Key message
We are uncertain if treatment in hospital or at home (outpatient) is better for some people with blood clots in the lungs. We did not find clear evidence of an important difference in the number of deaths, bleeding, recurrence of new blood clots, or patient satisfaction, because the results were imprecise and the studies did not report side effects on blood pressure or information on how well people followed medical advice. More well-designed studies are needed before doctors can make informed practice decisions.
Why is this question important?
A blood clot in the lungs (pulmonary embolism) is a major cause of death and illness. These can occur after a blood clot breaks off from somewhere else in the body and travels in the blood to the lungs. The clot can often travel from the leg, where it is called a deep vein thrombosis. How people are treated depends on whether they are low-risk or high-risk, but most people are given blood-thinning drugs (anticoagulants) in hospital. For some low-risk cases with sudden onset (acute) pulmonary embolism, treatment at home might be better than keeping them in hospital. Possible benefits include fewer people in hospital, less risk of picking up an infection in hospital, cost savings, and better health-related quality of life. We wanted to know if there were any differences in risks and benefits between people with blood clots in the lungs who are treated at home compared to those treated in the hospital.
What did we do?
We searched for randomised controlled trials that treated adults with sudden onset, low-risk, pulmonary embolism at home or in hospital. In randomised controlled trials, the treatments people receive are decided at random, and these types of studies give the most reliable evidence about treatment effects.
What did we find?
We found two studies involving 453 people with sudden onset pulmonary embolism who were treated at home or in hospital. One study used the same treatment for the people treated at home or in hospital, and the second study used different treatments. We did not find any clear differences in the number of deaths, bleeding, new clots, or patient satisfaction between the groups of people who were treated at home or in the hospital.
Neither study provided information on side effects of the treatment or on whether people were able to follow the correct instructions at home.
What are the limitations of the evidence?
We are not very certain about the evidence from the two included studies. This is because there were only small numbers of people in the studies (and small numbers of events) and because we could not be sure that reports of studies where no effect was shown were ever published.
How up to date is this evidence?
This review updates our previous review. The evidence is up to date to May 2021.
Currently, only low-certainty evidence is available from two published randomised controlled trials on outpatient versus inpatient treatment in low-risk patients with acute PE. The studies did not provide evidence of any clear difference between the interventions in overall mortality, bleeding, or recurrence of PE.
Pulmonary embolism (PE) is a common life-threatening cardiovascular condition, with an incidence of 23 to 69 new cases per 100,000 people each year. For selected low-risk patients with acute PE, outpatient treatment might provide several advantages over traditional inpatient treatment, such as reduction of hospitalisations, substantial cost savings, and improvements in health-related quality of life. This is an update of an earlier Cochrane Review.
To assess the effects of outpatient versus inpatient treatment in low-risk patients with acute PE.
We used standard, extensive Cochrane search methods. The latest search date was 31 May 2021.
We included randomised controlled trials (RCTs) of outpatient versus inpatient treatment of adults (aged 18 years and over) diagnosed with low-risk acute PE.
We used standard Cochrane methods. Our primary outcomes were short- and long-term all-cause mortality. Secondary outcomes were bleeding, adverse effects, recurrence of PE, and patient satisfaction. We used GRADE to assess certainty of evidence for each outcome.
We did not identify any new studies for this update. We included a total of two RCTs involving 453 participants. Both trials discharged participants randomised to the outpatient group within 36 hours of initial triage, and both followed participants for 90 days. One study compared the same treatment regimens in both outpatient and inpatient groups, and the other study used different treatment regimens. There was no clear difference in treatment effect for the outcomes of mortality at 30 days (risk ratio (RR) 0.33, 95% confidence interval (CI) 0.01 to 7.98; 2 studies, 453 participants; low-certainty evidence), mortality at 90 days (RR 0.98, 95% CI 0.06 to 15.58; 2 studies, 451 participants; low-certainty evidence), major bleeding at 14 days (RR 4.91, 95% CI 0.24 to 101.57; 2 studies, 445 participants; low-certainty evidence) and at 90 days (RR 6.88, 95% CI 0.36 to 132.14; 2 studies, 445 participants; low-certainty evidence), minor bleeding (RR 1.08, 95% CI 0.07 to 16.79; 1 study, 106 participants; low-certainty evidence), recurrent PE within 90 days (RR 2.95, 95% CI 0.12 to 71.85; 2 studies, 445 participants; low-certainty evidence), and patient satisfaction (RR 0.97, 95% CI 0.90 to 1.04; 2 studies, 444 participants; moderate-certainty evidence). We downgraded the certainty of the evidence because the CIs were wide and included treatment effects in both directions, the sample sizes and numbers of events were small, and it was not possible to determine the effect of missing data or the presence of publication bias. The included studies did not assess PE-related mortality or adverse effects, such as haemodynamic instability, or adherence to treatment.