ACCESS TOXO IGG, ACCESS TOXO IGG CALIBRATORS AND ACCESS TOXO IGG QC

{0} 1 # 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY A. 510(k) Number: K080869 B. Purpose for Submission: Initial Premarket Notification C. Measurand: Human IgG class antibodies to *Toxoplasma gondii* (Toxo IgG) in serum D. Type of Test: Chemiluminescent immunoassay for qualitative and quantitative determination of *Toxo IgG* in diagnosis of *Toxoplasma gondii* infection E. Applicant: Beckman Coulter, Inc. F. Proprietary and Established Names: Access Toxo IgG Assay, Access Toxo IgG Calibrators, Access Toxo IgG QC G. Regulatory Information: | Product Code | Classification | Regulation Section | Panel | | --- | --- | --- | --- | | LGD | Class II | 866.3780 | Microbiology (83) | ## H. Intended Use: The Access Toxo IgG assay is a paramagnetic-perticle, chemiluminescent immunoassay for the qualitative and quantitative determination of IgG antibodies to *Toxoplasma gondii* in human serum using the Access Immunoassay Systems. The Access Toxo IgG assay aids in the diagnosis of *Toxoplasma gondii* and may be used to assess the immune status of pregnant women. This product is not FDA cleared/approved for the screening of blood of plasma donors. Assay performance characteristics have not been established for immunocompromised or immunosuppressed patients, cord blood, neonatal specimens of infants. 3) Special conditions for use statement(s): For Prescription use only 4) Special instrument requirements: see I I. Device Description: The device consists of three different components: Access Toxo IgG Assay reagents, Toxo IgG Calibrators, and Toxo IgG QC. The assay is performed for the quantitative and qualitative determination of anti-*Toxoplasma gondii* IgG in human serum and is read using the Access Immunoassay Analyzers (Access, {1} Access 2, Synchron LXi 725, UniCel DxC 600i, UniCel DxI 600 and UniCel DxI 800). ## J. Substantial Equivalence Information: a) Predicate device name (s): Beckman Coulter, Inc. - Access Toxo IgG Assay, Calibrators, QC (Part Numbers: 34450, 34455, 34459) Bio-Rad Laboratories, Inc. - Access Toxo IgG Assay on the Access Immuno Assay Abbot Laboratories - AxSYM Toxo IgG Antibody Assay (Comparator) b) Predicate K numbers (s): Beckman Coulter, Inc. - K032162 Bio-Rad Laboratories, Inc. - K951495 Abbot Laboratories - K954575 (Comparator) Comparison with predicate: Three devices were listed as predicate devices. The AxSYM Toxo IgG Antibody Assay from Abbot Laboratories was used as a reference method for clinical data evaluation and calculation of positive and negative percent agreement. The following Table shows the similarities and differences between Beckman and Abbot Toxo IgG Assay | Similarities | Predicate Device Abbot Laboratories | Beckman Coulter, Inc. | | --- | --- | --- | | Attribute | AxSYM Toxo IgG - K954575 | New Access Toxo IgG (P/N A31588) | | Assay Methodology | Microparticle solid-phase, two-step enzyme immunoassay. | Microparticle solid-phase, two-step enzyme immunoassay. | | Intended Use | Qualitative and quantitative measurement of IgG antibodies to Toxoplasma gondii. | Qualitative and quantitative determination of IgG antibodies to Toxoplasma gondii. | | Solid Phase | Microparticles coated with partially-purified T. gondii antigen (RH strain from HeLa culture). | Microparticles coated with partially-purified T. gondii antigen (RH strain). | | Conjugate | Alkaline phosphatase-labeled anti-human IgG antibody. | Alkaline phosphatase-labeled anti-human IgG antibody. | | Calibrators | Six liquid re-calcified plasma | Six liquid defibrinated plasma | {2} | | calibrators (one non-reactive, five reactive). | calibrators (one non-reactive, five reactive). | | --- | --- | --- | | Controls | Two liquid re-calcified plasma controls (one non-reactive, one reactive). | Two liquid defibrinated plasma controls (one non-reactive, one reactive). | | Differences | Abbot Laboratories | Beckman Coulter Inc | | --- | --- | --- | | Attribute | AxSYM Toxo IgG - K954575 | Beckman New Access Toxo IgG (P/N A31588) | | Reporting Methodology | Enzyme immunoassay employing fluorescent detection. | Enzyme immunoassay employing chemiluminescent detection. | | Sample Type | Human serum or plasma (EDTA, heparin, sodium citrate). | Human serum. | | Solid Phase Capture Mechanism | Microparticles captured onto glass fibers for washing and signal detection. | Paramagnetic microparticles retained in a magnetic field for washing and signal detection. | | Conjugate Antibody | Goat polyclonal anti-human IgG antibody. | Mouse monoclonal anti-human IgG antibody. | | Substrate | 4-methyllumbelliferyl phosphate | Lumi-Phos 530 (dioxetane-based substrate) | | System Wash Solution(s) | Matrix Cell Wash - TRIA-buffered saline with sodium azide and antimicrobials. Line Diluent-phosphate buffer with sodium azide and antimicrobials. | Access Wash Buffer II - TRIS-buffered saline, Tween 20 surfactant, sodium azide and ProClin 300. | | Calibration method | Six-point calibration curve or two-point master curve. | Six-point calibration curve. | | Calibrator Reference | WHO 2^{nd} International Standard Preparation for Anti-Toxoplasma Serum. | WHO 3rd International Standard Preparation for Anti-Toxoplasma Serum. | | Calibration Validity | Indefinite (required with new reagent lot or upon quality control failure). | 28 Days | | Reactive Cut-off | >or = 3 IU/mL | >or = 10.5 IU/mL | | Gray Zone | 2 - 3 IU/mL | 7.5 - 10.5 IU/mL | {3} # K. Standard/Guidance Document Referenced (if applicable): NA L. Test Principle: The Access Toxo IgG assay is an enzyme immunoassay using an indirect technique. A sample is added to a reaction vessel with paramagnetic particles coated with Toxoplasma gondii membrane antigen. Specific antibodies present in the sample bind to the antigen. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field while unbound materials are washed away. Alkaline phosphatase-conjugated monoclonal anti-human IgG antibody is then added and attaches to the IgG antibodies captured on the particles. A second separation and wash step removes unbound conjugate. Then, the chemiluminescent substrate Lumi-Phos* 530 is added to the vessel and light generated by the reaction is measured with a luminometer. The light production is directly proportional to the concentration of Toxo IgG antibody in the sample. The amount of analyte in the sample is determined from a stored, multi-point calibration curve. # M. Performance Characteristics (if/when applicable): # 1. Analytical performance: a. Precision/Reproducibility: Reproducibility/repeatability of the Access Toxo IgG Assay was estimated at one internal (Site 3) and two external sites (Sites 1 and 2). Each site performed one run per day over seven test days. Nine serum samples were run in replicates of five in each run. Combined results for each serum sample from all three sites are presented in the table below. The observed average total $\% \mathrm{CV}$ was $12.6\%$ with daily calibration and $15.3\%$ using a stored calibration. Combined Results | | | | Daily Calibration | | | | Stored Calibration | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | Sample | N | Mean Dose (IU/mL) | Intra-assay %CV | Inter-assay %CV | Inter-site %CV* | Total %CV* | Mean Dose (IU/mL) | Intra-assay %CV | Inter-assay %CV | Inter-site %CV* | Total %CV* | | A001 | 105 | 3.70 | 13.5 | 6.9 | 13.0 | 20.0 | 3.73 | 12.1 | 5.7 | 6.9 | 15.1 | | A002 | 105 | 8.88 | 7.7 | 2.5 | 9.4 | 12.5 | 8.73 | 6.9 | 2.7 | 15.6 | 17.3 | | A010 | 105 | 12.7 | 8.1 | 2.4 | 10.5 | 13.5 | 12.4 | 6.3 | 0.3 | 15.2 | 16.4 | | A003 | 105 | 13.6 | 8.1 | 3.1 | 9.8 | 13.1 | 13.4 | 6.6 | 0.7 | 15.6 | 17.0 | | A004 | 105 | 18.7 | 7.6 | 3.1 | 6.3 | 10.3 | 18.3 | 7.8 | 1.8 | 11.8 | 14.3 | | A009 | 105 | 43.8 | 6.1 | 1.6 | 8.6 | 10.7 | 43.0 | 5.4 | 1.1 | 12.6 | 13.7 | | A005 | 105 | 89.4 | 7.2 | 3.4 | 5.1 | 9.5 | 88.9 | 7.1 | 3.9 | 12.3 | 14.8 | | A006 | 105 | 246.4 | 7.2 | 3.2 | 7.7 | 11.0 | 250.0 | 7.9 | 3.5 | 10.6 | 13.7 | | A007 | 105 | 286.7 | 7.0 | 1.3 | 10.6 | 12.7 | 292.5 | 8.8 | 2.9 | 12.8 | 15.8 | *The inter-site and total estimates also include contributions from inter-lot variation. b. Linearity/assay reportable range: # Dilution Recovery (Linearity) Recovery with WHO Standard: To calibrate the Access Toxo IgG assay to the $3^{\mathrm{rd}}$ {4} International Standard for Anti-Toxoplasma serum (TOXM 1-85), five dilutions of the Third International Standard for Anti-Toxoplasma Serum (TOXM) were tested in duplicate in a single run. The recovery performance is presented in the following Table. The average recovery for all dilutions is $93.5\%$ . WHO Standard Recovery | Expected Dose (IU/mL) | Observed Dose (IU/mL) | Mean Observed Dose (IU/mL) | Recovery | | --- | --- | --- | --- | | 6.0 | 5.8 | 5.9 | 98.3% | | | 6.0 | | | | 30.0 | 26.6 | 25.9 | 86.3% | | | 25.2 | | | | 60.0 | 65.4 | 65.1 | 108.5% | | | 64.8 | | | | 120.0 | 117.0 | 115.7 | 96.4% | | | 114.4 | | | | 240.0 | 183.6 | 187.4 | 78.1% | | | 191.1 | | | Linearity with High Patient Samples: Four highly reactive sera were diluted from 1/1.5 to 1/32 in Access Toxo IgG Calibrator, S0. These dilutions were tested in quadruplicate and the results were compared to expected values based on the neat sample determination (eight replicates). The mean recovery for the four sera was $100\%$ and ranged from $93.8\%$ to $109.1\%$ . c. Traceability, Stability, Expected values (controls, calibrators, or methods): Access Toxo Calibrators(A31589): The Access Toxo calibrators are traceable to the WHO $3^{\mathrm{rd}}$ Internationable Standard Preparation for Anti-Toxoplasma Serum (TOXM) based on EN ISO 17511. The calibrators are provided at six levels- zero(S0), and approximately 10.5 (S1), 50 (S2), 120(S3), 240(S4), and 450(S5) IU/mL. The recommended open use life of the Calibrators is 90 days. Access Toxo Quality Controls(A31590): There are two controls: 1) QC1- Pooled human defibrinated plasma negative (non-reactive) for anti- $T$ . gondii IgG; 2) QC2-Spiked human defibrinated plasma containing high levels of anti- $T$ . gondii IgG positive (reactive). The target range for QC1 is $< 2$ IU/mL; the target range for QC2 is 20-30 IU/mL. The recommended open use life of the Controls is 90 days. d. Analytical sensitivity: (i) Limit of Blank (LoB): The LoB was determined with three serum samples in 60 replicates (level of anti-Toxoplasma IgG approaching $0\mathrm{IU / mL}$ in each serum sample) and one lot of the S0 calibrator with two lots of Access Toxo IgG reagents (P1 and P2). The testing was conducted with one Access and one Access 2 Analyzer. The {5} LoB for the Access Toxo IgG is estimated at 0.10 IU/mL. (ii) Limit of Detection (LoD): Four low level (non-reactive) serum samples were tested in 60 replicates with two reagent lots. The testing was conducted with one Access and one Access 2 Analyzer. The LoD for the Access Toxo IgG is estimated at $0.40\mathrm{IU / mL}$ . (iii) Limit of Quantitation (LoQ): To estimate the LoQ for the Access Toxo IgG, two