Tandem measurement of D-dimer and myeloperoxidase or C-reactive protein to effectively screen for pulmonary embolism in the emergency department.

Objectives: The hypothesis was that the tandem measurement of D-dimer and myeloperoxidase (MPO) or C-reactive protein (CRP) could significantly decrease unnecessary pulmonary vascular imaging in emergency department (ED) patients evaluated for pulmonary embolism (PE) compared to D-dimer alone.

Methods: The authors measured the sequential combinations of D-dimer and MPO and D-dimer and CRP in a prospective sample of ED patients evaluated for PE at two centers. Patients were followed for 90 days for venous thromboembolism (VTE, either PE or deep venous thrombosis [DVT]), which required the consensus of two of three blinded physician reviewers.

Results: The authors enrolled 304 patients, 22 with VTE (7%; 95% confidence interval [CI] = 5% to 10%). The sensitivity and specificity of a D-dimer alone (cutoff > or = 500 ng/mL) were 100% (95% CI = 85% to 100%) and 59% (95% CI = 53% to 65%), respectively, and was followed by pulmonary vascular imaging negative for PE in 38% (115/304; 95% CI = 32% to 44%). The combination of either a negative D-dimer, or MPO < 22 mg/dL, had a sensitivity of 100% and specificity of 73% (95% CI = 67% to 78%). Thus, tandem measurement of D-dimer and MPO would have decreased the frequency of subsequent negative pulmonary vascular imaging from 38% to 25% (95% CI of the difference of -13% = -5% to -20%). The combination of CRP and D-dimer would not have significantly improved the rate of negative imaging.

Conclusions: The tandem measurement of D-dimer and MPO would have significantly decreased negative pulmonary vascular imaging compared with D-dimer alone and should be validated prospectively.