IMMULITE 2000 XPI ANTI-HBC IMG

P010053 · Siemens Healthcare Diagnostics Products, Ltd. · SEI · Jul 26, 2002 · Microbiology

Device Facts

• Record ID: P010053
• Device Name: IMMULITE 2000 XPI ANTI-HBC IMG
• Applicant: Siemens Healthcare Diagnostics Products, Ltd.
• Product Code: SEI · Microbiology
• Decision Date: Jul 26, 2002
• Decision: APRL
• Regulation: 21 CFR 866.3173
• Device Class: Class 2

Intended Use

IMMULITE Anti-HBc IgM is a solid-phase chemiluminescent enzyme immunoassay designed for use on the IMMULITE automated immunoassay analyzer for the qualitative measurement of IgM antibody to hepatitis B core antigen (anti-HBc IgM) in human serum or plasma (EDTA, heparinized, citrate). It is intended for in vitro diagnostic use for the laboratory diagnosis of acute or recent (usually within six months) hepatitis B viral infection. IMMULITE 2000 Anti-HBc IgM is a solid-phase chemiluminescent enzyme immunoassay designed for use on the IMMULITE 2000 automated immunoassay analyzer for the qualitative measurement of IgM antibody to hepatitis B core antigen (anti-HBc IgM) in human serum or plasma (EDTA, heparinized, citrate). It is intended for in vitro diagnostic use for the laboratory diagnosis of acute or recent (usually within six months) hepatitis B viral infection.

Device Story

Solid-phase, two-step chemiluminescent enzyme immunoassay; performed on automated IMMULITE or IMMULITE 2000 analyzers. Input: human serum or plasma. Process: patient sample incubated with monoclonal murine anti-IgM antibody-coated polystyrene bead; unbound sample removed via centrifugal wash; alkaline phosphatase-labeled recombinant HBc antigen added; second incubation; unbound conjugate removed; chemiluminescent substrate (phosphate ester of adamantyl dioxetane) added. Output: photon emission (cps) measured by photomultiplier tube; result compared to stored curve for qualitative determination. Used in clinical laboratories by technicians. Results aid physicians in diagnosing acute/recent HBV infection; used alongside clinical findings and other serological markers. Benefits: provides rapid, automated, reproducible detection of anti-HBc IgM to support clinical decision-making.

Clinical Evidence

Clinical studies across four sites (n=815 subjects) compared IMMULITE/IMMULITE 2000 Anti-HBc IgM to FDA-approved reference assays. Subjects included acute/chronic HBV patients, vaccinated individuals, pregnant women, and healthy controls. Primary endpoints were positive/negative agreement. Total positive agreement ranged from 85.7% to 91.4% (95% CI 42.1-99.6%); negative agreement ranged from 61.0% to 99.5% (95% CI 44.5-100.0%). Analytical studies confirmed no interference from bilirubin (up to 20 mg/dL), hemoglobin (up to 540 mg/dL), triglycerides, or common drugs. Precision studies showed acceptable intra-assay and total variance.

Technological Characteristics

Solid-phase, two-step chemiluminescent enzyme immunoassay. Solid phase: polystyrene bead coated with monoclonal murine anti-IgM antibody. Detection: alkaline phosphatase-labeled recombinant HBc antigen; chemiluminescent substrate (phosphate ester of adamantyl dioxetane). Analyzers: IMMULITE and IMMULITE 2000. Calibration range: 2-100 U/mL. Sample types: serum, EDTA/heparinized/citrate plasma. Automated processing with centrifugal wash steps. Photomultiplier tube for photon detection.

Indications for Use

Indicated for the qualitative detection of IgM antibody to Hepatitis B core antigen in human serum or plasma to aid in the laboratory diagnosis of acute or recent (within six months) hepatitis B viral 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 (microparticle enzyme immunoassay)
• Kit B

Submission Summary (Full Text)

{0}

1

# Summary of Safety and Effectiveness Data

## I. GENERAL INFORMATION

Device Generic Name: A solid-phase chemiluminescent enzyme immunoassay for the qualitative detection of IgM antibody to Hepatitis B core antigen

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

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

Premarket Approval Application (PMA) Number: P010053

Date of Panel Recommendation: None

Date of Notice of Approval to the Applicant: July 26, 2002

## II. INDICATIONS FOR USE

### IMMULITE Anti-HBc IgM

IMMULITE Anti-HBc IgM is a solid-phase chemiluminescent enzyme immunoassay designed for use on the IMMULITE automated immunoassay analyzer for the qualitative measurement of IgM antibody to hepatitis B core antigen (anti-HBc IgM) in human serum or plasma (EDTA, heparinized, citrate). It is intended for in vitro diagnostic use for the laboratory diagnosis of acute or recent (usually within six months) hepatitis B viral infection.

