Performance characteristics of the ARCHITECT anti-HCV assay

Evaluation of Three Commercial SARS-CoV-2 Serologic Assays and Their Performance in Two-Test Algorithms

Sensitive and specific severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serologic assays are needed to inform diagnostic, therapeutic, and public health decision-making. We evaluated three commercial serologic assays as stand-alone tests and as components of two-test algorithms. Two nucleocapsid antibody tests (Abbott IgG and Roche total antibody) and one spike protein antibody test (DiaSorin IgG) were included. We assessed sensitivity using 128 serum samples from symptomatic PCR-confirmed coronavirus disease 2019 (COVID-19)-infected patients and specificity using 1,204 samples submitted for routine serology prior to COVID-19’s emergence, plus 64 pandemic-era samples from SARS-CoV-2 PCR-negative patients with respiratory symptoms.

Sensitive and specific severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serologic assays are needed to inform diagnostic, therapeutic, and public health decision-making. We evaluated three commercial serologic assays as stand-alone tests and as components of two-test algorithms. Two nucleocapsid antibody tests (Abbott IgG and Roche total antibody) and one spike protein antibody test (DiaSorin IgG) were included. We assessed sensitivity using 128 serum samples from symptomatic PCR-confirmed coronavirus disease 2019 (COVID-19)-infected patients and specificity using 1,204 samples submitted for routine serology prior to COVID-19’s emergence, plus 64 pandemic-era samples from SARS-CoV-2 PCR-negative patients with respiratory symptoms. Assays were evaluated as stand-alone tests and as components of a two-test algorithm in which positive results obtained using one assay were verified using a second assay. The two nucleocapsid antibody tests were more sensitive than the spike protein antibody test overall (70% and 70% versus 57%; P ≤ 0.003), with pronounced differences observed using samples collected 7 to 14 days after symptom onset. All three assays were comparably sensitive (≥89%; P ≥ 0.13) using samples collected >14 days after symptom onset. Specificity was higher using the nucleocapsid antibody tests (99.3% and 99.7%) than using the spike protein antibody test (97.8%; P ≤ 0.002). When any two assays were paired in a two-test algorithm, the specificity was 99.9% (P < 0.0001 to 0.25 compared with the individual assays), and the positive predictive value (PPV) improved substantially, with a minimal effect on the negative predictive value (NPV). In conclusion, two nucleocapsid antibody tests outperformed a spike protein antibody test. Pairing two different serologic tests in a two-test algorithm improves the PPV, compared with the individual assays alone, while maintaining the NPV.

On detection thresholds-a review on diagnostic approaches in the infectious disease laboratory and the interpretation of their results

Diagnostic testing in the infectious disease laboratory facilitates decision-making by physicians at the bedside as well as epidemiological assessments and surveillance at study level. Problems may arise if test results are uncritically considered as being the same as the unknown true value. To allow a better understanding, the influence of external factors on the interpretation of test results is introduced with the example of prevalence, followed by the presentation of strengths and weaknesses of important techniques in the infectious disease laboratory like microscopy, cultural diagnostics, serology, mass spectrometry, nucleic acid amplification and hypothesis-free metagenomic sequencing with focus on basic, high-technology and potential future approaches. Special problems like multiplex testing as well as uncertainty of test evaluations, if no gold standard is available, are also stressed with a final glimpse on emerging future technologies for the infectious disease laboratory. In the conclusions, suitability for point-of-care-testing and field laboratory applications is summarized. The aim is to illustrate the limitations of diagnostic accuracy to both clinicians and study planners and to stress the importance of close cooperation with experts in laboratory disciplines so as to avoid potentially critical misunderstandings due to inappropriate interpretation of diagnostic test results.

