(87 days)
The Trinity Biotech Captia™ Measles IgM Enzyme-Linked Immunosorbent Assay (ELISA) is intended for the qualitative detection of Measles IgM antibodies in human serum of patients suspected of measles (rubeola) infection. This assay is intended for use as an aid in the diagnosis of a current or recent measles (rubeola) infection in conjunction with other clinical information and laboratory findings.
Performance characteristics have not been evaluated in immunocompromised or immunosuppressed individuals. This test is not intended for use in neonatal screening or for use at a point of care. This test is not intended for use in screening blood and plasma donors.
The Trinity Biotech Captia™ Measles IgM test is an Enzyme-Linked Immunosorbent Assays (ELISA). When measles antigen (Edmonston strain) is bound to the solid phase and brought into contact with a patient's serum, antigen specific antibody, if present, will bind to the antigen on the solid phase forming antibody complexes. Excess antibody is removed by washing. This is followed by the addition of goat anti-human IgM globulin conjugated with horseradish peroxidase which will bind to the antibody-antigen complexes. The excess conjugate is removed by washing, followed by the addition of Chromogen/Substrate tetramethylbenzidine (TMB). If specific antibody to the antigen is present in the patient's serum, a blue color develops. When the enzymatic reaction is stopped with 1N H2SO4. The contents of the wells turn yellow. The color, which is indicative of the concentration of antibody in the serum, can be read on a suitable spectrophotometer or ELISA microwell plate reader.
Here's an analysis of the acceptance criteria and the studies performed for the Trinity Biotech Captia™ Measles IgM ELISA Test Kit, presented in the requested format:
Acceptance Criteria and Device Performance for Trinity Biotech Captia™ Measles IgM ELISA
The provided document describes the performance characteristics and clinical studies of the Trinity Biotech Captia™ Measles IgM ELISA. The acceptance criteria are not explicitly stated as pass/fail thresholds in a dedicated table, but are inferred from the reported performance characteristics.
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (Inferred) | Reported Device Performance |
|---|---|---|
| Analytical Performance | ||
| High Dose Hook Effect | No dose hook effect (prozone) of antigen | Antigen is titrated to ensure no dose hook effect. Positive control in each kit lot is titrated to negative at each kit QC test stage to ensure no prozoning. |
| IgM/IgG Competition | Diminished competing virus-specific IgG and minimized RF interference | Serum Diluent Plus Solution diminishes competing virus-specific IgG (maximum 1380 mg/dL removed) and minimizes rheumatoid factor interference (highest titer of RF+ tested (1:1280; 500 IU/mL) did not adversely affect performance). |
| Precision (Interassay) | Acceptable %CV across sites, operators, and days | Interassay (Between All Sites): %CV ranged from 4.3% to 12.0% across 6 samples (averaged across 3 sites, each with 2 operators, 10 days, triplicate runs; N=180 data points/sample). |
| Inter-Lot Reproducibility: %CV ranged from 3.19% to 22.55% across 6 samples (averaged across 3 kit lots, triplicate runs). | ||
| Intra-run (Between Users): %CV ranged from 0.40% to 5.00% across 6 samples (averaged across 2 operators, 10 days, triplicate runs; N=60 data points/sample). | ||
| Analytical Specificity (Cross-Reactivity) | Limited or acceptable cross-reactivity with common interfering agents | Observed cross-reactivity: CMV IgM (3 positive, 1 equivocal out of 7), HSV1 IgM (7 positive out of 16), HSV2 IgM (2 positive, 1 equivocal out of 10). |
| No cross-reactivity observed: Mumps IgM (4/4 negative), VZV IgM (4/4 negative), Rubella IgM (4/4 negative). | ||
| Not ruled out: Parvovirus, Respiratory Syncytial Virus (RSV), Parainfluenza. | ||
| Analytical Specificity (Interfering Substances) | No adverse results or significant change with tested interferents | No adverse results or significant change observed with Hemoglobin (≥ 500 mg/dL) and Bilirubin (unconjugated, ≥ 20 mg/dL). |
| Not tested: Red cells, cholesterol, gamma globulin, triglycerides, beta carotene, protein, ascorbic acid, anticoagulants. | ||
