← Product Code [LGD](/submissions/MI/subpart-d%E2%80%94serological-reagents/LGD) · K233932

# Alinity i Toxo IgM (K233932)

_Abbott Laboratories · LGD · Aug 30, 2024 · Microbiology · SESE_

**Canonical URL:** https://fda.innolitics.com/submissions/MI/subpart-d%E2%80%94serological-reagents/LGD/K233932

## Device Facts

- **Applicant:** Abbott Laboratories
- **Product Code:** [LGD](/submissions/MI/subpart-d%E2%80%94serological-reagents/LGD.md)
- **Decision Date:** Aug 30, 2024
- **Decision:** SESE
- **Submission Type:** Traditional
- **Regulation:** 21 CFR 866.3780
- **Device Class:** Class 2
- **Review Panel:** Microbiology

## Indications for Use

The Alinity i Toxo IgM assay is a chemiluminescent microparticle immunoassay (CMIA) used for the qualitative detection of IgM antibodies to Toxoplasma gondii in human serum, serum separator, and plasma tubes (lithium heparin, lithium heparin separator, and tripotassium EDTA) on the Alinity i system. The Alinity i Toxo IgM assay is to be used as an aid in the diagnosis of acute or recent Toxoplasma gondii infection in suspected individuals including women of child-bearing age. It is recommended that the assay be performed in conjunction with a Toxoplasma gondii IgG assay. The Alinity i Toxo IgM assay has not been cleared for use in screening blood, plasma, or tissue donors.

## Device Story

Automated two-step chemiluminescent microparticle immunoassay (CMIA) for qualitative detection of anti-Toxoplasma gondii IgM antibodies. Input: human serum or plasma samples. Process: sample incubated with anti-human IgM coated paramagnetic microparticles; anti-Toxo IgM binds to microparticles; conjugate complex (acridinium-labeled anti-Toxo p30 antibody and native T. gondii lysate) added; chemiluminescent reaction measured as relative light units (RLU). Output: RLU compared to cutoff to determine reactive/nonreactive status. Used in clinical laboratories; operated by trained personnel. Results aid clinicians in diagnosing acute/recent Toxoplasma infection when used with IgG testing.

## Clinical Evidence

Clinical performance evaluated in two populations (n=897 and n=234) and a CDC serum panel (n=97). Population 1 PPA 94.94% (95% CI: 90.33-97.41%), NPA 94.44% (95% CI: 92.55-95.88%). Population 2 PPA 94.74% (95% CI: 75.36-99.06%), NPA 100% (95% CI: 98.24-100%). CDC panel showed 100% PPA and 100% NPA. Matrix equivalency confirmed for serum and various plasma tubes.

## Technological Characteristics

CMIA technology; uses anti-human IgM (murine monoclonal) coated paramagnetic microparticles and acridinium-labeled anti-Toxo p30 antigen (murine monoclonal) conjugate. Reagents include TRIS/phosphate buffers, bovine/goat protein stabilizers, and detergents. Automated system; connectivity via Alinity i platform. Calibration storage up to 30 days.

## Regulatory Identification

Toxoplasma gondii serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies to Toxoplasma gondii in serum. Additionally, some of these reagents consist of antisera conjugated with a fluorescent dye (immunofluorescent reagents) used to identify Toxoplasma gondii from clinical specimens. The identification aids in the diagnosis of toxoplasmosis caused by the parasitic protozoan Toxoplasma gondii and provides epidemiological information on this disease. Congenital toxoplasmosis is characterized by lesions of the central nervous system, which if undetected and untreated may lead to brain defects, blindness, and death of an unborn fetus. The disease is characterized in children by inflammation of the brain and spinal cord.

## Predicate Devices

- bioMérieux VIDAS TOXO IgM assay (k923166)

## Submission Summary (Full Text)

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>
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FDA U.S. FOOD & DRUG ADMINISTRATION

# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY

ASSAY ONLY

## I Background Information:

A 510(k) Number

K233932

B Applicant

Abbott Laboratories

C Proprietary and Established Names

Alinity i Toxo IgM

D Regulatory Information

|  Product Code(s) | Classification | Regulation Section | Panel  |
| --- | --- | --- | --- |
|  LGD | Class II | 21 CFR 866.3780 - Toxoplasma Gondii Serological Reagents | MI - Microbiology  |

