19 May Pulmonary Embolism: Urine Fibrinopeptide B As Screening Tool
MedicalResearch: What are the main findings of this study?
Dr. Fernandes: The fibrinopeptides are cleaved off of fibrinogen by thrombin during the generation of a new clot. These small molecules are excreted into the urine and we have developed a urine assay to measure the level of FPB. We examined the performance of urine FPB as a screening test for acute pulmonary embolism, blood clots that travel to the lungs.
The study group consisted of 344 patients: 61 (18%) with pulmonary embolism and 283 (83%) without. At a threshold of 2.5 ng/ml, urine FPB demonstrated sensitivity of 75.4% (95% CI: 62.4-85.2%), specificity of 28.9% (95% CI: 23.8-34.7%), and negative likelihood ratio of 0.18 (0.11-0.29), weighted by prevalence in the sample population. However, the thresholds of 5 ng/ml and 7.5 ng/ml had sensitivities of only 55.7% (95% CI: 42.5-68.2%), and 42.6% (30.3-55.9%), respectively.
The urine fibrinopeptide B assay at a cut-off of 2.5 ng/ml had a sensitivity of 75.4% for detecting pulmonary embolism. For diagnosis of PE, this sensitivity is comparable to previously published values for the first generation plasma latex and whole blood D-dimer assays (not as well and the D dimer ELISA assay).
MedicalResearch: What should patients and clinicians take away from this report?
Dr. Fernandes: The main advantage of our test is that it is non-invasive and can be developed into a urine dipstick point-of-care test that could have a rapid turn around time. This would be a tremendous boon to patients across the continuum of care – from the ED to the ICU to even the outpatient setting. Our next steps are to further improve the diagnostic accuracy and determine whether alternative cut-off values based on clinical characteristics such as age, sex, pregnancy, and cancer status could further improve the performance of the test. We also plan on evaluating urine FPB in other clinical settings where D-dimer has gained traction, such as in determining risk of venous thromboembolism recurrence after anticoagulation has been stopped.
The patent for the urine FPB test is held by the University of California Board of Regents.
Urine Fibrinopeptide B As A Screening Test For Acute Pulmonary Embolism
Type: Scientific Abstract
Category: 18.08 – Pulmonary Embolism: Acute and Chronic (PC)
Authors: T.M. Fernandes1, D. De Santis1, P.G. Chiles1, J.J. Marsh1, P.S. Wells2, T.A. Morris1; 1University of California, San Diego – La Jolla, CA/US, 2The Ottawa Hospital and the University of Ottawa – Ottawa, ON/CA