Prevalence of hepatitis C virus in adult population in the Czech Republic - time for birth cohort screening

Chronic hepatitis C is curable disease. Low detection rate could be one of the reasons of poor treatment uptake. It is important to identify HCV prevalence and anti-hepatitis C virus (HCV) positive patients in population by effective screening strategy such as risk-based or birth cohort screening programs. There are no national population-based estimates of the HCV prevalence in the Czech Republic (CZ). The most recent seroprevalence survey determined a prevalence of positive anti-HCV antibodies of 0.2% (in 2001). The aim of the study was to determine the seroprevalence of HCV, HCV viraemia and HCV genotype in the CZ adult population. We also estimated the number of persons living with chronic hepatitis C in CZ. The examined group included 3000 adults, 18-90 years of age enrolled in 2015. All serum samples were examined to determined anti-HCV antibodies positivity, HCV-RNA positivity and genotypes. Of the 3000 samples, 50 were found to be anti-HCV-positive, for a seroprevalence of 1.67% (2.39% in males, 0.98% in females). The overall prevalence of positive HCV RNA was 0.93%: 1.5% in males, 0.39% in females. HCV genotype (GT) 1a was determined in 25%, GT 1b in 25% and GT 3a in 46%. Since 2001, the HCV seroprevalence has increased 8-fold. The highest HCV seroprevalence occurred in males aged 30-44 years. We can estimate that there are more than 140,000 people with HCV antibodies and more than 80,000 people with chronic hepatitis C living in the CZ. The introduction of birth cohort HCV screening could be beneficial for the country.

Screening for Human Immunodeficiency Virus, Hepatitis B Virus, Hepatitis C Virus, and Treponema pallidum by Blood Testing Using a Bio-Flash Technology-Based Algorithm before Gastrointestinal Endoscopy

Currently, conventional enzyme immunoassays which use manual gold immunoassays and colloidal tests (GICTs) are used as screening tools to detect Treponema pallidum (syphilis), hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus type 1 (HIV-1), and HIV-2 in patients undergoing surgery. The present observational, cross-sectional study compared the sensitivity, specificity, and work flow characteristics of the conventional algorithm with manual GICTs with those of a newly proposed algorithm that uses the automated Bio-Flash technology as a screening tool in patients undergoing gastrointestinal (GI) endoscopy. A total of 956 patients were examined for the presence of serological markers of infection with HIV-1/2, HCV, HBV, and T. pallidum The proposed algorithm with the Bio-Flash technology was superior for the detection of all markers (100.0% sensitivity and specificity for detection of anti-HIV and anti-HCV antibodies, HBV surface antigen [HBsAg], and T. pallidum) compared with the conventional algorithm based on the manual method (80.0% sensitivity and 98.6% specificity for the detection of anti-HIV, 75.0% sensitivity for the detection of anti-HCV, 94.7% sensitivity for the detection of HBsAg, and 100% specificity for the detection of anti-HCV and HBsAg) in these patients. The automated Bio-Flash technology-based screening algorithm also reduced the operation time by 85.0% (205 min) per day, saving up to 24 h/week. In conclusion, the use of the newly proposed screening algorithm based on the automated Bio-Flash technology can provide an advantage over the use of conventional algorithms based on manual methods for screening for HIV, HBV, HCV, and syphilis before GI endoscopy.

Update on hepatitis B and C virus diagnosis

Viral hepatitis B and C virus (HBV and HCV) are responsible for the most of chronic liver disease worldwide and are transmitted by parenteral route, sexual and vertical transmission. One important measure to reduce the burden of these infections is the diagnosis of acute and chronic cases of HBV and HCV. In order to provide an effective diagnosis and monitoring of antiviral treatment, it is important to choose sensitive, rapid, inexpensive, and robust analytical methods. Primary diagnosis of HBV and HCV infection is made by using serological tests for detecting antigens and antibodies against these viruses. In order to confirm primary diagnosis, to quantify viral load, to determine genotypes and resistance mutants for antiviral treatment, qualitative and quantitative molecular tests are used. In this manuscript, we review the current serological and molecular methods for the diagnosis of hepatitis B and C.