## II Submission/Device Overview:

A Purpose for Submission:

Clearance of a new device

B Measurand:

IgM antibody to Toxoplasma gondii

C Type of Test:

Chemiluminescent Microparticle Immunoassay (CMIA)

Food and Drug Administration

10903 New Hampshire Avenue

Silver Spring, MD 20993-0002

www.fda.gov

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III Intended Use/Indications for Use:

A Intended Use(s):
The Alinity i Toxo IgM assay is a chemiluminescent microparticle immunoassay (CMIA) used for the qualitative detection of IgM antibodies to Toxoplasma gondii in human serum, serum separator, and plasma tubes (lithium heparin, lithium heparin separator, and tripotassium EDTA) on the Alinity i system.

The Alinity i Toxo IgM assay is to be used as an aid in the diagnosis of acute or recent Toxoplasma gondii infection in suspected individuals including women of child-bearing age. It is recommended that the assay be performed in conjunction with a Toxoplasma gondii IgG assay.

The Alinity i Toxo IgM assay has not been cleared for use in screening blood, plasma, or tissue donors.

B Indication(s) for Use:
NA

C Special Conditions for Use Statement(s):
Rx - For Prescription Use Only

Performance has not been established for the use of bodily fluids other than human serum or plasma.

D Special Instrument Requirements:
Alinity i system

IV Device/System Characteristics:

A Device Description:
The Alinity i system is a fully automated immunoassay analyzer using chemiluminescent microparticle immunoassay (CMIA) technology. The Alinity i Toxo IgM immunoassay requires the use of Alinity i Toxo IgM Reagent Kit (cartridges, microparticles, and conjugate), Alinity i Toxo IgM Calibrator, and the Alinity i Toxo IgM Controls (positive and negative). The Alinity i Toxo IgM immunoassay components, reagent kit, calibrator and controls are packaged separately and designed to be used on the Alinity i system.

B Principle of Operation:
The Alinity i Toxo IgM assay is an automated, two-step immunoassay for the qualitative detection of IgM antibodies to Toxoplasma gondii in human serum and plasma using chemiluminescent microparticle immunoassay (CMIA) technology.

Pre-diluted sample and anti-human IgM murine monoclonal antibody coated paramagnetic microparticles are combined and incubated. Together with IgM antibodies of other specificities, anti-Toxo specific IgM present in the sample binds to the anti-human IgM murine monoclonal

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antibody coated microparticles, forming an antibody-antibody complex. The mixture is washed. A conjugate complex consisting of an acridinium-labeled anti-Toxo p30 antigen murine monoclonal F(ab')2 fragment and native Toxoplasma gondii lysate, containing the p30 antigen, is added to create a reaction mixture and incubated. This conjugate complex is bound by anti-Toxo specific IgM that has been captured by the anti-human IgM murine monoclonal antibody coated microparticles, forming an antibody-antibody-conjugate complex. Following a wash cycle, PreTrigger and Trigger Solutions are added.

The resulting chemiluminescent reaction is measured as a relative light unit (RLU). There is a direct relationship between the amount of anti-Toxo IgM in the sample and the RLU detected by the system optics. The presence or absence of anti-Toxo IgM in the sample is determined by comparing the chemiluminescent RLU in the reaction to the cutoff RLU determined from an active calibration.

The cutoff is 1.00 S/CO. The Alinity i system automatically calculates the signal-to-cutoff (S/CO) ratios, and interprets the results as presented in Table 1.

Table 1: Alinity i Toxo IgM Results Interpretation

|  S/CO | Instrument Interpretation | Retest Procedure  |
| --- | --- | --- |
|  < 0.83 S/CO | Nonreactive for IgM antibodies to Toxoplasma gondii | Individuals with such results are presumed not to be recently infected with Toxoplasma gondii and susceptible to acute infection. No retest is required.  |
|  0.83 to < 1.00 S/CO | Grayzone/Equivocal | Specimens that are considered grayzone/equivocal may contain low levels of anti-Toxo IgM. It is recommended to take a second sample within a reasonable period of time (e.g. 2 weeks) and to repeat Alinity i Toxo IgM testing.  |
|  ≥ 1.00 S/CO | Reactive for IgM antibodies to Toxoplasma gondii | Individuals that are considered reactive for anti-Toxo IgM are presumed to have an acute or recent infection with Toxoplasma gondii. No retest is required.  |

