This large, retrospective study found the prevalence of PE in all patients presenting to the ED with a diagnosis of syncope was < 1% (0.06 - 0.55%). For hospitalized patients discharged with a diagnosis of syncope, prevalence was 0.15% to 2.1% and 0.35% to 2.63% at 90-day follow up. This was much lower than the PESIT trial, at 17.3%.
Why does this matter?
PESIT was published in the NEJM in late 2016 and found a surprisingly high rate of PE in hospitalized patients with syncope, 1 in 6 patients or about 17%. This didn't seem to square with reality for many of us in practice. A subsequent study last year found a much lower rate, 1.4%, but it was retrospective, small, and did not provide high quality evidence. A meta-analysis late last year agreed with the small study. The current study was massive, with over 1.5 million patients, and gives a better picture of PE prevalence.
PESIT takes another knock
This was a large, retrospective study of 5 databases from 4 countries spanning almost 17 years that included 1,671,944 adult patients with an ICD-9 discharge diagnosis of syncope. They found the prevalence of PE at hospital discharge was 0.15% to 2.1% and 0.35% to 2.63% at 90-day follow up and any venous thromboembolism at 90 days was 0.75% to 3.86%. For all patients presenting the the ED with a diagnosis of syncope the prevalence was < 1% (0.06 - 0.55%). All these numbers are much lower than PESIT. This data is limited because of the retrospective nature of the study and reliance on ICD-9 code to identify cases. PESIT was a prospective study design. So comparing these two is apples and oranges. However, the size and scope of this current study provide formidable observational evidence that PE prevalence may be much lower than the older, hospitalized patient population of the PESIT study and more in line with what we tend to see in ED practice.
Prevalence of Pulmonary Embolism in Patients With Syncope. JAMA Intern Med. Published online January 29, 2018. doi:10.1001/jamainternmed.2017.8175
Ryan Radecki, EM Lit of Note commented on this article.