Venous thromboembolism (VTE) continues to be a common and potentially life-threatening problem, with an estimated incidence of at least 1 in 1000 persons per year. (1,2) VTE includes both deep venous thrombosis (DVT) and the resultant pulmonary embolism (PE). PE occurs in as many as 50% of patients with proximal DVT. (3)
Up to 300,000 persons die of acute PE annually in the United States. (1, 4) PE accounts for 5% to 10% of deaths among hospitalized patients. (5-9)
This Clinical Update summarizes the results of recent studies on VTE-related topics, including risk factors, prophylaxis, diagnostic imaging, and treatment.
PE usually has its origin in DVT of the legs. DVT that is above the knee is associated with increased risk of PE (Figure). (3)
A number of risk factors for VTE have been identified, such as major surgery, reduced mobility, cancer, and advanced age.3,4 Nursing home residency is an important risk factor, 10,11 and VTE-related mortality has been shown to be higher in nursing home residents than in community-dwelling persons. (12)
* Risk in nursing home residents: Leibson and colleagues (13) conducted a population-based study of nursing home residents in Minnesota. A multivariate analysis indicated that the risk of VTE was increased among those who had returned from a hospital (odds ratio [OR], 6.29); needed assistance with mobility-related activities, such as grooming (OR, 5.10); and required assistance with behavior (OR, 10.26). Interestingly, there was an inverse association between VTE risk and the number of years since first nursing home admission (OR, 0.64), which is the opposite of what would be expected on the basis of long-term immobility.
In addition, the authors compared their VTE cases with an incident cohort of nursing home residents in whom VTE was diagnosed. The incidence of VTE per 1000 person-years was higher in the cohort than in the study cases. Moreover, 62% of the episodes in the cohort were identified as PE, compared with 21% to 24% in the study cases.
The authors concluded that accurate identification of VTE among nursing home residents requires that these persons be followed up across institutional settings, and they suggested that the transition from acute to long-term care represents an important opportunity for preventing VTE. They also suggested that the need for assistance with mobility-related activities may represent a subset of nursing home residents for whom the risk of VTE is particularly significant.
* Minor injuries and VTE risk: Although major injury is a well-known risk factor for VTE, a recent study in the Netherlands suggests that certain minor injuries--specifically, minor leg injuries--also are associated with increased risk. Van Stralan and coworkers14 conducted a population-based case-control study that included 2471 patients with VTE (either DVT or PE) and 3534 controls. The risk of VTE was higher in persons who had had a minor leg injury in the preceding 3 months (adjusted OR, 5.1). The risk was highest in the 4 weeks after the injury and decreased sharply thereafter. Injuries involving other sites were not associated with increased risk.