Evaluation of Novel Multiplex Antibody Kit for Human Immunodeficiency Virus 1/2 and Hepatitis C Virus Using Sol-Gel Based Microarray

Background. Microarrays enable high-throughput screening (HTS) of disease-related molecules, including important signaling proteins/peptides and small molecules that are in low abundance. In this study, we developed a multiplex blood bank screening platform, referred to as the Hi3-1 assay, for simultaneous detection of human immunodeficiency virus 1/2 (HIV 1/2) and hepatitis C virus (HCV). Methods. The Hi3-1 assay was tested using four panels (Panel 1, n = 4,581 patient samples; Panel 2, n = 15 seroconversion samples; Panel 3, n = 4 performance samples; and Panel 4, n = 251 purchased positive control samples), and the results were collected by the Department of Laboratory Medicine, Korea University Medical College, Republic of Korea. The present study compares the sensitivity of the multiplex detection platform for both HIV and HCV using a sol-gel based microarray, which was based on a reference test (Architect HIV Ag/Ab Combo and Architect anti-HCV assays), in Korean patients. Results. The sensitivity of the multiplex detection platform for both HIV and HCV was 100%, and the specificity was 99.96% for HIV and 99.76% for HCV, which is equivalent to that of the reference test. Conclusion. We have successfully applied a novel screening technology to multiplex HIV and HCV diagnoses in a blood bank screening test.

How to interpret borderline HCV antibody test results: a comparative study investigating four different anti-HCV assays

Anti-HCV testing is the first step to diagnose hepatitis C. Although anti-HCV assay performance improved during the last 2 decades, very high sensitivity required for screening may lead to limitations in specificity. Thus, there remains an uncertainty how to interpret anti-HCV test results with a borderline signal-to-cut-off ratio. Comparison was made of concordance and performance of four licensed anti-HCV assays in samples with borderline signal-to-cut-off ratios. Out of 12,090 consecutive samples tested for anti-HCV with the Abbott Architect Anti-HCV assay over a period of 29 months, 95 plasma samples with a signal-to-cut-off ratio between 0.5 and 2 were selected for this study. All samples were re-tested with the Enzygnost Anti-HCV version 4.0, the Ortho anti-HCV version 3.0, and the Monolisa anti-HCV-Plus version 2 assays. Discordant samples were classified by additional immunoblot testing. Overall, only 52% of the Architect borderline samples gave similar results in all four assays. Inter-assay concordance ranged between 58% and 80%. The highest discordance was observed between the Architect and the Monolisa assay (42%). In contrast, a high level of concordance was found between the Enzygnost and Ortho assays (80%). The Monolisa was best to identify negative samples (100%), while the Enzygnost correctly classified most of the positive samples (96%). Anti-HCV antibody assays show significant variation in classifying samples with low signal-to-cut-off ratios. Different performances may have cost and management implications, as false-positive results are not infrequent. However, sensitivities were good for all assays if indeterminate results are not considered as negative.

Seronegative hepatitis C virus infection in patients with lymphoproliferative disorders

It has been reported that hepatitis C virus (HCV) RNA may be present in serum and/or lymphoid cells in the absence of specific circulating antibodies. The current study analysed seronegative HCV infection in patients with lymphoproliferative disorders. We studied 77 anti-HCV-negative patients (45 male and 32 female, mean age 54.8 ± 14.2 years) with various lymphoproliferative disorders. HCV-RNA was detected by RT-PCR in plasma, peripheral blood mononuclear cells (PBMC) and bone marrow. Furthermore, the presence of viral nonstructural protein 3 (NS3) was determined in PBMC and bone marrow by immunostaining. HCV-RNA was detectable in at least one compartment in 27 (35.1%) patients. Viral RNA was found in bone marrow in 22 patients (28.6%), in PBMC in 13 (16.9%) and in plasma in 10 (13%) patients. In nine patients, evidence of infection was confined to the bone marrow compartment. Viral load in HCV-RNA-positive plasma ranged from 15 to 1.17 × 10(3) IU/mL. NS3 was detected in all but two HCV-RNA-positive bone marrow samples and in all but one HCV-RNA-positive PBMC samples. All 27 HCV-RNA-positive patients remained anti-HCV-negative when tested again after 6-12 months, but only four remained HCV-RNA positive. In conclusion, among patients with lymphoproliferative disorders, HCV can be present in plasma, PBMC and bone marrow despite the lack of circulating specific antibodies. Further studies are required to analyse the phenomenon of seronegative infection and to determine whether such patients are infectious.