| Assay Cut-off Determination | Clear distinction between negative, equivocal, and positive | Cut-off ISR = 1.00. Values ≤ 0.90 considered negative, values ≥ 1.10 considered positive, and 0.91 to 1.09 considered equivocal. Based on a study of 228 Measles IgM negative sera (mean OD=0.105, SD=0.070), positive threshold determined as mean + 4 SD = 0.385. |
| Seroconversion | Consistent IgM response with seroconversion panel | Demonstrated IgM response consistent with seroconversion panel (BIOMEX SCP-MEA-001) across 4 different lots. Trinity kit showed seroconversion at Day 20. |
| Specificity in Normal Population | Low incidence of positive results in healthy individuals | Out of 200 random serum samples, 0.5% (1 sample) was in the 0.91-1.10 equivocal range, 0.5% (1 sample) was in the 1.21-1.40 positive range, and 0.5% (1 sample) was >2.00 positive. The majority (approximately 92.5%) were in the 0.00-0.60 negative range. |
| Clinical Performance | ||
| Positive Agreement (Study 1 & 2) | High agreement with comparator algorithm for positive samples | 90.7% Positive Agreement (88/97 samples) with 95% CI (83.3-95.0%) (when indeterminate comparator algorithm results were included in total). |
| Negative Agreement (Study 1 & 2) | High agreement with comparator algorithm for negative samples | 80.5% Negative Agreement (70/87 samples) with 95% CI (70.9-87.4%) (when indeterminate comparator algorithm results were included in total). |
| Equivocal Rate (Study 1 & 2) | Low percentage of equivocal results | 8.6% (16 of 187) of Captia™ Measles IgM results were equivocal. |
| Positive Agreement (Study 3) | High agreement with comparator PCR algorithm for positive samples | 75.00% Positive Agreement (3/4 samples) with 95% CI (30.1-95.4%) (when indeterminate comparator algorithm results were included in total). |
| Negative Agreement (Study 3) | High agreement with comparator PCR algorithm for negative samples | 100.00% Negative Agreement (4/4 samples) with 95% CI (39.8-100.0%) (when indeterminate comparator algorithm results were included in total). |
2. Sample Sizes and Data Provenance
- Test Set (Clinical Studies 1 & 2): 188 samples from suspected measles infection cases.
- Data Provenance: Retrospective, collected from individuals in whom a measles IgM test was ordered by the Texas Department of Health, Austin, Texas (66 samples) and the State Laboratory of Public Health in Raleigh, North Carolina (122 samples), USA.
- Test Set (Clinical Study 3): 8 samples.
- Data Provenance: Retrospective, collected from submissions to the Kansas Department of Health and Environment Laboratory (KDHE), Topeka, Kansas, USA.
- Test Set (Specificity in a Normal Population): 200 random serum samples.
- Data Provenance: Not explicitly stated, but implied to be from a general population (individuals between ages 18-65 with no known clinically apparent Measles infection). Location not specified.
- Test Set (Cross-Reactivity): 47 samples.
- Data Provenance: Confirmed positive for other IgM antibodies (CMV, HSV1, HSV2, Rubella, VZV, Mumps, Parvo-B19) by Trinity Biotech Captia™ test kits. Location not specified.
- Test Set (Precision/Reproducibility): 6 blinded panel members (4 low-to-moderate positive, 2 negative).
- Data Provenance: Not specified, likely internal or commercially sourced panels.
3. Number of Experts and Qualifications for Ground Truth
- The document does not specify the number of experts used to establish the ground truth for the test sets in the clinical studies.
- The ground truth in Clinical Studies 1 & 2 was established using a "comparator testing algorithm" which consisted of "the results of other laboratory confirmation methods including comparator Measles IgM ELISA test kit, a comparator Measles IgM IFA test kit, Complement Fixation (CF), Hemagglutionation Inhibition (HI) and the Trinity Biotech Captia™ Measles ELISA IgG test kit." This implies multiple laboratory results were used to form a consensus or a defined algorithm, rather than individual expert adjudication of each case.
- Similarly, in Clinical Study 3, the "comparator algorithm included RNA polymerase chain reaction (PCR) on urine, nasopharyngeal swab (NPS) and/or throat swab (TS) samples."
