IMMULITE 2000 XPI ANTI-HBC

P010051 · Siemens Healthcare Diagnostics Products, Ltd. · SEI · Jul 24, 2002 · Microbiology

Device Facts

• Record ID: P010051
• Device Name: IMMULITE 2000 XPI ANTI-HBC
• Applicant: Siemens Healthcare Diagnostics Products, Ltd.
• Product Code: SEI · Microbiology
• Decision Date: Jul 24, 2002
• Decision: APRL
• Regulation: 21 CFR 866.3173
• Device Class: Class 2

Intended Use

IMMULITE Anti-HBc The IMMULITE Anti-HBc is a solid-phase chemiluminescent enzyme immunoassay designed for use on the IMMULITE automated immunoassay analyzer for the qualitative detection of total antibodies against hepatitis B core antigen (anti-HBc) in human serum or plasma (EDTA, heparinized, citrate). It is intended for in vitro diagnostic use for the presumptive laboratory diagnosis of ongoing or previous hepatitis B virus infection. IMMULITE 2000 Anti-HBc The IMMULITE 2000 Anti-HBc is a solid-phase chemiluminescent enzyme immunoassay designed for use on the IMMULITE 2000 automated immunoassay analyzer for the qualitative detection of total antibodies against hepatitis B core antigen (anti-HBc) in human serum or plasma (EDTA, heparinized, citrate). It is intended for in vitro diagnostic use for the laboratory diagnosis of ongoing or previous hepatitis B virus infection.

Device Story

IMMULITE and IMMULITE 2000 Anti-HBc are solid-phase, two-step chemiluminescent enzyme immunoassays for automated analyzers. Input: human serum or plasma. Principle: polystyrene beads coated with recombinant HBcAg capture patient anti-HBc; alkaline phosphatase-labeled monoclonal anti-HBc antibody binds to unoccupied sites; chemiluminescent substrate (phosphate ester of adamantyl dioxetane) added; light emission (cps) measured by photomultiplier tube. Output: qualitative result via comparison to established cutoff. Used in clinical laboratories by technicians. Output aids physicians in diagnosing HBV infection status, assessing prior immune status, and differential diagnosis of hepatitis. Benefits: provides diagnostic information for HBV management.

Clinical Evidence

Clinical studies across four sites (n=908) compared IMMULITE/IMMULITE 2000 Anti-HBc results against FDA-approved reference serological markers. Performance metrics: Total positive agreement ranged from 66.7% to 100%; negative agreement ranged from 98.7% to 100%; total agreement ranged from 93.6% to 99.0%. Study populations included acute/chronic HBV patients, vaccinated individuals, pregnant women, and healthy controls.

Technological Characteristics

Solid-phase chemiluminescent enzyme immunoassay. Solid phase: polystyrene bead coated with recombinant HBcAg. Detection: alkaline phosphatase-labeled monoclonal anti-HBc antibody. Substrate: phosphate ester of adamantyl dioxetane. Automated analyzer platform. Qualitative measurement via photomultiplier tube photon counting.

Indications for Use

Indicated for qualitative detection of total antibodies against hepatitis B core antigen (anti-HBc) in human serum or plasma to aid in the presumptive laboratory diagnosis of ongoing or previous hepatitis B virus (HBV) infection.

Regulatory Classification

Identification

A hepatitis B virus (HBV) antibody assay is identified as an in vitro diagnostic device intended for prescription use in the detection of antibodies to HBV in human serum, plasma, or other matrices, and as a device that aids in the diagnosis of HBV infection in persons with signs and symptoms of hepatitis and in persons at risk for hepatitis B infection. Results from assays may be qualitative or quantitative, such as quantitative anti-HBs. In addition, results from an anti-HBc IgM (IgM antibodies to core antigen) assay indicating the presence of anti-HBc IgM are indicative of recent HBV infection. Anti-HBs (antibodies to surface antigen) assay results may be used as an aid in the determination of susceptibility to HBV infection in individuals prior to or following HBV vaccination or when vaccination status is unknown. The assay is not intended for screening of blood, plasma, cells, or tissue donors. The assay is intended as an aid in diagnosis in conjunction with clinical findings and other diagnostic procedures.

