QUANTA LITE APS/PT IGG AND IGM ELISA

K090755 · Inova Diagnostics, Inc. · OPN · Feb 1, 2010 · Immunology

Device Facts

• Record ID: K090755
• Device Name: QUANTA LITE APS/PT IGG AND IGM ELISA
• Applicant: Inova Diagnostics, Inc.
• Product Code: OPN · Immunology
• Decision Date: Feb 1, 2010
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.5660
• Device Class: Class 2

Intended Use

QUANTA Lite™ aPS/PT IgG and QUANTA Lite™ aPS/PT IgM kits are semi-quantitative and qualitative enzyme-linked immunosorbent assays (ELISA) for the detection of IgG and IgM class antibodies to phosphatidylserine/prothrombin complex (PS/PT) in serum or plasma. For use as an aid in the diagnosis of certain autoimmune thrombotic disorders, such as anti-phospholipid syndrome (APS) and those secondary to systemic lupus erythematosus or other lupus-like diseases, in conjunction with other laboratory and clinical findings.

Device Story

Device uses semi-quantitative ELISA to detect IgG and IgM antibodies against phosphatidylserine/prothrombin (PS/PT) complex in human serum or plasma. Microwell plates are coated with purified PS/PT complex; patient samples are incubated; unbound proteins washed away; HRP-labeled anti-human IgG or IgM conjugate added; TMB chromogen substrate produces color proportional to antibody concentration. Color intensity measured spectrophotometrically at 450 nm (or 620 nm dual wavelength) and compared to a five-point calibration curve. Used in clinical laboratories by trained personnel. Output aids clinicians in diagnosing autoimmune thrombotic disorders alongside other clinical/laboratory findings.

Clinical Evidence

Clinical study evaluated 382 samples (247 normals, 24 LAC positive, 71 APS positive, 40 non-APS disease controls). Sensitivity: IgG 58% (95% CI: 47-68%), IgM 56% (95% CI: 45.2-66%); combined sensitivity 76%. Specificity: IgG 99% (95% CI: 97.1-99.8%), IgM 98.3% (95% CI: 96-99.5%); combined specificity 97.2%. Concordance studies with β2GPI assays showed overall agreement of 85.6% (IgG) and 82.2% (IgM).

Technological Characteristics

Polystyrene microwell ELISA plate coated with purified non-recombinant PS/PT complex. Sandwich ELISA technique. Energy source: spectrophotometer (450/620 nm). Sample type: serum or plasma. Linear range: 5.1-150 units (IgG), 3.6-150 units (IgM). Manual or automated plate reader required.

Indications for Use

Indicated for use as an aid in the diagnosis of autoimmune thrombotic disorders, including anti-phospholipid syndrome (APS) and conditions secondary to systemic lupus erythematosus (SLE) or lupus-like diseases, in patients requiring laboratory testing for auto-antibodies.

Regulatory Classification

Identification

A multiple autoantibodies immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the autoantibodies (antibodies produced against the body's own tissues) in serum and other body fluids. Measurement of multiple autoantibodies aids in the diagnosis of autoimmune disorders (disease produced when the body's own tissues are injured by autoantibodies).

Predicate Devices

• QUANTA Lite™ β2-GPI IgG and IgM ELISA (k970551)
• QUANTA Lite™ β2-GPI IgG and IgM ELISA (k973014)

Submission Summary (Full Text)

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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY ASSAY ONLY TEMPLATE

A. 510(k) Number:
k090755

B. Purpose for Submission:
New Device

C. Measurand:
IgM and IgG class antibodies to phosphatidylserine/prothrombin complex (PS/PT)

D. Type of Test:
Semi-quantitative ELISA

E. Applicant:
INOVA Diagnostics, Inc.

F. Proprietary and Established Names:
Quanta Lite™ aPS/PT IgG ELISA
Quanta Lite™ aPS/PT IgM ELISA

G. Regulatory Information:
1. Regulation section:
21 CFR 866.5660 Multiple auto-antibodies immunological test system
2. Classification:
Class II
3. Product code:
MSV, system, test, antibodies, β2-glycoprotein 1 (β2-GP1)
4. Panel:
Immunology (82)

