Multi-center Evaluation of the VITROS® Anti-HBc 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 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 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 GENDER ETHNICITY AGE RISK 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 assay as an aid in the laboratory diagnosis of individuals with acute or chronic hepatitis B. The VITROS Anti-HBc assay can be used to detect antibodies against hepatitis B core antigen (anti-HBc) in serum and plasma following exposure to infectious hepatitis B virus (HBV). Anti-HBc is detectable shortly after the appearance of hepatitis B surface antigen (HBsAg). As the appearance of anti-HBsAg may be delayed after HBsAg clearance, anti-HBc is sometimes the only serological marker for HBV infection and potentially infectious blood. Anti-HBc is found in acute and chronic hepatitis B patients and also indicates past resolved infection. The VITROS Anti-HBc assay is performed using the VITROS Anti-HBc Immunodiagnostic Products Reagent Pack and VITROS Immunodiagnostic Products Anti-HBc Calibrator on the VITROS ECi Immunodiagnostic System. A competitive immunoassay technique is used. This involves the reaction of anti-HBc in the sample with hepatitis B core antigen (HBcAg) coated wells. Unbound sample is removed by washing. Horseradish peroxidase (HRP)-labeled antibody conjugate (mouse monoclonal anti-HBc) is then allowed to react with the remaining exposed HBcAg on the well surface. Unbound conjugate 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 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 assay. Table 1: Demographic Profiles of the Prospective Study Subjects in Population I 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, IgM anti-HBc, total anti-HBc, anti-HBe, and antiHBs (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 an HBV disease classification. Table 3 summarizes how these classifications were determined. There were 28 distinct reference marker profiles Presented at the American Society for Microbiology 104th General Meeting, New Orleans, LA, USA, May 2004.

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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 5 summarizes the percent agreement between the VITROS and reference anti-HBc assays for each specimen classification in prospective sample Population I. Percent agreement was determined by dividing the number of positive or negative VITROS Anti-HBc...

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Table 7 summarizes the percent agreement between the VITROS and reference anti-HBc assays for each specimen classification in prospective sample Population II. Table 7: Positive and Negative Percent Agreement between the VITROS Anti-HBc and Reference Anti-HBc Assays in Population II (N=315) HBV Disease Classification Overall Acute Chronic Early Recovery Recovered HBV Vaccine Response Not Previously Infected with HBV Uninterpretable PRESUMABLY VITROS FALSE NEGATIVE RESULTS Within Populations I & II combined, 37 samples gave a positive anti-HBc result with the reference assay (initial S/C...

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