(261 days)
Immunoassays for the in vitro quantitative determination of the soluble fms like tyrosine kinase-1/placental growth factor (sFlt-1/PlGF) ratio in human serum.
The sFlt-1/PlGF ratio is indicated as an aid in the risk assessment of pregnant women, with a singleton pregnancy (23+0 to 34+6/7 weeks' gestation) hospitalized for hypertensive disorders of pregnancy (preeclampsia, chronic hypertension with or without superimposed preeclampsia, or gestational hypertension), to develop preeclampsia with severe features within two weeks from testing. The sFit-1/PlGF ratio should be used in conjunction with clinical assessment and routine laboratory testing.
The electrochemiluminescence immunoassay "ECLIA" is intended for use on cobas e immunoassay analyzers.
The Elecsys sFlt-1 and Elecsys PlGF assays employ a sandwich principle using electrochemiluminescence immunoassay "ECLIA" technology. The total duration of each assay is 18 minutes. Samples are incubated with biotinylated and ruthenium-labeled monoclonal antibodies specific to sFlt-1 or PlGF, forming a sandwich complex. Streptavidin-coated microparticles are added, binding the complex to the solid phase. The microparticles are magnetically captured, unbound substances are removed, and a voltage is applied to induce chemiluminescent emission, which is measured by a photomultiplier. Results are determined via a calibration curve generated by 2-point calibration and a master curve provided via the reagent barcode. The reagents for each assay are combined in a "rackpack".
Here's a breakdown of the acceptance criteria and study information for the Elecsys sFlt-1 and Elecsys PlGF assays, based on the provided document.
Acceptance Criteria and Device Performance
| Acceptance Criteria Category | Specific Criteria | Reported Device Performance |
|---|---|---|
| Clinical Performance | Risk Assessment for Preeclampsia with Severe Features within two weeks from testing (Cutoff: >38): high Negative Predictive Value (NPV) and acceptable Positive Predictive Value (PPV) for pregnant women with singleton pregnancy (23+0 to 34+6/7 weeks' gestation) hospitalized for hypertensive disorders of pregnancy. | Overall Intended Use Population (N=556): |
- Sensitivity: 91.40% (95% CI: 86.41, 95.00)
- Specificity: 77.30% (95% CI: 72.68, 81.47)
- NPV (ratio ≤ 38): 94.70% (95% CI: 91.54, 96.94)
- PPV (ratio > 38): 66.93% (95% CI: 60.77, 72.68) |
| Non-Clinical Performance | Precision: Low coefficients of variation (CV) for repeatability (within-run) and intermediate precision (within-laboratory). | Elecsys PlGF (N=84 per sample type): - Repeatability CV: 1.0% - 5.7%
- Intermediate precision CV: 1.4% - 9.9%
Elecsys sFlt-1 (N=84 per sample type): - Repeatability CV: 0.9% - 2.4%
- Intermediate precision CV: 1.7% - 3.7%
Ratio (N=84 per sample type): - Repeatability CV: 1.1% - 4.9%
- Intermediate precision CV: 1.4% - 7.0% |
| | Linearity/Assay Reportable Range: Measurements are linear across the claimed measuring range. | - Elecsys sFlt-1: 80-85000 pg/mL (claimed range) - Elecsys PlGF: 10-5400 pg/mL (claimed range)
(Study concludes measurements are linear across these ranges) |
| | Limit of Blank (LoB): ≤ 2 pg/mL for PlGF and 26.4 mg/dL can cause up to 10% decrease in ratio. - Hemoglobin, Intralipid, Rheumatoid Factors, Biotin (up to 1200 ng/mL): No significant interference reported (implies within acceptable limits though quantitative data not listed).
- Common Drugs (15 tested): No interference.
- Additional Substances (13 tested): No interference.
- Heparin: Interference with Elecsys PlGF for concentrations > 500 U/L. |
| | Analytical Specificity/Cross-Reactivity: Highly specific for sFlt-1 and PlGF, with minimal cross-reactivity with related substances. | - sFlt-1 cross-reactivity:
N/A