Treat low-risk patients with pulmonary embolism (PE) with low-molecular-weight heparin (LMWH) in an outpatient setting.1
Strength of recommendation
B: Based on one good quality randomized controlled trial (RCT).
Three months after undergoing surgical repair of an ankle fracture, a 50-year-old woman presents with acute-onset dyspnea at rest and pleuritic chest pain. Her left calf is tender and swollen. The patient has a history of hypertension and smokes about 10 cigarettes per day. Her temperature is 37ºC; ventricular rate, 98 beats/min; blood pressure, 135/85 mm Hg; respiratory rate, 25 breaths/min; and pulse oximetry, 92%. Spiral CT reveals a contrast filling defect indicative of a PE. Her score on the Pulmonary Embolism Severity Index (PESI) is 50, an indication of low risk. She wants to know if she can be treated at home. What should you tell her?
In the past, intravenous unfractionated heparin, administered in an inpatient setting, was the recommended initial anticoagulation therapy for patients with venous thromboembolism (VTE). LMWH, which can be administered subcutaneously and does not require laboratory monitoring, has made it possible to treat VTE without
Outpatient PE care hindered
by lack of evidence
Guidelines from the American College of Physicians, the American Academy of Family Physicians, and the British Thoracic Society recommend outpatient treatment of deep vein thrombosis with LMWH, which they find to be safe and cost-effective for select patients.2,3 Until recently, the safety and efficacy of outpatient management of PE has been less clear.
The lack of an accurate prediction tool to identify patients who could be treated safely outside the hospital was one barrier to the development of evidence-based recommendations for outpatient PE treatment. In 2005, the PESI,4 a validated tool that identifies patients with low risk for death from PE, was developed. Until recently, the absence of an RCT comparing inpatient and outpatient treatment for acute PE was another barrier.
Outpatient treatment measures up
The Outpatient Treatment of Pulmonary Embolism (OTPE) study compared outpatient vs inpatient treatment of low-risk patients with acute PE. Participants had to be 18 or older, have acute symptomatic and objectively verified PE, and be at low risk for death based on the PESI score.4 In addition to excluding patients at moderate or high risk, the researchers identified 14 other exclusion criteria, including hypoxia, chest pain requiring opiates, and high risk for bleeding.
Patients were randomly assigned to the outpatient (n = 171) or inpatient (n = 168) group. Both groups received subcutaneous LMWH (enoxaparin, 1 mg/kg bid) for ≥ 5 days, followed by oral anticoagulation with a vitamin K antagonist for ≥ 90 days. Patients in the outpatient group were discharged from the emergency department (ED) within
24 hours of randomization, after being trained by a nurse to self-inject. Therapy after discharge was managed either by the patient's primary care physician or the hospital's anticoagulation staff.
The LMWH was discontinued in patients with an INR ≥ 2.0 for two consecutive days. All patients were followed for 90 days and contacted by the study team daily for the first week and then at 14, 30, 60, and 90 days. On each occasion, participants were asked about symptoms of recurrent VTE, bleeding, and the use of health care resources.
The primary outcome was the recurrence of symptomatic, objectively confirmed VTE within the study period. Secondary outcomes were major bleeding and all-cause mortality. Outcomes were confirmed by clinicians who were unaware of treatment
Patients were also asked to rate their overall satisfaction with their care and their treatment preference 14 days after randomization, using a 5-point Likert questionnaire. Prior to the trial, the investigators decided that outpatient treatment would be considered noninferior to inpatient care if the difference between rates of recurrent VTE did not exceed 4%, a measure used in previous studies comparing treatment regimens for VTE and outpatient versus inpatient treatment of DVT.5,6
Little difference in readmission rates, ED or office visits
One in 171 outpatients (0.6%) and none of the inpatients had recurrent VTE. Two outpatients (1.2%)—and no inpatients—developed major bleeding within 14 days, the result of intramuscular hematomas that occurred on days 3 and 13. There was one additional bleeding event (menometrorrhagia) in the outpatient group on day 50, but it was believed to be unrelated to the PE treatment. Per-protocol analysis, a more conservative measure used in noninferiority studies, found a difference in major bleeding rates of 3.8%. One person in each group died of non-VTE and nontreatment-related causes.
Almost all participants (99%) completed the satisfaction survey, which indicated that 92% of outpatients and 95% of inpatients were satisfied or very satisfied with their care. Hospital readmission rates, ED visits, and visits to primary care physicians were similar, with no significant differences between the