Special Controls

*Classification.* Class II (special controls). The special controls for this device are:(1) The labeling required under § 809.10(b) of this chapter must include: (i) A prominent statement that the assay is not intended for the screening of blood, plasma, cells, or tissue donors. (ii) A detailed explanation of the principles of operation and procedures for performing the assay. (iii) A detailed explanation of the interpretation of results. (iv) Limitations, which must be updated to reflect current clinical practice and disease presentation and management. The limitations must include statements that indicate: (A) When appropriate, performance characteristics of the assay have not been established in populations of immunocompromised or immunosuppressed patients or other special populations where assay performance may be affected. (B) Detection of HBV antibodies to a single viral antigen indicates a present or past infection with hepatitis B virus, but does not differentiate between acute, chronic, or resolved infection. (C) The specimen types for which the device has been cleared, and that use of the assay with specimen types other than those specifically cleared for this device may result in inaccurate assay results. (D) Diagnosis of hepatitis B infection should not be established on the basis of a single assay result but should be determined by a licensed healthcare professional in conjunction with the clinical presentation, history, and other diagnostic procedures. (E) A non-reactive assay result may occur early during acute infection, prior to development of a host antibody response to infection, or when analyte levels are below the limit of detection of the assay. (F) Results obtained with this assay may not be used interchangeably with results obtained with a different manufacturer's assay. (v) For devices intended for the quantitative detection of HBV antibodies (anti-HBs), in addition to the special controls listed in paragraphs (b)(1) and (2) of this section, labeling required under § 809.10(b) of this chapter must include: (A) The assay calibrators' traceability to a standardized reference material that FDA has determined is appropriate ( *e.g.,* a recognized consensus standard) and the limit of blank (LoB), limit of detection (LoD), limit of quantitation (LoQ), linearity, and precision to define the analytical measuring interval.(B) Performance results of the analytical sensitivity study testing a standardized reference material that FDA has determined is appropriate ( *e.g.,* a recognized consensus standard).(2) Design verification and validation must include the following: (i) Detailed device description, including all parts that make up the device, ancillary reagents required but not provided, an explanation of the device methodology, and design of the antigen(s) and capture antibody(ies) sequences, rationale for the selected epitope(s), degree of amino acid sequence conservation of the target, and the design and composition of all primary, secondary and subsequent standards used for calibration. (ii) Documentation and characterization ( *e.g.,* supplier, determination of identity, and stability) of all critical reagents (including description of the antigen(s) and capture antibody(ies)), and protocols for maintaining product integrity throughout its labeled shelf life.(iii) Risk analysis and management strategies, such as Failure Modes Effects Analysis and/or Hazard Analysis and Critical Control Points summaries and their impact on assay performance. (iv) Final release criteria to be used for manufactured assay lots with appropriate evidence that lots released at the extremes of the specifications will meet the identified analytical and clinical performance characteristics as well as stability. (v) Stability studies for reagents must include documentation of an assessment of real-time stability for multiple reagent lots using the indicated specimen types and must use acceptance criteria that ensure that analytical and clinical performance characteristics are met when stability is assigned based on the extremes of the acceptance range. (vi) All stability protocols, including acceptance criteria. (vii) When applicable, analytical sensitivity of the assay that is the same or better than that of other cleared or approved assays. (viii) Analytical performance studies and results for determining the limit of blank (LoB), limit of detection (LoD), cutoff, precision (reproducibility), including lot-to-lot and/or instrument-to-instrument precision, interference, cross reactivity, carryover, hook effect, seroconversion panel testing, matrix equivalency, specimen stability, reagent stability, and cross-genotype antibody detection sensitivity, when appropriate. (ix) For devices intended for the detection of antibodies for which a standardized reference material (that FDA has determined is appropriate) is available, the analytical sensitivity study and results testing the standardized reference material. Detailed documentation of that study and its results must be provided, including the study protocol, study report, testing results, and all statistical analyses. (x) For devices with associated software or instrumentation, documentation must include a detailed description of device software, including software applications and hardware-based devices that incorporate software. The detailed description must include documentation of verification, validation, and hazard analysis and risk assessment activities, including an assessment of the impact of threats and vulnerabilities on device functionality and end users/patients as part of cybersecurity review. (xi) Detailed documentation of clinical performance testing from a clinical study with an appropriate number of HBV reactive and non-reactive samples in applicable risk categories and conducted in the appropriate settings by the intended users. Performance must be analyzed relative to an FDA cleared or approved HBV antibody assay or a comparator that FDA has determined is appropriate. Additional relevant patient groups must be validated as appropriate. The samples must include prospective (sequential) samples for each identified specimen type and, as appropriate, additional characterized clinical samples. Samples must be sourced from geographically diverse areas. (3) For any HBV antibody assay intended for quantitative detection of anti-HBV antibodies, the following special controls, in addition to those special controls listed in paragraphs (b)(1) and (2) of this section, also apply: (i) Detailed documentation of the metrological calibration traceability hierarchy to a standardized reference material that FDA has determined is appropriate. (ii) Detailed documentation of the following analytical performance studies conducted, as appropriate to the technology, specimen types tested, and intended use of the device, including upper and lower limits of quantitation (UloQ and LloQ, respectively), linearity using clinical samples, and an accuracy study using the recognized international standard material.

