DIASORIN LIAISON TREPONEMA ASSAY
Device Facts
| Record ID | K061247 |
|---|---|
| Device Name | DIASORIN LIAISON TREPONEMA ASSAY |
| Applicant | DiaSorin, Inc. |
| Product Code | LIP · Microbiology |
| Decision Date | Jul 31, 2006 |
| Decision | SESE |
| Submission Type | Traditional |
| Regulation | 21 CFR 866.3830 |
| Device Class | Class 2 |
Intended Use
The LIAISON® Treponema assay uses chemiluminiscence immunoassay (CLIA) technology for the qualitative detection of total antibodies of any class (IgG/IgM) directed against Treponema pallidum in human serum. The presence of antibodies to Treponema pallidum specific antigen, in conjunction with non treponemanal laboratory tests and clinical findings, may aid in the diagnosis of syphilis infection. The LIAISON® Treponema assay is not intended for use in screening blood or plasma donors.
Device Story
The LIAISON® Treponema Assay is a one-step chemiluminescence immunoassay (CLIA) performed on the LIAISON® Analyzer. It detects total antibodies (IgG/IgM) against Treponema pallidum in human serum. Recombinant T. pallidum antigens coat magnetic particles (solid phase) and are linked to an isoluminol derivative (tracer). Patient samples, calibrators, or controls are incubated with the solid phase; antibodies bind to the antigen-coated particles. After washing, starter reagents induce a flash chemiluminescence reaction. A photomultiplier measures the light signal (Relative Light Units, RLU), which is proportional to the amount of antibody present. The assay is used in clinical laboratories by trained personnel to aid in syphilis diagnosis, either as a screening test or a confirmatory test depending on the clinical algorithm. Results assist clinicians in diagnosing syphilis infection when combined with non-treponemal tests and clinical findings.
Clinical Evidence
Clinical performance evaluated via method comparison against predicate (CAPTIA™ Syphilis-G) across 3 US sites and European sites. Study populations included medically diagnosed syphilis (n=51 US, n=127 EU), routine lab samples (n=999), HIV+ (n=200), pregnancy (n=200), and healthy adults (n=992). Overall percent agreement varied by population (e.g., 94.1% for diagnosed syphilis, 93.2% for routine lab). Discordant samples were resolved using additional testing (RPR/TP-PA). Analytical studies included precision (overall %CV 6.07-23.66%), cross-reactivity (244 samples tested), and interference (hemoglobin, bilirubin, triglycerides).
Technological Characteristics
Chemiluminescence immunoassay (CLIA). Solid phase: magnetic particles coated with recombinant Tp17 DNA antigen. Tracer: isoluminol-antigen conjugate. Energy source: flash chemiluminescence reaction measured by photomultiplier. Form factor: Reagent Integral (plastic container with compartments). Connectivity: Automated on LIAISON® Analyzer. Software: Automated processing of incubation, wash, and signal measurement. Storage: 2-8°C.
Indications for Use
Indicated for use in conjunction with nontreponemal laboratory tests and clinical findings to aid in the diagnosis of syphilis infection. Not for use in screening blood or plasma donors.
Regulatory Classification
Identification
Treponema pallidum treponemal test reagents are devices that consist of the antigens, antisera and all control reagents (standardized reagents with which test results are compared) which are derived from treponemal sources and that are used in the fluorescent treponemal antibody absorption test (FTA-ABS), the Treponema pallidum immobilization test (T.P.I.), and other treponemal tests used to identify antibodies to Treponema pallidum directly from infecting treponemal organisms in serum. The identification aids in the diagnosis of syphilis caused by bacteria belonging to the genus Treponema and provides epidemiological information on syphilis.
Predicate Devices
- Trinity CAPTIA™ Syphilis (T. Pallidum) G (K014233)
Related Devices
- K091361 — IMMULITE 2000 SYPHILIS SCREEN TEST SYSTEM · Siemens Healthcare Diagnostics · Dec 16, 2009
- K153145 — Lumipulse G TP-N Immunoreaction Cartridge Set · Fujirebio Diagnostics,Inc. · Jul 5, 2016
Submission Summary (Full Text)
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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY ASSAY ONLY TEMPLATE
A. 510(k) Number:
k061247
B. Purpose for Submission:
Addition of the DiaSorin LIAISON® Treponema Assay to the LIAISON® Chemiluminescence Assay
C. Measurand:
To detect antibodies to *T. pallidum*
D. Type of Test:
Chemiluminescence immunoassay
E. Applicant:
DiaSorin Inc.
