Elevated heart rate and bilateral emboli were associated with hospitalization in low-risk patients with pulmonary embolism in the ED.

When managing acute pulmonary embolism (PE), clinicians often use clinical decision rules to assess risk and determine the appropriate site of care. However, some low-risk patients with acute PE still experience adverse outcomes. Although recent studies have identified several key predictors of adverse outcomes, it remains unclear as to which factors physicians use to decide whether low-risk patients require hospitalization.

When considering outpatient management, guidelines recommend assessing patients for PE severity, comorbidities, and contraindications to home treatment. Two widely used, validated tools are the PE Severity Index, which assesses 30-day mortality risk, and the Hestia criteria, which assess suitability for outpatient management based on PE severity, comorbidities, and social factors. If any Hestia criteria are present, hospitalization is recommended.

While these tools help identify low-risk patients with PE, they have inherent failure rates. Heart rate, a key component for predicting PE-related mortality and clinical deterioration, may prompt hospital admissions when abnormal, even in patients classified as low risk.

Characteristics of Patients With Acute, Low-Risk PE

For a study published in Annals of Emergency Medicine, Scott D. Casey, MD, MS, and colleagues sought to better understand the characteristics of patients with acute, low-risk PE who were selected for outpatient management or hospitalization. “A more thorough understanding of predictors of hospitalization and patient-level contributors to this decision may guide quality improvement initiatives for outpatient PE management,” say Dr. Casey and colleagues. Such data may also provide insights into decisions about the site of care and inform new research into the prognostic significance of key variables.

The retrospective cohort study included 461 adults in the ED with a PE Severity Index score of less than 86 points. The researchers assessed the highest observed ED heart rate, the most proximal embolus location, and embolism laterality. The primary outcome was hospitalization.

Many Patients Hospitalized Despite a Low-Risk Classification  

Results from the study showed that 57.5% of patients in the analysis were hospitalized and 30.8% had an elevated risk by other criteria, such as Hestia criteria or biochemical or radiographic right ventricular dysfunction. Most patients were hospitalized despite being classified as low risk by a validated risk stratification tool and members of a health system well-resourced to accomplish outpatient management, the authors reported. Many patients classified as low risk by the PE Severity Index had clinical, laboratory, or radiographic findings that might increase risks for adverse events.

The study also identified variables associated with an increased likelihood of hospital admission. A multivariate analysis showed that compared with patients who had heart rates lower than 90 beats/min, those with heart rates of 110 beats/min or higher or with heart rates of 90 to 109 beats/min had a greater risk for hospitalization (Table). The presence of bilateral (vs unilateral) PE was also independently associated with a higher risk for hospitalization. Conversely, proximal (vs distal) embolus location was not associated with the likelihood of hospitalization.

Recognize Factors That Can Guide Decision Making on Patient Care

Dr. Casey and colleagues noted that knowing perceived influential factors may help address hospitalization decisions when caring for patients with low-risk PE. Based on the study findings, it is possible that the highest observed ED heart rate and the presence of bilateral PE are being used to guide physicians in site-of-care decision making. However, some factors not included in traditional PE severity risk scores may also drive site-of-care decision making. As such, the study group reported it is important for physicians to recognize that they may attribute increased perceived risk to patients with higher heart rates and bilateral PE when making site-of-care decisions.