### IMMULITE 2000 Anti-HBc IgM

IMMULITE 2000 Anti-HBc IgM is a solid-phase chemiluminescent enzyme immunoassay designed for use on the IMMULITE 2000 automated immunoassay analyzer for the qualitative measurement of IgM antibody to hepatitis B core antigen (anti-HBc IgM) in human serum or plasma (EDTA, heparinized, citrate). It is intended for in vitro diagnostic use for the laboratory diagnosis of acute or recent (usually within six months) hepatitis B viral infection.

{1}

2

# III. DEVICE DESCRIPTION

The IMMULITE and IMMULITE 2000 Anti-Hepatitis B Core IgM Antigen kits are the subject of this PMA. The data and information are presented separately for each assay in this document.

The IMMULITE and IMMULITE 2000 Anti-Hepatitis B Core IgM Antigen 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 IgM antibodies against hepatitis B core antigen in human serum or plasma. The kits are intended for *in vitro* diagnostic use as an aid in the laboratory diagnosis of acute or recent hepatitis B viral infection.

The kits' solid phase is a polystyrene bead coated with a monoclonal murine anti-IgM antibody. The patient sample and a protein-based buffer are simultaneously introduced into the Test Unit or reaction tube and incubated for approximately 30 minutes at 37°C with intermittent agitation. During this time, HBc IgM in the patient sample binds to the monoclonal, anti-IgM antibody coated bead. Unbound serum is then removed by a centrifugal wash. An alkaline phosphatase-labeled recombinant HBc antigen is introduced, and the reaction tube is incubated with agitation for another 30 minute cycle, during which time the HBc antigen binds to the patient's anti-HBc antibody which is bound to the anti-IgM antibody 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 productions of these intermediates results in the sustained emission of light. The bound complex and the resulting photon output, measured as cps by the photomultiplier tube, are related to the presence of HBc IgM antibodies in the sample. A qualitative result is then obtained by comparing the patient results to a stored curve.

# IV. CONTRAINDICATIONS, WARNINGS AND PRECAUTIONS

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

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

# V. ALTERNATIVE PRACTICES OR PROCEDURES

The early assays of IgM antibodies to hepatitis B core antigen (IgM anti-HBc) were based on the principle of immune adherence hemagglutination. These assays were

{2}

largely supplanted by radioimmunoassay (RIA) and enzyme immunoassay (EIA) methodologies, which were considered more sensitive, and reproducible. IgM antibody – specific molecules were originally detected either by immunosubtration of IgG in the sample prior to testing or by using anti-human IgM conjugates.

These procedures have been replaced by the IgM capture immunosorbent assays (RIA and ELISA). In capture assays, anti-human IgM (chain-specific) bound to the solid phase is first used to capture IgM in the sample. Detection of specific IgM is then accomplished by the addition of assay-specific antisera and enzyme-labeled anti-HBc conjugate. Because interference from rheumatoid factor or specific IgG antibodies is minimized, the IgM-capture assays usually have better clinical and analytical sensitivity and specificity. There are currently a variety of commercially available, FDA licensed or approved serological tests. When anti-HBc IgM test results are used in combination with supplemental clinical laboratory serological testing, a laboratory diagnosis of HBV infection with HBV can be established. A clinical diagnosis is based on clinical findings, biochemical testing, and serological findings.

## VI. MARKETING HISTORY

IMMULITE Anti-HBc IgM and IMMULITE 2000 Anti-HBc IgM have been marketed internationally as an aid in the determination of acute and chronic hepatitis B virus infection since June 1999. IMMULITE and IMMULITE 2000 Anti-HBc IgM 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

Potential adverse effects from this device on health can be caused by inaccurate test results and a misdiagnosis. False Negative results can occur when blood specimens are obtained from a subject infected with hepatitis B prior to the appearance of IgM antibody. This may likely result in the patient misdiagnosed 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 have False Positive results and lead to misdiagnosis of a hepatitis B infected patient.

## VIII. SUMMARY OF NON CLINICAL STUDIES

### Analytical Specificity

Analytical specificity was evaluated at two clinical sites in the United States and at 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

3

{3}

Anti-HBc IgM, IMMULITE 2000 Anti-HBc IgM, and a commercially available microparticle enzyme immunoassay for anti-HBc IgM (Kit A). The results are displayed in the package insert.