H. Intended Use:
1. Intended use(s):
QUANTA Lite™ aPS/PT IgG and QUANTA Lite™ aPS/PT IgM kits are semi-quantitative and qualitative enzyme-linked immunosorbent assays (ELISA) for the detection of IgG and IgM class antibodies to phosphatidylserine/prothrombin complex (PS/PT) in serum or plasma. For use as an aid in the diagnosis of certain autoimmune thrombotic disorders, such as anti-phospholipid syndrome (APS) and those secondary to systemic lupus erythematosus or other lupus-like diseases, in conjunction with other laboratory and clinical findings.
2. Indication(s) for use:
Same as intended use
3. Special conditions for use statement(s):
For prescription only
4. Special instrument requirements:
Microplate reader capable of measuring OD at 450 nm (or 620 for dual wavelength readings)

I. Device Description:
QUANTA Lite™ aPS/PT IgG and IgM ELISA consists of a polystyrene microwell ELISA plate coated with purified non-recombinant PS/PT complex; high positive, low positive, and negative controls; sample diluent; wash concentrate; goat anti-

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human IgG or IgM, horseradish peroxidase conjugate; TMB chromogen; and stop solution. The PS/PT antigen consists of naturally occurring lipid phosphatidylserine complexed with human prothrombin.

# J. Substantial Equivalence Information:

1. Predicate device name(s): QUANTA Lite™ β2-GPI IgG and IgM ELISA
2. Predicate 510(k) number(s): k970551 and k973014
3. Comparison with predicate:

| SIMILARITIES | | |
| --- | --- | --- |
| | QUANTA Lite™ aPS/PT IgG and IgM ELISAs | QUANTA Lite™ β2-GPI IgG and IgM ELISAs |
| Intended Use | QUANTA Lite™ aPS/PT IgG and QUANTA Lite™ aPS/PT IgM kits are semi-quantitative and qualitative enzyme-linked immunosorbent assays (ELISA) for the detection of IgG and IgM class antibodies to phosphatidylserine/ prothrombin complex (PS/PT) in serum or plasma. For use as an aid in the diagnosis of certain autoimmune thrombotic disorders, such as anti-phospholipid syndrome (APS) and those secondary to systemic lupus erythematosus or other lupus-like diseases in conjunction with other laboratory and clinical findings. | QUANTA Lite™ β2 GPI IgG and IgM ELISA kits are enzyme-linked immunosorbent assays (ELISA) for the semi-quantitative detection of β2 GPI IgG and IgM antibodies in human serum. The presence of β2 GPI IgG and IgM antibodies can be used in conjunction with other clinical findings and laboratory tests to aid in the diagnosis of certain autoimmune disorders, such as those secondary to systemic lupus erythematosus (SLE) or other lupus-like thrombotic diseases |
| Methodology | ELISA | Same |
| Assay format | Semi-quantitative | Same |
| Conjugate | Anti-human IgG HRP Anti-human IgM HRP | Same |
| Substrate/ Chromogen | TMB Chromogen | Same |
| Screening dilution | 1:101 | Same |
| Reading | 450 nm (620 nm for dual wavelength readings) | Same |

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| DIFFERENCES | | |
| --- | --- | --- |
| | Device | Predicate |
| Analyte | Anti-phosphatidylserine/prothrombin complex (aPS/PT) | β2-glycoprotein 1 (β2-GP1) |
| Sample type | Serum or plasma | Serum |
| Cutoff | 30 Units | 20 Units |
| Positive Control | PS/PT IgG or IgM ELISA control | β2 GPI IgG ELISA control
β2 GPI IgM ELISA control |
| Calibrators | PS/PT IgG or IgM Calibrators (A-E) | β2 GPI IgG or IgM Calibrators (A-E) |
| Linear Range | PS/PT IgG: 5.1-150 units
PS/PT IgM: 3.6-150 units | Not given |
| Limit of Detection | PS/PT IgG: 5.1 units
PS/PT IgM: 3.6 units | Not given |

# K. Standard/Guidance Document Referenced (if applicable):

Evaluation of the Linearity of Quantitative Analytical Methods (EP6-P2)

# L. Test Principle:

QUANTA Lite™ aPS/PT IgG and IgM ELISAs employ the sandwich ELISA technique. Plastic microwell plate wells are coated with purified PS/PT complex and then stabilized. Upon incubation, sample containing PS/PT IgG or IgM antibodies bind to the PS/PT complexes. Unbound protein is removed by washing and polyclonal goat anti-human IgG or IgM horseradish peroxidase (HRP) labeled conjugate is added to the wells. After incubation, the unbound conjugate is removed by washing. A peroxidase substrate is added, which undergoes a color change in the presence of the conjugated enzyme. After stopping the enzymatic production of colored product, the presence or absence of phosphatidylserine/prothrombin antibody is determined spectrophotometrically by measuring and comparing the color intensity that develops in the patient wells with that of a five point calibration curve.

