science, and Cochrane Library were searched until 10 January 2023. The protocol was registered at the prospective international register of systematic reviews (PROSPERO: CRD42022337191). Abbott ARCHITECT HCV Ag assay was the test for evaluation, and nucleic acid amplification tests with a cut-off ≤50 IU/mL were the gold standard. Statistical analysis was performed using STATA with the MIDAS module and random-effects models. The bivariate analysis was conducted on 46 studies (18,116 samples). The pooled sensitivity was 0.96 (95% CI = 0.94-0.97), specificity 0.99 (95% CI = 0.99-1.00), positive likelihood ratio 141.81 (95% CI = 72.39-277.79), and negative likelihood ratio 0.04 (95% CI = 0.03-0.06). The area under the summary receiver operating characteristic curve was 1.00 (95% CI = 0.34-1.00). For active hepatitis C prevalence values of 0.1%-15%, the probability that a positive test was a true positive was 12%-96%, respectively, indicating that a confirmatory test should be necessary, particularly with a prevalence ≤5%. However, the probability that a negative test was a false negative was close to zero, indicating the absence of HCV infection. The validity (accuracy) of the Abbott ARCHITECT HCV Ag assay for screening active HCV infection in serum/plasma samples was excellent. Although the HCVcAg assay showed limited diagnostic utility in low prevalence settings (≤1%), it might help diagnose hepatitis C in high prevalence scenarios (≥5%).

Meta-analysis: diagnostic accuracy of hepatitis C core antigen detection during therapy with direct-acting antivirals

BACKGROUND

Treatment of hepatitis C virus (HCV) infection with direct-acting antivirals (DAAs) is monitored by assessing plasma HCV-RNA load. However, detection of HCV core antigen (HCVcAg) may be an alternative.

AIM

To evaluate the diagnostic performance of the HCVcAg assay to monitor the efficacy of DAAs in HCV-infected patients METHODS: We performed searches in multiple electronic databases until 6 July 2022, of studies evaluating the HCVcAg detection in plasma or serum compared with the HCV-RNA test (gold standard). We calculated pooled measurement at 2 and 4 weeks of treatment, and at end-of-treatment (EOT), as well as sustained virological response (SVR; 12 weeks after EOT).

RESULTS

We selected 16 studies from 2016 to 2022, with 3237 patients and 8958 samples. Overall, the diagnostic performance and clinical utility of the HCVcAg assay were poor at week 2 (sensitivity = 0.40, specificity = 0.96, positive likelihood ratio (PLR) = 9.16, negative likelihood ratio (NLR) = 0.63, and area under the summary receiver operating curve (SROC) = 0.57), fair at week 4 (sensitivity = 0.30, specificity = 0.90, PLR = 3.18, NLR = 0.77, and AUC = 0.79), acceptable at EOT (sensitivity = 0.40, specificity =0.98, PLR = 16.54, NLR = 0.62, and AUC = 0.97) and excellent for SVR (sensitivity = 0.94, specificity = 0.99, PLR = 107.54, NLR = 0.06, and AUC = 0.99).

CONCLUSIONS

The HCVcAg assay may be helpful for monitoring the efficacy of HCV treatment with DAAs in HCV-infected patients at EOT and for documenting SVR, but not at weeks 2 and 4 of treatment due to poor diagnostic performance.

Performance of HCV Antigen Testing for the Diagnosis and Monitoring of Antiviral Treatment: A Systematic Review and Meta-Analysis

BACKGROUND AND AIMS

Active hepatitis C virus (HCV) infection is based on the detection of HCV RNA that it is effective but presents high cost and the need to hire trained personnel. This systematic review and meta-analysis is aimed at evaluating the diagnostic accuracy of HCV Ag testing to identify HCV cases and to monitor antiviral treatment including DAA treatment.

METHODS

The studies were identified through a search in PubMed, Lilacs, and Scopus from 1990 through March 31, 2020. Cohort, cross-sectional, and randomized controlled trials were included. Two independent reviewers extracted data and assessed quality using an adapted Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Our primary outcome was to determine the accuracy of HCV Ag detection for the diagnosis, which we estimated using random-effects meta-analysis.