Reference Devices

• Kit A (commercially available enzyme immunoassay for anti-HBc)

Submission Summary (Full Text)

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Summary of Safety and Effectiveness Data

I. GENERAL INFORMATION

Device Generic Name: Reagent system for the measurement of antibodies against hepatitis B core antigen

Device Trade Name: IMMULITE® Anti-HBc
IMMULITE® 2000 Anti-HBc

Applicant’s Name and Address: Diagnostic Products Corporation
5700 West 96th Street
Los Angeles, California 90045-5597

Premarket Approval Application (PMA) Number: P010051

Date of Panel Recommendation: None

Date of Notice of Approval to the Applicant: July 24, 2002

II. INDICATIONS FOR USE

IMMULITE Anti-HBc

The IMMULITE Anti-HBc is a solid-phase chemiluminescent enzyme immunoassay designed for use on the IMMULITE automated immunoassay analyzer for the qualitative detection of total antibodies against hepatitis B core antigen (anti-HBc) in human serum or plasma (EDTA, heparinized, citrate). It is intended for in vitro diagnostic use for the presumptive laboratory diagnosis of ongoing or previous hepatitis B virus infection.

IMMULITE 2000 Anti-HBc

The IMMULITE 2000 Anti-HBc is a solid-phase chemiluminescent enzyme immunoassay designed for use on the IMMULITE 2000 automated immunoassay analyzer for the qualitative detection of total antibodies against hepatitis B core antigen (anti-HBc) in human serum or plasma (EDTA, heparinized, citrate). It is intended for in vitro diagnostic use for the laboratory diagnosis of ongoing or previous hepatitis B virus infection.

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# III. DEVICE DESCRIPTION

The IMMULITE and IMMULITE 2000 Anti-HBc kits are the subject of this PMA. Data for each assay is presented separately in this document.

The IMMULITE and IMMULITE 2000 Anti-HBc kits are solid phase, two step chemiluminescent enzyme immunoassays designed for use on the automated IMMULITE and IMMULITE 2000 analyzers, for the qualitative measurement of total antibodies against hepatitis B core antigen (HBcAg) in human serum or plasma. The kits are intended for *in vitro* use as an aid in the determination of a prior immune status to the hepatitis B virus.

The kits' solid phase is a polystyrene bead coated with purified recombinant HBcAg. The patient sample and a protein-based buffer are simultaneously introduced into the Test Unit and incubated for approximately 30 minutes at 37 °C with intermittent agitation. During this time, anti-HBc in the patient sample binds to the recombinant HBcAg-coated bead. Unbound serum is then removed by a centrifugal wash. An alkaline phosphatase-labeled monoclonal anti-HBc antibody is introduced, and the reaction tube is incubated with agitation for another 30 minute cycle, during which time the monoclonal antibody binds to unoccupied sites on the recombinant HBcAg-coated bead. The unbound enzyme conjugate is removed by a centrifugal wash. After the wash, a chemiluminescent substrate is added, and the reaction tube is incubated with agitation for a further 5 – 10 minutes.

The chemiluminescent substrate is a phosphate ester of adamantyl dioxetane which undergoes hydrolysis in the presence of alkaline phosphatase to yield an unstable intermediate. The continuous production of this intermediate results in the sustained emission of light. The bound complex and the resulting photon output, measured as cps by the photomultiplier tube, are inversely related to the presence of antibodies to HBcAg in the sample. A qualitative result is then obtained by comparing the patient results to an established cutoff.

# IV. CONTRAINDICATIONS, WARNINGS AND PRECAUTIONS

There are no known contraindications for the IMMULITE Anti-HBc and the IMMULITE 2000 Anti-HBc assay.

Warning and precautions for users of the IMMULITE Anti-HBc and IMMULITE 2000 Anti-HBc assays are stated in the product labeling.

# V. ALTERNATIVE PRACTICES OR PROCEDURES

Commercially available, FDA licensed or approved serological tests have been used to measure antibodies against hepatitis B core antigen in individuals suspected of having hepatitis. When patient test results are used in combination with other serological markers expressed during the three phases of incubation, the presence of HBV virus can

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be determined.

## VI. MARKETING HISTORY

IMMULITE Anti-HBc and IMMULITE 2000 Anti-HBc have been marketed internationally as an aid in the determination of acute and chronic hepatitis B virus infection since July 1996. IMMULITE and IMMULITE 2000 Anti-HBc have received European Union CE Mark approval and have been marketed in Europe since June 2001. The devices have not been withdrawn from any country for reasons related to safety and effectiveness.

## VII. POTENTIAL ADVERSE EFFECTS OF DEVICE ON HEALTH

As an *in vitro* diagnostic test system, there is no direct adverse effect of IMMULITE and IMMULITE 2000 Anti-HBc assays on the health of the patient. The possibility of erroneous test results due to test malfunctions or operator errors exists. A false non-reactive result would make the patients unnecessarily receive a vaccine, vaccine booster, hyperimmune globulin, or be considered not to have recovered from an HBV infection when in fact they have recovered.

Blood specimens obtained from a subject infected with hepatitis B prior to the appearance of an antibody titer have the potential to misdiagnose the patient as not being infected. Additionally, specimens obtained after the disappearance of anti-HBc IgM antibodies, in the absence of test results for other hepatitis B markers, may lead to misdiagnosis of a hepatitis B infected patient.