In the European study, four rubella IgM positive specimens, six antinuclear antibody (ANA) positive specimens, and 26 rheumatoid factor (RF) positive specimens were tested by IMMULITE Anti-HBc IgM. IMMULITE Anti-HBc IgM test results were negative for all specimens. The specimens were also tested by IMMULITE 2000 Anti-HBc IgM. The results are shown in the package insert.

In the European study, four rubella IgM positive specimens, five antinuclear antibody (ANA) positive specimens, and 23 rheumatoid factor (RF) positive specimens were tested by IMMULITE 2000 Anti-HBc IgM. IMMULITE 2000 Anti-HBc IgM test results were negative for all specimens.

## Calibration Range

The calibration range for IMMULITE and IMMULITE 2000 Anti-HBc IgM is $2 - 100\mathrm{U / mL}$ (P.E.I., Paul Ehrlich Institute).

## Analytical Sensitivity

The analytical sensitivities were evaluated by testing 20 replicates of each serum and plasma sample. Means and standard deviations were calculated from the counts per second (CPS) for the 20 replicates. The analytical sensitivity, defined as the concentration corresponding to 2 standard deviations above the mean, was established at $= 2.0\mathrm{U / mL}$ (P.E.I., Paul Ehrlich Institute) for IMMULITE and IMMULITE 2000 Anti-HBc IgM.

## Effects of Bilirubin, Lipemia and Hemolysis

To simulate moderate and severe icterus, different volumes of each of 6 patient samples ranging from non-detectable to high positive IgM antibodies against hepatitis B core antigen were pipetted into lyophilized unconjugated bilirubin to achieve 2 levels of bilirubin concentrations (10 and $20\mathrm{mg / dL}$) for each sample. The spiked and unspiked samples were assayed by the IMMULITE and IMMULITE 2000 Anti-HBc IgM assays. In the IMMULITE Anti-HBc IgM tests, the measurable spiked samples had averages of $96\%$ and $92\%$ recovery for 10 and $20\mathrm{mg / dL}$ bilirubin concentrations, respectively. In the IMMULITE 2000 Anti-HBc IgM tests, the measurable spiked samples had averages of $99\%$ and $97\%$ recovery for 10 and $20\mathrm{mg / dL}$ bilirubin concentrations, respectively. This study demonstrated that the measurement of IgM antibodies against hepatitis B core antigen was not affected by the presence of unconjugated bilirubin up to $20\mathrm{mg / dL}$.

To simulate mild, moderate and severe hemolysis, the same 6 samples were spiked with hemolysate to achieve final hemoglobin levels of 270, 404 and $540\mathrm{mg / dL}$. The samples were assayed, both spiked and unspiked, by the IMMULITE and IMMULITE 2000 Anti-HBc IgM assays. In the IMMULITE Anti-HBc IgM tests, the measurable spiked samples

4

{4}

had averages of 95%, 95% and 97% recovery for 270, 404 and 540 mg/dL hemoglobin concentrations, respectively. In the IMMULITE 2000 Anti-HBc IgM tests, the spiked samples had averages of 102%, 100% and 104% recovery for 270, 404 and 540 mg/dL hemoglobin concentrations, respectively. It was concluded that the measurement of IgM antibodies against hepatitis B core antigen was not affected by the presence of hemoglobin up to 540 mg/dL.

The same 6 samples were each spiked with 4 levels of triglyceride at 500, 1000, 2000 and 3000 mg/dL to evaluate the lipemia effect on the IMMULITE and IMMULITE 2000 Anti-HBc IgM assays. Unspiked and spiked samples were tested by the IMMULITE and IMMULITE 2000 Anti-HBc IgM 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 IgM antibodies against hepatitis B core antigen was not affected by the presence of triglycerides.

## Hook Effect and Carryover

The hook effect study demonstrated that the IMMULITE and IMMULITE 2000 Anti-HBc IgM assays did not have a hook effect up to at least 175 U/mL. The carryover study demonstrated that the IMMULITE and IMMULITE 2000 Anti-HBc IgM assays did not exhibit a carryover phenomenon when samples were preceded by a sample with a very high titer of IgM antibodies against hepatitis B core antigen

## Interfering Substances

A study was conducted to evaluate the effects of interfering substances on IMMULITE and IMMULITE 2000 Anti-HBc IgM 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 IgM. The substances and their test levels (concentration) are listed below.

