SESSION TITLE: Pulmonary Embolism
SESSION TYPE: Original Investigation Slide
PRESENTED ON: Tuesday, October 29, 2013 at 04:30 PM - 05:30 PM
PURPOSE: The presence of acute dyspnea, fever and tachycardia may cause confusion in differential diagnosis of pulmonary embolism (PE) versus pneumonia in patient’s presenting to the hospital. Because of the high mortality associated with PE many patients undergo CTA, especially patients with positive D-dimer levels. One of the most common causes of an elevated D-dimer and a masquerader of PE is bacterial sepsis. PCT is a specific bio-marker of bacterial sepsis first available in this institution in 2008. This single-center retrospective study (2008-2012) looks at patients who underwent PE imaging after having a PCT and D-dimer measured within 24 hours of presentation and prior to the PE imaging. We hypothesized that the PCT + D-Dimer is more discriminatory than D-dimer by itself for the diagnosis of PE.
METHODS: This study is a retrospective review of all pts presenting to our urban teaching hospital from 2008-2012 who were suspected of having PE and had evaluation of their serum PCT and D-dimer. This data was used to measure the sensitivity and specificity of D-dimer alone versus D-dimer plus PCT. ROCs were created. The CTA and V/Q scans were evaluated by the in-house radiologists using standard techniques and procedures. The radiologists were unaware of the results of the lab tests.
RESULTS: There were 459 pts with both D-dimer and PCT results who underwent either CTA or V/Q. 39 had PE. All pts with PE had positive D Dimer (sensitivity = 100%). The specificity however was 9%. Using a PCT cutoff of 0.25, 0.5, 0.75 and 1.0 the specificity increased to 73%, 78%, 84% and 95% respectively. The AUC for PCT of 1.0 was .88. Using the combined tests would reduce the need for CTA by 73%.
CONCLUSIONS: Combining PCT with those pts with a positive D Dimer can improve the laboratory evaluation of pts in whom PE is a possible diagnosis and possibly reduce the need for CTA.
CLINICAL IMPLICATIONS: CTA is a tool that is often over-utilized because of its diagnostic power and availability. There is short and long term risk associated with its use including contrast induced nephropathy and radiation exposure. The inexpensive and increasingly widely available sepsis biomarker PCT can increase the specificity of D-dimer and give the clinician confidence in an alternative diagnosis.
DISCLOSURE: The following authors have nothing to disclose: Thomas Murphy, Craig Backous, Eric Gluck
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