← Product Code [DHR](/submissions/IM/subpart-f%E2%80%94immunological-test-systems/DHR) · K162263

# Optilite Rheumatoid Factor Kit (K162263)

_The Binding Site Group , Ltd. · DHR · May 3, 2017 · Immunology · SESE_

**Canonical URL:** https://fda.innolitics.com/submissions/IM/subpart-f%E2%80%94immunological-test-systems/DHR/K162263

## Device Facts

- **Applicant:** The Binding Site Group , Ltd.
- **Product Code:** [DHR](/submissions/IM/subpart-f%E2%80%94immunological-test-systems/DHR.md)
- **Decision Date:** May 3, 2017
- **Decision:** SESE
- **Submission Type:** Traditional
- **Regulation:** 21 CFR 866.5775
- **Device Class:** Class 2
- **Review Panel:** Immunology

## Indications for Use

The Optilite Rheumatoid Factor (RF) Kit is intended for the quantitative in vitro measurement of rheumatoid factor in serum using the Binding Site Optilite analyser. Measurement of rheumatoid factor may aid in the diagnosis of rheumatoid arthritis. This test should be used in conjunction with other laboratory and clinical findings.

## Device Story

The Optilite Rheumatoid Factor Kit is an in vitro diagnostic reagent set used on the Binding Site Optilite analyser. It utilizes immunoturbidimetry to measure rheumatoid factor concentration in serum samples. The assay involves a reaction between the rheumatoid factor in the patient sample and human IgG adsorbed onto latex particles, forming insoluble complexes. As light passes through the suspension, the amount of transmitted light is measured by a photodiode; this transmission is inversely proportional to the protein concentration. The analyser automatically calculates concentrations using a stored calibration curve. The device is intended for use in clinical laboratory settings by trained personnel. Results assist clinicians in diagnosing rheumatoid arthritis when interpreted alongside other clinical and laboratory findings.

## Clinical Evidence

Bench testing only. Performance evaluated per CLSI guidelines (EP05-A2, EP6-A, EP17-A, EP07-A2). Precision studies (n=84 replicates) showed total CVs between 3.8% and 6.9%. Linearity confirmed across 7–100 IU/mL. Method comparison with 103 clinical samples yielded a Pearson correlation of 0.984 and Passing Bablok regression y = 0.90x + 2.51. Positive percent agreement was 95.8% and negative percent agreement was 71.4%. Reference range verified using 50 normal serum samples.

## Technological Characteristics

Quantitative immunoturbidimetric assay. Reagents include glycine buffer, latex particles adsorbed with human IgG, and sodium azide. Measuring range: 7–100 IU/mL (standard) and 70–1000 IU/mL (diluted). Operates on the Binding Site Optilite analyzer using photodiode detection. Traceable to WHO Standard 64/2. Stability: 12 months unopened, 3 months open-vial, 30 days on-board.

## Regulatory Identification

A rheumatoid factor immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the rheumatoid factor (antibodies to immunoglobulins) in serum, other body fluids, and tissues. Measurement of rheumatoid factor may aid in the diagnosis of rheumatoid arthritis.

## Predicate Devices

- Rheumatoid Factor (RF) Kit for use on SPAPLUS ([K160070](/device/K160070.md))

## Submission Summary (Full Text)

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>
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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY

A. 510(k) Number:
K162263

B. Purpose for Submission:
New assay

C. Measurand:
Rheumatoid Factor (IgM)

D. Type of Test:
Quantitative immunoturbidimetry

E. Applicant:
The Binding Site, Ltd.

F. Proprietary and Established Names:
Optilite® Rheumatoid Factor Kit

G. Regulatory Information:

1. Regulation section:
21 CFR § 866.5775: Rheumatoid factor immunological test system

2. Classification:
Class II

3. Product code:
DHR: System, test, Rheumatoid Factor

4. Panel:
Immunology (82)

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H. Intended Use:

1. Intended use:

The Optilite Rheumatoid Factor (RF) Kit is intended for the quantitative in vitro measurement of rheumatoid factor in serum using the Binding Site Optilite analyser. Measurement of rheumatoid factor may aid in the diagnosis of rheumatoid arthritis. This test should be used in conjunction with other laboratory and clinical findings.

