(170 days)
VIDAS® BRAHMS PCT is an automated test for use on the VIDAS instruments for the determination of human procalcitonin in human serum or plasma (lithium heparin) using the ELFA (Enzyme-Linked Fluorescent Assay) technique. The VIDAS BRAHMS PCT assay is intended for use in conjunction with other laboratory findings and clinical assessments to aid in the risk assessment of critically ill patients on their first day of ICU admission, for progression to severe sepsis and septic shock.
The VIDAS BRAHMS PCT Assay is an enzyme-linked fluorescent immunoassay (ELFA) performed in an automated VIDAS® instrument. The assay principle combines a one-step immunoassay sandwich method with a final fluorescent detection (ELFA). The Solid Phase Receptacle (SPR), serves as the solid phase as well as the pipetting device for the assay. Reagents for the assay are ready-to-use and pre-dispensed in the sealed reagent strips. All of the assay steps are performed automatically by the instrument. The sample is transferred into the wells containing anti-procalcitorin antibodies labeled with alkaline phosphatase (conjugate). The sample/conjugate mixture is cycled in and out of the SPR several times. This operation enables the antigen to bind with the immunoglobulins fixed to the interior wall of the SPR and the conjugate to form a sandwich. Unbound compounds are eliminated during washing steps. Two detection steps are performed successively. During each step, the substrate (4-Methylumbellifery| phosphate) is cycled in and out of the SPR. The conjugate enzyme catalyzes the hydrolysis of this substrate into a fluorescent product (4-Methyl-umbelliferone) the fluorescence of which is measured at 450 nm. The intensity of the fluorescence is proportional to the concentration of antigen present in the sample. At the end of the assay, results are automatically calculated by the instrument in relation to two calibration curves corresponding to the two revelation steps and stored in memory, and then printed out.
The provided document describes the VIDAS® B-R.A.H.M.S PCT Assay, an enzyme-linked fluorescent immunoassay (ELFA) for determining human procalcitonin in serum or plasma. It is intended for critically ill patients on their first day of ICU admission to aid in the risk assessment for progression to severe sepsis and septic shock.
The study presented focuses on establishing substantial equivalence to a predicate device, the BRAHMS PCT LIA Assay, rather than proving the device meets specific acceptance criteria via a standalone study with pre-defined metrics. Therefore, a table of acceptance criteria and reported device performance as typically understood for a novel device demonstrating efficacy against disease outcomes is not explicitly provided. Instead, the document compares analytical and clinical performance between the new device and the predicate.
Here's an analysis based on the provided information, framed to address your questions as much as possible, interpreting "acceptance criteria" as meeting or exceeding the performance of the predicate device.
1. Table of "Acceptance Criteria" and Reported Device Performance
As mentioned, explicit "acceptance criteria" for clinical performance are not stated in terms of specific sensitivity, specificity, PPV, or NPV targets for predicting severe sepsis/septic shock against a definitive ground truth. Instead, the comparison is against the predicate device's performance. The analytical performance comparisons can be seen as meeting "acceptance criteria" if they are comparable to or better than the predicate's.
| Metric (Implied Acceptance Criteria: Comparable to or Better than Predicate) | VIDAS BRAHMS PCT (Device) Performance | BRAHMS PCT LIA (Predicate) Performance |
|---|---|---|
| Analytical Performance | ||
| Matrix Comparison | Serum similar to Plasma | Same |
| Precision (Total CV) | 6.17 - 15.31% CV | 5.3 - 16.6% CV |
| Precision (Intra-run CV) | 1.93 - 4.61% CV | 2.4 - 10% CV |
| Precision (Inter-run CV) | 3.57 - 7.04% CV | Not explicitly separated |
| Precision (Inter-site CV) | 4.21 - 11.40% CV | Not explicitly separated |
| Analytical Detection Limit | 2 ng/ml | Same |
| Cut-off for low risk |
§ 866.3210 Endotoxin assay.
(a)
Identification. An endotoxin assay is a device that uses serological techniques in whole blood. The device is intended for use in conjunction with other laboratory findings and clinical assessment of the patient to aid in the risk assessment of critically ill patients for progression to severe sepsis.(b)
Classification. Class II (special controls). The special control for this device is the FDA guidance entitled “Class II Special Controls Guidance Document: Endotoxin Assay.” See § 866.1(e) for the availability of this guidance document.