The Use of Empiric Parenteral Anticoagulation for Acute Pulmonary Embolisms: A Cohort Study

Abstract

SESSION TITLE: Venous Thromboembolism SESSION TYPE: Original Investigation Poster PRESENTED ON: Wednesday, November 1, 2017 at 01:30 PM - 02:30 PM PURPOSE: Timely anticoagulation for patients diagnosed with acute pulmonary embolism (PE) is paramount in reducing morbidity and mortality. In fact, guidelines recommend the administration of empiric anticoagulation when the pretest probability for PE is high, or for moderate risk, when diagnostic testing will be delayed greater than 4 hours. However, the risk-benefit ratio must be carefully considered as empiric anticoagulation increases risk for bleeding. We hypothesize that empiric anticoagulation is inadequately administered in moderate to high-risk probability PE patients. METHODS: We conducted a retrospective cohort study of adult patients, between October-December 2016, who were suspected of having a PE. All patients who underwent a CT chest with PE protocol or ventilation-perfusion (V/Q) scan were enrolled. PE was defined as a positive CT chest or a high probability V/Q scan. Data collected included baseline demographics, risk stratification scores for PE (PERC, Geneva, and Wells), and use of full strength anticoagulants prior to diagnostic testing. Risk stratification scores were dichotomized to those with low vs moderate-high pretest probability for PE. The primary outcome measure was the use of empiric anticoagulation based on risk stratification scoring. Fisher’s exact test and student’s t-test was used when appropriate. A p-value of <0.05 was considered significant with a two-tailed approach. RESULTS: The cohort consisted of 104 patients (mean age: 64.1+/-15.5, male: 51%) with a PE diagnostic rate of 10.6%. In patients diagnosed with PE, 27.3% received empiric anticoagulation compared to 1.1% without a PE diagnosis (p-value: <0.0001). When using PERC, 2.9% of low risk patients received empiric anticoagulation compared to 12.9% in the moderate-high risk group (p-value: 0.108). For Well’s criteria, empiric anticoagulation was lower in the low risk group (1.9% vs 17.6%, p-value: 0.006). Finally, 13.0% of low risk patients for the Geneva score received empiric anticoagulation versus 8.6% of moderate-high risk scores (p-value: 0.527). CONCLUSIONS: Only 12.9-17.6% of patients with a moderate-high pretest probability for PE were given empiric anticoagulation. In contrast, 1.9-13.0% of patients determined to be low risk for PE received anticoagulation. Thus, we are not aggressive enough in providing empiric anticoagulation in moderate-high risk patients, but may be too aggressive in those who are low risk. CLINICAL IMPLICATIONS: The use of empiric anticoagulation must be thoughtfully administered in those suspected of PE. The risk-benefit ratio must be carefully weighed and should be adjusted based on the pretest probability for PE. A protocolized approach that couples the use of risk stratification tools with administration of empiric anticoagulation may decrease the risks for significant morbidity and mortality associated with acute PE, while minimizing the risks of bleeding in those where clinical suspicion is low. DISCLOSURE: The following authors have nothing to disclose: Kimberley Doucette, Bilal ElChaarani, Tanuj Sharma, Chee Chan No Product/Research Disclosure Information