samples with established levels of anti-Toxoplasma IgG reactivity was tested over 5 days in one run of 5 replicates per day. The testing was conducted with two reagent lots on a single Access Analyzer. The mean LoQ for the Access Toxo IgG is 3.2 IU/mL. e. Analytical specificity/Interference: A study was conducted to investigate potential cross-reactivity with immunoglobulins resulting from exposure to other infectious agents that can produce symptoms similar to Toxoplasma infection (CMV, Epstein-Barr virus, HIV, HSV-1, HSV-2, malaria, measles, rubella VZV, mumps and Treponema). In addition, interference due to heterophilic antibodies (HAMA), abnormal immune system conditions (myeloma, rheumatoid factor, ANA) and influenza vaccine was evaluated. A total of 311 samples were tested. Nine samples $(2.9\%)$ , including HIV, HSV-2 IgG, HAMA, mumps, syphilis) that were non-reactive by another commercially available assay were equivocal or reactive in the Access Toxo IgG Assay. The observed performance with each condition is presented in the following Table: | Condition | Number tested | Equivocal or Reactive in Access Toxo IgG | | --- | --- | --- | | ANA | 14 | 0 | | CMV IgG | 8 | 0 | | EBV IgG | 13 | 0 | | HAV Ab | 10 | 0 | | HBV (HBsAg) | 11 | 0 | | HCV Ab | 14 | 0 | | HIV | 43 | 2 | | HSV-1 IgG | 3 | 0 | | HSV-2 IgG | 8 | 2 | | Malaria | 7 | 0 | | Measles IgG | 13 | 0 | | Myeloma IgG | 12 | 0 | | Rheumatoid Factor | 15 | 0 | | Rubella IgG | 12 | 0 | | VZV IgG | 11 | 0 | | HAMA/Heterophilic Antibody | 20 | 2 | | Mumps IgG | 65 | 2 | | Influenza (vaccine recipients) | 23 | 0 | | Syphilis | 43 | 1 | {6} The Access Toxo IgG Assay was not significantly affected by the presence of 300 mg/L bilirubin (100 mg/L free + 200 mg/L conjugated), 30 g/L triolein (triglycerides), 90 g/L albumin or 20 g/L hemoglobin. f. Assay cut-off: The assay cutoff was established by an evaluation of 959 non-reactive and 1091 reactive samples characterized by another enzyme immunoassay method. Cutoff for the Access Toxo IgG assay was determined to be 10.5 IU/mL based on receiver operating characteristic (ROC) curves. - All test samples < 7.5 IU/mL are considered non-reactive for the presence of Toxoplasma gondii IgG antibodies. - Sample results ≥ 7.5 IU/mL and < 10.5 IU/mL are considered equivocal for the presence of Toxoplasma gondii IgG antibodies. - All test samples ≥ 10.5 IU/mL are considered reactive for the presence of T. gondii IgG antibodies. 2. Comparison studies: a. Method comparison with reference method: Abbot AxSYM Toxo IgG Antibody Assay b. Matrix comparison: NA 3. Clinical studies: a. Clinical Sensitivity: see below b. Clinical specificity: see below Performance Characteristics Summary of Clinical Studies Method Comparison: Studies comparing the performance of the Access Toxo IgG assay with the Abbott AxSYM Toxo IgG method were conducted at one external site in south-central France (Site 1), one external site in the northeastern United States (Site 2) and at the manufacturer's site (Site 3). The external sites tested samples collected from their own routine prenatal screening population as well as specimens from males and non-pregnant females that had Toxo IgG testing ordered. Two clinical sample suppliers provided the routine Toxo IgG test specimens for the U.S. site. The manufacturer tested prenatal specimens collected at three hospitals in north-central France. Method agreement results for the prospective (fresh) and retrospective (frozen) collections by test site are presented in the following two Tables. 