2. Indication for use:

Same as Intended Use above.

3. Special conditions for use statement:

For prescription use only.

4. Special instrument requirements:

The Binding Site Optilite

I. Device Description:

The Optilite Rheumatoid Factor Kit contains:

Reaction Buffer: Containing glycine buffer (pH 8.3), sodium chloride, sodium ethylenediamine tetra acetic acid disodium salt dehydrate, bovine serum albumin, sodium azide (0.09%, w/v).

Latex Reagent: Containing glycine buffer (pH 7.3), sodium chloride, latex particle adsorbed human IgG, sodium azide (0.09%, w/v).

RF Controls: Supplied at two levels, Low and High. Target values and ranges are supplied in the Quality Control certificate. Supplied ready for use.

RF Calibrator 1–5: Calibration has been carried out and values have been assigned using an immunoturbidimetric method standardized to the international reference preparation, WHO Standard 64/2. Supplied ready for use.

J. Substantial Equivalence Information:

1. Predicate device name and Predicate 510(k) number:

Rheumatoid Factor (RF) Kit for use on SPAPLUS, K160070

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2. Comparison with predicate:

|  Similarities  |   |   |
| --- | --- | --- |
|  Item | Optilite®RF Kit | Predicate  |
|  Intended Use | The Optilite Rheumatoid Factor (RF) Kit is intended for the quantitative in vitro measurement of rheumatoid factor in serum using the Binding Site Optilite analyser. Measurement of rheumatoid factor may aid in the diagnosis of rheumatoid arthritis. This test should be used in conjunction with other laboratory and clinical findings. | The Rheumatoid Factor (RF) Kit for use on SPAPLUS® is intended for the quantitative in vitro measurement of rheumatoid factor in serum using the Binding Site SPAPLUS® analyser. Measurement of rheumatoid factor may aid in the diagnosis of rheumatoid arthritis. This test should be used in conjunction with other laboratory and clinical findings.  |
|  Assay type | Quantitative | Same  |
|  Specimen Type | Serum | Same  |
|  Antibody | Human IgG anti-human-IgM | Same  |
|  Intended use | Turbidimetric in vitro quantification of rheumatoid factor | Same  |
|  Calibration | WHO 64/2 | Same  |
|  Calibrator | 5 levels | Same  |
|  Expected value | 12.5 IU/mL | Same  |
|  RF Control | Two levels | Same  |
|  Unopened Kit | 12 months | Same  |
|  Open Vial Stability | 3 months | Same  |
|  On-board stability | 30 days | Same  |
|  Differences  |   |   |
| --- | --- | --- |
|  Item | RF Kit on SPAPLUS® | Predicate  |
|  Instrument | Binding Site Optilite | Binding Site SPAPLUS  |
|  Measuring range | 7–100 IU/mL (1+0 dilution) | 10–104 IU/mL (1/1: Standard Dilution)  |
|   |  70–1000 IU/mL (1+9 dilution) | 70–1040 IU/mL (1/10: Automatic reflex dilution on high results at standard dilution)  |

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

- CLSI EP05-A2, Evaluation of Precision Performance of Quantitative Measurement Methods; Approved Guideline—Second Edition
- CLSI EP6-A, Evaluation of the Linearity of Quantitative Measurement Procedures: A Statistical Approach; Approved Guideline
- CLSI EP17-A, Protocols for Determination of Limits of Detection and Limits of Quantitation; Approved Guideline
- CLSI EP07-A2, Interference Testing in Clinical Chemistry; Approved Guideline

L. Test Principle:

The determination of soluble antigen concentration by turbidimetric methods involves the reaction with specific antiserum to form insoluble complexes. When light is passed through the suspension formed, a portion of the light is transmitted and focused onto a photodiode by an optical lens system. The amount of transmitted light is indirectly proportional to the specific protein concentration in the test sample.

M. Performance Characteristics (if/when applicable):

All results from all studies met the manufacturer’s pre-specified acceptance criteria.

