Elsevier

Thrombosis Research

Volume 130, Issue 3, September 2012, Pages 327-333
Thrombosis Research

Regular Article
LR–PED Rule: Low Risk Pulmonary Embolism Decision Rule – A new decision score for low risk Pulmonary Embolism

https://doi.org/10.1016/j.thromres.2012.03.010Get rights and content

Abstract

Introduction

When accurately diagnosed, non-massive Pulmonary embolism (PE) has a low mortality rate. However, some patients initially considered to be low risk show progressive deterioration. This research aims at developing a preliminary score that allows detection of low risk patients potentially eligible for outpatient treatment.

Materials and Methods

Retrospective cohort study involving 142 asymptomatic/mildly symptomatic and hemodynamically stable patients with PE and no clinical/echocardiographic signs of right ventricular dysfunction. Collected data: risk factors, analytic/gasometric parameters, admission echocardiogram, thoracic CT angiography. Patients followed for 6 months. Primary endpoint: 1-month all-cause mortality. Secondary endpoints: Intrahospital and 6-month all-cause mortality. A score designed for identification of very low risk patients eligible for outpatient treatment was developed and its prognostic accuracy compared to that of the Geneva and simplified PESI models.

Results

A score for predicting 1-month mortality (Low Risk Pulmonary Embolism Decision [LR-PED] rule) was obtained using Binary Logistic Regression, including: age, atrial fibrillation at admission, previous heart failure, admission heart rate, creatinine, glycaemia, troponin I and C-reactive protein at admission. ROC curve analysis assessed its overall accuracy for predicting 1-month, intrahospital and 6-month mortality (AUC = 0.756, 0.763 and 0.854, respectively). Compared to Geneva and simplified PESI, the LR-PED rule showed higher sensitivity and negative predictive value for the detection of the lowest risk patients. The net reclassification improvement index revealed significant successful upward risk reclassification by the LR-PED model of patients reaching primary or secondary outcomes.

Conclusions

LR-PED rule seems more attractive than Geneva or simplified PESI in its ability to identify patients at very low mortality risk who would be potentially eligible for outpatient treatment. Prospective validation of this score in larger cohorts is mandatory before its potential implementation.

Introduction

Pulmonary embolism (PE) is a common and potentially lethal condition. Despite diagnostic advances in the last decades, delays in PE diagnosis are common and represent a very important issue, leading some authors to suggest public health and educational initiatives to improve efficiency in PE diagnosis [1].

Massive PE is one of the most prevalent causes of sudden death and this form of presentation is frequently the first manifestation of that condition [2]. However, non-massive PE is the most common form of presentation of PE, bearing a much lower mortality rate when appropriate anticoagulant therapy is started early (less than 5% in the first 3–6 months of treatment) [3]. Still, some patients initially considered to be low risk show progressive deterioration of their clinical condition, warranting the postponement of their discharge, with exponential increase in health care costs and hospital-acquired infection risk.

Over the past decade, subcutaneously low molecular weight heparins have replaced much of IV unfractionated heparin therapy and have facilitated outpatient deep vein thrombosis (DVT) therapy. Although most patients with acute PE remain hospitalized during initial therapy, some may be suitable for partial or complete outpatient management. However, a very small but significant proportion of patients with low risk acute PE will die or have hemorrhagic or thromboembolic complications during the initial therapy period or the subsequent months [4], [5], reinforcing the need for reliable prognostic information at presentation in order to risk stratify patients for ambulatory treatment. The new oral anticoagulants Dabigatran [6] and Rivaroxaban [7] have emerged as new ambulatory therapeutics for patients with venous thromboembolism.

Therebeing considerable interest in the identification of patients eligible for outpatient treatment, several authors have studied the application of particular analytical, clinical or angiographic prognostic markers [8], [9] or renowned PE risk scores for the prognostic stratification of low risk PE patients. Although the Well's criteria and the PERC rule have never been shown to have prognostic value in acute PE, the Geneva score, initially and primarily developed for diagnostic purposes [10], [11], has shown reasonable prognostic stratification accuracy in subsequent studies [4] and the Pulmonary Embolism Severity Index (PESI) score showed modest prognostic superiority compared to the Geneva rule [5]. Despite these advances, active research is ongoing for the development of new scores that can identify low risk acute PE patients with greater specificity, in order to reduce the tremendous health care costs associated to the inpatient treatment of this condition.

Therefore, this investigation aims at developing a new and improved score that allows detection of very low risk PE patients who are eligible for outpatient treatment.

Section snippets

Study Design

Retrospective cohort study that attempted to include all patients with a diagnosis of low risk acute PE between January 1, 2007, and April 30, 2011. Using collected baseline data at the time of PE diagnosis and outcome data from this cohort, we retrospectively assessed the Geneva and simplified PESI scores for all patients and their prognostic accuracy for predicting intrahospital, 1 month and 6 month mortality risk. We compared the ability of each score to predict primary or secondary endpoints

Results

Overall characteristics of the study population are shown on Table 1.

Intrahospital mortality rate was 11.3%, while 1-month and 6-month all cause mortality rates were 14.1% and 22.5%, respectively.

Discussion

Our sample included 142 hemodynamically stable patients with non-massive PE, asymptomatic or mildly symptomatic six hours following admission. Hypotension at any time during those first six hours or the documentation of clinical or echocardiographic signs of right ventricular dysfunction/overload were exclusion criteria, as these patients do not benefit from an early discharge. Patients in our sample were older and had a higher prevalence of most comorbid illnesses compared to those in the PESI

Conclusion

Given the enormous burden of venous thromboembolism in the developed world in terms of public healthcare cost, the identification of very low risk patients eligible for early discharge and outpatient treatment is a very important issue. This priority had not been entirely and successfully addressed by existing risk scores, including PESI and Geneva.

The Low Risk Pulmonary Embolism Decision (LR-PED) score seems more attractive in its ability to identify patients at very low mortality risk who

Conflict of Interest Statement

None.

Acknowledgments

Financial support: none.

Writing assistance: none.

References (29)

  • R.M. Subramaniam et al.

    The Geneva prognostic score and mortality in patients diagnosed with pulmonary embolism by CT pulmonary angiogram

    J Med Imaging Radiat Oncol

    (2009)
  • S. Schulman et al.

    Dabigatran versus warfarin in the treatment of acute venous thromboembolism

    N Engl J Med

    (Dec. 10 2009)
  • Einstein Investigators et al.

    Oral rivaroxaban for symptomatic venous thromboembolism

    N Engl J Med

    (Dec. 23 2010)
  • I. Mastora et al.

    Severity of acute pulmonary embolism: evaluation of a new spiral CT angiographic score in correlation with echocardiographic data

    Eur Radiol

    (2003)
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