F. Proprietary and Established Names:
DiaSorin LIAISON® Treponema Assay
G. Regulatory Information:
1. Regulation section:
CFR 866.3830 Enzyme-linked immunoabsorption assay, *Treponema pallidum*
2. Classification:
II
3. Product code:
LIP
4. Panel:
83 Microbiology
H. Intended Use:
1. Intended use(s):
The LIAISON® Treponema assay uses chemiluminiscence immunoassay (CLIA) technology for the qualitative detection of total antibodies of any class (IgG/IgM) directed against *Treponema pallidum* in human serum. The presence of antibodies to *Treponema pallidum* specific antigen, in conjunction with non treponemanal laboratory tests and clinical findings, may aid in the diagnosis of syphilis infection. The LIAISON® Treponema assay is not intended for use in
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screening blood or plasma donors.
2. **Indication(s) for use:**
In conjunction with nontreponemal laboratory tests and clinical findings, may aid in the diagnosis of syphilis infection.
3. **Special conditions for use statement(s):**
For prescription use only
The LIAISON® Treponema assay is not intended for use in screening blood or plasma donors.
**Warning:** A positive result is not useful for establishing a diagnosis of syphilis. In most situations, such a result may reflect prior treated infection; a negative result can exclude a diagnosis of syphilis except for incubating or early primary disease.
**Warning:** “When a sample result displays the exclamation mark (!) flag, the result obtained lies below the assay’s signal range. The sample should be retested and graded negative if the result is still below the signal range upon retest.”
“Assay interference due to circulating antibodies against Hepatitis A viruses, yaws, pinta and leptospirosis have not been evaluated. The user is responsible for establishing cross-reactivity performance with these infectious agents.”
4. **Special instrument requirements:**
LIAISON® Chemiluminescence Analyzer
I. **Device Description:**
The LIAISON® Treponema assay is an *in vitro* diagnostic device consisting of reagents provided in individual compartments within a plastic container called the **Reagent Integral**. The assay configuration for the LIAISON® Treponema assay allows for the performance of 200 tests.
**Reagent Integral Composition:**
a. Magnetic Particles
b. 2 Calibrators that are human serum or defibrinated plasma
c. Specimen diluent
d. Conjugate which is a Tp17 DNA recombinant protein (obtained in *E. coli*)
J. **Substantial Equivalence Information:**
1. **Predicate device name(s):**
CAPTIA™ Syphilis (T. pallidum)-G
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2. Predicate 510(k) number(s): k014233
3. Comparison with predicate:
| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| 1. Intended Use | Qualitative detection of antibodies to T. pallidum in human serum | Qualitative detection of antibodies in serum specimens |
| 2. Controls | 2 (Negative and Positive) | 2 (Negative and High Titer Positive control) |
| 3. CutOff | 1.0 Index | Same |
| 4. Equivocal zone | 0.9 – 1.1 | Same |
| 5. Reagent Storage | 2 - 8°C, On board or in Refrigerator | 2 - 8°C Refrigerator only |
| 6. Laboratory Use | Clinical diagnostic Confirmation Clinical Laboratory Screen | Same |
| | | |
| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| 1. Antibody identification | Qualitative detection of total antibodies of any class (IgG/IgM) directed against T. pallidum in humans serum | Qualitative detection of IgG antibodies to T. pallidum in serum specimens |
| 2. Calibrators | 2 | Low titer reactive control in duplicate (mean value is assay cutoff) |
| 3. Sample Matrix | Serum | Serum and Plasma |
| 4. Type of Assay | Indirect Chemiluminescence Immunoassay | Enzyme Immunoassay (EIA) |
| 5. Sample Handling/Processing | Automated | Manual or in conjunction with a qualified Automatic or Semi-automatic processor/liquid handling system |
| 6. Antigen Used | DNA-Tp17 Recombinant antigen (obtained in E. coli) | Whole cell sonicated T. pallidum antigens, Nichols strain |
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| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| 7. Detector | Tp17 DNA recombinant protein (obtained in E. coli) conjugated to an isoluminol derivative | Horseradish-peroxidase (HRP) labeled mAb |
| 8. Capture Reagent | Magnetic particles coated with Tp17 DNA recombinant protein (obtained in E. coli) | Microtitration wells coated with whole-cell sonicated T. pallidum antigens, Nichols strain |
| 8. Calibration | Two-point verification (in triplicate) of stored 10 point master curve | Low titer reactive control in duplicate (mean value is assay cutoff) |
| 9. Measurement system | Photomultiplier (flash chemiluminescence reader) | Spectrophotometer (EIA Microtiter plate reader) |
| 10. Total incubation | 40 minutes | 2.5 hours (150 minutes) |
## K. Standard/Guidance Document Referenced (if applicable):
Not Applicable
## L. Test Principle:
Recombinant antigens specific for *T. pallidum* are used for coating the magnetic particles (solid phase) and are used in the tracer when linked to an isoluminol derivative (isoluminol-antigen conjugate).