# M. Performance Characteristics (if/when applicable):

# 1. Analytical performance:

# a. Precision/Reproducibility:

Eight clinical samples were tested spanning a range of values from low negative (1-3 units) to high positive (139-150 units). Each sample was run 6 times on 6 different days on the PS/PT IgG ELISA by the same operator for a total of 36 runs. The unit value results are summarized below:

| IgG units value (Units) | 1.4 | 1.7 | 8.3 | 22.2 | 36.8 | 53.8 | 79.3 | 139.3 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Intra-assay Sdev | 0.1 | 0.1 | 0.8 | 1.7 | 2.5 | 3.4 | 4.9 | 6.8 |
| %CV | 8.1 | 7.1 | 9.9 | 7.8 | 6.7 | 6.4 | 6.2 | 4.9 |
| Inter-assay Sdev | 0.2 | 0.1 | 0.4 | 1.2 | 1.6 | 2.3 | 3.3 | 4.2 |
| %CV | 12.0 | 8.3 | 5.2 | 5.3 | 4.5 | 4.2 | 4.2 | 3.0 |

Another eight samples were tested as six replicates on the PS/PT IgM ELISA on the same six different days (total $n = 36$ ). The results are summarized below.

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For each assay, 2 additional clinical samples were run, one near the clinical decision point (30 units) and one near the top of the measuring range of each assay. These samples were run in duplicate over 3 days for a total of 6 runs. These results are summarized below:

PS/PT IgG Units

| Sample | Avg Units | SD | %CV |
| --- | --- | --- | --- |
| 1 | 40.4 | 4.16 | 10.3 |
| 2 | 159.15 | 17.53 | 11.0 |

PS/PT IgM Units

| Sample | Avg Units | SD | %CV |
| --- | --- | --- | --- |
| 1 | 31.5 | 3.38 | 10.7 |
| 2 | 255.9 | 16.55 | 6.5 |

# b. Linearity/assay reportable range:

To assess the linearity of the PS/PT IgG and PS/PT IgM assays, 3 high positive samples at or near the upper limit of the assay range (150 units) and one sample in the mid-range of the assays (about 75 units) were serially diluted and run on each of the PS/PT IgG and PS/PT IgM assays. Observed vs. expected values were plotted. $\mathbb{R}^2$ values for the curves generated ranged from 0.932 to 0.992 for PS/PT IgG and 0.967 to 0.986 for PS/PT IgM. The linear range is 5.1-150 units for IgG and 3.6-150 units for IgM.

PS/PT IgG

| Dilution (neg. serum + sample) | Sample H1 (Units) | | Sample H2 (Units) | | Sample H4 (Units) | | Sample H5 (Units) | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | Obs | Exp | Obs | Exp | Obs | Exp | Obs | Exp |
| 0.875+0.125 | 38.6 | 22.9 | 22.0 | 22.3 | 9.4 | 12.8 | 8.8 | 9.2 |
| 0.750+0.250 | 58.8 | 45.9 | 32.4 | 44.7 | 21.8 | 25.6 | 17.0 | 18.5 |
| 0.625+0.375 | 79.7 | 69.1 | 59.4 | 67.3 | 34.9 | 38.6 | 24.8 | 27.8 |
| 0.500+0.500 | 107.5 | 91.9 | 76.1 | 89.5 | 45.1 | 51.4 | 29.7 | 36.9 |
| 0.375+0.625 | 115.7 | 114.9 | 88.7 | 111.8 | 56.3 | 64.3 | 40.9 | 46.2 |
| 0.250+0.750 | 151.1 | 138.3 | 111.9 | 134.5 | 71.0 | 77.2 | 51.9 | 55.6 |
| 0.125+0.875 | 139.2 | 161.3 | 112.6 | 157 | 81.1 | 90.1 | 54.6 | 64.8 |
| H1 | 183.9 | 183.9 | 179 | 179 | 102.7 | 102.7 | 73.9 | 73.9 |
| Regression eq. | y=1.13x- 20.34 | | y=1.05x+ 11.19 | | y=1.00x + 4.92 | | y=1.03x + 2.72 | |
| R2 | 0.962 | | 0.932 | | 0.992 | | 0.976 | |