1. Analytical performance:

a. Precision/Reproducibility:

The studies were based on CLSI EP05-A2; five sample preparations were tested in two runs per day (each of the two runs in duplicate) over 21 days using three analysers and three lots for a total of 84 replicates. A summary of the results is shown below. All results are in IU/mL.

|  RF Sample | Mean | Within-Run |   | Between-Run |   | Between-Day |   | Total Precision  |   |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|   |   |  SD | %CV | SD | %CV | SD | %CV | SD | %CV  |
|  1 | 12.3 | 0.30 | 2.5 | 0.26 | 2.2 | 0.74 | 6.0 | 0.84 | 6.9  |
|  2 | 19.4 | 0.12 | 0.7 | 0.29 | 1.5 | 0.71 | 3.7 | 0.78 | 4.0  |
|  3 | 38.1 | 0.22 | 0.6 | 0.50 | 1.3 | 1.49 | 3.9 | 1.59 | 4.2  |
|  4 | 75.7 | 1.26 | 1.7 | 0.95 | 1.3 | 2.83 | 3.7 | 3.24 | 4.3  |
|  5 | 191.0 | 2.79 | 1.5 | 2.82 | 1.5 | 6.11 | 3.2 | 7.28 | 3.8  |

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|  RF Sample | Mean | Between-lot |   | Between-instrument  |   |
| --- | --- | --- | --- | --- | --- |
|   |   |  SD | %CV | SD | %CV  |
|  1 | 12.3 | 0.2 | 1.43 | 0.52 | 4.2  |
|  2 | 19.4 | 0.2 | 1.08 | 0.54 | 2.8  |
|  3 | 38.1 | 1.2 | 3.10 | 0.67 | 1.8  |
|  4 | 75.7 | 3.1 | 4.10 | 0.74 | 1.0  |
|  5 | 191.0 | 5.5 | 2.87 | 2.98 | 1.6  |

b. Linearity/assay reportable range:

A linearity study was performed following CLSI guideline EP6-A. The linearity of this assay has been confirmed by dilution of serum samples with analyte-depleted serum to cover the range 7–100 IU/mL (total of 9 dilutions). Deviation from linearity calculated according to CLSI guideline EP6-A was ≤ ±5%. The regression equation for the linear range (7–100 IU/mL) was y = 0.999x + 0.04 IU/mL-.

Antigen Excess: No antigen excess was observed up to a level of 59 times the top of the calibration curve at the standard 1+0 sample dilution. This is equivalent to 5900 IU/mL.

c. Traceability, Stability, Expected values (controls, calibrators, or methods):

(i) Traceability: The calibration of the assay is traceable to the International Reference Preparation of Rheumatoid Arthritis Serum WHO 64/2.

(ii) Kit Stability:

Unopened kit stability- The manufacturer provided data that supports a real-time stability claim of 12 months.

Open-vial stability- The manufacturer provided data that the RF Reagent, Calibrator and Controls can be stored opened at 2–8°C for up to 3 months.

On-board stability- The manufacturer provided data that the RF Reagent can be stored on-board the Optilite Analyzer for at least 30 days.

d. Detection limit:

The detection limits of the assay were evaluated based on CLSI EP17-A. Study results follow the explanation below:

The Limit of Blank (LoB) was based on 60 determinations of a blank sample

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(consisting of a pool of analyte-depleted samples) and was estimated as the 95% percentile of the distribution.

The Limit of Detection (LoD) was calculated according to the equation $\mathrm{LoB} + 1.645 \times \mathrm{SDs}$ where SDs, the standard deviation, was based on six determinations of four samples with analyte levels near the lower limit of the reportable range.

The Limits of Quantitation (LoQ) were calculated from the total error of the LoD study; four separate dilutions of the International Reference Preparation were prepared, and tested three times each on two lots using the test assay on the Optilite analyser over four days. The total error at LoQ was within the maximum allowable total error for each sample matrix. The bottom of the measuring range, $7\mathrm{IU/mL}$ is set at the limit of quantitation (LoQ) for this assay.