All assay steps and incubations are performed by the LIAISON® Analyzer, with the exception of initial magnetic particle resuspension.
During the incubation step antibodies present in the calibrators, samples or controls bind to the solid phase. The conjugate reacts with the antibodies already bound to the solid phase. After the incubation, the unbound material is removed with a wash cycle.
Subsequently, the starter reagents are added and a flash Chemiluminescence reaction is induced. The light signal and hence the amount of isoluminol-antigen conjugate is measured by a photomultiplier as relative light units (RLU) and is indicative of total antibodies to *Treponema pallidum* present in calibrators, controls or samples.
## M. Performance Characteristics (if/when applicable):
1. Analytical performance:
a. Precision/Reproducibility:
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Reproducibility testing was performed at 3 US sites, using four replicates per run in one run per day during five operating days and a different lot of the LIAISON® Treponema Reagent Integral kit lot was used for each site. A coded panel comprised of 9 frozen “engineered” serum samples and the LIAISON® Treponema Serum controls were included in the study. The panel consisted of 4 samples near the cut-off, 2 negative, 2 low positive and 1 positive. The table below reflects the summary of results of the reproducibility study among the 3 sites.
## Reproducibility Index
| Sample ID | N | Mean Index | Within run %CV | Between run %CV | Between site %CV | Overall %CV Index | Overall SD Index |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1001 | 60 | 0.94 | 4.90 | 4.19 | 5.76 | 7.91 | 0.07 |
| 1002 | 60 | 1.07 | 2.86 | 3.99 | 4.54 | 6.07 | 0.06 |
| 1003 | 60 | 1.42 | 3.03 | 3.57 | 7.02 | 8.08 | 0.11 |
| 1004 | 60 | 0.95 | 3.86 | 3.60 | 6.76 | 7.43 | 0.07 |
| 1005 | 60 | 0.99 | 2.62 | 6.22 | 6.81 | 8.60 | 0.09 |
| 1006 | 58 | 1.26 | 1.89 | 3.93 | 6.70 | 6.93 | 0.09 |
| 1007* | 58 | 1051 | 7.78 | 5.91 | 13.65 | 14.87 | 157 |
| 1008* | 60 | 1047 | 11.17 | 8.95 | 4.32 | 23.66 | 248 |
| 1009 | 60 | 13.13 | 3.11 | 3.75 | 4.87 | 6.93 | 0.91 |
| NC | 60 | 0.25 | 7.02 | 12.16 | 17.76 | 20.06 | 0.05 |
| PC | 60 | 5.06 | 2.70 | 4.94 | 5.76 | 7.28 | 0.37 |
*Sample numbers 1007 and 1008 were negative samples that read below the assay range and Index values were nondetectable. Relative Light Units (Signal) were used in the precision summary table.
## b. Linearity / Assay Reportable Range
The assay range is 0.1 to 70 Index. Negative results can be below the assay range, these samples are reported as $< 0.1$ Index and positive samples above 70 are reported as $>70$ Index.
Samples containing extremely high antibody concentrations (prozone) when tested in a one-step sandwich assay may exhibit a hook effect and mimic concentrations that are lower than expected. Analysis of the hook effect for the LIAISON® Treponema assay was evaluated by testing 3 high titered samples positive for total antibodies against Treponema pallidum. All 3 neat samples had Index values $>70$ (the high end of the reportable range). The samples were serially diluted and the results of the dilutions gave expected results with the sample Index decreasing in value with each dilution. An approximation of the total Index value by correcting for the dilution factor (i.e.1:2) shows no high dose hook effect in samples with an anti-Treponema Index between 73.4 and 132. Two other samples that had high antibody concentrations, but did not read above the assay range of 70, were also analyzed. Both of these samples were serially diluted and results obtained gave expected results with the sample Index decreasing in value
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with each dilution as well.
