Major Trends Identified in Emergency Department Discharges Linked to Acute Pulmonary Embolism

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These data indicate that in the US, the outpatient management of patients with pulmonary embolism identified as lower-risk may continue to be underutilized.

Two-thirds of individuals at low-risk of pulmonary embolism (PE) check into hospitals unnecessarily, according to a new nationwide analysis, and a third of low-risk patients were discharged for outpatient management.1

These findings and more were assessed in a recent study led by Nathan W. Watson, a Smith Center research fellow and Harvard Medical School student. Funding for Watson and colleagues’ research was provided by the National Institutes of Health/ National Heart, Lung and Blood Institute.

The investigators noted that there has been little research into contemporary trends related to real-world rates of discharge from emergency departments in the US resulting from cases of acute PE. The team sought to assess whether the amount of emergency department discharges linked to acute PE saw any changes from 2012 - 2020, as well as which baseline characteristics were linked with such discharges.

“Previous studies have established the safety of outpatient management among select patients, resulting in changes in international clinical societies’ guidelines,” author Eric A. Secemsky, MD, MSc, director of Vascular Intervention in the CardioVascular Institute at Beth Israel Deaconess Medical Center, said in a statement. “Widespread adoption of these guidelines can improve patient care, decrease unnecessary time in the hospital and substantially reduce overall healthcare spending by limiting costly inpatient admissions.”2

Background and Findings

The blockage which can occur in cases of pulmonary embolism can happen suddenly and lead to rates of survival as low as 65 percent if the condition remains untreated. The likelihood of survival does, however, exceed 90 percent if treated early.

This analysis led by investigators from Beth Israel Deaconess Medical Center noted that updates made recently to clinical guidelines had shifted towards emphasizing outpatient care for those that have low-risk pulmonary embolism. Despite this fact, they report that discharge rates for those with this condition in emergency departments have continued to be low over time.

The research team used data drawn from American emergency departments taking part in the National Hospital Ambulatory Medical Care Survey. The team looked at trends nationwide as far as discharge rates from 2012 - 2020, as well as assessing characteristics of patients and any other elements shown to be linked with discharges.1

Over the course of the aforementioned period, the investigators found about 1,635,300 visits to emergency departments for acute pulmonary embolism. Despite changes in clinical guidelines, the overall discharge rates continued to be stable, with rates of 38.2% (95% CI, 17.9% to 64.0%) between 2012 - 2014 and of 33.4% (CI, 21.0% to 49.0%) between 2018 - 2020 (adjusted risk ratio, 1.01 per year [CI, 0.89 to 1.14]).

A notable finding the team came across was that there was not a single baseline characteristic, including risk scores, which could predict an increased likelihood of discharge from these departments. They added that, in looking at hemodynamic stability criteria, Pulmonary Embolism Severity Index (PESI) class, and simplified PESI scores, only a minority of admitted patients were discharged.

Despite ongoing recommendations promoting outpatient management for low-risk PE patients, the discharge rate remained consistent throughout the study period. Overall, the investigators speculated that outpatient management for low-risk cases of acute pulmonary embolism are severely underutilized in the United States.

Each of the clinical variables the research team assessed, including sex, age, race, and hospital qualities, did not predict outpatient management trends. They only found that about a third of low-risk individuals ended up being discharged during the 9 total years of study, and that there was not a statistically significant increase seen as time passed.

The potential rationale behind the continued lower outpatient management rates were shown to be opaque. The team did, however, suggest that there could be a general lack of infrastructure which is needed for short-term follow-up and management, contributing to providers' reluctance to discharge patients.

“Our findings are particularly important as U.S. healthcare costs continue to surge and overcrowding within EDs remains a critical issue,” Watson said in a statement. “We hypothesize that additional resources will be needed for patients to get timely follow-up visits and clinical oversight over newly prescribed anticoagulants to manage PE. However, the costs of maturing these outpatient pathways will most likely offset the costs incurred from a hospital admission and be overall more desirable to the patient.”2

Watson concluded that additional research may be necessary to assess the reasons in a more precise manner.


  1. Watson NW, Carroll BJ, Krawisz A, Schmaier A, Secemsky EA. Trends in Discharge Rates for Acute Pulmonary Embolism in U.S. Emergency Departments. Ann Intern Med. Published online January 30, 2024. doi:10.7326/M23-2442.
  2. Two-thirds of patients with low-risk pulmonary embolism are admitted to hospital unnecessarily. EurekAlert!. January 29, 2024. Date accessed: February 6, 2024.