The risk of incorrect test results is inherent with all *in vitro* diagnostic products. Therefore, the above potential risks are not unusual in the laboratory setting. Appropriate warnings for each of these risks are contained in the labeling and package insert instructions. Standard good laboratory practices are considered sufficient to minimize risks to the end user.

## VIII. SUMMARY OF NON CLINICAL STUDIES

### Analytical Specificity

Analytical specificity was evaluated at two clinical sites in the United States and one European site. In the United States, serum specimens from 17 subgroups of patients with potentially cross-reacting microorganisms or conditions were tested by IMMULITE Anti-HBc, IMMULITE 2000 Anti-HBc, and a commercially available enzyme immunoassay for anti-HBc (Kit A), and the results are listed in the package insert.

In the European study, eight specimens from antinuclear antibody (ANA) positive patients and 28 specimens from patients with positive rheumatoid factor (RF) were tested by IMMULITE Anti-HBc. IMMULITE Anti-HBc test results were all negative for the

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eight ANA specimens. IMMULITE Anti-HBc test results were negative for 25/28 RF specimens and positive for 3/28 RF specimens.

The specimens were also tested by IMMULITE 2000 Anti-HBc, and the results are listed in the package insert.

In the European study, eight specimens from antinuclear antibody (ANA) positive patients were tested by IMMULITE 2000 Anti-HBc. IMMULITE 2000 Anti-HBc test results were negative for all eight ANA specimens.

## Analytical Sensitivity

Based on studies with serial dilution of Paul Erlich Institute reference material Anti-HBc IgG 100 U/mL, the analytical sensitivity (last positive dilution) for IMMULITE 2000 Anti-HBc is 0.42 PEI U/mL. The 95% confidence interval at this level (0.42 PEI IU/mL) is 0.37 - 0.48 PEI U/mL precision of IMMULITE and IMMULITE 2000 Anti-HBc.

## Precision

Precision studies for the IMMULITE and IMMULITE 2000 Anti-HBc assays were conducted at three sites. Three controls and six patient samples with different hepatitis B core antibody levels representing negative, high negative, around the cutoff, low positive, medium positive and high positive samples were evaluated. All controls and samples were tested in duplicate by three different IMMULITE Anti-HBc kit lots and one IMMULITE 2000 Anti-HBc kit lot for a total of 40 runs at each of the three sites.

Statistics including the means, standard deviations, intra-assay and total precision were based on the adjustor to sample CPS ratios in the summary shown below.

EDTA, heparin and sodium citrate samples were assayed in duplicate in three runs on three days at three U.S. sites for three lots of IMMULITE Anti-HBc and one lot of IMMULITE 2000 Anti-HBc. The median total variance of coefficients (EDTA, 4.9%; heparin, 4.4%; sodium citrate, 5.5%) demonstrated that these alternative sample types do not affect the precision of IMMULITE and IMMULITE 2000 Anti-HBc.

The IMMULITE 2000 Anti-HBc lot-to-lot precision has not been evaluated. Because the lot-to-lot precision of the assay had previously been established, and the Stability studies included three lots, no additional data was required.

## Effects of Anticoagulants

The measurement of specimens is not significantly affected by the presence of heparin. IMMULITE 2000 Anti-HBc results were negative for 23/26 and positive for 3/26 RF specimens. EDTA, heparin, and sodium citrate samples were assayed in duplicate in three runs on three days at three U.S. sites for three lots of IMMULITE Anti-HBc and one lot of IMMULITE 2000 Anti-HBc. The median total variance of coefficients (EDTA, 4.9%; heparin, 4.4%; sodium citrate, 5.5%) demonstrated that these alternative sample types do not affect the sodium citrate, or EDTA anti-coagulants, as shown in a study

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(Study 1) that included 57 specimens collected into plain, heparinized, sodium citrate, and EDTA vacutainer tubes. Data graphs are in the package insert. The following is a summary showing cutoff-to-signal rations with correlation regression (r =).

IMMULITE Anti-HBc (in cutoff-to-signal ratio)

(Heparin) = 1.08 (Serum) + 0.006 r = 0.99

(Na Citrate) = 1.10 (Serum) + 0.026 r = 0.95

(EDTA) = 0.99 (Serum) + 0.034 r = 0.98

In another study, 18 specimens collected into plain and sodium citrate vacutainer tubes were tested by IMMULITE Anti-HBc assay. By regression: (in cutoff-to-signal ratio)

(Na Citrate) = 1.14 (Serum) - 1.54. r = 0.97

IMMULITE 2000 Anti-HBc (in cutoff-to-signal ratio)

(Heparin) = 0.98 (Serum) + 0.018 r = 0.99

(Na Citrate) = 1.07 (Serum) + 0.027 r = 0.94

(EDTA) = 0.97 (Serum) + 0.031 r = 0.99

In another study, 18 specimens collected into plain and sodium citrate vacutainer tubes were tested by IMMULITE 2000 Anti-HBc assay. By regression: (in cutoff-to-signal ratio)

(Na Citrate) = 0.92 (Serum) + 0.776 r = 0.91

## Analytical Specificity

Analytical specificity was evaluated at two clinical sites in the United States and one European site. In the United States, serum specimens from 17 subgroups of patients with potentially cross-reacting microorganisms or conditions were tested by IMMULITE 2000 Anti-HBc and a commercially available enzyme immunoassay for anti-HBc (Kit A). The data is presented in the package insert.

