A prediction rule to identify low-risk patients with pulmonary embolism

Arch Intern Med. 2006 Jan 23;166(2):169-75. doi: 10.1001/archinte.166.2.169.


Background: A simple prognostic model could help identify patients with pulmonary embolism who are at low risk of death and are candidates for outpatient treatment.

Methods: We randomly allocated 15,531 retrospectively identified inpatients who had a discharge diagnosis of pulmonary embolism from 186 Pennsylvania hospitals to derivation (67%) and internal validation (33%) samples. We derived our rule to predict 30-day mortality using classification tree analysis and patient data routinely available at initial examination as potential predictor variables. We used data from a European prospective study to externally validate the rule among 221 inpatients with pulmonary embolism. We determined mortality and nonfatal adverse medical outcomes across derivation and validation samples.

Results: Our final model consisted of 10 patient factors (age > or = 70 years; history of cancer, heart failure, chronic lung disease, chronic renal disease, and cerebrovascular disease; and clinical variables of pulse rate > or = 110 beats/min, systolic blood pressure < 100 mm Hg, altered mental status, and arterial oxygen saturation < 90%). Patients with none of these factors were defined as low risk. The 30-day mortality rates for low-risk patients were 0.6%, 1.5%, and 0% in the derivation, internal validation, and external validation samples, respectively. The rates of nonfatal adverse medical outcomes were less than 1% among low-risk patients across all study samples.

Conclusions: This simple prediction rule accurately identifies patients with pulmonary embolism who are at low risk of short-term mortality and other adverse medical outcomes. Prospective validation of this rule is important before its implementation as a decision aid for outpatient treatment.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Aged
  • Aged, 80 and over
  • Cohort Studies
  • Decision Support Techniques
  • Discriminant Analysis
  • Female
  • Humans
  • Male
  • Middle Aged
  • Pennsylvania / epidemiology
  • Predictive Value of Tests*
  • Probability
  • Pulmonary Embolism / classification*
  • Pulmonary Embolism / diagnosis
  • Pulmonary Embolism / epidemiology*
  • Pulmonary Embolism / therapy
  • Registries
  • Reproducibility of Results
  • Retrospective Studies
  • Risk Factors
  • Severity of Illness Index
  • Survival Analysis