A statement concerning High-Dose hook effect will be included in the Instructions for Use "Whenever samples containing extremely high antibody concentrations are tested in a one-step sandwich method, the hook effect can mimic concentrations lower than expected. Analysis of hook effect was done by serially diluting three high-titered samples positive for total antibodies to Treponema pallidum. All neat samples had an Index value above the measuring range (>70), which would be expected with high-titer sera. An approximation of the Index value by correcting for the dilution factor (i.e. 1:2) shows no high dose hook effect was observed in samples with an anti-Treponema Index of approximately 132."
c. Traceability, Stability, Expected values (controls, calibrators, or methods):
The LIAISON® Treponema Serum controls consist of 1 negative and 1 positive and are intended for use as assayed quality control samples to monitor the performance of the LIAISON® Treponema assay. Control performance has not been established for matrices other than serum. The reference range of each control is reported on the corresponding vial label.
LIAISON® Treponema Serum controls
| NEGATIVE CONTROL
2 vials – 2mL each | Human Serum or defibrinated plasma negative for antibodies to Treponema pallidum
Preservatives: 0.1% ProClin® 300 |
| --- | --- |
| POSITIVE CONTROL
2 vials – 2mL each | Human Serum or defibrinated plasma positive/reactive for IgG/IgM antibodies to Treponema pallidum in diluted in human serum negative for antibodies to Treponema pallidum.
Preservatives: 0.1% ProClin® 300 |
QC was performed once each day of use with results in the expected range most of the time.
Summary of Controls
| | Acceptance | Site 1 | | Site 2 | | Site 3 | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | Range (Index) | Mean | Total %CV | Mean | Total %CV | Mean | Total %CV |
| Serum Controls | | | | | | | |
| Negative | <0.8 | 0.23 | 11.24 | 0.22 | 23.72 | 0.3 | 5.75 |
| Positive | 3 – 8 | 5.24 | 4.46 | 4.73 | 7.81 | 5.23 | 2.07 |
European Buffer based control results were provided. However, this data was not evaluated because we do not have sufficient information to assess this matrix for control material.
On Board stability was evaluated using one lot that was left on board the instrument, in the refrigerated area (12 - 19°C), for 28 days. The kit performance was evaluated without any integral calibration, testing positive and negative
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samples. The data obtained showed results within the expected range. A claim of four weeks on-board stability has been included in the package insert.
Calibration stability study was also performed using one lot. After initial calibration of newly opened reagent integral, samples were tested and integral was stored on board the instrument, in the refrigerated area. At established intervals, positive and negative samples were tested using the stored integral and original calibration. 2-week calibration stability is claimed in the insert.
Open vial stability was evaluated using 2 lots of LIAISON® Treponema Serum controls. These controls were placed on the analyzer and tested in replicates of 6 at specified time intervals. 4-week open vial stability will be used.
d. Detection limit:
This is a qualitative assay (Pos, Neg, or Equivocal Results) so there is no limit of detection. Negative samples can be read below the low end of the assay range of 0.1 and are given a <0.1 result. There is a low limit of 350 RLU, for the LIAISON® Treponema Assay. Any sample below this limit will have an error code (!) next to the result and sample must be repeated.
The following warning statement has been added to the package insert under the Interpretation of results section to address results below the low limit of the assay range "When a sample result displays the exclamation mark (!) flag, the result obtained lies below the assay's signal range. The sample should be retested and graded negative if the result is still below the signal range upon retest."
e. Analytical specificity:
Cross-Reactivity Study
Two hundred forty four samples were tested for cross-reactivity; which was performed at DiaSorin S.p.A., DiaSorin, Inc. and at European clinical laboratories. Samples with negative or equivocal results by the predicate device and the LIAISON® Treponema Assay were considered not to demonstrate cross reactivity. Cross reactivity could not be determined in samples that returned positive values by the reference method as no additional testing of the samples by darkfield or DFA-TP or equivalent methods was done. The table below reflects the cross reactivity study.