In the European study, eight specimens from antinuclear antibody (ANA) positive patients were tested by IMMULITE 2000 Anti-HBc. IMMULITE 2000 Anti-HBc test results were negative for all eight ANA specimens.

## Effects of Bilirubin, Lipemia and Hemolysis

To simulate moderate and severe icterus, different volumes of each of 5 patient samples ranging from very negative to high positive total antibodies against hepatitis B surface antigen were pipetted into lyophilized unconjugated bilirubin to achieve 3 levels of bilirubin concentrations (10, and 20 mg/dL) for each sample. The spiked and unspiked samples were assayed by the IMMULITE and IMMULITE 2000 Anti-HBc assays. In the IMMULITE Anti-HBc tests, the spiked samples had averages of 98%, and 90% recovery

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for all samples for 10, and 20 mg/dL bilirubin concentrations, respectively. In the IMMULITE 2000 Anti-HBc tests, the spiked samples had averages of 96%, and 97% recovery for all samples for 10, and 20 mg/dL bilirubin concentrations, respectively. This study demonstrated that the measurement of antibodies against hepatitis B surface antigen was not affected by the presence of bilirubin up to 20 mg/dL.

To simulate mild, moderate and severe hemolysis, the same five samples were spiked with hemolysate to achieve final hemoglobin levels of 168, 252 and 504 mg/dL. The samples were assayed, both spiked and unspiked, by the IMMULITE and IMMULITE 2000 Anti-HBc assays. In both the IMMULITE and IMMULITE 2000 Anti-HBc tests, the low samples had significant increases in the antibodies against hepatitis B surface antigen when spiked with hemolysate. It was concluded that the measurement of antibodies against hepatitis B surface antigen may be affected by the presence of red blood cells. The results of hemolyzed samples should be interpreted with caution.

The same 6 samples were each spiked with 4 levels of triglycerides at 500, 1000, 2000 and 3000 mg/dL to evaluate the lipemia effect on the IMMULITE and IMMULITE 2000 Anti-HBc assays. Unspiked and spiked samples were tested by the IMMULITE and IMMULITE 2000 Anti-HBc assays. Since no significant increases of antibody levels were observed in the spiked samples with the increase of triglyceride levels, it was concluded that the measurement of antibodies to hepatitis surface antigen was not affected by the presence of lipemia (triglycerides up to 3000 mg/dL).

## Hook Effect and Carryover

The hook effect study demonstrated that the IMMULITE and IMMULITE 2000 Anti-HBc assays did not have a hook effect up to at least 10,000 mIU/mL.

The carryover study demonstrated that the IMMULITE and IMMULITE 2000 Anti-HBc assays did not exhibit a carryover phenomenon when samples were preceded by a sample with a very high titer of antibodies against hepatitis B surface antigen.

## Interfering Substances

A study was conducted to evaluate the effects of interfering substances on IMMULITE and IMMULITE 2000 Anti-HBc assays. Potential interfering substances that included common serum constituents, chemotherapeutic and other drugs were spiked into serum samples with 5 or 6 different levels of anti-HBc. Listed below are the substances and their test levels (concentration).

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| Interferring Substance | Concentration |
| --- | --- |
| HUMAN ALBUMIN | 6 g/dL |
| ASCORBIC ACID | 3 mg/dL |
| ALT | 7000 U/L |
| AST | 7000 U/L |
| ALK PHOSPHATASE | 5000 U/L |
| CORTISONE | 400 ug/dL |
| CYCLOSPORIN A | 18.02 ug/dL |
| GANCICLOVIR | 11.8 ug/mL |
| ETHANOL | 350 mg/dL |
| INTRON A | 2730 IU/mL |
| LAMIVUDINE | 20 ug/mL |
| LDH | 6000 U/L |
| NELFINAVIR | 40 ug/mL |

This study demonstrated that the measurement of antibodies against hepatitis B surface antigen by IMMULITE and IMMULITE 2000 Anti-HBc was not affected by the presence of any of the interfering substances listed up to the levels tested.

## Stability

Stability studies for IMMULITE and IMMULITE 2000 Anti-HBc were conducted by using 3 lots of IMMULITE Anti-HBc, and one lot of IMMULITE 2000 Anti-HBc. The kits and components were subjected to different storage/stress conditions to simulate adverse conditions that might be encountered during shipment and use at clinical laboratories, to establish the long-term (shelf-life) claims, to approximate and support the real time stability and to test the robustness of individual components.