RESULTS

Of 3,062 articles identified, 54 met our eligibility criteria. The studies described cohorts from 20 countries, including 14,286 individuals with chronic HCV individuals. Studies for ECLIA technology demonstrated highest quality compared to studies that used ELISA. The pooled sensitivity and specificity (95% CI) for HCV Ag detection of active HCV infection were 98.82% (95%CI = 98.04%; 99.30%) and 98.95% (95%CI = 97.84%; 99.49%), respectively. High concordance was found between HCV Ag testing and HCV RNA detection 89.7% and 95% to evaluate antiviral treatment.

CONCLUSIONS

According to our findings, HCV Ag testing could be useful to identify HCV active cases in low-resource areas. For antiviral treatment, HCV Ag testing will be useful at the end of treatment.

Hepatitis C Virus Core Antigen as an Alternative to RNA in the Assessment of Response to Treatment with Direct-acting Oral Antivirals

Background: Affordable and effective diagnostic and treatment monitoring algorithms are urgently needed to achieve the global elimination of hepatitis C virus (HCV) infection. Methods: A total of 274 patients were treated with direct-acting antivirals (DAAs) in the Spanish Hospital of Albacete between 2004 and 2020. This study compared the enzyme-immunoassay technique for HCV core antigen (HCVcAg) with the determination of RNA of HCV (HCV RNA) by polymerase chain reaction (PCR) in monitoring treatment with DAA, setting the lower limit of detection of HCVcAg < 3 fmol/L and RNA < 10 IU/mL. In all cases, the P value of differences associated with the contrast test was less than or equal to 0.05. Results: We evaluated the viral loads of our patients before treatment, during their treatment, and after its completion. The HCV RNA quantification at diagnosis was 2309327 IU/mL. The mean HCVcAg load was 5972 fmol/L. There was a strong correlation between HCVcAg levels and RNA levels with a Spearman rho of 0.832 (P < 0.01). The HCVcAg sensitivity at diagnosis was 99%, but the specificity could not be calculated because there were no true negatives or false positives at this point. Twelve weeks after treatment, in patients with treatment failure, we obtained a mean of 19084 IU/mL for RNA, while for HCVcAg, the mean was 103 fmol/L. At this time point, we also found a strong correlation between HCVcAg levels and HCV RNA levels with a Spearman rho of 0.775 (P < 0.01). Finally, the virological cure was achieved in 99% of our patients. The results for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 100%, 99.87%, 86.33%, and 100%, respectively. Conclusions: HCVcAg determination is an excellent alternative to HCV RNA in the assessment of treatment response. This is particularly relevant in lower- and middle-income countries and resource-limited settings where the high cost of labor, equipment, and reagents can prohibit molecular testing.

Current position of viral load versus hepatitis C core antigen testing

Quantification of hepatitis C virus (HCV) RNA (viral load) is the most widely used marker to diagnose and confirm active HCV infection. The HCV core antigen forms part of the internal structure of the virus and, like HCV RNA, its detection also indicates viral replication and presents certain advantages over viral load testing such as its lower cost, the greater stability of the target, the possibility of working with the same primary tube as that used for HCV serology, and the rapidity of obtaining results, since there is no need to work in batches, unlike the situation with most viral load platforms. Although the core antigen has lower analytical sensitivity than HCV RNA for the detection of low viremia levels, several studies and guidelines have already shown their utility in the identification of patients with active HCV infection. This article summarises current platforms for viral load determination, including point-of-care systems, and also reviews the indications attributed to this marker by the main HCV treatment guidelines. The article also reviews the characteristics of HCV core antigen, the available platforms for its determination, its correlation with viral load determination, and the indications for this marker in the distinct guidelines.

