The Problem and the Need for Prevention

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are major health problems with potential serious outcomes. Acute PE may be fatal. Pulmonary hypertension can develop in the long term from recurrent PE. Often overlooked is postthrombotic chronic venous disease occurring as a result of DVT causing deep venous reflux or obstruction, with skin changes and ulceration causing an adverse impact on quality of life and escalation of health care costs. In North America and Europe, the annual incidence is approximately 160 per 1 00 000 for DVT, 20 per 1 00 000 for symptomatic nonfatal PE, and 5 per 1 00 000 for fatal autopsy-detected PE.^1–6 The prevalence of venous ulceration is at least 300 per 1 00 000 and approximately 25% are due to DVT.^7,8 Estimates of the overall annual costs of cumulative volume index vary from 600 to 900 million € (US$720 million-1 billion) in Western European countries,^9,10 representing 1% to 2% of the total health care budget, to 2.5 billion € (US$3 billion) in the United States. ¹¹

Virchow triad of factors that predispose to venous thromboembolism (VTE) are venous stasis, alterations in blood constituents, and changes in the endothelium; these are as true today as when postulated in the 19th century. Principal clinical predisposing factors are immobilization, trauma, surgery, malignancy, and previous history of venous thrombosis. ¹² Other predisposing factors are age, obesity, infection, the postpartum period, varicose veins, dehydration, and hormone therapy.^6,13–22 In the background for all of these is predisposition due to thrombophilia. ²³

Patients admitted to hospital, surgical or medical, are particularly at risk of VTE and the problem continues after discharge.^24–28 Without prophylaxis, the incidence of DVT is high and depends, among others, on age, number of risk factors, and type and duration of surgery. The annual number of VTE-related deaths in 6 European countries has been estimated as 3 70 000 and three-fourth of these was from hospital-acquired VTE. ²⁹

Although VTE is an appealing target for maximally effective prevention, there is still a low rate of appropriate prophylaxis worldwide, particularly for acute medically ill patients.^30–32 Continuing efforts to educate combined with hospital-wide protocols, ³³ local audits for VTE prevention, ³⁴ electronic alerts,^28,35 and use of clinical nurse specialists have been shown to result in a marked increase in appropriate application of guidelines. The use of electronic medical alerts is particularly effective.