The studies demonstrated that the performance of IMMULITE and IMMULITE 2000 Anti-HBc assays was not affected if properly stored at package insert conditions for at least 720 days.

These studies also demonstrated that the performance of IMMULITE and IMMULITE 2000 Anti-HBc assays was not affected following initial stresses (37°C, or –20°C) for at least 720 days.

## IX. SUMMARY OF CLINICAL STUDIES

## Expected Values

Individuals acutely infected with the hepatitis B virus will exhibit anti-HBc approximately two weeks after the disappearance of HBsAg. This antibody response will reach peak levels after several months and gradually decline over a period of years. The majority of persons who have been vaccinated against HBV will also have detectable levels of anti-HBc.

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Demographics and expected prevalence rates for different categories of subjects (apparently healthy individuals, HBV Chronic Patients, HBV Acute Patients and individuals at high risk or low risk of exposure to hepatitis B.) each of whom provided one specimen, from four clinical studies, one in the northwestern United States (Study 1), two in the southern United States (Study 3 using specimens from China and Study 4), and one in Europe, are summarized in the package insert.

## Clinical Studies

The sponsor conducted clinical studies at four sites to assess the performance of the IMMULITE Anti-HBc assay and IMMULITE 2000 Anti-HBc. The study included 908 subjects, whose status was determined using FDA-approved or licensed hepatitis B assays (Reference markers), of those 139 specimens were evaluated in a comparison study. Only initial test results were reported in the analyses.

The data were analyzed using the test results obtained from the HBV reference serological marker assays, reactive(+)/ nonreactive(-). Specimen designation was based only on the HBV serological marker results for that particular specimen. No other laboratory or clinical information was used in the characterization process.

Site 1: Conducted in the northwestern United States, this study included 281 patients, consisting of 138 males and 88 females. Gender for 55 subjects was not reported. These subjects had an average age of 43 years, ranging from 21 to 85 years. Distributions of the ethnicity of the subjects are shown in the following table.

| Ethnicity | n | % |
| --- | --- | --- |
| African American | 15 | 5.3% |
| Caucasian | 169 | 60.1% |
| Hispanic | 2 | 0.7% |
| Asian | 32 | 11.4% |
| Other | 3 | 1.1% |
| Unknown | 60 | 21.4% |
| Total | 281 | 100.0% |

These subjects included acute and chronic hepatitis B patients, vaccinated individuals, pregnant women, and apparently healthy individuals, and patients with potentially cross-reactive substances and medical conditions.

A total of 281 specimens were prospectively (n=92) and retrospectively (n=189) collected and tested by FDA-approved or licensed hepatitis B assays for six HBV serological markers (HBsAg, Anti-HBc, Anti-HBs, Anti-HBc IgM, HBeAg, and Anti-HBe). Characterization based on single point specimens by the reference serological markers demonstrated 17 unique patterns:

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| Characterization based on single point specimens | Number of patients | HBV Reference Markers | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HBsAg | HBeAg | Anti-HBc IgM | Anti-HBc | Anti-HBe | Anti-HBs |
| Acute | 2 | + | - | - | - | - | - |
| Acute | 1 | + | + | - | - | - | - |
| Acute | 32 | + | - | +/- | + | + | - |
| Acute | 34 | + | + | +/- | + | - | - |
| Chronic | 2 | + | - | - | + | - | - |
| Chronic | 3 | + | +/- | - | + | + | + |
| Chronic | 1 | + | - | - | + | - | + |
| Chronic | 1 | + | + | +/- | + | - | + |
| Early Recovery | 16 | - | - | +/- | + | + | + |
| Early Recovery | 4 | - | - | - | + | + | - |
| Early Recovery | 19 | - | - | - | + | +/- | - |
| Early Recovery | 1 | - | - | + | + | +/- | + |
| HBV vaccine response | 27 | - | - | - | - | - | + |
| Not previously infected | 120 | - | - | - | - | - | - |
| Recovered | 16 | - | - | - | +/- | - | + |
| Recovered | 1 | - | +/- | - | + | - | + |
| Uninterpretable | 1 | - | + | - | - | - | - |

Based on the above classifications the IMMULITE Anti-HBc and IMMULITE 2000 Anti-HBc results were compared to Kit A, a reference assay for the determination of anti-HBc. Data charts are presented in the package insert.

For the IMMULITE Anti-HBc the combined Total Positive agreement is $87.7\%$ (114/130) with a $95\%$ CI of 80.8 to $92.8\%$ . The Negative agreement is $98.7\%$ (149/151) with a $95\%$ CI of 95.3 to $99.8\%$ . The combined Total agreement is $93.6\%$ (263/281) with a $95\%$ CI of 90.1 to $96.2\%$ .

For the IMMULITE 2000 Anti-HBc the combined Total Positive agreement is $88.7\%$ (114/130) with a $95\%$ CI of 80.8 to $92.8\%$ . The Negative agreement is $99.3\%$ (150/151) with a $95\%$ CI of 96.4 to $100.0\%$ . The Total agreement is $94.0\%$ (264/281) with a $95\%$ CI of 90.5 to $96.4\%$ .