Evaluation of Hepatitis C Virus Core Antigen Assay in a Resource-Limited Setting in Pakistan

The diagnosis of Hepatitis C virus (HCV) infection can be challenging due to its cost and a lack of access to centralized testing. There is an urgent need to develop simplified HCV testing algorithms. The aim of this study was to evaluate the performance characteristics of a Hepatitis C core antigen (HCVcAg) assay in a decentralized, resource-limited setting. This is a descriptive cross-sectional study from a highly endemic area of Karachi, Pakistan. Between October 2019 and July 2020, subjects aged 12 years and above who screened positive for HCV antibodies were simultaneously tested for HCV RNA (Xpert HCV Viral Load, GeneXpert^® IV, Cepheid, France) and HCVcAg (ARCHITECT HCV Ag assay, Abbott^® Diagnostics) to confirm active HCV infection. An Abbott ARCHITECT^® i1000SR Immunoassay Analyser was installed at a local district hospital as a point-of-care (POC) facility for HCVcAg testing, while samples for HCV RNA were tested in a central lab. Two hundred individuals (mean age 46.4 ± 14.5 years, 71.5% females), who screened positive for HCV antibody, were included in the study. HCV RNA was detected in 128 (64.0%) while HCVcAg was reactive in 119 (59.5%) cases. Performance of the Immunoassay Analyser was excellent with a higher throughput and quicker readout value compared to the GeneXpert System. The sensitivity and specificity of HCVcAg (≥10 fmol/L) at HCV RNA thresholds of ≥12 was 99.1% (95% CI: 95–100%) and 87.6% (95%CI: 78.4–94%). A strong agreement was observed between the HCVcAg assay and HCV RNA. The ARCHITECT HCV Ag assay showed high sensitivity and specificity compared to HCV RNA in a decentralized, resource-limited setting. It can therefore be used as a confirmatory test in HCV elimination programs, particularly for low-income countries such as Pakistan.

HCV core antigen plays an important role in the fight against HCV as an alternative to HCV-RNA detection

Objective

To discuss the clinical significance of HCV‐cAg testing in the diagnosis, activity determination, and monitoring of therapeutic effectiveness of HCV infection and its advantages compared with HCV‐RNA and anti‐HCV antibodies detection.

Methods

By summarizing the published literature, the advantages and significance of HCV core antigen detection were sought.

Results

The expression of HCV‐cAg is highly consistent with that of HCV‐RNA, but compared with HCV‐RNA, detection of HCV‐cAg is easy to operate, time saving, and low cost. HCV‐cAg can be detected within 12~15 days after infection, and the window period can be shortened by5~7 weeks. HCV‐cAg is a serological indicator of virus replication, which can distinguish previous infection of HCV or current infection. HCV‐cAg detection is more suitable for immunocompromised, hemodialysis, organ transplant patients. HCV‐cAg also can be used to monitor antiviral efficacy and predict sustained virological response (SVR).

Conclusion

HCV core antigen has similar clinical sensitivity to NAT and can be used as a substitute for HCV‐RNA in the diagnosis of virus infection. Combined detection of HCV‐cAg and antibody serology can help doctors detect HCV infection earlier, accurately diagnose different stages of HCV infection, and evaluate the therapeutic effect of antiviral drugs, which are beneficial in the prevention and treatment of hepatitis C.

Evaluation of the Xpert HCV VL Fingerstick point-of-care assay and dried blood spot HCV-RNA testing as simplified diagnostic strategies among people who inject drugs in Catalonia, Spain

BACKGROUND

Catalonia requires decentralized and simplified strategies for the diagnosis of viremic HCV infection among people who inject drugs (PWID). We aimed to perform a direct comparison of the diagnostic performance between two, single-step strategies for the screening and diagnosis of viremic HCV infection in PWID attending a drug consumption room (DCR) in Barcelona: i) on-site HCV-RNA testing using the point-of-care test (PoCT) Xpert HCV VL Fingerstick; and ii) on-site dried blood spots (DBS) collection for HCV-RNA testing at the laboratory (in-house assay). Additionally, we aimed to assess participants' preferences in receiving HCV-RNA testing results and feasibility of same-day delivery of PoCT results.

METHODS

The real-world, clinical performance of these two strategies was established in comparison with the reference method (HCV viral load testing with the Xpert HCV Viral Load assay at the laboratory from venous plasma collected at the DCR). HCV genotypes/subtypes and HIV status were also determined by sequencing and serology, respectively. A questionnaire including preferences regarding the delivery of test results was administered.