7 {7} Retrospective/Prospective Patient Population | Comparison EIA | | | + | + | + | EQV | EQV | EQV | - | - | - | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | n | Access | | + | EQV | - | + | EQV | - | + | EQV | - | | Site 1 | 406 | Frozen | 154 | 3 | 2 | 3 | 3 | 4 | 0 | 2 | 235 | | Site 2 | 28 | Fresh | 4 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 23 | | Site 2 | 433 | Frozen | 190 | 2 | 0 | 4 | 6 | 0 | 1 | 0 | 230 | | Site 3 | 558 | Frozen | 356 | 2 | 0 | 2 | 0 | 0 | 1 | 1 | 196 | Agreement Table for Retrospective/Prospective Patient Population | | | | Positive Agreement (%) | 95% Conf. Int. | Negative-Agreement (%) | 95% Conf. Int. | | --- | --- | --- | --- | --- | --- | --- | | Site 1 | 406 | Frozen | 94.5 | 89.8 - 97.4 | 97.9 | 95.2 - 99.3 | | Site 2 | 28 | Fresh | 80.0 | 28.5 - 99.5 | 100 | 85.3 - 100 | | Site 2 | 433 | Frozen | 99.0 | 96.3 - 99.9 | 97.9 | 95.1 - 99.3 | | Site 3 | 558 | Frozen | 99.4 | 98.0 - 99.9 | 98.0 | 94.9 - 99.4 | Method agreement results for the prenatal and diagnostic populations (male and female) by test site are presented in the following two Tables. Pregnant/Non-Pregnant Population | Comparison EIA | | | + | + | + | EQV | EQV | EQV | - | - | - | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | n | Access | | + | EQV | - | + | EQV | - | + | EQV | - | | Site 1 | 229 | Pregnant | 37 | 3 | 0 | 2 | 2 | 2 | 0 | 1 | 182 | | Site 2 | 173 | Pregnant | 13 | 0 | 1 | 0 | 0 | 0 | 1 | 0 | 158 | | Site 3 | 558 | Pregnant | 356 | 2 | 0 | 2 | 0 | 0 | 1 | 1 | 196 | | Site 1 | 76 | Female | 47 | 0 | 2 | 1 | 0 | 2 | 0 | 0 | 24 | | Site 1 | 101 | Male | 70 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 29 | | Site 2 | 180 | Female | 97 | 2 | 0 | 4 | 6 | 0 | 0 | 0 | 71 | | Site 2 | 108 | Male | 84 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 24 | Agreement Table for Pregnant/Non-Pregnant Population | | | | Positive Agreement (%) | 95% Conf. Int. | Negative Agreement (%) | 95% Conf. Int. | | --- | --- | --- | --- | --- | --- | --- | | Site 1 | 229 | Pregnant | 88.1 | 74.4 – 96.0 | 98.4 | 95.3 – 99.7 | | Site 2 | 173 | Pregnant | 92.9 | 66.3 – 99.8 | 99.4 | 96.5 – 100 | | Site 3 | 558 | Pregnant | 99.4 | 98.0 – 99.9 | 98.0 | 94.9 – 99.4 | | Site 1 | 76 | Female | 92.2 | 81.1 – 97.8 | 96.0 | 79.7 – 99.9 | | Site 1 | 101 | Male | 100 | 94.9 – 100 | 96.7 | 82.8 – 99.9 | | Site 2 | 180 | Female | 98.0 | 92.9 – 99.8 | 94.7 | 86.9 – 98.5 | | Site 2 | 108 | Male | 100 | 95.7 - 100 | 100 | 85.8 - 100 | {8} 9 # CDC Toxoplasma 1998 Human Serum Panel The Access Toxo IgG Assay exhibited 100% positive and negative agreement with the 100-member CDC Toxoplasma 1998 Human Serum Panel. 4. Clinical cut-off: As described in Assay cut-off. 5. Expected values/Reference range: The worldwide prevalence of Toxoplasma infection varies widely, influenced by such factors as environmental conditions, sanitation, dietary practices and companion and farm animal contact. Local prevalence is also influenced by population age and immigration patterns. Published estimates of seroprevalence for selected population in Europe, Asia, Africa and south America range from <5 -90% while a recent study estimate the overall United States prevalence to be approximately 22%. Due to this substantial variability, it was recommended to establish prevalence expectations based on its own specific patient population. 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. The Access Toxo IgG Assay, Calibrators and QC (Part numbers: A31588, A31589, A31590) on the Access Immunoassay Systems are substantially equivalent to the AxSYM Toxo IgG Assay and the Access Toxo IgG Assay, Calibrators and QC (Part numbers: 34450, 34455, 34459) for the quantitative and qualitative determination of IgG antibodies to Toxoplasma gondii in human serum.