(80 days)
The EUROIMMUN ANA Screen ELISA (IgG) is intended for the qualitative determination of IgG class antibodies against nuclear antigens (mixture of dsDNA, histones, ribosomal P-proteins, rRNP/Sm, Sm, SS-A, SS-B, Scl-70, Jo-1 and centromeres) in human serum and plasma (EDTA, Li-heparin, Citrate). It is used as an aid in the diagnosis of mixed connective tissue diseases (MCTD), systemic lupus erythematosus, Sjögren's syndrome, progressive systemic sclerosis and polymyositis and dermatomyositis, in conjunction with other laboratory and clinical findings.
The EUROIMMUN ANA Screen ELISA (IgG) consists of a microwell ELISA plate coated with a mixture of dsDNA, histones, ribosomal P proteins, nRNP/Sm, Sm, SS-A, SS-B, Scl-70. Jo-1 and centromeres antigens, calibrator, positive and negative control, peroxidaselabeled anti-human IgG conjugate, sample buffer, wash buffer concentrate, TMB chromogen/substrate solution and stop solution.
The EUROIMMUN ANA Screen ELISA (IgG) is a qualitative enzyme immunoassay used to detect IgG class antibodies against nuclear antigens. This device is intended as an aid in diagnosing various connective tissue diseases.
Here's an analysis of its acceptance criteria and supporting studies:
1. Acceptance Criteria and Reported Device Performance
The acceptance criteria for the EUROIMMUN ANA Screen ELISA (IgG) are demonstrated through its analytical performance (precision/reproducibility, analytical specificity) and comparison studies (method comparison with predicate device, matrix comparison, and clinical studies for sensitivity and specificity). The reported device performance meets these criteria, supporting its substantial equivalence to a legally marketed predicate device.
| Acceptance Criteria Category | Specific Metric | Acceptance Criteria (Implied by Study Results) | Reported Device Performance |
|---|---|---|---|
| Precision/Reproducibility | Intra-Assay Reproducibility (% positive/% negative) | Consistent qualitative results (100% positive or 100% negative) for samples across 20 determinations. | Achieved 100% positive or 100% negative calls for all 22 samples tested. |
| Inter-Assay Reproducibility (% positive/% negative) | Consistent qualitative results (100% positive or 100% negative) for samples across 30 determinations in 10 runs over 5 days. | Achieved 100% positive or 100% negative calls for all 22 samples tested. | |
| Lot-to-Lot Reproducibility (% positive/% negative) | Consistent qualitative results (100% positive or 100% negative) for samples across different lots. | Achieved 100% positive or 100% negative calls for all 19 QC samples across different lots, with ranges like 0.1-2.0 for a negative sample (mean 0.15) and 2.7-3.2 for a positive sample (mean 2.9). | |
| Analytical Specificity | Cross-reactivity (Celiac, Wegener's, RA, Infectious) | No significant cross-reactivity (implying very few positive results in known negative samples). | All but 2 out of 82 samples (10 celiac disease, 17 Wegener's granulomatosis, 39 rheumatoid arthritis, 16 infectious diseases) were negative. This demonstrates high specificity. |
| Interference (Hemoglobin, Triglycerides, Bilirubin, RF) | Recovery of 90-110% for positive/borderline samples when spiked with interfering substances. | Recoveries for positive/borderline samples were within 92-107% for hemoglobin (up to 1000 mg/dl), triglycerides (up to 2000 mg/dl), and bilirubin (up to 40 mg/dl). Recoveries were 100-110% for rheumatoid factor (up to 500 IU/ml). No significant interference observed. | |
| Method Comparison (vs. Predicate) | Overall Agreement | High overall agreement with the predicate device (Aesku Aeskulisa ANA Hep-2). | Overall Agreement: 97.2% (282/290) with 95% C.I.: 94.6% - 98.8%. |
| Positive Agreement | High positive agreement with the predicate device. | Positive Agreement: 96.5% (137/142) with 95% C.I.: 92.0% - 98.8%. | |