4. Adjudication Method for the Test Set
- For Clinical Studies 1 & 2, the ground truth was established by a "comparator algorithm" based on multiple laboratory confirmation methods (e.g., other ELISAs, IFA, CF, HI). The specific adjudication rule (e.g., 2 out of 3, 3 out of 4) is not explicitly detailed, but it generally implies a form of consensus derived from multiple test results rather than human expert adjudication.
- For Clinical Study 3, the ground truth was established by a "comparator algorithm" based on PCR results from various sample types. Again, the specific adjudication rules for discrepant PCR results (e.g., "NPS negative at two sites, urine positive at one site and urine indeterminate at one site") are not explicitly detailed for how the final "positive," "indeterminate," or "negative" comparator algorithm result was reached.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
- No, an MRMC comparative effectiveness study was not performed. This device is an Enzyme-Linked Immunosorbent Assay (ELISA), which is an automated or semi-automated laboratory test. It does not involve human readers interpreting images or data where AI assistance would be applicable in the traditional sense of an MRMC study for imaging diagnostics. The "readers" are the laboratory technicians operating the ELISA equipment.
6. Standalone Performance Study
- Yes, standalone performance was done for the device. All reported performance metrics (analytical performance, seroconversion, cross-reactivity, clinical agreement with comparator algorithms) represent the performance of the Captia™ Measles IgM ELISA as an algorithm/device only, without human "in-the-loop" assistance for interpreting the result of the ELISA itself. While humans perform the test and interpret the final ISR value against predefined cut-offs, the "algorithm" is determining the ISR.
7. Type of Ground Truth Used
- The ground truth used was a combination of other laboratory confirmation methods and algorithms.
- For Clinical Studies 1 & 2: "comparator testing algorithm used at each institution to determine the presence of current or recent measles infection" which included "comparator Measles IgM ELISA test kit, a comparator Measles IgM IFA test kit, Complement Fixation (CF), Hemagglutionation Inhibition (HI) and the Trinity Biotech Captia™ Measles ELISA IgG test kit." This represents a form of expert-defined algorithm/consensus from multiple laboratory tests.
- For Clinical Study 3: "comparator algorithm included RNA polymerase chain reaction (PCR) on urine, nasopharyngeal swab (NPS) and/or throat swab (TS) samples." This is essentially molecular pathology/laboratory results.
- For Cross-Reactivity: Confirmed positive status based on other specific IgM ELISA tests.
- For Seroconversion: A commercially available seroconversion panel.
8. Sample Size for the Training Set
- The document does not explicitly state a separate "training set" in the context of machine learning model development. This is an ELISA kit, not typically a machine learning algorithm that requires a distinct training phase in the same way. The development and optimization of the assay (e.g., antigen titration, calibrator development, component formulation) would be part of an iterative development process that could be considered analogous to "training," but not in the sense of a labeled dataset for an AI model.
- The cut-off determination study involved 228 Measles IgM negative sera, which were used to establish the positive threshold (mean + 4SD). This could be considered a form of "training" or "calibration" data for the assay's interpretive criteria.
9. How the Ground Truth for the Training Set Was Established
- As noted above, there isn't a traditional "training set" for a machine learning algorithm.
- For the cut-off determination, the 228 Measles IgM negative sera were explicitly described as "Measles IgM negative sera" and were used to calculate statistical parameters (mean and standard deviation of optical density readings) to define the initial positive threshold. Four samples were disqualified because they were in the equivocal range on Trinity IgM ELISA or indeterminate on a comparator Measles IFA test kit (due to non-specific staining). This implies an initial screening or pre-classification of these samples as "negative" before their use in cut-off calculation. The final cut-off was derived using these empirical observations.
§ 866.3520 Rubeola (measles) virus serological reagents.
(a)
Identification. Rubeola (measles) virus serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies to rubeola virus in serum. The identification aids in the diagnosis of measles and provides epidemiological information on the disease. Measles is an acute, highly infectious disease of the respiratory and reticuloendothelial tissues, particularly in children, characterized by a confluent and blotchy rash.(b)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 866.9.