We undertook an open-label, randomised non-inferiority trial at 19 emergency departments in Switzerland, France, Belgium, and the USA. We randomly assigned patients with acute, symptomatic pulmonary embolism and a low risk of death (pulmonary embolism severity index risk classes I or II) with a computer-generated randomisation sequence (blocks of 2–4) in a 1:1 ratio to initial outpatient (ie, discharged from hospital greater than or equal to 24 h after randomisation) or inpatient treatment with subcutaneous enoxaparin (greater than or equal to 5 days)...
So in the outpatient arm the entirety of treatment was not really outpatient. Evidently patients remained in the ER or in an observation unit for up to 24 hours. More from the article:
...one (0·6%) of 171 outpatients developed recurrent venous thromboembolism within 90 days compared with none of 168 inpatients (95% upper confidence limit [UCL] 2·7%; p=0·011). Only one (0·6%) patient in each treatment group died within 90 days (95% UCL 2·1%; p=0·005), and two (1·2%) of 171 outpatients and no inpatients had major bleeding within 14 days (95% UCL 3·6%; p=0·031). By 90 days, three (1·8%) outpatients but no inpatients had developed major bleeding (95% UCL 4·5%; p=0·086).
So while there was no difference in mortality there was a small increase in recurrent VTE and bleeding with outpatient treatment. Despite this the authors concluded that outpatient treatment was safe in selected low risk patients. How did they define low risk? Using the the pulmonary embolism severity index (PESI). I discussed the PESI previously here. As I cited in that post, an older study had suggested that the PESI could help select patients for outpatient treatment. The original study on the PESI is here.
Biomarkers and echocardiography are the traditional tools for acute risk assessment in PE, but clinical scores like the PESI are emerging as comparable means.
HT to Hospital Medicine Quick Hits.