# V Substantial Equivalence Information:

# A Predicate Device Name(s):

Vidas Toxoplasma gondii IgM Asssay

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B Predicate 510(k) Number(s):

K923166

# C Comparison with Predicate(s):

|  Device & Predicate Device(s): | Predicate K923166 | Candidate Test K233932  |
| --- | --- | --- |
|  Device Trade Name | VIDAS TOXO IgM Assay | Alinity i Toxo IgM  |
|  General Device Characteristic Similarities  |   |   |
|  Intended Use/Indications For Use | The VIDAS TOXO IgM (TXM) assay is intended for use on the instruments of the VIDAS family (VITEK ImmunoDiagnostic Assay System) as an automated enzyme-linked fluorescent immunoassay (ELFA) for the presumptive qualitative detection of anti-Toxoplasma gondii IgM antibodies in human serum, as an aid in the diagnosis of acute, recent, or reactivated Toxoplasma gondii infection. This assay must be performed in conjunction with an anti-Toxoplasma gondii IgG antibody assay. VIDAS TOXO IgM (TXM) assay performance has not been established for prenatal screening or newborn testing. This assay has not been cleared by the FDA for blood/plasma donor screening. | The Alinity i Toxo IgM assay is a chemiluminescent microparticle immunoassay (CMIA) used for the qualitative detection of IgM antibodies to Toxoplasma gondii in human serum, serum separator, and plasma tubes (lithium heparin, lithium heparin separator, and tripotassium EDTA) on the Alinity i system. The Alinity i Toxo IgM assay is to be used as an aid in the diagnosis of acute or recent Toxoplasma gondii infection in suspected individuals including women of child-bearing age. It is recommended that the assay be performed in conjunction with a Toxoplasma gondii IgG assay. The Alinity i Toxo IgM assay has not been cleared for use in screening blood, plasma, or tissue donors.  |
|  Calibrator(s) | 1 Calibrator | 1 Calibrator  |
|  Control(s) | 2 (Negative and Positive) | 2 (Negative and Positive)  |
|  General Device Characteristic Differences  |   |   |

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|  Antigen and Antibody Used | • Anti-Toxoplasma p30 antigen antibody (murine, monoclonal) and native Toxoplasma gondii lysate
• Anti-human IgM murine monoclonal antibody | • Immunocomplex of T. gondii antigen (RH Sabin strain)
• Mouse monoclonal anti-P30 antibodies  |
| --- | --- | --- |
|  Type of Specimen | Serum | Serum and Plasma  |
|  Methodology | Enzyme-linked fluorescent immunoassay | Chemiluminescent microparticle immunoassay  |
|  Interpretation of Results | Negative: < 0.55 Test Value
Equivocal: ≥ 0.55 to < 0.65 Test Value
Positive: ≥ 0.65 Test Value | Nonreactive: < 0.83 S/CO
Grayzone/Equivocal: 0.83 to < 1.00 S/CO
Reactive: ≥ 1.00 S/CO  |
|  Components | Solid Phase Receptacle (SPR) – SPR coated goat anti-μ chain antibodies

Reagent Strip – Strip consists of 10 wells covered with labeled, foil seal. The wells contain the various reagents required for the assay including:
• Sample diluent: 300 μL of TRIS buffered saline (0.05 mol/L, pH 7.4) with protein and chemical stabilizers and 1 g/L sodium azide.
• Pre-wash: 600 μL of TRIS buffered saline (0.05 mol/L, pH 7.4) with protein and chemical stabilizers and 1 g/L sodium azide.
• Wash buffer: 600 μL of TRIS buffered saline (0.05 mol/L, pH 7.4) with protein and chemical stabilizers and 1 g/L sodium azide.
• Conjugate: 400 μL of immunocomplex of T. gondii antigen (RH Sabin strain) grown in mice (9) and mouse | Microparticles – Anti-human IgM (murine, monoclonal) antibody coated microparticles in TRIS buffer with protein (bovine and goat) stabilizers, and detergent. Minimum concentration: 0.08 % solids.
Preservatives: antimicrobial agents.