Tools for the diagnosis of hepatitis C virus infection and hepatic fibrosis staging

Hepatitis C virus (HCV) infection represents a major public health issue. Hepatitis C can be cured by therapy, but many infected individuals are unaware of their status. Effective HCV screening, fast diagnosis and characterization, and hepatic fibrosis staging are highly relevant for controlling transmission, treating infected patients and, consequently, avoiding end-stage liver disease. Exposure to HCV can be determined with high sensitivity and specificity with currently available third generation serology assays. Additionally, the use of point-of-care tests can increase HCV screening opportunities. However, active HCV infection must be confirmed by direct diagnosis methods. Additionally, HCV genotyping is required prior to starting any treatment. Increasingly, high-volume clinical laboratories use different types of automated platforms, which have simplified sample processing, reduced hands-on-time, minimized contamination risks and human error and ensured full traceability of results. Significant advances have also been made in the field of fibrosis stage assessment with the development of non-invasive methods, such as imaging techniques and serum-based tests. However, no single test is currently available that is able to completely replace liver biopsy. This review focuses on approved commercial tools used to diagnose HCV infection and the recommended hepatic fibrosis staging tests.

Clinical performance of the novel DiaSorin LIAISON(®) XL murex: HBsAg Quant, HCV-Ab, HIV-Ab/Ag assays

BACKGROUND

The fully automated and closed LIAISON(®)XL platform was developed for reliable detection of infection markers like hepatitis B virus (HBV) surface antigen (HBsAg), hepatitis C virus (HCV) antibodies (Ab) or human immunodeficiency virus (HIV)-Ag/Ab. To date, less is known about the diagnostic performance of this system in direct comparison to the common Abbott ARCHITECT(®) platform.

OBJECTIVES

We compared the diagnostic performance and usability of the DiaSorin LIAISON(®)XL with the commonly used Abbott ARCHITECT(®) system.

STUDY DESIGN

The qualitative performance of the above mentioned assays was compared in about 500 sera. Quantitative tests were performed for HBsAg-positive samples from patients under therapy (n=289) and in vitro expressed mutants (n=37). For HCV-Ab, a total number of 155 selected samples from patients chronically infected with different HCV genotypes were tested.

RESULTS

The concordance between both systems was 99.4% for HBsAg, 98.81% for HCV-Ab, and 99.6% for HIV-Ab/Ag. The quantitative LIAISON(®)XL murex HBsAg assay detected all mutants in comparable amounts to the HBsAg wild type and yielded highly reliable HBsAg kinetics in patients treated with antiviral drugs. Dilution experiments using the 2nd International Standard for HBsAg (WHO) showed a high accuracy of this test. HCV-Ab from patients infected with genotypes 1-3 were equally detected in both systems. Interestingly, S/CO levels of HCV-Ab from patients infected with genotype 3 seem to be relatively low using both systems.

CONCLUSIONS

The LIAISON(®)XL platform proved to be an excellent system for diagnostics of HBV, HCV, and HIV with equal performance compared to the ARCHITECT(®) system.

Evaluation of a rapid on-site anti-HCV test as a screening tool for hepatitis C virus infection

BACKGROUND

In settings such as needle-stick injuries or intravenous drug abuse, immediate knowledge of the anti-hepatitis C virus (HCV) serostatus instead of waiting for the results of a laboratory-based test can be important to guide further medical procedures and appropriate hygienic advises. Thus, a rapid on-site anti-HCV test was evaluated in daily clinical routine and compared with a laboratory-based certified assay.

PATIENTS AND METHODS

Ten microliters of serum or EDTA whole blood was analyzed using a chromatographic immunoassay (Toyo anti-HCV test). Results were available on-site 5-15 min after sample centrifugation. The Architect anti-HCV test served as a reference method.

RESULTS

Sera of 189 patients were analyzed (without HCV infection: n=105; HCV infection: n=84). The assay was evaluable in 185 cases (98%). The sensitivity and specificity were 99 and 88%, respectively. With EDTA whole blood, the test was evaluable in 47/52 samples (90%). Forty-six of 47 evaluable EDTA tests were concordant with serum results. The one HCV patient with an unevaluable serum test was diagnosed correctly with the EDTA sample.

