Mortality rates and risk factors for asymptomatic deep vein thrombosis in medical patients

Summary

The clinical importance of asymptomatic proximal and distal deep vein thrombosis (DVT) remains uncertain and controversial. The aim of this retrospective,post-hoc analysis was to examine mortality and risk factors for development of proximal DVT in hospitalized patients with acute medical illness who were recruited into a randomized, prospective clinical trial of thromboprophylaxis with dalteparin (PREVENT).We analyzed 1738 patients who had not sustained a symptomatic venous thromboembolic event by Day 21 and who had a complete compression ultrasound of the proximal and distal leg veins on Day 21. We examined the 90-day mortality rates in patients with asymptomatic proximal DVT (Group I, N = 80), asymptomatic distal DVT (Group II, N = 118) or no DVT (Group III, N = 1540).The 90-day mortality rates were 13.75%, 3.39%, and 1.92% for Groups I–III, respectively. The difference in mortality between Group I and Group III was significant (hazard ratio 7.63, 95% CI = 3.8–15.3;p < 0.0001),whereas the difference between Groups II and III did not reach significance (hazard ratio 1.36, 95% CI = 0.41–4.45).The association of asymptomatic proximal DVT with increased mortality remained highly significant after adjusting for differences in baseline demographics and clinical variables. Risk factors significantly associated with the development of proximal DVT included advanced age (p = 0.0005), prior DVT (p = 0.001), and varicose veins (p = 0.04). In conclusion, the high mortality rate in patients with asymptomatic proximal DVT underscores its clinical relevance and supports targeting of asymptomatic proximal DVT as an appropriate endpoint in clinical trials of thromboprophylaxis.

Keywords

Venous embolism - deep vein thrombosis - proximal - prevention - dalteparin

• References

• 1 Geerts WH, Heit JA, Clagett GP. et al Prevention of venous thromboembolism. Chest 2001; 119 (Suppl. 01) 132S-75S.
• 2 Haas SK. Venous thromboembolic risk and its prevention in hospitalized medical patients. Semin Thromb Hemost 2002; 28: 577-84.
• 3 Hyers TM, Agnelli G, Hull RD. et al Antithrombotic therapy for venous thromboembolic disease. Chest 2001; 119 (Suppl. 01) 176S-93S.
• 4 Kakkar VV, Howe CT, Flanc C. et al Natural history of postoperative deep-vein thrombosis. Lancet 1969; 2: 230-2.
• 5 Meignan M, Rosso J, Gauthier H. et al Systematic lung scans reveal a high frequency of silent pulmonary embolism in patients with proximal deep venous thrombosis. Arch Intern Med 2000; 160: 159-64.
• 6 Kearon C. Natural history of venous thromboembolism. Circulation 2003; 107 (23) (Suppl. 01) I22-30.
• 7 Moser KM, LeMoine JR. Is embolic risk conditioned by location of deep venous thrombosis?. Ann Intern Med 1981; 94 4 Pt 1 439-44.
• 8 Monreal M, Ruiz J, Fraile M. et al Prospective study on the usefulness of lung scan in patients with deep vein thrombosis of the lower limbs. Thromb Haemost 2001; 85: 771-4.
• 9 Girard P, Decousus M, Laporte S. et al Diagnosis of pulmonary embolism in patients with proximal deep vein thrombosis: specificity of symptoms and perfusion defects at baseline and during anticoagulant therapy. Am J Respir Crit Care Med 2001; 164: 1033-7.
• 10 Vaitkus PT, Leizorovicz A, Goldhaber SZ. Rationale and design of a clinical trial of a low-molecular- weight heparin in preventing clinically important venous thromboembolism in medical patients: the prospective evaluation of dalteparin efficacy for prevention of venous thromboembolism in immobilized patients trial (the PREVENT study). Vasc Med 2002; 7: 269-73.
• 11 Leizorovicz A, Cohen AT, Turpie AGG. et al A randomized, placebo-controlled trial of dalteparin for the prevention of venous thromboembolism in acutely ill medical patients. Circulation 2004; 110: 874-9.
• 12 Decousus H, Leizorovicz A, Parent F. et al A clinical trial of vena caval filters in the prevention of pulmonary embolism in patients with proximal deep-vein thrombosis. N Engl J Med 1998; 338: 409-15.
• 13 Goldhaber SZ, Visani L, De Rosa M. Acute pulmonary embolism: clinical outcomes in the International Cooperative Pulmonary Embolism Registry (ICOPER). Lancet 1999; 353: 1386-9.
• 14 Kearon C, Julian JA, Newman TE. et al Noninvasive diagnosis of deep venous thrombosis. McMaster Diagnostic Imaging Practice Guidelines Initiative. Ann Intern Med 1998; 128: 663-7.