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PS/PT IgM

| Dilution (neg. serum + sample) | Sample H1 (Units) | | Sample H2 (Units) | | Sample H3 (Units) | | Sample H5 (Units) | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | Obs | Exp | Obs | Exp | Obs | Exp | Obs | Exp |
| 0.875+0.125 | 31.7 | 19.5 | 21.1 | 19.3 | 28.1 | 19.9 | 8.8 | 11.1 |
| 0.750+0.250 | 46.7 | 38.9 | 38.7 | 38.6 | 51.9 | 39.9 | 21.7 | 22.2 |
| 0.625+0.375 | 78.2 | 58.6 | 65.7 | 57.9 | 74.4 | 60.1 | 34.9 | 33.3 |
| 0.500+0.500 | 85.1 | 77.9 | 75.6 | 77.1 | 88.1 | 79.9 | 40.9 | 44.3 |
| 0.375+0.625 | 115.4 | 97.4 | 90.6 | 96.4 | 104.9 | 99.9 | 49.0 | 55.4 |
| 0.250+0.750 | 108 | 117.2 | 103.8 | 115.9 | 122.4 | 120.2 | 57.1 | 66.6 |
| 0.125+0.875 | 145.1 | 136.8 | 126.5 | 135.2 | 124.5 | 140.3 | 64.6 | 77.7 |
| H1 | 155.9 | 155.9 | 154.2 | 154.2 | 159.9 | 159.9 | 88.6 | 88.6 |
| Regression eq. | y=1.07x- 14.62 | | y=1.065x-3.23 | | y=1.14x-17.2 | | y=1.06x 1.27 | |
| R² | 0.966 | | 0.986 | | 0.978 | | 0.968 | |

c. Traceability, Stability, Expected values (controls, calibrators, or methods): There is no internationally recognized standard for PS/PT. Calibrators and controls are prepared in-house. The results are reported in arbitrary units.

Stability:

Microwell plates:

Three separate lots of coated plates were placed in $37^{\circ}\mathrm{C}$ incubators and then tested at 7, 14, 21, and 28 days with 5 standards for varying reactivity and a positive control. Optical densities at each time point were compared back to a plate stored at $4^{\circ}\mathrm{C}$ . For all test points, opened, but resealable foil mylar pouches were used. An average remaining activity of over $85\%$ was maintained through the 28 day period.

Standard and controls:

Two different lots of standards and controls were tested at 7, 14, 21, and 28 days at $37^{\circ}\mathrm{C}$ and compared to material kept at $4^{\circ}\mathrm{C}$ . Over $90\%$ activity was maintained at 21 days.

d. Detection limit:

The limit of blank was determined by running three different lots of Reagent blank (sample diluent) five times each, calculating the average and the standard deviation. The results are as follows:

| PS/PT IgG | | PS/PT IgM | |
| --- | --- | --- | --- |
| | UNITS | | UNITS |
| AVG | 2.5 | AVG | 0.70 |
| STDEV | 0.23368 | STDEV | 0.04522 |

The limit of detection was assessed by serially diluting 2 high positive PS/PT IgG and 2 high positive PS/PT IgM sera (1:100 to 1:3,276,800), and the diluted

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samples were run on the PS/PT IgG and PS/PT IgM tests. The dilution below which the OD plateaus out was noted. For both the IgG and IgM tests, the dilution of 1:25,600 was empirically determined to yield the lowest limit of detection. All four sera were run 16 times at this dilution. The results are below:

| PS/PT IgG | | PS/PT IgM | |
| --- | --- | --- | --- |
| Sample #1978 | UNITS | Sample #62 | UNITS |
| AVG | 7.2 | AVG | 3.2 |
| STDEV | 1.172 | STDEV | 0.516 |
| Sample #343 | UNITS | Sample #676 | UNITS |
| AVG | 3.172 | AVG | 4.5 |
| STDEV | 0.419 | STDEV | 0.361 |

The limit of detection for the PS/PT IgG assay was calculated to be 5.1 (0.795 SD) and the limit of detection for the PS/PT IgM assay is 3.8 (0.438 SD).