Site 2: Conducted in the northeastern United States, this study included 209 patients, consisting of 104 males, 103 females. Gender for two patients was not reported. These patients had an average age of 47 years, ranging from newborn to 93 years. Distributions of the ethnicity of the patients are shown in the following table.

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| Ethnicity | N | % |
| --- | --- | --- |
| African American | 21 | 10.0% |
| Caucasian | 101 | 48.3% |
| Hispanic | 3 | 1.4% |
| Asian | 6 | 2.9% |
| Other | 7 | 3.3% |
| Unknown | 71 | 34.0% |
| Total | 209 | 100.0% |

Included were patients with potentially cross-reactive substances and medical conditions. A total of 209 retrospective specimens were collected and tested by FDA-approved or licensed hepatitis B assays for four HBV serological markers (HBsAg, Anti-HBc IgM, Anti-HBc, and Anti-HBs). Characterization based on single point specimens by the reference serological markers demonstrated eight unique patterns:

| Characterization based on single point specimens | No. of patients | HBV Reference Markers | | | |
| --- | --- | --- | --- | --- | --- |
| | | HbsAg | Anti-HBc IgM | Anti-HBc | Anti-HBs |
| Acute | 8 | + | - | - | - |
| Acute | 9 | + | +/- | + | - |
| Chronic | 2 | + | - | + | + |
| Early recovery | 33 | - | +/- | + | + |
| Early recovery | 17 | - | - | + | - |
| HBV vaccine response | 32 | - | - | - | + |
| Not previously infected | 107 | - | - | - | - |
| Uninterpretable | 1 | + | - | - | + |

Based on the above classifications the IMMULITE Anti-HBc and IMMULITE 2000 Anti-HBc results were compared to Kit A. Data charts are presented in the package insert.

For the IMMULITE Anti-HBs the combined Total Positive agreement is $91.8\%$ (56/61) with a $95\%$ CI of 81.9 to $97.3\%$ . The Negative agreement is $99.3\%$ (147/148) with a $95\%$ CI of 96.3 to $100.0\%$ . The combined Total agreement is $97.1\%$ (203/209) with a $95\%$ CI of 93.9 to $98.9\%$ .

For the IMMULITE 2000 Anti-HBs the combined Total Positive agreement is $91.8\%$ (56/61) with a $95\%$ CI of 81.9 to $97.3\%$ . The Negative agreement is $99.3\%$ (147/148) with a $95\%$ CI of 96.3 to $100.0\%$ . The combined Total agreement is $97.1\%$ (203/209) with a $95\%$ CI of 93.9 to $98.9\%$

Site 3: Specimens obtained from China were tested in the southern United States, this study included 79 patients and was comprised of 13 females and 55 males (gender for 11

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patients was not reported) with an average age of 36 years, ranging from 18 to 82 years. These were prospectively recruited patients from a clinically well-characterized, homogeneous population: acute hepatitis B patients who presented with symptoms typical of acute hepatitis B such as jaundice, persistent fatigue, loss of appetite, pale stools and liver enlargement. Their ALT and AST results were significantly elevated at the time of diagnosis.

A total of 79 specimens were prospectively collected and tested using FDA-approved or licensed hepatitis B assays for six HBV serological markers (HBsAg, HBeAg, Anti-HBc IgM, Anti-HBc, Anti-HBeAg, and Anti-HBs). Characterization based on single point specimens by the reference serological markers demonstrated 11 unique patterns:

| Characterization based on single point specimens | Number of patients | HBV Reference Markers | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HBsAg | HBeAg | Anti-HBc IgM | Anti-HBc | Anti-HBe | Anti-HBs |
| Acute | 23 | + | - | +/- | + | + | - |
| Acute | 8 | + | +/- | + | + | + | - |
| Acute | 1 | + | - | + | +/- | - | - |
| Acute | 35 | + | + | +/- | + | - | - |
| Acute | 4 | + | + | + | + | - | +/- |
| Chronic | 1 | + | - | - | + | - | - |
| Chronic | 3 | + | +/- | - | + | + | - |
| Chronic | 1 | + | + | +/- | + | - | + |
| Chronic | 1 | + | + | + | + | + | + |
| Recovered | 1 | - | - | - | +/- | - | + |
| Uninterpretable | 1 | + | - | + | + | + | + |

Based on the above classifications the IMMULITE Anti-HBc and IMMULITE 2000 Anti-HBc results were compared to Kit A. The data charts are presented in the package insert.

For the IMMULITE Anti-HBs the combined Total Positive agreement is $100.0\%$ (79/79) with a $95\%$ CI of 95.4 to $100.0\%$ . There were no negative specimens therefore the Negative agreement could not be calculated.

