Elsevier

The Lancet

Volume 360, Issue 9349, 14 December 2002, Pages 1914-1920
The Lancet

Articles
Diagnostic strategy for patients with suspected pulmonary embolism: a prospective multicentre outcome study

https://doi.org/10.1016/S0140-6736(02)11914-3Get rights and content

Summary

Background

We designed a prospective multicentre outcome study to evaluate a diagnostic strategy based on clinical probability, spiral CT, and venous compression ultra-sonography of the legs in patients with suspected pulmonary embolism (PE). The main aim was to assess the safety of withholding anticoagulant treatment in patients with low or intermediate clinical probability of PE and negative findings on spiral CT and ultrasonography.

Methods

1041 consecutive inpatients and outpatients with suspected PE were included. Patients with negative spiral CT and ultrasonography and clinically assessed as having a low or intermediate clinical probability were left untreated. Those with high clinical probability underwent lung scanning, pulmonary angiography, or both. All patients were followed up for 3 months.

Findings

PE was diagnosed in 360 (34–6%) patients; 55 had positive ultrasonography despite negative spiral CT. Of 601 patients with negative spiral CT and ultrasonography, 76 were clinically assessed as having a high probability of PE; lung scanning or angiography showed PE in four (5·3% [95% Cl 1·5–13·1]). The remaining 525 patients were assessed as having low or intermediate clinical probability, and 507 of them were not treated. Of these patients, nine experienced venous thromboembolism during follow-up (1·8% [0·8–3·3]). The diagnostic strategy proved inconclusive in 95 (9·1%) patients, and pulmonary angiography was done in 74 (7·1%).

Interpretation

Withholding of anticoagulant therapy is safe when the clinical probability of PE is assessed as low or intermediate and spiral CT and ultrasonography are negative.

Published online Nov 26, 2002 http://image.thelancet.com/extras/02art2278web.pdf

Introduction

The diagnosis of pulmonary embolism (PE) remains difficult in clinical practice, because clinical findings are non-specific1 and all available objective tests have practical or clinical limitations.2, 3 Pulmonary angiography remains the gold-standard diagnostic test but it is invasive4 and difficult to interpret,5, 6 it can give false-negative results,4 and it is not readily available in many centres. Various combinations of non-invasive aids to diagnosis, including assessment of clinical probability of PE, plasma D-dimer concentrations, ventilation-perfusion (V/Q) lung scanning, and venous compression ultrasonography of the legs, have been developed and validated to reduce the need for pulmonary angiography.2, 7 Nevertheless, this procedure is still necessary in around 10% of patients with suspected PE even when a combination of all available non-invasive diagnostic tests is used.7

Contrast-enhanced spiral computed tomography (spiral CT) of the chest was introduced 10 years ago for the diagnosis of PE. Initially, sensitivity of 100% and specificity of 96% were reported in 42 patients with suspected PE who underwent both spiral CT and pulmonary angiography.8 The sensitivity reported in subsequent studies, however, ranged from 53% to 100%, and specificity from 81% to 100%.9 Accordingly, a thrombus found on spiral CT in a segmental or more proximal pulmonary artery is generally deemed to establish the diagnosis of PE.9 However, the sensitivity of spiral CT remains too low for PE to be ruled out without additional tests.10 The combination of spiral CT and leg compression ultrasonography might have better sensitivity than spiral CT alone, and normal findings from both of these investigations might safely exclude PE.10, 11 There has been no prospective study in a large population of patients with suspected PE and normal findings on spiral CT and venous ultrasonography.9

We designed a prospective multicentre outcome study to assess a diagnostic strategy consisting of a combination of clinical probability of PE, spiral CT, and ultrasonography in patients with suspected PE. The main aim was to assess the safety of withholding anticoagulant therapy in patients with low or intermediate clinical probability of PE and negative findings on spiral CT and leg ultrasonography. All patients were followed up for 3 months. Patients and methods

Section snippets

Patients

1902 consecutive inpatients and outpatients with clinically suspected PE were considered for inclusion in the study in 14 centres in France between June, 1999, and December, 2000. Inclusion criteria were clinical suspicion of PE and age 18 years or older. 861 patients were excluded because of pregnancy (n=40), renal insufficiency assessed by a serum creatinine concentration of more than 200 (imol/L (n=87), known allergy to contrast media (n=76), refusal or inability to consent to the study

Study population

Between September, 1999, and December, 2000, 1041 patients with suspected PE (median age 66 years, range 18–97) were enrolled at 14 centres. The overall frequency of PE (ie, patients with positive spiral CT, positive ultrasonography, high-probability V/Q lung scan, positive pulmonary angiography, or any combination of these) in the study population was 34·6% (360 patients: four with negative findings by the diagnostic strategy; 345 with positive findings; 11 with inconclusive findings). The

Discussion

In this study, we found a low rate of venous thromboembolic events during 3 months of follow-up in patients with suspected PE who were not given anticoagulant therapy on the basis of negative findings with spiral CT and ultrasonography, and a low or intermediate clinical probability. These results are based on 507 patients, representing nearly 50% of the study population. The practical relevance of these results is supported by the design of this multicentre study, which included a broad range

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