# e. Analytical specificity:

# 1. Interference:

Three serum samples were selected for each PS/PT assay. One sample was negative, one near the clinical decision point and one a high positive after spiking with pooled NHS (normal human serum) @ 1:1 dilution. Interferents tested were bilirubin; triglyceride; RF IgM positive serum (final concentration- 77 RLU and hemoglobin (final concentration - 200 mg/dL).

| Interferent | PS/PT IgG Units | PS/PT IgM Units |
| --- | --- | --- |
| RF IgM Pos (77 RLU) | 5.7 | 4.1 |
| Triglyceride (508 mg/dL) | 4.8 | 10.5 |
| Bilirubin (15 mg/dL) | 6.8 | 4.3 |
| NHS (pooled normal human serum for diluting test samples) | 2.7 | 4.8 |
| Hemoglobin | | |

PS/PT IgG

| Sample | Control (Units) | Sample + Triglyceride (Units) | % Change | Sample + Bilirubin (Units) | % Change | Sample + Hemoglobin (Units) | % Change | Sample + RF IgM (Units) | % Change |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 4.1 | 5.3 | +29.2% | 5.6 | +36.5% | 4 | -2.4% | 4.9 | +19.5% |
| 2 | 32.4 | 37.2 | +14.8% | 37.2 | +14.8% | 34.5 | +6.5% | 33 | +1.8% |
| 3 | 151 | 140.9 | -6.7% | 171.8 | +13.7% | 173.5 | +14.9% | 165.8 | +9.8% |

PS/PT IgM

| Sample | Control (Units) | Sample + Triglyceride (Units) | % Change | Sample + Bilirubin (Units) | % Change | Sample + Hemoglobin (Units) | % Change | Sample + RF IgM (Units) | % Change |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 4.9 | 7.9 | +61% | 5.5 | +12.2% | 4.1 | +16.0% | 4.5 | -8.1% |
| 2 | 28.4 | 31 | +9% | 28.9 | +1.8% | 25.9 | -8.8% | 28.6 | +0.7% |
| 3 | 131.1 | 105.8 | -19.8% | 136.5 | +4.1% | 125.7 | -4.1% | 116.5 | -10.9% |

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f. Assay cut-off:

A total of 382 clinically defined samples; including 247 normals, 24 known Lupus Anticoagulant (LA) positive, 71 anti-phospholipid syndrome (APS) positive and 40 non-APS disease controls; were tested with the PS/PT IgG and IgM kits. A non-parametric rank order analysis of the data was performed and a cut-off of 30 units was chosen.

2. Comparison studies:

a. Method comparison with predicate device:

Two method comparison studies were performed at two different sites, one internal and one external. In both studies, the PS/PT IgG and IgM assays were compared with the predicate assay.

A total of 62 samples were used for the IgG kit comparison and 63 samples were used for the IgM kit comparison. All samples had values within the claimed linear range of the assays. The results are below:

| IgG PS/PT ELISA | | | | |
| --- | --- | --- | --- | --- |
| | | Positive | Negative | Total |
| IgG β2 GPI ELISA | Positive | 13 | 7 | 20 |
| | Negative | 6 | 36 | 42 |
| | Total | 19 | 43 | 62 |
| Positive Percent Agreement | | 65% (95% CI: 44.1-85.9) | | |
| Negative Percent Agreement | | 83.7% (95% CI: 75.1-96.3) | | |
| Relative Agreement | | 77.8% (95% CI: 70.5-87.5) | | |
| IgM PS/PT ELISA | | | | |
| --- | --- | --- | --- | --- |
| | | Positive | Negative | Total |
| IgG β2 GPI ELISA | Positive | 13 | 3 | 16 |
| | Negative | 11 | 36 | 47 |
| | Total | 24 | 39 | 63 |
| Positive Percent Agreement | | 81.3% (95% CI: 62.1-100) | | |
| Negative Percent Agreement | | 76.6% (95% CI: 64.5-88.7) | | |
| Relative Agreement | | 77.8% (95%CI: 68.2-86.4) | | |

The low percent agreements between the predicate and the new devices are due to the fact that different analytes are being measured.

b. Matrix comparison:

Twelve samples submitted for LAC testing at an outside laboratory (6 positive and 6 negative) were tested. Half of each sample was converted to serum by addition of calcium, followed by freeze-thawing and then centrifugation. The 24 paired citrated plasma/serum samples were then run on both the IgG and IgM PS/PT kits. The results are shown below. The values between serum and plasma samples had coefficients of correlation of over $0.99\%$ with slopes ranging from 0.92-1.04.