Conjugate – Conjugate complex consisting of acridinium-labeled anti-Toxoplasma p30 antigen antibody (murine, monoclonal) and native Toxoplasma gondii lysate in phosphate buffer with protein (bovine) stabilizer, and detergent. Minimum concentration: 25 μg/mL. Preservative: sodium azide.  |

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|   | monoclonal anti-P30 antibodies conjugated to alkaline phosphatase with gentamycin 0.02% and 0.9 g/L sodium azide.
• Reading cuvette with substrate: 4-Methyl-umbelliferyl phosphate (0.6 mmol/L) + diethanolamine (DEA) (0.62 mol/L or 6.6%, pH 9.2) + 1 g/L sodium azide (300 μL). |   |
| --- | --- | --- |
|  Calibration Storage | 14 days | Maximum of 30 days  |

VI Standards/Guidance Documents Referenced:

Standards
- CLSI EP05-A3, Evaluation of Precision of Quantitative Measurement Procedures; Approved Guideline–Third Edition
- CLSI EP07 3rd ed., Interference Testing in Clinical Chemistry
- CLSI EP37 1st ed., Supplemental Tables for Interference Testing in Clinical Chemistry
- CLSI EP12-A2, User Protocol for Evaluation of Qualitative Test Performance; Approved Guideline—Second Edition

VII Performance Characteristics (if/when applicable):

A Analytical Performance:

1. Precision/Reproducibility:

Within-Laboratory Precision: A 20-day within-laboratory precision study was conducted using 3 lots of the Alinity i Toxo IgM reagents, 3 lots of the Alinity i Toxo IgM Calibrator, 3 lots of the Alinity i Toxo IgM Controls, and 1 Alinity i system. Two controls and 4 recalcified human plasma samples (representing serum matrix) were tested in 3 replicates at 2 separate times per day over 20 days using 3 reagent lot/calibrator lot combinations, where a unique reagent lot and a unique calibrator lot are paired. The within laboratory precision data summary is shown in Table 2.

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Table 2: Alinity i Toxo IgM Assay Within-Laboratory Precision

|  Sample ID | n | Mean (S/CO) | Repeatability (Within-Run) |   | Between-Run |   | Between-Day |   | Between-Lota |   | Overall Within Laboratoryb  |   |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|   |   |   |  SD | %CV | SD | %CV | SD | %CV | SD | %CV | SD | %CV  |
|  Negative Control | 360 | 0.14 | 0.012 | NAc | 0.000 | NAc | 0.004 | NAc | 0.008 | NAc | 0.014 | NAc  |
|  Positive Control | 360 | 2.72 | 0.077 | 2.8 | 0.034 | 1.3 | 0.031 | 1.2 | 0.051 | 1.9 | 0.104 | 3.8  |
|  1 | 358d | 0.14 | 0.013 | NAc | 0.000 | NAc | 0.005 | NAc | 0.006 | NAc | 0.015 | NAc  |
|  2 | 360 | 0.81 | 0.028 | NAc | 0.006 | NAc | 0.009 | NAc | 0.027 | NAc | 0.040 | NAc  |
|  3 | 359d | 1.34 | 0.047 | 3.5 | 0.000 | 0.0 | 0.007 | 0.5 | 0.042 | 3.2 | 0.064 | 4.7  |
|  4 | 359d | 2.54 | 0.078 | 3.1 | 0.000 | 0.0 | 0.023 | 0.9 | 0.073 | 2.9 | 0.109 | 4.3  |

a Alinity i Toxo IgM reagent lot and Alinity i Toxo IgM calibrator lot are confounded, and the confounding effect is represented by between-lot.
b Overall within-laboratory variability contains repeatability (within-run), between-run, between-day, and between-lot variance components.
c Not applicable
d In cases where  $n &lt; 360$ , replicate(s) were excluded due to an instrument error and no results were reported.

Reproducibility Study (multi-site precision): A 5-day reproducibility study was conducted at 3 US sites, using the same samples panel used in the within-laboratory precision study, in addition to one positive and one negative controls. Four replicates per sample were evaluated in 2 runs per day over 5 days. The testing was performed using 3 lots of Alinity i Toxo IgM Reagents, 2 lots of Alinity i Toxo IgM Calibrators, and 1 lot of Alinity i Toxo IgM Controls at each of the 3 testing sites. The reproducibility data summary is shown in Table 3.