| Negative Agreement | High negative agreement with the predicate device. | Negative Agreement: 98.0% (145/148) with 95% C.I.: 94.2% - 99.6%. | |
| Matrix Comparison | Equivalence of serum and plasma | Regression equation near ideal (intercept 0; slope 1.0) and coefficient of determination (R2) > 0.99, mean %recovery 90-110%. | EDTA plasma: y = 0.04 + 0.99 x, R2 = 0.9988, Mean %recovery = 103% (Range: 98-112%) |
| Li-heparin plasma: y = -0.04 + 1.00 x, R2 = 0.9992, Mean %recovery = 99% (Range: 90-109%) | |||
| Citrate plasma: y = -0.00 + 0.99 x, R2 = 0.9990, Mean %recovery = 98% (Range: 95-104%) (All within acceptable limits). | |||
| Clinical Performance | Overall Clinical Sensitivity | Overall clinical sensitivity for various connective tissue diseases, with specific ranges for each disease, demonstrating the test's ability to detect antibodies in affected patients. | Overall Sensitivity: 72.5% (311/429) With 95% C.I.: 68.0 - 76.7%. |
| Specific sensitivities: MCTD (95.2%), SLE (73.2%), Polymyositis/Dermatomyositis (15.4%), Systemic Sclerosis (72.8%), Sjögren's Syndrome (81.8%). The lower sensitivity for Poly-/dermatomyositis might be noted but isn't explicitly an "acceptance criteria failure" as overall sensitivity is presented. | |||
| Overall Clinical Specificity | High overall clinical specificity across different control/non-ANA disease groups, showing the test's ability to correctly identify unaffected individuals. | Overall Specificity: 95.8% (296/309) with 95% C.I.: 92.9 - 97.7%. Specific specificities: Celiac disease (100.0%), Wegener's granulomatosis (94.1%), Rheumatoid arthritis (94.1%), Other autoimmune diseases (100.0%), Bacterial/viral infections (100.0%). |
2. Sample Size Used for the Test Set and Data Provenance
-
Method Comparison Study (vs. Predicate):
- Sample Size: 290 clinically characterized samples (158 from patients with connective tissue diseases and 132 from control groups).
- Data Provenance: The origin of the data (e.g., country) is not explicitly stated. The study used samples from "different sources," and given it's a 510(k) submission to the FDA, it is likely that parts of the study, especially clinical correlation, would involve US data or data from regions with equivalent clinical standards. It is explicitly indicated as retrospective as the samples were "obtained from different sources".
-
Clinical Sensitivity and Specificity Studies:
- Sample Size:
- Clinical Sensitivity: 429 samples from patients with various connective tissue diseases.
- Clinical Specificity: 309 samples from control groups (celiac disease, Wegener's granulomatosis, rheumatoid arthritis, other autoimmune diseases, bacterial/viral infections).
- Total: 738 clinically characterized samples.
- Data Provenance: Clinical studies were performed "in cooperation with different sites." The specific countries are not mentioned. This part of the study is retrospective, as it used "clinically characterized samples" which implies they were collected and characterized prior to the study.
- Sample Size:
-
Analytical Specificity (Cross-reactivity):
- Sample Size: 82 clinically and serologically characterized samples (10 celiac, 17 Wegener's, 39 RA, 16 infectious diseases).
- Data Provenance: Not specified, but these are identified as "clinically and serologically characterized samples," suggesting retrospective collection.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The document does not explicitly state the number of experts or their specific qualifications (e.g., "radiologist with 10 years of experience") used to establish the "ground truth" for the test set.
Instead, the ground truth for the clinical studies relies on:
- "clinically characterized samples from patients" for patients with mixed connective tissue diseases, systemic lupus erythematosus, Sjögren's syndrome, progressive systemic sclerosis, and polymyositis/dermatomyositis.
- "clinically characterized samples" for various control groups.