CONCLUSION

The rapid chromatographic anti-HCV immunoassay has limited specificity, which impairs clinical practicability. A positive result warrants re-evaluation with a certified serologic assay.

[Evaluation of HBs Ag, HCV and HIV Ag-Ab Assays using Bio-Rad Elite Microplate Analyzer.]

BACKGROUND

In this study, we evaluated the performance of Elite microplate analyzer (Bio-Rad Laboratories, France) and the related assays (ULTRA line) for the detection of hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV).

METHODS

Seroconversion panels, HBsAg positive/HBsAg negative (n=99/n=1,422), anti-HCV positive/negative (n=97/n=1,670), and anti-HIV positive/negative (n=112/n=1,704) samples were used to evaluate the performance of Monolisa HBsAg ULTRA, Monolisa HCV Ag-Ab ULTRA, and Genscreen ULTRA HIV Ag-Ab, respectively. The agreement of Elite microplate analyzer with CODA analyzer (Bio-Rad Laboratories, CA, USA) was also evaluated.

RESULTS

The detection limit of Monolisa HBsAg ULTRA was 0.034 IU/mL. For Monolisa HBsAg ULTRA, Monolisa HCV Ag-Ab ULTRA, and Genscreen ULTRA HIV Ag-Ab, diagnostic sensitivities were all 100%, diagnostic specificities were 100%, 99.8% and 99.9%, and total CVs (coefficients of variation) were 13.8-17.5%, 3.4-5.2%, and 7.5-9.5%, respectively. The agreement of Elite microplate analyzer with CODA analyzer was 99.5%.

CONCLUSIONS

The performance of Elite microplate analyzer and the related assays on analytical sensitivity, precision, early detection, diagnostic sensitivity and specificity was all adequate for a mass screening. However, further large multi-center studies should be performed to validate our results.

HBsAg blood screening and diagnosis: performance evaluation of the ARCHITECT HBsAg qualitative and ARCHITECT HBsAg qualitative confirmatory assays

A low initial reactive rate for screening assays is important for time- and cost-effective infectious disease testing. Therefore, the new ARCHITECT HBsAg Qualitative screening assay, in conjunction with the new ARCHITECT HBsAg Qualitative Confirmatory assay, was introduced. As the role of hepatitis B surface antigen (HBsAg) as surrogate marker for HBV resolution and the monitoring of drug effectiveness are becoming increasingly important, the established ARCHITECT HBsAg Quantitative assay remains available on the market. Precision, sensitivity, and specificity of the newly developed screening assay were in the range of established HBsAg assays. Seroconversion sensitivity was slightly superior compared to other commercially available assays. An initial reactive rate of 0.2% (without HBsAg-confirmed positive samples of 0.17%) for the ARCHITECT HBsAg Qualitative assay was observed. As the new screening assay is a 1-step assay format, the "high-dose hook effect" was investigated to assess the risk of false-negative results, but even very high positive HBsAg samples obtained signals clearly above the cutoff.

Multicenter evaluation of a fully automated third-generation anti-HCV antibody screening test with excellent sensitivity and specificity

Early detection of hepatitis C virus (HCV) is an important step in preventing progression to cirrhosis and hepatocellular carcinoma. Serologic assays for anti-hepatitis C (anti-HCV) antibody are valuable first-line tests in the screening and diagnosis of HCV infection. The aim of this multicenter study was to compare the Elecsys(®) Anti-HCV assay with alternative CE-marked Anti-HCV antibody assays against a range of samples that included 1,138 blood donors, 3,553 unselected routine daily specimens, and 46 pre-selected seroconversion panels. Specificity of the Elecsys Anti-HCV assay was 99.5% with blood donor samples and 99.4% with routine clinical specimens. These were similar to those obtained with the Prism(®) Anti-HCV, Architect(®) Anti-HCV assay, ADVIA(®) Centaur Anti-HCV assay and Vitros(®) Eci aHCV assays. Seroconversion sensitivity for the Elecsys Anti-HCV assay was similar to that of the Architect Anti-HCV, AxSYM HCV version 3.0, ADVIA Centaur Anti-HCV, and Vitros Eci aHCV assays. In fact, seroconversion testing on 46 commercially available panels showed that the difference in first detecting a positive blood sample was less than one day between assays (not statistically significant). The Elecsys Anti-HCV assay as well as the Architect, Prism, and Vitros Anti-HCV immunoassays revealed a seroconversion sensitivity of 100%, whereas the ADVIA Centaur HCV immunoassay showed a sensitivity of only 97.5% (39/40). Overall, the performance of the Elecsys Anti-HCV assay was similar to the performances of the comparator CE-marked Anti-HCV antibody assays.