Table 3: Alinity i Toxo IgM Assay Reproducibility

|  Sample ID | n | Mean S/CO | Repeatability |   | Between-Run |   | Between-Day |   | Between-Site |   | Between-Lota |   | Reproducibilityb  |   |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|   |   |   |  SD | %CV | SD | %CV | SD | %CV | SD | %CV | SD | %CV | SD | %CV  |
|  Negative Control | 360 | 0.13 | 0.013 | NAc | 0.002 | NAc | 0.001 | NAc | 0.009 | NAc | 0.008 | NAc | 0.018 | NAc  |
|  Positive Control | 360 | 2.62 | 0.074 | 2.8 | 0.031 | 1.2 | 0.022 | 0.8 | 0.056 | 2.1 | 0.075 | 2.9 | 0.132 | 5.1  |
|  1 | 360 | 0.11 | 0.013 | NAc | 0.000 | NAc | 0.004 | NAc | 0.006 | NAc | 0.008 | NAc | 0.017 | NAc  |
|  2 | 360 | 0.76 | 0.030 | NAc | 0.009 | NAc | 0.006 | NAc | 0.000 | NAc | 0.023 | NAc | 0.041 | NAc  |
|  3 | 360 | 1.30 | 0.042 | 3.2 | 0.017 | 1.3 | 0.000 | 0.0 | 0.016 | 1.3 | 0.040 | 3.1 | 0.067 | 5.1  |
|  4 | 360 | 2.49 | 0.077 | 3.1 | 0.032 | 1.3 | 0.019 | 0.8 | 0.059 | 2.4 | 0.080 | 3.2 | 0.136 | 5.5  |

a Alinity i Toxo IgM reagent lot and Alinity i Toxo IgM calibrator lot are confounded, and the confounding effect is represented by between-lot.
b Reproducibility contains repeatability, between-run, between-day, between-lot, between-site, and site-lot interaction variance components.
c Not applicable

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2. Linearity:

Not applicable.

3. Analytical Specificity/Interference:

a. Potential Cross-Reactivity: Potential cross-reactivity for the Alinity i Toxo IgM assay was determined by testing a total of 177 serum samples from individuals with other medical conditions unrelated to Toxoplasmosis infection, in addition to samples from individuals with High titer Toxoplasma gondii IgG antibodies. Out of 10 Rheumatoid Factor specimens, one resulted in a false reactive result with the Alinity i Toxo IgM assay.

Table 4: Alinity i Toxo IgM Assay Cross-Reactivity study

|  Potential Cross reactants | N | Number of Alinity i Toxo IgM False Reactive Results  |
| --- | --- | --- |
|  Anti-dsDNA antibodies | 10 | 0  |
|  Anti-Nuclear Antibodies (ANA) | 10 | 0  |
|  Cytomegalovirus (IgM) | 10 | 0  |
|  Epstein-Barr virus (IgM) | 9 | 0  |
|  Herpes simplex virus types 1/2 (IgG/IgM) | 18 | 0  |
|  Human anti-mouse antibody (HAMA) | 10 | 0  |
|  Hyper IgG | 10 | 0  |
|  Hyper IgM | 10 | 0  |
|  Influenza vaccine recipients | 10 | 0  |
|  Measles (IgM) | 10 | 0  |
|  Parvo-B19 virus (IgG) | 6 | 0  |
|  Parvo-B19 virus (IgM) | 4 | 0  |
|  Rheumatoid Factor (RF) | 10 | 1a  |
|  Rubella (IgM) | 10 | 0  |
|  Samples from Immunocompromised patients | 10 | 0  |
|  Syphilis | 10 | 0  |
|  Toxoplasmosis high Titer IgG | 10 | 0  |
|  Varicella Zoster Virus | 10 | 0  |
|  TOTAL | 177 | 1  |

a One out of 10 RF specimens was falsely reactive with the Alinity i Toxo IgM assay.