This implies that the samples were classified based on established clinical diagnostic criteria, likely involving a consensus of medical specialists (e.g., rheumatologists) and potentially other laboratory findings, but the process of "ground truthing" itself is not detailed as an expert review process for each case.
4. Adjudication Method for the Test Set
The document does not describe an explicit adjudication method (e.g., 2+1, 3+1, none) for discrepancies in the test set.
- For the method comparison study, it notes that "The discrepant samples were from controls and one MCTD sample in the cut-off range." It does not specify how these discrepancies were resolved or adjudicated beyond this observation.
- For clinical sensitivity and specificity, the samples were "clinically characterized," suggesting their diagnostic status was pre-established, rather than determined by a real-time adjudication process during the study.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This submission is for an in vitro diagnostic device (ELISA kit), which is a laboratory test, not an imaging diagnostic device that typically involves human readers interpreting images. Therefore, the concept of human readers improving with AI vs. without AI assistance is not applicable here.
6. Standalone Performance Study
Yes, a standalone performance study was done.
The entire submission details the standalone performance of the EUROIMMUN ANA Screen ELISA (IgG) through its analytical performance characteristics (precision, analytical specificity, interference) and clinical performance (sensitivity and specificity) when run as an algorithm-only (kit-only) test. The results are reported as the device's inherent capability to detect ANA antibodies and correlate with clinical disease.
7. Type of Ground Truth Used
The ground truth used for both the method comparison and clinical studies was based on:
- Clinical Characterization: Samples were derived from "clinically characterized patients" and "control groups." This means the diagnosis of the patients (e.g., systemic lupus erythematosus, Sjögren's syndrome) and the health status of controls were established through standard clinical diagnostic procedures, likely involving a combination of clinical symptoms, physical examination, and other laboratory or imaging tests, according to medical guidelines.
- Serological Characterization: For the cross-reactivity study, samples were "clinically and serologically characterized," indicating that their antibody status for other conditions (e.g., celiac disease, ANCA, anti-CCP) was already known.
- Predicate Device Comparison: For the method comparison, the predicate device's results served as a comparison point, but the ultimate ground truth for the samples themselves was still their clinical status.
It does not rely on pathology, expert consensus on images (as it's not an imaging device), or direct patient outcomes data as the primary ground truth, but rather on established clinical diagnoses.
8. Sample Size for the Training Set
The document does not explicitly mention a "training set" in the context of machine learning or AI development. This device is an ELISA kit, which is a chemical assay, not an AI/ML algorithm that requires a training set in the conventional sense. The performance characteristics are established through validation studies using defined sample cohorts, not through an iterative training process.
9. How the Ground Truth for the Training Set Was Established
As noted above, the concept of a "training set" is not applicable to this type of device. The ground truth for the samples used in the validation studies was established through:
- Clinical Characterization: As described in point 7, samples were from patients with established clinical diagnoses and controls, determined through standard medical practice.
- External Reference Panels/Characterized Samples: The reproducibility studies used samples with "expected results" (negative or positive), and analytical specificity studies used "clinically and serologically characterized samples" or CDC ANA reference panels. This indicates that these samples were pre-defined with known characteristics based on previous clinical and/or laboratory evaluations.
§ 866.5100 Antinuclear antibody immunological test system.
(a)
Identification. An antinuclear antibody immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the autoimmune antibodies in serum, other body fluids, and tissues that react with cellular nuclear constituents (molecules present in the nucleus of a cell, such as ribonucleic acid, deoxyribonucleic acid, or nuclear proteins). The measurements aid in the diagnosis of systemic lupus erythematosus (a multisystem autoimmune disease in which antibodies attack the victim's own tissues), hepatitis (a liver disease), rheumatoid arthritis, Sjögren's syndrome (arthritis with inflammation of the eye, eyelid, and salivary glands), and systemic sclerosis (chronic hardening and shrinking of many body tissues).(b)
Classification. Class II (performance standards).