Laboratory evaluation of the UniCel DxI 800 analyser (Beckman Coulter) for detecting HBV and HCV serological markers

BACKGROUND

Due to their high prevalence, hepatitis B virus (HBV) and hepatitis C virus (HCV) infections need accurate and rapid diagnosis tools.

OBJECTIVES

Technical performances of the UniCel DxI 800 analyser (Beckman Coulter) and a comparison with the Vitros ECi (Ortho Clinical Diagnostics) were performed for five serological markers: HBsAg, total anti-HBc, anti-HBc IgM, anti-HBs and anti-HCV.

STUDY DESIGN

Reproducibility was determined by repeated tests on the manufacturers' controls. The performance of the UniCel DxI 800 was assessed by testing negative and positive samples previously analysed with the Vitros ECi. The accuracy and linearity of anti-HBs assay were evaluated using the WHO international standard (W1042).

RESULTS

The intra-assay and inter-assay coefficients of variation were: 0.8% and 4.4% for HBsAg, 2.4% and 6.2% for anti-HBc, 5% and 8.7% for anti-HBc IgM, 2.1% and 5.1% for anti-HBs and 3.7% and 7.4% for anti-HCV. The two methods were concordant: 100% agreement for the five markers except for the negative HBsAg sera (99%). The anti-HBs results correlated well with the Vitros ECi (r=0.925 with p<0.0001) and the WHO standard (r2=0.9996). Throughput was 216 tests/h.

CONCLUSION

The high throughput, specificity and sensitivity make UniCel DxI 800 assays useful for routine diagnoses of HCV and HBV infections.

Clinical performance evaluation of four automated chemiluminescence immunoassays for hepatitis C virus antibody detection

Various automated chemiluminescence immunoassay (CLIA) analyzers for the detection of antibodies to hepatitis C virus (HCV) are now commercially available in clinical laboratories and are replacing conventional enzyme immunoassays. We investigated the performance of four anti-HCV CLIAs (the Architect Anti-HCV assay on the Architect i2000 system, the Vitros Anti-HCV assay on the Vitros ECiQ Immunodiagnostic System, the Access HCV Ab PLUS assay on the UniCel DxI 800 analyzer, and the newly developed Elecsys Anti-HCV assay on the Cobas e 411 analyzer). The total percent coefficient of variation values of imprecision were 3.5 to 5.7% with positive control materials and 7.2 to 10.2% with negative control materials. The agreement between the results of the Elecsys, Architect, Vitros, and Access CLIAs ranged from 94.5 to 98.1%. The clinical sensitivity of all CLIAs was 100%. Each CLIA showed excellent reproducibility and clinical sensitivity. The Elecsys, Architect, Vitros, and Access CLIAs showed clinical specificities of 98.2, 98.8, 96.5, and 98.2%.

Evaluation of the new ARCHITECT anti-HCV screening test under routine laboratory conditions

BACKGROUND

An improved test version of the Abbott ARCHITECT anti-hepatitis C virus (HCV) test became available at the end of 2005.

STUDY DESIGN

We compared the new test version with the Ortho Vitros anti-HCV test by evaluating 2034 serum samples in parallel on both systems under routine laboratory conditions. Discordant samples were tested in the Inno-LIA HCV Score assay as well as in the RIBA HCV 3.0.

RESULTS

Of the 2034 samples 140 (6.9%) yielded positive and 1856 (91.2%) negative results in both assays. We observed discordant results in 38 samples (1.9%). All discrepant samples showed a low S/CO ratio of 1.0-6.9 (mean 2.8) in the Ortho assay and of 1.3-3.0 (mean 1.96) in the ARCHITECT assay. As expected, most of them could not be confirmed by immunoblot testing. Comparison of the results of the two immunoblots (Inno-LIA and RIBA) revealed a great variability in test results.