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b. Potentially Interfering Endogenous Substances: The Alinity i Toxo IgM assay was evaluated for potential interference caused by endogenous substances. Each substance was evaluated using samples containing anti-Toxo IgM at the target ranges of 0.60 to 0.99 S/CO and 1.00 to 2.00 S/CO. No significant interference was observed at the following concentrations:

Table 5: Endogenous Interfering Substances Evaluated

|  Substance | Concentrations tested  |
| --- | --- |
|  Unconjugated bilirubin | 40 mg/dL  |
|  Conjugated bilirubin | 40 mg/dL  |
|  Hemoglobin | 1000 mg/dL  |
|  Triglycerides | 3000 mg/dL  |
|  Total protein (high) | 150 g/L  |

c. Potentially Interfering, Other Conditions: The Alinity i Toxo IgM assay was evaluated for potential interference caused by HAMA and RF using samples containing anti-Toxo IgM at the following target range: 1.00 to 1.40 S/CO. No significant interference was observed at the following concentrations:

Table 6: Potentially Interfering Other Conditions Evaluated

|  Substance | Concentrations tested  |
| --- | --- |
|  Human anti-mouse antibody (HAMA) | 800 ng/mL  |
|  Rheumatoid Factor (RF) | 200 IU/mL  |

d. Potentially Interfering Drugs and Other Substances: The Alinity i Toxo IgM assay was evaluated for potential interference caused by exogenous substances using samples containing anti-Toxo IgM at the target ranges of 0.60 to 0.99 S/CO and 1.00 to 2.00 S/CO. No significant interference was observed at the following concentrations:

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Table 7: Exogenous Interfering Substances Evaluated

|  Substance | Concentrations tested  |
| --- | --- |
|  Ascorbic Acid | 300 mg/L  |
|  Atovaquone | 120 mg/L  |
|  Beta Carotene | 6 mg/L  |
|  Biotin | 4250 ng/mL  |
|  Clindamycin | 5.1 mg/dL  |
|  Folic Acid | 100 nmol/L  |
|  Pyrimethamine | 15 mg/L  |
|  Spiramycine | 4.2 mg/L  |
|  Sulfadiazine | 25.5 mg/dL  |
|  Sulfamethoxazole | 210 mg/dL  |
|  Trimethoprim | 4.2 mg/dL  |

4. Assay Reportable Range:
Not Applicable.

5. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods):
Not Applicable.

6. Detection Limit:
Not Applicable.

7. Assay Cut-Off:
The cut-off for the Alinity i Toxo IgM assay was established using samples characterized with a commercially available anti-Toxo IgM assay. A total of 1219 samples (1053 anti-Toxo IgM nonreactive samples, and 166 anti-Toxo IgM reactive samples) were included. A receiver-operating characteristic analysis supports a cut-off of 1.00 S/CO (with a grayzone from 0.83 to 1.00 S/CO).

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# B Comparison Studies:

# 1. Method Comparison:

# Clinical Agreement:

A clinical study was conducted to evaluate the clinical performance of the Alinity i Toxo IgM assay. To evaluate the percent agreement between the Alinity i Toxo IgM assay and an FDA-cleared, commercially available anti-Toxo IgM assay with samples collected from two populations. Population 1 was comprised of 897 consecutively collected remnant specimens sent to a laboratory for anti-Toxo IgM testing including specimens collected in the US  $(n = 169)$  and outside of the US  $(n = 710)$ , and Population 2 was comprised of 207 consecutively collected remnant specimens from pregnant women sent to a laboratory for anti-Toxo IgM testing in the US.

Demographic information for specimens collected in the US from Population 1 and 2 is shown in the Table 8 below (n=376).

Table 8: Subject Demographics (US specimens)

|  Specimen | Age | Female (n) | Male (n) | Unknown (n) | Total (n)  |
| --- | --- | --- | --- | --- | --- |
|  Population 1 (n=169) | ≤ 5 years | 2 | 2 | 0 | 4  |
|   |  6 to 21 years | 5 | 7 | 0 | 12  |
|   |  22 to 59 years | 75 | 36 | 1 | 112  |
|   |  ≥ 60 years | 20 | 19 | 0 | 39  |
|   |  Unknown | 0 | 2 | 0 | 2  |
|   |  Total | 102 | 66 | 1 | 169  |
|  Population 2 (n=207) | ≤ 5 years | 0 | 0 | 0 | 0  |
|   |  6 to 21 years | 8 | 0 | 0 | 8  |
|   |  22 to 59 years | 196 | 0 | 0 | 196  |
|   |  ≥ 60 years | 0 | 0 | 0 | 0  |
|   |  Unknown | 3 | 0 | 0 | 3  |
|   |  Total | 207 | 0 | 0 | 207  |
|  Total | ≤ 5 years | 2 | 2 | 0 | 4  |
|   |  6 to 21 years | 13 | 7 | 0 | 20  |
|   |  22 to 59 years | 271 | 36 | 1 | 308  |
|   |  ≥ 60 years | 20 | 19 | 0 | 39  |
|   |  Unknown | 3 | 2 | 0 | 5  |
|   |  Total | 309 | 66 | 1 | 376  |

Positive percent agreement (PPA) and negative percent agreement (NPA) between the Alinity I Toxo IgM assay and an FDA-cleared was calculated for each population separately and are shown in Tables 9 and 10 below.