Summary of Cross reactivity testing
| Organism / condition | # of Samples | Positive Result |
| --- | --- | --- |
| Borrelia f. IgG (European strain) | 3 | 0/3 |
| Borrelia f. IgM (European strain) | 10 | 0/10 |
| Borrelia f. IgG /IgM (European strain) | 2 | 0/2 |
| CMV IgG | 4 | 0/4 |
| CMV IgM | 2 | 0/2 |
| Rubella IgG | 4 | 0/4 |
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| Rubella IgM | 2 | 0/2 |
| --- | --- | --- |
| Toxoplasma gondii IgG | 4 | 0/4 |
| Toxoplasma gondii IgM | 3 | 0/3 |
| VZV IgG | 5 | 0/5 |
| EBV VCA IgM | 12 | 0/12 |
| Streptococcus β haemolyticus | 10 | 0/10 |
| ANA | 16 | 0/16 |
| RF | 10 | 0/10 |
| Borrelia burgdorferi (US strain) | 20 | 1/20 |
| Systemic Lupus Erythematosis (SLE) | 23 | 0/23 |
| HIV | 95 | 0/95 |
| E. coli | 3 | 0/3 |
| HBsAg | 3 | 0/3 |
| Anti-HBs | 5 | 0/5 |
| HCV | 5 | 0/5 |
| Total | 244 | 1/244 |
Samples that are positive for antibodies against Hepatitis A virus and negative for $T$ pallidum and samples for yaws, pinta and leptospirosis are unavailable therefore the following **limitation statement** will be included “Assay interference due to circulating antibodies against Hepatitis A viruses, yaws, pinta and leptospirosis have not been evaluated. The user is responsible for establishing cross-reactivity performance with these infectious agents.”
## Interference Study
Testing was performed to determine whether the presence of hemoglobin, bilirubin or triglycerides will interfere with assay results. Ten negative and 10 positive samples at different level of antibodies to $T$ pallidum were spiked with a known amount of an interfering substance with no significant difference between the two sample types.
### Interfering Substances Data
| Substance | Expected Range | Tested Concentration |
| --- | --- | --- |
| Hemoglobin | <3 mg/dL | 1000 mg/dL |
| Bilirubin | 0.2 to 1.0 mg/dL | 20 mg/dL |
| Triglycerides | 40 to 160 mg/dL | 3000 mg/dL |
## Influence of Sample Storage
1) Freeze-thawing
The effect of freeze-thawing sample was evaluated using 4 negative and 4 positive samples. Although samples cycled through freeze-thaws did not have any apparent effect on the assay performance, the following statement has been included in the package insert to follow CLSI’s recommendation “Samples should not be repeatedly frozen and thawed. Self-defrosting freezers are not recommended for sample storage.”
2) Sample Storage at $2 - 8^{\circ}\mathrm{C}$
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In this study, 4 negative and 4 positive samples were used to demonstrate the effect of sample storage at 2 - 8°C with no effect on assay performance. The following statement has been included in the submission “Samples may be kept at 2 - 8°C for no longer than 7 days, otherwise they should be dispensed in aliquots and stored deep-frozen (-20°C or below).”
## Carry Over Effect
Sample carry-over has been evaluated by testing a negative sample before and after a high positive sample with no observable effect.
### f. Assay cut-off:
The cut-off for the LIAISON® Treponema Assay was determined during European clinical trials using 3,625 samples. An analysis of the cumulative frequency distributions (ROC analysis) was performed on the LIAISON® Treponema Assay results for the 1000 non selected routine laboratory samples, 131 characterized syphilis samples and 2494 donor samples. The relevant cumulative frequency distribution graph was generated by calculating sensitivity from the 131 (positive) characterized syphilis samples and the 48 (positive) routine laboratory samples while specificity was determined from 952 (negative) routine laboratory samples, and the 2494 blood donors. Analysis of the data showed that the cut-off value discriminating between the presence and the absence of T. pallidum total antibodies has an Index value of 1.0 with an equivocal zone between 0.9 and <1.1.
The cut-off was verified in the United States during clinical trials where 97% gave Index values less than 0.5 and 97.9% gave Index values greater than 1.4.