For the IMMULITE 2000 Anti-HBs the combined Total Positive agreement is $100.0\%$ (79/79) with a $95\%$ CI = 95.4 to $100.0\%$ . There were no negative specimens therefore the Negative agreement could not be calculated

Site 4: Conducted in the southern United States, this study included retrospectively collected specimens from 200 pregnant subjects. These subjects had an average age of 28 years, ranging from 17 to 41 years.

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A total of 200 specimens were tested by FDA-approved hepatitis B assays for four HBV serological markers (HBsAg, Anti-HBc IgM, Anti-HBc, and Anti-HBs).

Characterization based on single point specimens by the reference serological markers demonstrated three unique patterns:

| Characterization based on single point specimens | Number of subjects | HBV Reference Markers | | | |
| --- | --- | --- | --- | --- | --- |
| | | HbsAg | Anti-HBc IgM | Anti-HBc | Anti-HBs |
| Early recovery | 4 | - | +/- | + | + |
| Early recovery | 2 | - | - | + | - |
| HBV vaccine response | 42 | - | - | - | + |
| Not previously infected | 152* | - | - | - | - |

*Two specimens were not tested for IMMULITE Anti HBc.

Based on the above classifications the IMMULITE Anti-HBc and IMMULITE 2000 Anti-HBc results were compared to Kit A. The data charts are presented in the package insert.

For the IMMULITE Anti-HBs the combined Total Positive agreement is 66.7% (4/6) with a 95% CI of 22.3 to 95.7%. The Negative agreement is 99.5% (191/192) with a 95% CI of 97.1 to 100.0%. The combined Total agreement is 98.5% (195/198) with a 95% CI of 95.6 to 99.7%.

For the IMMULITE 2000 Anti-HBs the combined Total Positive agreement is 66.7% (4/6) with a 95% CI of 22.3 to 95.7%. The Negative agreement is 100.0% (194/194) with a 95% CI of 98.1 to 100.0%. The combined Total agreement is 99.0% (198/200) with a 95% CI of 96.4 to 99.9%.

Site 5: In an additional study conducted at Diagnostic Products Corporation, IMMULITE Anti-HBc was compared to IMMULITE 2000 Anti-HBc. Presented below are the comparisons between IMMULITE and IMMULITE 2000 Anti-HBc on a total of 139 specimens.

| IML Anti-HBc | | | | | | | | | Total |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| + | | | Ind | | | - | | | |
| IML 2000 Anti-HBc | | | | | | | | | |
| + | Ind | - | + | Ind | - | + | Ind | - | |
| 78 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 60 | 139 |

Positive agreement = 100.0% (78/78)

95% CI = 95.4 to 100.0%

Negative agreement = 98.4% (60/61)

95% CI = 91.2 to 100.0%

Total agreement = 99.3% (138/139)

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95% CI = 96.1 to 100.0%

# X. CONCLUSIONS DRAWN FROM STUDIES

The data from both the non-clinical and clinical studies demonstrate acceptable performance is obtained with the IMMULITE and IMMULITE 2000 Anti-HBc assays when used as directed in the package insert.

## Safety

As a diagnostic test, the anti-HBc Ag assay involves removal of blood from an individual for testing purposes. The test, therefore, presents no more safety hazard to an individual being tested than other tests where blood is removed. The misdiagnosis due to false negative or false positive results, or inappropriate use of the assay, can affect the safe use of the assay.

## Benefit/Risk Analysis

The PMA studies provide reasonable assurance that the IMMULITE and IMMULITE 2000 Anti-HBs assay results may be used:

- As an aid in the determination of susceptibility to hepatitis B virus (HBV) infection for individuals prior to or following HBV vaccination, or where vaccination status is unknown.
- Along with other HBV serological markers for the laboratory diagnosis of HBV disease associated with HBV infection.
- To allow a differential diagnosis in individuals displaying signs and symptoms of hepatitis when etiology is unknown.
- As an indication of seroconversion from hepatitis B virus (HBV) infection.

The potential risks seen for these in vitro diagnostic tests are not unusual in the laboratory setting, and appropriate warnings for these risks are contained in the labeling and package insert instructions for these devices. Standard good laboratory practices are considered sufficient to minimize the risks to the end user.

The benefits to HBV-infected individuals tested by these devices outweigh any potential adverse event or risk to the patient or user due to device malfunction or operator error.

# XI. PANEL RECOMMENDATION

Pursuant to Section 515(c)(2) of the act as amended by the Safe Medical Devices Act of 1990, this PMA was not the subject of an FDA Microbiology Devices Advisory Panel meeting because the information in the PMA substantially duplicated information previously reviewed by this Panel.

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XII. CDRH DECISION

The applicant’s manufacturing facility was found to be in compliance with the Quality Systems Regulation (21 CFR 820).

FDA issued an approval order on July 24, 2002.

XIII. APPROVAL SPECIFICATIONS

Directions for Use: See labeling

Hazards to Health from Use of the Device: See Contraindications, Warnings, Precautions and Adverse Events in the labeling.

Postapproval Requirements and Restrictions: See approval order.