Multi-center Evaluation of the VITROS® Anti-HBc IgM Assay in Patients with Signs and Symptoms of Hepatitis and in Persons at Risk for Hepatitis - 6 Pages

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Multi-center Evaluation of the VITROS® Anti-HBc IgM Assay in Patients with Signs and Symptoms of Hepatitis and in Persons at Risk for Hepatitis

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Multi-center Evaluation of the VITROS® Anti-HBc IgM Assay in Patients with Signs and Symptoms of Hepatitis and in Persons at Risk for Hepatitis E. Schiff1, M. Latimer2, D. Uettwiller-Geiger3, B. Attar4, H. F. Yee, Jr.5, J. Gorlin6, J. Peterson7, L. Bergmeyer7 J. Calcagno7, M. DeLucia7, 1 U of Miami, School of Med, Miami, FL, 2Parkland Mem Hosp, Dallas, TX, 3JT Mather Mem Hosp, Port Jefferson, NY, 4 Cook County Hosp, Chicago, IL, 5UCLA, Dept of Med, Los Angeles, CA, 6 Memorial Blood Centers of Minnesota, Minneapolis, MN, and 7Ortho-Clinical Diagnostics, Raritan, NJ Table 1: Demographic Profiles of the Prospective Study Subjects in Population I Test Site TOTAL Male Female Caucasian African-American Hispanic Asian Indian Haitian Other Unknown ≤10 11-30 31-50 51-70 >70 Unknown No Risk Factor(s) Risk Factor(s) Table 2: Demographic Profiles of the Prospective Study Subjects in Population II A multi-center outcomes based study was conducted to evaluate the clinical effectiveness of the VITROS Anti-HBc IgM assay as an aid in the laboratory diagnosis of individuals with acute or chronic hepatitis B. The VITROS Anti-HBc IgM assay is designed to detect anti-HBc IgM at an appropriate level of sensitivity as an aid for the diagnosis of acute or chronic hepatitis B infection. The detection of anti-HBc IgM can be useful for the differential diagnosis of hepatitis B from other forms of viral hepatitis. IgM class antibodies against HBc are detected soon after infection and the presence of high concentrations of antiHBc IgM has been shown to be an indicative marker of acute infection. The level of anti-HBc IgM decreases throughout the course of infection. However, low levels of anti-HBc IgM may persist for over a year after infection in some patients and are found occasionally in chronic carriers. The VITROS Anti-HBc IgM assay is performed using the VITROS Anti-HBc IgM Reagent Pack and the VITROS Immunodiagnostic Products Anti-HBc IgM Calibrator on the VITROS ECi Immunodiagnostic System. An antibody class capture technique is used. This involves the dilution of the sample and the simultaneous reaction of IgM in the diluted sample with biotinylated mouse monoclonal anti-human IgM antibody. The immune complex is captured by streptavidin on the wells. Unbound materials are removed by washing. Horseradish peroxidase (HRP)- labeled mouse monoclonal anti-HBc IgM antibody, which has been complexed with recombinant HBc antigen (conjugate) is then captured by anti-HBc specific IgM bound to the wells. Unbound material is removed by washing. The bound HRP conjugate is measured by a luminescent reaction. A reagent containing luminogenic substrates (a luminol derivative and a peracid salt) and an electron transfer agent, is added to the wells. The HRP in the bound conjugate catalyzes the oxidation of the luminol derivative, producing light. The electron transfer agent increases the level and duration of the light produced. The light signals are read by the VITROS ECi System. The amount of HRP conjugate bound is indicative of the concentration of anti-HBc IgM present in the sample. Two at-risk prospective sample populations were evaluated. Population I (N=1691) was collected in the U.S. from persons with signs or symptoms or biochemical manifestations of hepatitis (elevated liver function tests) and those at high risk of hepatitis infection due to lifestyle, behavior, occupation, or known exposure event. These specimens were obtained from subjects enrolled at three collection sites that were located in Miami, FL (37.0%), Dallas, TX (28.1%) and Chicago, IL (34.9%). These specimens were tested at diagnostic laboratories located in Miami, FL, Port Jefferson, NY, and Minneapolis MN. Population II (N=315) was obtained from subjects prospectively enrolled from an area in India with a high prevalence of viral hepatitis; all subjects in this population reported signs or symptoms of viral hepatitis. Testing of these specimens was done at diagnostic laboratories located in Miami, FL, Minneapolis MN, and Los Angeles, CA. The demographic profiles of these prospective study populations are shown in Tables 1 and 2. These results are listed by testing site rather than by collection site. A third, unlinked population of samples (N=100) from a population of pediatric and adolescent subjects in Utah at low risk for viral hepatitis was also tested with the VITROS Anti-HBc IgM assay. Tables 1 and 2 present the demographic profiles of subjects in Populations I and II, respectively. Test Site TOTAL Male Female 11-30 31-50 51-70 >70 STUDY DESIGN AND HBV DISEASE CLASSIFICATION The HBV disease classification of each study subject was assigned by using a hepatitis B marker profile that consisted of reference assays (previously licensed or approved by the FDA) for the detection of HBsAg, HBeAg, total anti-HBc, IgM anti-HBc, anti-HBe, and anti-HBs (quantitative). All reference assays were from one manufacturer with the exception of the HBeAg and anti-HBe assays used to test samples from Population II. The positive (+) / negative (-) results from this reference assay testing were used to assign each sample/subject to Presented at the American Society for Microbiology 104th General Meeting, New Orleans, LA, USA, May 2004.

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an HBV disease classification. Table 3 summarizes how these classifications were determined. There were 28 distinct reference marker profiles observed among the subjects in Populations I and II. Both populations demonstrated 14 profiles in common; 10 profiles were observed only in Population I and 4 profiles were found only in Population II. Six of the 28 profiles did not allow assignment to any of the recognized HBV disease classifications and are reported as “uninterpretable.” Table 3: HBV Reference Marker Profiles and HBV Disease Classification HBsAg* Total aHBc Acute Acute Acute Acute...

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Table 7 summarizes the percent agreement between the VITROS and reference anti-HBc IgM assays for each specimen classification in prospective sample Population II. Table 7: Positive and Negative Percent Agreement between the VITROS Anti-HBc IgM and Reference Anti-HBc IgM Assays in Population II (N=315) HBV Disease Classification Overall Acute Chronic Early Recovery Recovered HBV Vaccine Response Not Previously Infected with HBV Uninterpretable 95% Exact Confidence Interval 68.69 - 86.63 PRESUMABLY VITROS FALSE NEGATIVE RESULTS In prospective Populations I and II combined, 26 samples gave...

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