Outpatient Versus Inpatient Treatment for Patients With Acute Pulmonary Embolism: An International, Open-Label, Randomised, Non-Inferiority Trial

Study Questions:

What is the effectiveness, safety, and efficiency of outpatient versus inpatient care for low-risk patients with acute, symptomatic pulmonary embolism?


The authors reported the results of OTPE (Safety Study of Outpatient Treatment for Pulmonary Embolism), an open-label, randomized, noninferiority clinical trial of consecutive adults over age 18 with acute, symptomatic pulmonary embolism at low risk of death, randomly assigned to either outpatient or inpatient treatment, conducted in 19 emergency departments in Switzerland, France, Belgium, and the United States. Outpatient and inpatient treatment included subcutaneous low molecular weight heparin for at least 5 days, and oral anticoagulation for at least 90 days. The primary outcome was symptomatic recurrent venous thromboembolism (VTE) within 90 days, as well as major bleeding in 14 or 90 days, and mortality within 90 days. A noninferiority margin of 4% was prespecified, using intention-to-treat analysis.


Among 344 eligible subjects enrolled between February 2007 and June 2010, recurrent VTE within 90 days was seen in 1 of 171 outpatients (0.6%) versus none in 168 inpatients (95% upper confidence limit [UCL], 2.7%; p = 0.011). There was one death in each treatment group within 90 days (95% UCL, 2.1%; p = 0.005), and major bleeding in 2 out of 171 outpatients (1.2%) versus no inpatients within 14 days (95% UCL, 3.6%; p = 0.031). Up to 90 days, major bleeding was seen in 3 of 171 outpatients (1.8%) versus no inpatients (95% UCL, 4.5%; p = 0.086).


The authors concluded that in selected low-risk patients with pulmonary embolism, outpatient care can safely and effectively be used in place of inpatient care.


Although previous studies of outpatient treatment for low-risk pulmonary embolism have reported acceptable results, there remains a great deal of reticence to treat such patients in the outpatient setting. The current study should go a long way toward reassuring providers that patients with pulmonary embolism at low risk for mortality can safely be treated in the outpatient setting, just as deep vein thrombosis patients are treated. However, some caution in extrapolating the results of the current study is warranted. Its small size, and the lack of surveillance for recurrent VTE, have led to very small numbers of outcomes. Furthermore, given that the anticipated rate of recurrent VTE was 0.9%, a prespecified noninferiority margin of 4% seems rather large. So while these data may bolster the belief that outpatient treatment for low-risk pulmonary embolism is warranted, skeptics may find reason to remain skeptical.

Clinical Topics: Pulmonary Hypertension and Venous Thromboembolism, Vascular Medicine

Keywords: Intention, France, Outpatients, Belgium, Pulmonary Embolism, Venous Thromboembolism, Switzerland, Emergency Service, Hospital, Inpatients, Hospitalization, United States

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