Prevention of Venous Thromboembolism in the Elderly
Gena Piliotis, MD1
William H. Geerts, MD1,2
1Departments of Medicine and
2Health Policy, Management and Evaluation;
Sunnybrook & Women's College Health Sciences Centre,
University of Toronto, Toronto, ON.
Abstract
Venous thromboembolism is predominantly a disease of the elderly. However, geriatric patients often fail to receive appropriate thromboprophylaxis because of under-recognition of age as an important risk factor for thromboembolism and perhaps, in part, because of the perception of a greater potential for bleeding complications associated with anticoagulants. Although there is a paucity of literature specifically addressing thromboprophylaxis in geriatric populations, it is suggested that elderly patients with thromboembolic risk factors receive similar prophylaxis to that recommended for younger patients with the same risk factors. Routine prophylaxis should, therefore, be provided to elderly patients undergoing general, urologic and gynecologic surgery, neurosurgery, hip or knee arthroplasty, surgery for hip fracture, to those who experience major trauma, and to elderly patients with acute medical illnesses plus additional risk factors.
Introduction
Venous thromboembolic disease (VTED), which includes both deep vein thrombosis (DVT) and its primary complication, pulmonary embolism (PE), is a very important condition for health professionals who provide care for the elderly (Table 1).1,2 Increasing age is a strong risk factor for venous thromboembolism.3-5 Below age 40, the annual incidence of VTED is approximately 1 per 10,000 while, over the age of 75, the risk is almost 1 per 100 per year.2,6-8 Some of this age-related risk is due to an increased prevalence of major surgery, malignancy, stroke and other medical illnesses in the elderly. However, thrombosis risk increases with age independent of these additional factors (Table 2).9 Aging is associated with increased levels of procoagulant molecules, reduced levels of endogenous clotting inhibitors and evidence of increased thrombin generation.10 Therefore, even the healthy elderly have an acquired prothrombotic state.
Increasing age is clearly additive to other thromboembolic risk factors--for any given factor, the elderly have a greater prevalence of thromboembolic complications. For example, although the traditional molecular hypercoagulability disorders generally manifest by middle age, the more recently discovered (and much more common) abnormalities, such as factor V Leiden, prothrombin 20210A, and hyperhomocysteinemia, are associated with an age-related increased risk for VTED.11
VTED is more dangerous for the elderly than for younger patients. The case fatality rate for PE has been shown to depend on the size of the embolus and the underlying cardiorespiratory reserve (often reduced in the elderly), as well as on increased age.12,13
Increased age is under-appreciated as a risk factor for thrombosis.14,15 There is also a widespread perception that the risk of bleeding is increased in geriatric patients.16,17 This concern is certainly appropriate when full-dose oral anticoagulants are used18,19 but not for heparin or low molecular weight heparins.20,21 Clinical bleeding complications are very uncommon with use of anticoagulant prophylaxis both in controlled trials and in clinical practice.
Since it is not possible to predict whether or not a specific patient will develop a clinically-important thromboembolic event related to hospitalization, the prevention of VTED is essential for elderly patients at risk. Patients with chronic, degenerative diseases or cognitive impairment should also be strongly considered for thromboprophylaxis. How does one decide whether or not to provide prophylaxis for such patients? Our rule is as follows: if we would investigate an elderly, severely impaired patient for clinically-suspected DVT or PE and treat him/her if acute thromboembolism is found, then it is appropriate to provide effective prophylaxis both to reduce the morbidity and mortality of thromboembolism and because screening for asymptomatic DVT is ineffective