Summary:
$\mathrm{LoB} = 0.000 \mathrm{IU/mL}$
$\mathrm{LoD} = 0.142 \mathrm{IU/mL}$
$\mathrm{LoQ} = 7 \mathrm{IU/mL}$

e. Analytical specificity:

Interferences were assessed according to CLSI EP7-A2 by testing samples at different RF concentrations (8.3, 12.2, 80). Each sample was spiked with interfering substances and tested and compared with results from non-spiked samples. The data demonstrated that the assay was not affected by the following substances at the concentrations given below.

|  Interferent | Concentration | Interferent | Concentration  |
| --- | --- | --- | --- |
|  Ascorbic Acid | 342 μmol/L | Acetylsalicylic | 1.815 mmol/L  |
|  Conj. Bilirubin | 200 mg/L | Penicillin | 75 mg/L  |
|  Hemoglobin | 4 g/L | Caffeine | 308 μmol/L  |
|  Intralipid | 500 mg/dL | Prednisolone | 100 μg/mL  |
|  Triglyceride | 500 mg/dL | Digoxin | 7.8 nmol/L  |
|  Acetaminophen | 1324 μmol/L | Cimetidine | 79.2 μmol/L  |
|  Ibuprofen | 2425 μmol/L | Theophylline | 222 μmol/L  |
|  Methotrexate | 2 mmol | Phenytoin | 198 μmol/L  |

f. Assay cut-off:

Not applicable

2. Comparison studies:

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a. Method comparison with predicate device:

A comparison study was performed by testing the predicate and the Optilite RF Kit with 103 samples (including 19 Rheumatoid Arthritis, 1 Osteoarthritis, 1 Psoriatic arthritis, 1 SLE, 3 Sjögrens Syndrome, 3 HCV, 1 Ulcerative Colitis, , 2 Syphilis, 2 Systemic Sclerosis, 1 Vasculitis, and 69 other clinical conditions) all within the assays' measuring ranges; the samples covered the range 8.1-589 IU/mL. The Pearson's correlation coefficient (r value) was 0.984 and the Passing Bablok regression analysis generated the following results:

$$
y = 0.90x + 2.51 IU/mL \quad (y = \text{Optilite}; x = \text{predicate})
$$

$$
(95\% \text{ CI: Intercept} = 0.76 - 3.88; \text{Slope} = 0.87 - 0.97)
$$

The same comparison study was also analyzed by calculating the % Positive Agreement, % Negative Agreement and % Overall Agreement calculations with the following results:

|   | Predicate Assay  |   |   |   |
| --- | --- | --- | --- | --- |
|   |   |  Positive | Negative | Total  |
|  Optilite RF Kit | Positive | 92 | 2* | 94  |
|   |  Negative | 4** | 5 | 9  |
|   |  Total | 96 | 7 | 103  |

Positive Percent Agreement: 95.8% (92/96) (95% CI: 95.8% - 98.4%)

Negative Percent Agreement: 71.4% (5/7) (95% CI: 35.9% - 91.8%)

Overall Percent Agreement: 94.2% (97/103) (95% CI: 87.8% - 97.3%)

b. Matrix comparison:

Not applicable; serum is the only sample matrix indicated for this assay.

3. Clinical studies:

a. Clinical Sensitivity:

Not applicable

b. Clinical specificity:

Not applicable

c. Other clinical supportive data (when a. and b. are not applicable):

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4. Clinical cut-off:

Not applicable.

5. Expected values/Reference range:

The expected value of rheumatoid factor in normal serum in the predicate assay is < 12.5 IU/mL. To verify that the predicate’s reference range can be used in the Optilite assay, 50 apparently normal U.S. serum samples were tested with a protocol based on CLSI C28-A3. Only one of the 50 samples exceeded 12.5 IU/mL, thus verifying the predicate device’s reference interval. The manufacturer encourages users to develop their own laboratory’s reference range.

N. Proposed Labeling:

The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.

O. Conclusion:

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

---

**Source:** [https://fda.innolitics.com/submissions/IM/subpart-f%E2%80%94immunological-test-systems/DHR/K162263](https://fda.innolitics.com/submissions/IM/subpart-f%E2%80%94immunological-test-systems/DHR/K162263)

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**Cite:** Innolitics at https://innolitics.com