CONCLUSIONS

This study represents the first comparative evaluation of the modified version of the Abbott ARCHITECT anti-HCV assay in comparison with the Ortho Vitros anti-HCV test. Under routine laboratory testing, we observed good overall concordance between the two assays and no evidence that one assay shows more false-reactive or negative results than the other.

[Development of a Web-based Program to Calculate Sample Size for Evaluating the Performance of In Vitro Diagnostic Kits.]

BACKGROUND

Many studies evaluating the performance of in vitro diagnostic kits have been criticized for the lack of reliability. To attain reliability those evaluation studies should be preceded by sample size calculation ensuring statistical power. This study was intended to develop a web-based system to estimate the sample size, which was often neglected because it would require expert knowledge in statistics.

METHODS

For sample size calculation, we extracted essential parameters from the performance studies on the 3rd generation anti-hepatitis C virus (HCV) kits reported in the literature. We developed a system with PHP web-script language and MySQL. The statistical models used in this system were as follows; one sample without power consideration (model 1), one sample with power consideration (model 2), and two samples with power consideration (model 3).

RESULTS

Among the articles published between 1989 and 2005, 13 articles that evaluated the performance of anti-HCV kits were identified by searching with Medical Subject Headings (MeSH). The diagnostic sensitivity was 83-100% with a median of 145 samples (range; 12-1,091) and the specificity was 97-100% with a median of 1,025 samples (range; 33-4,381). The estimated sample size would be 280 in the model 1, 817 in the model 2, and 1,510 in the model 3, when we set 2% prevalence of HCV infection, 95% sensitivity of a conventional kit, 97% sensitivity of a new kit , 95% significance level (two-sided test), 2% allowable error, and 80% power.

CONCLUSIONS

Our study indicates that an insufficient sample size is still a problem in performance evaluation. Our system should be helpful in increasing the reliability of performance evaluation by providing an appropriate sample size.

[Hepatitis C virus screening: performances characteristics of a commercial automated chemiluminescent microparticle immunoassay (CMIA-ARCHITECT anti-HCV)]

OBJECTIVES

In spite of improvement of the third-generation enzyme immunoassay (EIA) for screening HCV antibodies, some non-specific reactions persist. With commercialisation of a new chemiluminescence microparticle immunoassay (CMIA), we assessed the specificity of 2 assays providing by Abbott Diagnostics: CMIA-ARCHITECT anti-HCV and MEIA-AxSYM HCV 3.0 for qualitative detection of HCV antibodies in serum sample of patients collected in CHU of Caen.

PATIENTS AND METHODS

Anti-HCV results of 9753 serum samples tested by MEIA-AxSYM V.3 (2004), 6135 tested by CMIA-ARCHITECT1 (April to December 2005) and 5598 tested by CMIA-ARCHITECT2 (February to August 2006) were retrospectively analysed. Prevalences were calculated according to S/C ratio. The serum samples with an average S/C ratio from 1 to 2 for CMIA-ARCHITECT2 were confirmed with an immunoblot assay (Chiron RIBA HCV 3.0 SIA).

RESULTS

The CMIA-ARCHITECT assays showed a strong discrimination between negative and positive samples. We observed a tiny distribution of negative results. The percentage of "low positive" was respectively 1.26% for the MEIA-AxSYM, 0.68% for the CMIA-ARCHITECT1 and 0.36% for the CMIA-ARCHITECT2. Thirty-three of 54 (61%) samples yielding S/C ratio between 1 and 2 in the initial screening analysis with the CMIA-ARCHITECT1 were tested negative with CMIA-ARCHITECT2. Among the 21 remaining, 62% of RIBA results were interpretable.

CONCLUSION

CMIA-ARCHITECT assays improve the anti-HCV screening with a decrease of low-positive reactivity. However, low-positive results persist for which it is difficult to distinguish false-positive from low titer of antibodies. Supplemental assays such as immunoblot can be recommended in particularly context to more improve specificity and HCV-RNA detection should exclude a seroconversion.