Safe outpatient management of low-risk patients with acute pulmonary embolism

- Kenny Lin, MD, MPH

I've practiced family medicine long enough to remember when treatment of any patient with acute deep venous thrombosis (DVT) required hospitalization for several days administering intravenous unfractionated heparin and oral warfarin while waiting for the patient's international normalized ratio (INR) to reach a therapeutic level. Thanks to the development of low molecular-weight heparins and direct-acting oral anticoagulants (DOAC), outpatient treatment of uncomplicated DVT is now the norm. But patients with newly diagnosed pulmonary embolism (PE) are still typically hospitalized, since they often have hemodynamic instability or other potentially life-threatening conditions.

According to a 2017 article in American Family Physician, the American College of Chest Physicians suggests considering outpatient treatment of acute PE "if the risk of nonadherence is low and the patient is clinically stable; has no contraindications to anticoagulation, such as recent bleeding, severe renal or liver disease, or platelet count of less than 70; and feels capable of managing the disease at home." A recent Point-of-Care Guide reviewed clinical decision tools that predict mortality in patients with newly diagnosed PE. The simplified Pulmonary Embolism Severity Index (sPESI) stratifies patients into low and high risk categories. Low risk patients have a 30-day mortality rate of 1%, while high risk patients have a 9% mortality rate.

A prospective cohort study published in CHEST earlier this year enrolled 200 consecutive adults with newly diagnosed PE and a low risk of mortality using the related Pulmonary Embolism Severity Index (PESI). Participants were observed in the emergency department (ED) for 12 to 24 hours, then treated with anticoagulant medications in the outpatient setting (173 patients were treated with DOACs). After 90 days, no patients had died or suffered a recurrent venous thromboembolism (VTE). One patient had a major bleed after a traumatic thigh injury that required a blood transfusion and surgery.

A pragmatic controlled trial in Annals of Internal Medicine evaluated the effect of implementing an electronic clinical decision support system (CDSS) that included the PESI tool and an educational intervention on decision making for patients with acute PE in the 21 community EDs of Kaiser Permanente Northern California. 10 EDs received access to the CDSS and in-person education and feedback from an onsite emergency physician-researcher ("study champion"); the other 11 EDs served as control sites. The primary outcome was discharge to home from the ED or an ED-based outpatient observation unit. At the intervention sites, home discharge increased from 17.4% to 28%, while there were no changes in discharge practices at control sites. The intervention was not associated with increases in 30-day major adverse events (recurrent VTE, major hemorrhage, or all-cause mortality).

One day, one of my trainees will be able to write, "I've practiced family medicine long enough to remember when even low-risk patients with acute PE required hospitalization ..."