Travel and the risk of symptomatic venous thromboembolism.

Whether long-distance travel and symptomatic venous thromboembolism (VTE) are associated is debated. On the basis of the available literature a fair risk estimate cannot be obtained. We estimated an accurate odds ratio for the relationship between recent travelling and symptomatic VTE. From three case-control studies consisting of 788 and 170 patients with clinically suspected deep vein thrombosis (DVT) and 989 patients with clinically suspected pulmonary embolism (PE) referred for diagnostic work-up, a pooled odds ratio for the relation between travel and symptomatic VTE was calculated. Cases were patients in whom the diagnosis was confirmed according to a diagnostic management strategy, whereas controls were patients in whom the diagnosis was excluded and who had an uneventful clinical follow-up. Patients were seen in the period April 1997 to September 2000. Travel history was recorded prior to diagnostic work-up. The pooled odds ratio for the association between any travel and symptomatic venous thromboembolism was 0.9 (95% CI: 0.6-1.4). The median travel time was 7 h (quartile range 4 to 10 h). Separate analyses performed for different types of transport (plane, car, bus or train) yielded comparable odds ratios. The analysis for duration of travelling showed an increased odds ratio of 2.5 (95% CI: 1.0-6.2) in the category of 10-15 h of travelling. This study shows that the average traveller does not have an increased risk for symptomatic venous thromboembolism. Only very long travelling (more than 10 h) may be associated with venous thromboembolic disease.

Single-detector helical computed tomography as the primary diagnostic test in suspected pulmonary embolism: a multicenter clinical management study of 510 patients.

BACKGROUND: Helical computed tomography (CT) is a readily available tool for diagnosing pulmonary embolism (PE); however, its role in the management of patients with clinically suspected PE has not been fully established. OBJECTIVE: To determine the effectiveness and safety of using helical CT of the pulmonary arteries as the primary diagnostic test in patients with suspected PE. DESIGN: Multicenter, prospective clinical outcome study. SETTING: Two academic hospitals and one large teaching hospital in the Netherlands. PATIENTS: 510 consecutive inpatients and outpatients with clinically suspected PE followed for 3 months. INTERVENTIONS: Patients underwent helical CT of the pulmonary arteries within 24 hours after presenting with signs and symptoms of PE. If CT results were normal or inconclusive, compression ultrasonography was performed on the same day as CT and repeated on days 4 and 7 if findings on the first compression ultrasonography were normal. When CT or compression ultrasonography results were positive for thromboembolism, anticoagulation was started. Anticoagulation was not started when results of CT were negative for PE or indicated an alternative diagnosis that explained the clinical signs and symptoms, or when results on serial compression ultrasonography were normal. MEASUREMENTS: Patients received instructions to report any symptoms or signs of PE or deep venous thrombosis (DVT) during the 3-month follow-up period. The authors performed compression ultrasonography or phlebography for suspected DVT and pulmonary angiography for suspected PE. RESULTS: Computed tomography identified PE in 124 of 510 patients (24.3%) and an alternative diagnosis in 130 patients (25.5%); CT scans were normal in 248 patients (48.6%). The CT scan could not be interpreted in 8 patients (1.6%) and was not obtained in 2. Compression ultrasonography revealed DVT in 2 patients at the first examination; findings on repeated compression ultrasonography at days 4 and 7 were normal. Mortality in the patients with normal helical CT scans was 4.1% (10 of 246 patients). No patients in this group died of fatal PE, 1 patient developed nonfatal PE, and venous thromboembolism occurred in 0.4% of these patients (95% CI, 0% to 2.2%). In the patients with alternative diagnoses, 1 patient had DVT on objective testing during follow-up. Mortality in this group was 21.5% (28 of 130 patients); in 1 of these patients, PE could not be confidently ruled out as a contributing cause of death. Venous thromboembolism occurred in 1.5% of these patients (CI, 0.2% to 5.6%). CONCLUSIONS: In patients with suspected PE, helical CT can be used safely as the primary diagnostic test to rule out PE. Serial compression ultrasonography has limited additional value.