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Original Investigation
Less Is More
March 2018

Prevalence of Pulmonary Embolism in Patients With Syncope

Author Affiliations
  • 1Dipartimento di Medicina Interna, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca’ Granda, Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy
  • 2Department of Cardiology, Copenhagen University Hospital, Herlev and Gentofte Hospital, Hellerup, Denmark
  • 3Department of Emergency Medicine, Stanford University, Stanford, California
  • 4Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston
  • 5Danish Heart Foundation, Copenhagen, Denmark
  • 6The National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark
  • 7Department of Medicine, University of Alberta, Edmonton, Canada
  • 8Epidemiology Unit, Agency for Health Protection of the Province of Milan, Milan, Italy
  • 9Division of Cardiology, Department of Cardiac Sciences, University of Calgary, Calgary, Alberta, Canada
  • 10Center for Policy Research–Emergency Medicine, Department of Emergency Medicine, Oregon Health and Science University, Portland
  • 11Dipartimento di Scienze Biomediche e Cliniche “L. Sacco,” Università degli Studi di Milano, Milan, Italy
JAMA Intern Med. 2018;178(3):356-362. doi:10.1001/jamainternmed.2017.8175
Key Points

Question  What is the estimated prevalence of pulmonary embolism in patients who present to the emergency department with syncope?

Findings  In this study of 5 administrative databases that included more than 1.5 million people from 4 different countries, pulmonary embolism was identified in less than 1% of patients with syncope.

Meaning  Although pulmonary embolism should be considered at first evaluation in every patient with syncope, not all patients warrant a diagnostic algorithm to exclude it, and the algorithm may increase false-positive results and overtreatment, resulting in more adverse events.


Importance  Sparse data and conflicting evidence exist on the prevalence of pulmonary embolism (PE) in patients with syncope.

Objective  To estimate the prevalence of PE among patients presenting to the emergency department (ED) for evaluation of syncope.

Design, Setting, and Participants  This retrospective, observational study analyzed longitudinal administrative data from 5 databases in 4 different countries (Canada, Denmark, Italy, and the United States). Data from all adult patients (aged ≥18 years) who presented to the ED were screened to identify those with syncope codes at discharge. Data were collected from January 1, 2000, through September 30, 2016.

Main Outcomes and Measures  The prevalence of PE at ED and hospital discharge, identified using codes from the International Classification of Diseases, was considered the primary outcome. Two sensitivity analyses considering prevalence of PE at 90 days of follow-up and prevalence of venous thromboembolism were performed.

Results  A total of 1 671 944 unselected adults who presented to the ED for syncope were included. The prevalence of PE, according to administrative data, ranged from 0.06% (95% CI, 0.05%-0.06%) to 0.55% (95% CI, 0.50%-0.61%) for all patients and from 0.15% (95% CI, 0.14%-0.16%) to 2.10% (95% CI, 1.84%-2.39%) for hospitalized patients. The prevalence of PE at 90 days of follow-up ranged from 0.14% (95% CI, 0.13%-0.14%) to 0.83% (95% CI, 0.80%-0.86%) for all patients and from 0.35% (95% CI, 0.34%-0.37%) to 2.63% (95% CI, 2.34%-2.95%) for hospitalized patients. Finally, the prevalence of venous thromboembolism at 90 days ranged from 0.30% (95% CI, 0.29%-0.31%) to 1.37% (95% CI, 1.33%-1.41%) for all patients and from 0.75% (95% CI, 0.73%-0.78%) to 3.86% (95% CI, 3.51%-4.24%) for hospitalized patients.

Conclusions and Relevance  Pulmonary embolism was rarely identified in patients with syncope. Although PE should be considered in every patient, not all patients should undergo evaluation for PE.