### 2. Comparison studies:
#### a. Method comparison with predicate device:
Clinical testing was performed at 3 US sites - 2 external and 1 in-house testing using frozen prospective and retrospective samples received from sample procurement organizations that have been supplied with the selection criteria.
The clinical study was divided into 2 groups where in Study #1 LIAISON® Treponema Assay was utilized as a clinical laboratory screen (diagnostic test), and Study #2 LIAISON® Treponema Assay was utilized as a diagnostic confirmatory test.
All samples were tested with the LIAISON® Treponema Assay and the predicate device, Trinity CAPTIA™ Syphilis (T. pallidum) – G. Discordant samples were further tested as described in the Use of Treponemal Tests to Screen for Syphilis.
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# Study #1 LIAISON® Treponema Assay as a clinical laboratory screen (diagnostic test). Treponemal test followed by a non treponemal test.
# A. Medically Diagnosed Syphilis Samples
Fifty one US samples of medically diagnosed syphilis were tested with the LIAISON® Treponema assay and the Trinity CAPTIA™ Syphilis (T. pallidum) -G with the following results.
US Data for Medically Diagnosed Syphilis
| LIAISON® Treponema Assay | Syphilis G ELISA Assay | | | Total |
| --- | --- | --- | --- | --- |
| | Positive | Negative | Equivocal | |
| Positive | 47 | | 1* | 48 |
| Negative | 1* | 1 | 1* | 3 |
| Equivocal | | | | |
| Total | 48 | 1 | 2 | 51 |
Three discordant samples resolved upon further testing.
| | Percent Agreement | | Exact 95% Confidence Interval |
| --- | --- | --- | --- |
| Positive | 97.9 % | (47/48) | 89.0 – 99.9% |
| Negative | 100% | (1/1) | 2.5 – 100% |
| Overall | 94.1% | (48/51) | 83.8 – 98.8% |
One hundred twenty seven samples were tested in Europe with the following results.
European data for Medically Diagnosed Syphilis
| LIAISON® Treponema Assay | Syphilis – G ELISA Assay | | | Total |
| --- | --- | --- | --- | --- |
| | Positive | Negative | Equivocal | |
| Positive | 118 | 5* | 3* | 126 |
| Negative | | | | |
| Equivocal | 1* | | | 1 |
| Total | 119 | 5 | 3 | 127 |
| European | Percent Agreement | | Exact 95% Confidence Interval |
| --- | --- | --- | --- |
| Positive | 99.2 % | (118/119) | 95.0 - 99.9% |
| Negative | 0% | (0/5) | 0.0 – 45.0% |
| Overall | 92.9% | (118/127) | 88.0 – 96.2% |
# B. Samples sent to the Laboratory for Syphilis Testing
Nine hundred ninety-nine samples were collected in the State of New York and
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the Southeastern United States from patients sent to the laboratory for syphilis testing. Testing of these samples was split between 2 US sites. The table below shows comparison of the new and the predicate devices.
Samples sent for Laboratory testing
| LIAISON® Treponema Assay | Syphilis G ELISA Assay | | | Total |
| --- | --- | --- | --- | --- |
| | Positive | Negative | Equivocal | |
| Positive | 22 | 9* | 10* | 41 |
| Negative | 18* | 909 | 30* | 957 |
| Equivocal | | 1* | | 1 |
| Total | 40 | 919 | 40 | 999 |
Even after additional testing following the Algorithm to Screen for Syphilis: Treponema Test as Screen, there were 12 samples that remained unresolved.
| | Percent Agreement | | Exact 95% Confidence Interval |
| --- | --- | --- | --- |
| Positive | 55% | (22/40) | 38.6 – 70.7% |
| Negative | 98.9% | (909/919) | 98.0 – 99.5% |
| Overall | 93.2% | (931/999) | 91.4 – 94.7% |
# C. HIV Positive Samples
Two hundred HIV positive samples were collected from patients in the southeastern US with the following results. Testing of these samples was split between 2 US sites.
