Safe Treatment of Pulmonary Embolism on An Outpatient Basis.
Authors: Kovacs Michael J. , Hawel Jeffrey D.E. , Rekman Janelle F. , Lazo-Langner Alejandro 
Published: April 2020

Abstract
Background: Acute pulmonary embolism (PE) is a common medical problem in outpatient clinics and emergency rooms. Treatment with heparin and warfarin is well established and effective. In some centres (such as ours) eligible patients with PE are treated as outpatients, however many centres remain reluctant to do so. We review our experience with outpatient treatment of acute PE.
Methods: We reviewed hospital charts for all inpatients and thrombosis clinic charts for all outpatients with a diagnosis of acute PE that was made prior to a decision on hospital admission from January 1, 2003 to January 30, 2008. All diagnoses were objectively proven by high probability V/Q scan or non-diagnostic V/Q scan with positive compression U/S or segmental or greater perfusion defect on CTPA. Patients were eligible to be treated as outpatients if they were hemodynamically stable, not high risk for bleeding, not requiring oxygen therapy, not requiring unfractionated heparin due to renal failure, and not having another indication for hospital admission. Most patients were treated with low molecular weight heparin (LMWH) for 5–7 days together with warfarin except for cancer patients who were treated with LMWH alone. All patients were instructed to call the thrombosis service or to go the emergency room if they developed symptoms of new PE or bleeding. Outpatients were seen in follow-up at 1, 4, and 12 weeks in the thrombosis clinic. Inpatient charts were reviewed for demographics and reason for hospital admission. For outpatients, in addition to demographics, charts were reviewed for the three month outcomes of major bleeding, recurrent venous thromboembolism and death.
Results: There were a total of 633 patients with PE. 319 were admitted to the hospital whereas 314 (49.7%) were managed entirely as outpatients. The mean age for inpatients was 64 years. Inpatients were admitted for the following reasons: 125 (39%) for concomitant illness, 84 (26%) for hypoxia, 21 (7%) for hemodynamic instability, 14 (4%) for pain control, 1 (0.3%) for thrombolysis, 24 (7%) for other investigations, and 50 (16%) for other or unlcear reasons. For the 314 outpatients the mean age was 55 years and 184 (59%) were female. Eight (2.8%) patients were lost to follow-up. There were 195 (62%) idiopathic PE, 62 (20%) had PE secondary to cancer and 57(18%) to other transient risk factors. There were 247 (79%) patients who were managed with LMWH and warfarin, 51 (16%) managed with LMWH alone and 16 (5%) patients had experimental treatment. At 3 months of follow up there were 3 (1%) patients who developed major hemorrhage (GI bleed, hemoptysis, hemarthrosis), 3 (1%) patients who had objectively documented recurrent thrombosis (1 deep vein thrombosis, 2 PE), and 9 (2.9%) patients died, all of them from cancer progression. None of these events occurred within the first 7 days after diagnosis.
Conclusions: To our knowledge this is the largest report of outpatient PE management. In our hospital 50% of ambulatory patients who have a diagnosis of PE are managed entirely as outpatients with a low risk for bleeding or thrombosis recurrence. For those admitted the majority was due to a concomitant illness that required admission itself. Many centres remain hesitant to treat patients with PE in this fashion but will treat patients with deep vein thrombosis as outpatients. Both conditions are at risk of recurrent PE and bleeding but it is not clear how a hospital admission would prevent that from happening. Our findings suggest that uncomplicated PE is not an indication for hospital admission per se. Outpatient management of PE deserves further consideration.