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

5

{5}

| 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 |

## Effects of Anticoagulants

The measurement of anti-HBc IgM is not affected by the presence of heparin, sodium citrate, and EDTA anti-coagulants. A study that included 44 specimens collected into plain, heparinized, sodium citrate, and EDTA vacutainer tubes was conducted. The results are shown in the package insert.

## Precision

Precision studies for the IMMULITE and IMMULITE 2000 Anti-HBc IgM assays were conducted at three sites. Included in the studies were three controls and seven patient samples covering the entire working range (2 – 100 U/mL) of both assays. All controls and samples were tested in duplicate by three IMMULITE Anti-HBc IgM kit lots and one IMMULITE 2000 Anti-HBc IgM kit lot for a total of 40 runs at each of the three sites.

IMMULITE and IMMULITE 2000 Anti-HBc IgM are qualitative assays with results expressed in U/mL. Statistics including the means, standard deviations, the intraassay and total precision were calculated for samples 2 through 6. Statistics for samples 1 and 7 were not calculated because sample 1 consistently yielded <2 U/mL results and sample 7 consistently yielded results greater than 100 U/mL.

IMMULITE Anti-HBs IgM Intra-assay and Total Precision (U/mL), IMMULITE 2000 Anti-HBs IgM Intra-assay and Total Precision (U/mL), IMMULITE Anti-HBc IgM Lot-to-Lot and Site-to-Site, and IMMULITE 2000 Anti-HBc IgM Site-to-Site Precision data are shown in the package insert.

The IMMULITE 2000 Anti-HBc IgM lot-to-lot precision has not been evaluated. Because lot-to-lot evaluation of the assay had previously been demonstrated, and the Stability studies were done on three lots and the data was acceptable, no additional studies were requested of the sponsor.

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 IgM and one lot of IMMULITE 2000 Anti-HBc IgM. The median total variance of coefficients (EDTA,

{6}

7.7%; heparin, 7.2%; sodium citrate, 8.3%) demonstrated that these alternative sample types do not affect the precision of IMMULITE and IMMULITE 2000 Anti-HBc IgM.

## Stability

Stability studies for IMMULITE and IMMULITE 2000 Anti-HBc IgM were conducted by using 3 lots of IMMULITE Anti-HBc IgM, and one lot of IMMULITE 2000 Anti-HBc IgM. 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 IgM 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 IgM 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 develop anti-HBc IgM between two weeks and four months after exposure, usually through the course of clinical illness. IgM antibody levels decline in cases of uncomplicated acute infection, but remain elevated in chronic HBV infection.

Demographics and expected prevalence rates for different categories of subjects (HBV Chronic patients, HBV Acute patients), 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 inserts.

## Clinical Studies

A total of 815 subjects were tested at four clinical laboratories to assess the performance of the IMMULITE and IMMULITE 2000 Anti-HBc IgM assays when compared to FDA-approved or licensed hepatitis B assays (Reference markers). All specimens in the analyses were initial test results. The specimens were categorized based on the results of testing with the HBV reference serological markers, reactive(+)/ nonreactive(-). No other laboratory or clinical information was used in the disease classification process.

7

{7}

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% |

These subjects included acute and chronic hepatitis B patients, vaccinated individuals, pregnant women, and apparently healthy individuals, and patients with potentially crossreactive 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, HBeAg, Anti-HBc IgM, Anti-HBc, Anti-HBe, and Anti-HBs). Characterization based on single point specimens by the reference serological markers demonstrated 17 unique patterns:

{8}

| 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 IgM results were compared to Kit A, a reference assay for the determination of anti-HBc IgM.

There were not sufficient patient samples to calculate each Negative and Positive Agreement. However, the Total Positive agreement is $85.7\%$ (6/7) with a $95\%$ CI of 42.1 to $99.6\%$ . The Negative agreement is $97.0\%$ (262/270) with a $95\%$ CI of 94.2 to $98.7\%$ . The Total agreement is $96.8\%$ (268/277) with a $95\%$ CI of 93.9 to $98.5\%$ . This data is in the package insert.

Based on the above classifications the IMMULITE 2000 Anti-HBc IgM results were compared to Kit A, a reference assay for the determination of anti-HBc IgM.

There were not sufficient patient samples to calculate each Negative and Positive Agreement. However, the Total Positive agreement is $85.7\%$ (6/7) with a $95\%$ CI = 42.1 to $99.6\%$ . The Negative agreement is $95.2\%$ (257/270) with a $95\%$ CI of 91.9 to $97.4\%$ . The Total agreement is $94.9\%$ (263/277) with a $95\%$ CI = 91.7 to $97.2\%$ . This data is in the package insert.