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| Sample | PS/PT IgG (Units) | | PS/PT IgM (Units) | |
| --- | --- | --- | --- | --- |
| | Plasma | Serum | Plasma | Serum |
| Ca | 134.1 | 129.4 | 52.5 | 49.3 |
| C2 | 149.3 | 148.5 | 61.1 | 61.2 |
| C5 | 135.7 | 125.7 | 53.3 | 53.3 |
| L0 | 26.2 | 26 | 103.1 | 113 |
| V1 | 251.9 | 239.9 | 9.6 | 9.7 |
| V2 | 245.6 | 236 | 9.1 | 8.3 |
| 1 | 2.4 | 2.5 | 8.7 | 8 |
| 2 | 15.7 | 14.2 | 22.1 | 15.5 |
| 3 | 2.8 | 2.4 | 7.1 | 5.4 |
| 5 | 5.5 | 5.9 | 4.9 | 4.4 |
| 6 | 2.4 | 2.3 | 7.3 | 5.8 |
| 7 | 3.2 | 3.7 | 6.7 | 5.4 |
| R value | 0.999 | | 0.996 | |
| Intercept | 0.203 | | 2.73 | |
| Slope | 1.043 | | 0.921 | |

3. Clinical studies:

a. Clinical Sensitivity and Specificity:

Two hundred forty-seven normal samples along with 24 lupus anticoagulant positive, 71 Anti-Phospholipid Syndrome (APS) positive samples, and samples from other similar conditions were tested with the QUANTA Lite™ aPS/PT IgG and IgM kits. Testing was done at one internal and one external site. The results are tabulated in the table below.

The sensitivity of the IgG Assay is 58% (95% CI: 47%-68%) and the sensitivity of the IgM assay is 56% (95% CI: 45.2%-66%). The combined sensitivity of both is 76%.

The specificity of the IgG Assay is calculated to be 99% (95% CI: 97.1%-99.8%), and the specificity of the IgM assay is 98.3% (95% CI: 96%-99.5%). The combined specificity is 97.2%.

| | Number Positive (percent) | | | |
| --- | --- | --- | --- | --- |
| Patient Group | No. Samples | PS/PT IgG | PS/PT IgM | IgG and/or IgM |
| Normals | 247 | 3 (1.2) | 4 (1.6) | 7 (2.8) |
| Lupus Anticoagulant (LAC) Positive | 24 | 21 (87.5) | 19 (79.2) | 24 (100) |
| Anti-Phospholipid Syndrome (APS) | 71 | 33 (46.5) | 34 (47.9) | 48 (67.6) |
| Rheumatoid Arthritis | 6 | 0 | 0 | 0 |
| Crohn's Disease | 2 | 0 | 0 | 0 |
| Ulcerative Colitis | 2 | 0 | 0 | 0 |
| Celiac disease | 5 | 0 | 0 | 0 |

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b Other clinical supportive data (when a. is not applicable):
Clinical Concordance with β2GPI IgG and β2GPI IgM assays - The QUANTA Lite™ aPS/PT IgG and IgM kits were compared with the QUANTA Lite™ β2GPI IgG and β2GPI IgM assays on clinical samples. The devices measure different analytes, but they are used as aids in the diagnosis of autoimmune thrombotic diseases in the SLE and lupus-like disease populations. The samples tested included 71 APS patients, 24 Lupus anticoagulant positive patients, and 85 normals. The results are summarized below:

| IgG PS/PT ELISA | | | | |
| --- | --- | --- | --- | --- |
| | | Positive | Negative | Total |
| IgG β2 GPI ELISA | Positive | 38 | 10** | 48 |
| | Negative | 16* | 116 | 132 |
| | Total | 54 | 126 | 180 |
| Positive Percent Agreement | | 79.2% | | |
| Negative Percent Agreement | | 87.9% | | |
| Overall Agreement | | 85.6% | | |

*1/16 was LAC positive, 15/16 were APS patients
**All 10 were from the APS group

| IgM PS/PT ELISA | | | | |
| --- | --- | --- | --- | --- |
| | | Positive | Negative | Total |
| IgM β2 GPI ELISA | Positive | 28 | 7* | 35 |
| | Negative | 25** | 120 | 155 |
| | Total | 53 | 127 | 180 |
| Positive Percent Agreement | | 80% | | |
| Negative Percent Agreement | | 77.4% | | |
| Overall Agreement | | 82.2% | | |

*1 was normal and 6 were APS patients
**22 were APS patients and 3 were LAC positives

4. Clinical cut-off:
Not applicable

5. Expected values/Reference range:
Not applicable

N. Proposed Labeling:
The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.

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O. Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.

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