RESULTS

The prevalence of HCV-RNA was 63.0% (of which 25.8% were co-infected with HIV). The RNA-PoCT showed a sensitivity of 98.4% for detectable viral loads (>4 IU/mL) and of 100% for quantifiable viral loads (≥10, ≥1000 and ≥3000 IU/mL). For the DBS-based assay, a sensitivity of 93.7% was obtained for detectable viral loads, 96.7% for the quantifiable ≥10 IU/mL threshold, and 98.3% for both the quantifiable ≥1000 and ≥3000 IU/mL thresholds. No significant differences were detected between the sensitivity values of these two strategies, and the specificity was 100% in both cases. Half of the participants preferred to receive the HCV-RNA result on the same day, and 80% of participants received their RNA-PoCT results on the same day.

CONCLUSIONS

Both the HCV-RNA PoCT and the DBS-based assay are highly reliable tools for the simplified diagnosis of viremic HCV infection among current PWID. These strategies allow for on-site sample collection and delivery of test results, facilitating decentralized care in harm reduction services.

Quantitative measurement of HCV core antigen for management of interferon-free therapy in HCV-infected patients

BACKGROUND

According to current recommendations diagnosis and management of HCV infection need detection and quantification of nucleic acids. In the era of direct-acting antivirals (DAA) it is essential to develop an inexpensive and simple method replacing polymerase chain reaction. Since there is no available data on HCV core antigen (HCVcAg) versus HCV RNA kinetics in the early phase of treatment with DAA, we carried out this study to evaluate the possible application of HCVcAg quantitative measurement for management of HCV infection.

METHODS

33 patients with HCV infection were enrolled and treated with either ombitasvir/paritaprevir/ritonavir ± dasabuvir ± ribavirin (OBV/PRV/r±DSV±RBV) or ledipasvir/sofosbuvir (LDV/SOF). Samples for quantitative HCV RNA and HCVcAg measurement were collected at the baseline, after 1, 7, 28 days and at the end of treatment, and then after 12 and 24 weeks of post-treatment follow-up.

RESULTS

There was positive correlation between HCVcAg and HCV RNA levels at the baseline and after 1 day of treatment. Mean HCVcAg concentration declined faster than HCV RNA levels during the treatment phase. At week 4 HCV RNA was undetectable in 24, whereas HCVcAg in 28 patients. At the end of treatment and after 12 weeks of follow-up all patients were undetectable for both HCV RNA and HCVcAg.

CONCLUSIONS

HCVcAg concentration and its early on-treatment testing can predict virological response. Simple testing procedures and significantly lower cost compared to HCV RNA testing support possible replacement of the viral load measurement in management of the majority of HCV-infected patients.

Study of Hepatitis C Virus Detection Assays

Background

Hepatitis C virus is a small, enveloped, positive-sense single-stranded RNA virus that causes and liver cancer like hepatocellular carcinoma and lymphomas.Aim of the study: to assess different methods in diagnosis HCV infection.

Patients and methods

A retrospective study of 426 patients was admitted to Al-Kindy Teaching Hospital, Baghdad-Iraq for surgical operations or renal dialysis from January-2015 to December-2016. Their serum tested for HCV Abs by rapid immunochromatography, Enzyme Linked ImunoSorbent Assay (ELISA), and RIBA test.

Results

The study sample was 426 patients, their age was ranged from 15 to 65 years. Males were represented 58% and the rest were females. The serum of all samples has tested by rapid Immunochromatography test. Fifty percent of them showed positive results by this test and the rest were negative. Those fifty serum samples who were positive by Immunochromatography test were reexamined by ELISA test and showed 39out of 50 (78%) were true positive by ELISA test and the rest were negative (P = 0.0001).The positive samples by ELISA have tested by RIBA test that showed 200(80%)were true positive in males and 130(74%)were true positive in females and the rest were false positive (P = 0.0001).

Conclusions

Early screening of the high risk group of population by highly sensitive test is important to treat infected patients and prevent dissemination among population.