Site 2: Conducted in the northeastern United States, this study included 209 patients, consisting of 104 males and 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.

{9}

| 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 crossreactive 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 IgM results were compared to Kit A. There were not sufficient patient samples to calculate each Negative and Positive Agreement, or the Total Positive agreement. However, Negative agreement is $99.0\%$ (202/204) with a $95\%$ CI of 96.5 to $99.9\%$ .

Based on the above classifications the IMMULITE Anti-HBc IgM results were compared to Kit A, a reference assay for the determination of anti-HBc IgM. There were not sufficient patient samples to calculate each Negative and Positive Agreement, or the Total Positive agreement. However, the Total Negative agreement is $98.5\%$ (201/204) with a $95\%$ CI of 95.8 to $99.7\%$ . The data is in the package insert.

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 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

{10}

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 by 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 IgM results were compared to Kit B, a reference assay for the determination of anti-HBc IgM. There were insufficient data to calculate each Negative and Positive Agreement. However the Total Positive agreement is $88.6\%$ (31/35) with a $95\%$ CI of 73.3 to $96.8\%$ . The Negative Agreement is $65.9\%$ (27/41) with a $95\%$ CI of 49.4 to $79.9\%$ . The Total agreement is $76.3\%$ (58/76) with a $95\%$ CI = 65.2 to $85.3\%$ . The data is shown in the package insert.

Based on the above classifications the IMMULITE 2000 Anti-HBc IgM results were compared to Kit B, a reference assay for the determination of anti-HBc IgM. There were not sufficient patient samples to calculate each Negative and Positive Agreement. However, the Total Positive agreement is $91.4\%$ (32/35) with a $95\%$ CI of 76.9 to $98.2\%$ . The Negative agreement is $61.0\%$ (25/41) with a $95\%$ CI of 44.5 to $75.8\%$ . The Total agreement is $75.0\%$ (57/76) with a $95\%$ CI of 63.7 to $84.2\%$ . The data is presented in the package insert.

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.

{11}

A total of 200 specimens were 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 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* | - | - | - | - |

Based on the above classifications the IMMULITE and IMMULITE 2000 Anti-HBc IgM results were compared to Kit B. Note: Five specimens were not tested for IMMULITE Anti-HBc IgM. There were no data points to calculate the Total Positive agreement. The Total Negative agreement is $99.5\%$ (194/195) with a $95\%$ CI of 97.2 to $100.0\%$ . For the IMMULITE 2000 the Total Negative agreement is $99.5\%$ (199/200) with a $95\%$ CI of 97.2 to $100.0\%$ . The data is presented in the package insert.

Site 5: In an additional study conducted in-house at DPC, IMMULITE Anti-HBc IgM was compared to DPC's IMMULITE 2000 Anti-HBc IgM on 46 samples. (Concentration range: approximately 2 to $95\mathrm{U / mL}$ ). By linear regression:

$$
\begin{array}{l} (\mathrm {I M L} 2 0 0 0) = 0. 9 9 (\mathrm {I M L}) - 0. 3 4 \mathrm {U} / \mathrm {m L} \\ \mathrm {r} = 0. 9 8 1 \\ \end{array}
$$

Slope $95\%$ CI: 0.93, 1.05

Intercept $95\%$ CI: -3.22, 2.54

# 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 IgM assays for the qualitative measurement of IgM antibodies against hepatitis B core antigens in human serum or plasma.

# Safety

As a diagnostic test, the IMMULITE and IMMULITE 2000 Anti-HBc IgM assays involve 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

{12}

is removed. However, misdiagnosis may result when the patient receives a False Positive or False Negative results.

## Benefit/Safety

The submitted clinical studies have shown that the IMMULITE and IMMULITE 2000 Anti-HBc IgM assays, when compared to reference clinical laboratory procedures, has a similar ability to detect the presence of IgM anti-HBc in specimens from individuals infected with HBV. The rate of false positivity and false negativity are within acceptable limits compared to the reference assay. It has been shown that the device has no demonstrable cross-reactivity with other viruses or organisms that may cause clinical hepatitis. Therefore, these devices should benefit the physician in the diagnosis of HBV.

Based on the results of the preclinical and clinical laboratory studies the IMMULITE and IMMULITE 2000 Anti-HBc IgM, when used according to the provided directions and in conjunction with other serological and clinical information, should be safe and effective and pose minimal risk to the patient due to false test results.

## 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.

## XII. CDRH DECISION

FDA issued an approval order on July 26, 2002.

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

## 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.

13