Credit: Andre E.X. Brown
SAN DIEGO—New research suggests a urine test can be used to detect a pulmonary embolism (PE), providing similar sensitivity and greater specificity than the D-dimer test.
The urine test measures levels of fibrinopeptide B (FPB), a peptide released when a thrombus forms.
“The urine FPB test offers advantages over other screening methods because it doesn’t require blood to be drawn, and it can provide more accurate results than the D-dimer test,” said Timothy Fernandes, MD, of the University of California, San Diego.
Dr Fernandes and his colleagues presented results observed with the FPB test at the American Thoracic Society’s 2014 International Conference (abstract 53841).
The researchers tested samples taken from 344 patients who participated in the Pulmonary Embolism Diagnosis Study (PEDS), a multicenter study of patients considered likely to have an acute PE. Sixty-one of these patients (18%) had a confirmed PE, and 283 (83%) did not.
For all urine samples, the researchers measured the FPB concentration and evaluated the sensitivity and specificity of the test at various cut-off points in relation to its ability to predict the presence of PE.
The team found that, at concentrations of 2.5 ng/mL, urine FPB demonstrated sensitivity comparable to previously published values for plasma latex and whole-blood D-dimer levels, but with greater specificity.
Specifically, at a threshold of 2.5 ng/mL, urine FPB could predict PE with sensitivity of 75.4%, specificity of 28.9%, and a negative likelihood ratio of 0.18. Sensitivity was lower at thresholds of 5 ng/mL and 7.5 ng/mL, at 55.7% and 42.6%, respectively.
The researchers noted that the FPB test has the potential for greater specificity than the D-dimer test because FPB can reflect ongoing clot activity, while D-dimer can only be measured once a thrombus has already become degraded.
“The results of our study indicate that urine FPB tests may be a useful complement to current biomarkers such as D-dimer to measure for the
presence and activity of venous thromboembolism,” Dr Fernandes said.
He and his colleagues are now planning to develop a urine dipstick test for FBP. The patent for the urine FPB test is held by the University of California Board of Regents.
The researchers are also planning studies to assess urine FPB in other settings where D-dimer is used, including the use of urine FPB after anticoagulation to determine the risk of recurrent venous thromboembolism.