HIV Positive Samples
| LIAISON® Treponema Assay | Syphilis G ELISA Assay | | | Total |
| --- | --- | --- | --- | --- |
| | Positive | Negative | Equivocal | |
| Positive | 69 | 4* | 2* | 75 |
| Negative | 20* | 100 | 3* | 123 |
| Equivocal | 2* | | | |
| Total | 91 | 104 | 5 | 200 |
There were 11 samples that were not resolved even after additional testing with RPR and TP-PA.
| | Percent Agreement | | Exact 95% Confidence Interval |
| --- | --- | --- | --- |
| Positive | 75.8% | (69/91) | 65.8 – 83.5% |
| Negative | 96.2% | (100/104) | 90.4 – 98.9% |
| Overall | 84.5% | (169/200) | 78.7 – 89.2% |
# D. Pregnancy Samples
Two hundred pregnancy samples (first, second and third trimester) were collected in the Mid-Atlantic and Northeastern US with the following results. Testing was done in house.
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Pregnancy Samples
| LIAISON® Treponema Assay | Syphilis G ELISA Assay | | | Total |
| --- | --- | --- | --- | --- |
| | Positive | Negative | Equivocal | |
| Positive | 4 | | | 4 |
| Negative | | 192 | 4* | 196 |
| Equivocal | | | | |
| Total | 4 | 192 | 4 | 200 |
All 4 discordant samples resolved on further testing.
| | Percent Agreement | | Exact 95% Confidence Interval |
| --- | --- | --- | --- |
| Positive | 100% | (4/4) | 39.8 - 100% |
| Negative | 100% | (192/192) | 98.1 – 100% |
| Overall | 98.0% | (196/200) | 95.0 – 99.5% |
## E. Apparently Healthy Adults
Nine hundred ninety-two unselected samples were collected from apparently healthy adults in the Southeastern US. The table below reflects the results between the LIAISON® Treponema Assay and the Trinity CAPTIA™ Syphilis (T. pallidum) – G. Testing of samples was split between 2 US sites.
Apparently Healthy Adults
| LIAISON® Treponema Assay | Syphilis G ELISA Assay | | | Total |
| --- | --- | --- | --- | --- |
| | Positive | Negative | Equivocal | |
| Positive | 54 | 6* | 3* | 63 |
| Negative | 32* | 881 | 16* | 929 |
| Equivocal | | | | |
| Total | 86 | 887 | 19 | 992 |
Seventeen samples remained unresolved even after additional testing.
| | Percent Agreement | | Exact 95% Confidence Interval |
| --- | --- | --- | --- |
| Positive | 62.7% | (54/86) | 51.7 – 73.0% |
| Negative | 99.3% | (881/887) | 98.5 – 99.8% |
| Overall | 94.2% | (935/992) | 92.6 – 95.6% |
Study #2 LIAISON® Treponema Assay as a diagnostic confirmatory test.
## A. RPR/VDRL Positive Samples
Two hundred four samples collected from the Northeastern and Southeastern regions of the United States were tested between the new and the predicate devices with the following results.
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RPR/VDRL Positive Samples
| LIAISON® Treponema Assay | Syphilis G ELISA Assay | | | Total |
| --- | --- | --- | --- | --- |
| | Positive | Negative | Equivocal | |
| Positive | 200 | | 1* | 201 |
| Negative | | 2 | | 2 |
| Equivocal | 1* | | | 1 |
| Total | 201 | 2 | 1 | 204 |
There were 2 samples from the RPR positive sample with a discordant result however 1 sample was QNS for testing and the other resolved on further testing.
| | Percent Agreement | | Exact 95% Confidence Interval |
| --- | --- | --- | --- |
| Positive | 99.5% | (200/201) | 98.2 – 100% |
| Negative | 100% | (2/2) | 15.8 – 100% |
| Overall | 99.0% | (202/204) | 97.3 - 100% |
b. Matrix comparison: Not applicable
3. Clinical studies:
a. Clinical Sensitivity: Not applicable
b. Clinical specificity: Not applicable
4. Clinical cut-off: Not applicable
5. Expected values/Reference range:
Negative Index Value < 0.9
Positive Index Value ≥ 1.1
Equivocal Index Value 0.9 – 1.1
Equivocal samples must be retested in order to confirm the initial result. Samples which are positive at the second test should be considered positive. Samples which are negative at the second test should be considered negative. A second sample should be collected and tested no less than one week later when the result is repeated equivocal.
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Samples giving equivocal or positive results must be supplemented with a quantitative nontreponemal test (RPR or VDRL).
## N. Proposed Labeling:
The labeling is sufficient and satisfies the requirements of 21 CFR 809.10.
## O. Conclusion:
The submitted information in this premarket notification is complete and supports substantial equivalence decision.
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