(90 days)
The TBI test is a panel of in vitro diagnostic chemiluminescent microparticle immunoassays (CMIA) used for the quantitative measurements of glial fibrillary acidic protein (GFAP) and ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) in human plasma and serum and provides a semi-quantitative interpretation of test results derived from these measurements using the Alinity i system.
The interpretation of test results is used, in conjunction with other clinical information, to aid in the evaluation of patients, 18 years of age or older, presenting with suspected mild traumatic brain injury (Glasgow Coma Scale score 13-15) within 12 hours of injury, to assist in determining the need for a CT (computed tomography) scan of the head. A negative test result is associated with the absence of acute intracranial lesions visualized on a head CT scan.
The TBI test is intended for use in clinical laboratory settings by healthcare professionals.
The TBI test is a panel of in vitro diagnostic quantitative measurements of GFAP and UCH-L1 and provides a semi-quantitative interpretation of GFAP and UCH-L1 in human plasma and serum.
The GFAP assay (subject device) is an automated immunoassay for the quantitative measurement of GFAP in plasma and serum using chemiluminescent microparticle immunoassay (CMIA) technology on the Alinity i system.
The UCH-L1 assay (subject device) is an automated immunoassay for the quantitative measurement of UCH-L1 in plasma and serum using chemiluminescent microparticle immunoassay (CMIA) technology on the Alinity i system.
Here's a breakdown of the acceptance criteria and the study proving the device meets them, based on the provided FDA 510(k) summary for the Abbott Laboratories TBI test:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria for the TBI test are implicitly defined by the clinical performance observed in the pivotal study, particularly regarding its ability to aid in determining the need for a head CT scan in patients with suspected mild TBI. The key performance metrics are Sensitivity and Negative Predictive Value (NPV) as these are critical for a rule-out test for a serious condition like intracranial lesions.
| Acceptance Criteria Category | Metric (Target/Requirement) | Reported Device Performance (Pivotal Study - Archived Samples) | Reported Device Performance (Supplemental Study - Fresh Samples) |
|---|---|---|---|
| Clinical Performance (Rule-Out Test) | High Sensitivity (to minimize false negatives for acute intracranial lesions) | 96.7% (95% CI: 91.7%, 98.7%) | 100.0% (95% CI: 78.5%, 100.0%) |
| High Negative Predictive Value (NPV) (to ensure negative results reliably indicate absence of acute intracranial lesions) | 99.4% (95% CI: 98.6%, 99.8%) | 100.0% (95% CI: 85.7%, 100.0%) | |
| Adjusted NPV (for 6% CT scan positive prevalence) | 99.5% (95% CI: 98.6%, 99.8%) | 99.2% (95% CI: 89.1%, 99.9%) | |
| Other Clinical Metrics | Specificity (percentage of true negatives) | 40.1% (95% CI: 37.8%, 42.4%) | 27.7% (95% CI: 19.2%, 38.2%) |
| Positive Predictive Value (PPV) | 9.8% (95% CI: 8.2%, 11.6%) | 18.9% (95% CI: 11.6%, 29.3%) | |
| Adjusted PPV (for 6% CT scan positive prevalence) | 9.3% (95% CI: 8.9%, 9.8%) | 8.1% (95% CI: 7.2, 9.1%) | |
| Likelihood Ratio Negative (LR-) | 0.08 (95% CI: 0.03, 0.22) | 0.12 (95% CI: 0.01, 1.91) | |
| Likelihood Ratio Positive (LR+) | 1.61 (95% CI: 1.53, 1.70) | 1.38 (95% CI: 1.21, 1.58) | |
| Analytical Performance | Limit of Quantitation (LoQ) for GFAP and UCH-L1 must be suitable for clinical application. | GFAP: 6.1 pg/mL; UCH-L1: 26.3 pg/mL | N/A (Analytical performance is consistent across sample types) |
| Linearity across the analytical measuring interval. | GFAP: 6.1 - 42,000.0 pg/mL; UCH-L1: 26.3 - 25,000.0 pg/mL | N/A | |
| Overall Within-Laboratory Precision (for GFAP and UCH-L1) | GFAP CV |
§ 866.5830 Brain trauma assessment test.