Hepatitis C virus core antigen for screening organ donors and recipients

Organ donors and recipients are routinely screened for hepatitis C virus (HCV) infection, typically via anti-HCV detection. We analyze the utility of an alternative HCV core antigen (HCV-Ag) quantification system, the ARCHITECT HCV Ag Assay, in this setting. We simultaneously tested 315 samples from potential organ donors and recipients using two chemiluminescent microparticle immunoassays: ARCHITECT Anti-HCV and HCV Ag (Abbott, Germany). HCV-Ag was detected in 81 of the serum samples (25.71%) and anti-HCV in 87 (27.62%). Seventy-five of the HCV-Ag-positive samples were positive for anti-HCV (92.59%). Overall concordance between the two assays was 94.29%. Of the six HCV-Ag-positive/anti-HCV-negative patients, five had HCV-Ag values <32 fmol/L, and the sixth had a concentration of 477.50 fmol/L (viral load, 137,000 IU/mL). The HCV AG Assay detects HCV infections missed by the Anti-HCV Assay. Both markers should be used to screen for HCV infection in potential organ donors and recipients.

HCV core antigen is an alternative marker to HCV RNA for evaluating active HCV infection: implications for improved diagnostic option in an era of affordable DAAs

The core antigen of the hepatitis C virus (HCV Ag) presents an alternative marker to HCV RNA when screening patients for HCV viremia. This study sought to evaluate the utility of HCV Ag as a marker to assess active HCV infection in individuals residing in an HCV-endemic area. From 298 HCV-seropositive individuals evaluated for the presence of anti-HCV antibody, HCV Ag and HCV RNA, anti-HCV antibody was detected in 252 individuals (signal-to-cutoff ratios ≥5), HCV RNA was detected in 222 individuals (88%), and HCV Ag was reactive (≥3 fmol/L) in 220 individuals (87%). HCV genotype 1, 3, and 6 were identified. HCV Ag significantly correlated with HCV RNA irrespective of HCV genotype and/or HBV co-infection (log HCV RNA = 2.67 + 0.95 [log HCV Ag], R2 = 0.890, p < 0.001). To predict HCV viremia (HCV Ag ≥ 3 fmol/L), the accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were 99%, 99%, 100%, 100% and 97%, respectively. We concluded that HCV Ag was a good surrogate marker for HCV RNA and could be used to diagnose active HCV infection in a resource-limited setting. As a result, a cost-effective strategy for screening and identifying active HCV carriers using HCV Ag detection would enable more patients access to efficacious and increasingly affordable direct-acting antivirals (DAAs) for the treatment of HCV infection.

Multicenter Evaluation of the Cepheid Xpert Hepatitis C Virus Viral Load Assay

Viral load monitoring for hepatitis C virus (HCV) is necessary to diagnose infection and monitor response to therapy, but the tests involved are currently confined to specialist institutions. There is a need for a fast, accurate assay with limited operator input to enhance the access to viral load monitoring. We evaluated the quantification of HCV RNA in serum and plasma by the Cepheid Xpert HCV Viral Load assay in comparison to the Abbott RealTime HCV assay. Serum and plasma samples were gathered from HCV-infected individuals at four international sites. These were tested with the Xpert HCV Viral Load assay, and results were compared to quantification by the Abbott RealTime HCV assay. An external quality assessment panel of eight samples was also tested. In total, 614 samples were analyzed in the study, and the qualitative results agreed on the two platforms for 588 (95.8%) samples. Further analysis of 396 samples quantified by both tests showed strong correlation (correlation coefficient r = 0.99) across the quantifiable range, with Bland-Altman plot data showing a mean difference (±1.96 standard deviation) of 0.03 ± 0.44 log10 IU/ml. In the external quality assessment panel, the Xpert HCV Viral Load assay results (quantified in log10 IU per milliliter) were within 1 standard deviation of the target value for all but one sample, which was also similarly misquantified by the Abbott RealTime HCV assay. The Xpert HCV Viral Load assay performs well compared to a market-leading HCV viral load test and should be considered for instances where rapid near-to-patient testing is required.