Is Recent Travel a Set-up for DVT and PE?
Is Recent Travel a Set-up for DVT and PE?
ABSTRACT & COMMENTARY
Source: Ferrari E, et al. Travel as a risk factor for venous thromboembolic disease. Chest 1999;115:440-444.
The association between recent travel and venous thromboembolic disease (VTED) is often quoted, yet is based on case report and retrospective data in the literature. Recently, a French group undertook a case-control study to determine whether travel represents a risk factor for VTED. One hundred sixty patients admitted to a cardiology department with VTED comprised the case group, and were compared with 160 control patients hospitalized for a first event of another etiology (chest pain, hypertension, or syncope). Patients with concurrent mobility-limiting disease were excluded from the control group, as were patients on anticoagulant or antiplatelet therapy. "Recent travel" was defined as a trip that was made during the preceding four weeks, lasting greater than four hours, whether by plane, train, or automobile. All patients with VTED were screened for circumstance (post-surgery, bed rest, pregnancy, venous trauma, contraceptive pill, steroid therapy, known cancer, or known coagulation abnormality) or newly diagnosed coagulation abnormality (protein C or S deficiency, antithrombin III deficiency) that would predispose to VTED.
The case group had a significantly higher incidence of male gender (P = 0.04), history of VTED (P = 0.02), and obesity (P = 0.01). The latter variable was not operationally defined in the paper. The case group also had a markedly higher incidence of recent travel (25% vs 8%; P < 0.0001). The mean time between travel and first VTED symptoms in the study group was 12.6 ± 8.9 days. Looking at the 160 patients with VTED, 29 of the 39 patients with a history of recent travel had no other identifiable risk for VTED, whereas 46 of the 121 with VTED but without history of recent travel were similarly "idiopathic" (P = 0.001). Ferrari and colleagues conclude that recent travel, as they defined it, is a risk factor for VTED.
Comment by Richard Harrigan, MD
This paper is interesting and useful for a couple of reasons. First, it provides data suggesting that recent travel does predispose a patient to VTED. Second, it begins to answer the question "how recent is recent?" in that the mean time to VTED symptom onset was just under two weeks (although the range appears wide). Ferrari et al provide physiologic explanations justifying the role of recent travel as a cause for VTED. The argument can be made that at least some of those patients with VTED attributed to recent travel may have had an undiagnosed cancer. Indeed, Ferrari et al admit they sought to rule this out by "means of blood cell count,’ chest radiograph, abdominal examination, and pelvis ultrasound examination"—assumably not a case of all tests in all patients, and still an attempt to rule-out cancer with significant limitations. It would be interesting to follow those patients whose VTED was attributed to recent travel, and determine how many developed cancer within the follow-up period.
With regard to the development of venous thromboembolic disease (VTED), recent travel appears to be:
a. a risk factor only in cases of plane travel.
b. an independent risk factor for VTED.
c. defined as a journey within the last five years.
d. the most common risk factor for those patients traveling by car.
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