(a)
Identification. A brain trauma assessment test is a device that consists of reagents used to detect and measure brain injury biomarkers in human specimens. The measurements aid in the evaluation of patients with suspected mild traumatic brain injury in conjunction with other clinical information to assist in determining the need for head imaging per current standard of care.(b)
Classification. Class II (special controls). The special controls for this device are:(1) The 21 CFR 809.10(b) compliant labeling must include detailed descriptions of and results from performance testing conducted to evaluate precision, accuracy, linearity, analytical sensitivity, interference, and cross-reactivity. This information must include the following:
(i) Performance testing of device precision must, at minimum, use one unmodified clinical specimen from the intended use population with concentration of the brain injury biomarker(s) near the medical decision point. Contrived specimens that have been generated from pooling of multiple samples or spiking of purified analyte to cover the measuring range may be used, but the contrived samples must be prepared to mimic clinical specimens as closely as possible. This testing must evaluate repeatability and reproducibility using a protocol from an FDA-recognized standard.
(ii) Device performance data must be demonstrated through a clinical study and must include the following:
(A) Data demonstrating clinical validity including the clinical sensitivity and specificity, and positive and negative predictive value of the test in the intended use population of patients with suspected mild traumatic brain injury (
i.e., Glasgow Coma Score (GCS) of 13-15), or equivalent standard of care for determination of severity of traumatic brain injury (TBI).(B) Study must be performed using the operators and in settings that are representative of the types of operators and settings for which the device is intended to be used.
(C) All eligible subjects must meet the well-defined study inclusion and exclusion criteria that define the intended use population. The prevalence of diseased or injured subjects in the study population must reflect the prevalence of the device's intended use population, or alternatively, statistical measures must be used to account for any bias due to enrichment of subpopulations of the intended use population.
(D) All eligible subjects must have undergone a head computerized tomography (CT) scan or other appropriate clinical diagnostic standard used to determine the presence of an intracranial lesion as part of standard of care and must also be evaluated by the subject device. All clinical diagnostic standards used in the clinical study must follow standard clinical practice in the United States.
(E) Relevant demographic variables and baseline characteristics including medical history and neurological history. In addition, head injury characteristics, neurological assessments, and physical evidence of trauma must be provided for each subject. This information includes but is not limited to the following: Time since head injury, time from head injury to CT scan, time from head injury to blood draw, GCS score or equivalent, experience of loss of consciousness, presence of confusion, episodes of vomiting, post-traumatic amnesia characteristics, presence of post-traumatic seizures, drug or alcohol intoxication, mechanism of injury, acute intracranial lesion type, neurosurgical lesion, and cranial fracture.
(F) Each CT scan or other imaging result must be independently evaluated in a blinded manner by at least two board-certified radiologists to determine whether it is positive or negative as defined by the presence or absence of acute intracranial lesions. This independent review must be conducted without access to test results of the device. Prior to conducting the review, the criteria and procedures to be followed for scoring the images must be established, including the mechanism for determining consensus.
(G) All the clinical samples must be tested with the subject device blinded to the TBI status and the neurological-lesion-status of the subject.
(H) Details on how missing values in data are handled must be provided.
(I) For banked clinical samples, details on storage conditions and storage period must be provided. In addition, a specimen stability study must be conducted for the duration of storage to demonstrate integrity of archived clinical samples. The samples evaluated in the assay test development must not be used to establish the clinical validity of the assays.
(iii) Performance testing of device analytical specificity must include the most commonly reported concomitant medications present in specimens from the intended use population. Additionally, potential cross-reacting endogenous analytes must be evaluated at the highest concentration reported in specimens from the intended use population.
(iv) Expected/reference values generated by testing a statistically appropriate number of samples from apparently healthy normal individuals.
(2) The 21 CFR 809.10(a) and (b) compliant labeling must include the following limitations:
(i) A limiting statement that this device is not intended to be used a stand-alone device but as an adjunct to other clinical information to aid in the evaluation of patients who are being considered for standard of care neuroimaging.
(ii) A limiting statement that reads “A negative result is generally associated with the absence of acute intracranial lesions. An appropriate neuroimaging method is required for diagnosis of acute intracranial lesions.”
(iii) As applicable, a limiting statement that reads “This device is for use by laboratory professionals in a clinical laboratory setting.”