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Table 9: Alinity i Toxo IgM Clinical Performance - Population 1 (n= 897)

|  Alinity i Toxo IgM | Comparator  |   |   |
| --- | --- | --- | --- |
|   |  Positive | Equivocal | Negative  |
|  Reactive | 150 | 16 | 11  |
|  Grayzone/Equivocal | 1 | 1 | 14  |
|  Nonreactive | 6 | 1 | 697  |
|  Total | 157 | 18 | 722  |
|  |   |   |   |
|  PPAa | 94.94% (150/158) |   | 95%CI=90.33% to 97.41%  |
|  NPAa | 94.44% (697/738) |   | 95% CI=92.55% to 95.88%  |

aThe  $95\%$  CI for PPA and NPA were estimated using the Wilson score method.

Table 10: Alinity i Toxo IgM Clinical Performance - Population  $2^{\text{b}}$  (n=234)

|  Alinity i Toxo IgM | Comparator  |   |   |
| --- | --- | --- | --- |
|   |  Positive | Equivocal | Negative  |
|  Reactive | 18 | 0 | 0  |
|  Grayzone/Equivocal | 0 | 0 | 0  |
|  Nonreactive | 1 | 0 | 215  |
|  Total | 19 | 0 | 215  |
|  |   |   |   |
|  PPAa | 94.74% (18/19) |   | 95% CI=75.36% to 99.06%  |
|  NPAa | 100.00% (215/215) |   | 95% CI=98.24% to 100.00%  |

aThe  $95\%$  CI for PPA and NPA were estimated using the Wilson score method.
bTwenty seven specimens from Population 1 were from pregnant females and therefore, were also included in the Population 2.

# CDC Panel study:

The Centers for Disease Control and Prevention (CDC) Toxoplasma 1998 Human Serum Panel was tested using the Alinity i Toxo IgM assay. The Alinity i Toxo IgM assay results were submitted to the CDC for data analysis and for the result interpretation for each sample.

The panel consisted of 32 true positive Toxoplasma specimens and 65 true negative Toxoplasma specimens. The Alinity i Toxo IgM assay reported the 32 positive specimens as reactive and the 65 negative specimens, as nonreactive. The positive percent agreement

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(PPA) was 100% with a 95% confidence interval (CI) of 89.28% to 100.00%. The negative percent agreement (NPA) was 100% with a 95% CI of 94.42% to 100%.

The results are presented as a means to convey further information on the performance of this assay with a masked, characterized serum panel. This does not imply endorsement of the assay by the CDC.

2. Matrix Equivalency:

A study was performed to evaluate whether specific blood collection tube types are suitable for use with the Alinity i Toxo IgM assay.

The matrix collection tube type equivalency study was conducted including 43 donors of reactive (20 donors) and nonreactive (23 donors) samples in 5 types of blood collection tubes; serum, serum separator, lithium heparin plasma, lithium heparin plasma (separator tube), and K3 EDTA plasma for use with the Alinity i Toxo IgM assay. Data was analyzed using regression comparing numerical S/CO value results of all matrices to serum. All of the blood collection tube types tested are acceptable for use with the Alinity i Toxo IgM assay.

C Clinical Studies:

1. Clinical Sensitivity:

Not applicable

2. Clinical Specificity:

Not applicable

3. Other Clinical Supportive Data (When 1. and 2. Are Not Applicable):

Not applicable

D Clinical Cut-Off:

Not applicable

E Expected Values/Reference Range:

Not applicable

VIII Proposed Labeling:

The labeling supports the finding of substantial equivalence for this device.

K233932 - Page 13 of 14

{13}

IX Conclusion:

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

K233932 - Page 14 of 14

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**Source:** [https://fda.innolitics.com/submissions/MI/subpart-d%E2%80%94serological-reagents/LGD/K233932](https://fda.innolitics.com/submissions/MI/subpart-d%E2%80%94serological-reagents/LGD/K233932)

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