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Preventing venous thromboembolism in long-term care residents: Cautious advice based on limited data

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ABSTRACTIn hospitalized medical patients, randomized trials have established that anticoagulant prophylaxis has an acceptable benefit-to-risk ratio: ie, it lowers the incidence of clinically silent and symptomatic venous thromboembolism (VTE), including fatal pulmonary embolism, more than it raises the risks of bleeding and other complications. However, no similar trials have been done in long-term care residents. More research is needed to ascertain which long-term care residents would benefit most from VTE prophylaxis. In the absence of evidence-based guidelines, we advocate a selective approach.

KEY POINTS

  • Assessment of VTE risk and consideration of need for anticoagulant prophylaxis in long-term care residents are based on indirect data, derived primarily from studies of acutely ill hospitalized medical patients.
  • Drugs and devices for thromboprophylaxis have been studied in medical and surgical populations, but issues of efficacy and safety are likely to also pertain to long-term care residents.
  • Thromboprophylaxis should be considered for long-term care residents if they are definitely at increased risk of VTE—ie, if they have an acute exacerbation of congestive heart failure or chronic obstructive pulmonary disease; acute inflammatory disease; acute infection; active cancer; or immobility and prior VTE.


 

References

Randomized trials that included more than 20,000 medical patients have shown that anticoagulant therapy is safe and effective in preventing venous thromboembolism (VTE), ie, deep vein thrombosis and pulmonary embolism.

However, these trials were done in hospitalized patients, who typically had an acute medical illness and who, if eligible, received a short (7- to 10-day) course of anticoagulant prophylaxis.

Little attention has been given to VTE prophylaxis in residents of long-term care facilities. These patients have risk profiles similar to those of hospitalized medical patients. Some of them may have been transferred from an acute care hospital. In addition, most are elderly, and many have reduced mobility and are at risk for illnesses such as stroke and cardiorespiratory insufficiency, which increase the risk of VTE.

VTE in residents of long-term care facilities is a growing concern. By some estimates, by the year 2030 more than 20% of the US population (70.2 million people) will be over 65 years of age.1 Of those who reached age 65 in 1990, an estimated 43% will enter a nursing home at least once before they die—32% for 3 months, 24% for at least a year, and 9% for at least 5 years.2

Against this background, the objectives of this review are to consider:

  • The scope of the problem of VTE in long-term care residents
  • Why VTE prophylaxis is often overlooked in medical patients
  • Evidence—or lack of evidence—for the safety and efficacy of VTE prophylaxis in long-term care residents and other medical patients
  • Available options for VTE prophylaxis
  • Which long-term care residents should or should not be considered for prophylaxis.

THE TRUE SCOPE OF THE PROBLEM IS UNKNOWN

The incidence of acute VTE among nursing home residents is reported to be 1.3 events per 100 person-years.3 About 8% of cases of pulmonary embolism and 10% of cases of deep venous thrombosis in the elderly are in nursing home residents.4

However, only 20% of patients with VTE have typical symptoms such as leg pain and swelling or acute dyspnea and chest pain, while 80% have no symptoms.5

Furthermore, deep venous thrombosis is more likely to be clinically silent in patients whose mobility is impaired, such as nursing home residents, as the symptoms arising from obstruction of venous flow are more pronounced with walking.

Pulmonary embolism is also underdiagnosed in this group. An autopsy study of 234 nursing home residents found undiagnosed pulmonary embolism to be the cause of death in 8%, and 40% of cases of pulmonary embolism were not suspected before the patient died.6 Yet pulmonary embolism has a higher case-fatality rate in the elderly than in younger patients, particularly when elderly patients have comorbidities.7

A reason why the diagnosis is so often missed is that pulmonary embolism can present atypically in the elderly, with syncope being more common and tachycardia being less common than in younger patients.8

Since so many cases of VTE are clinically silent and most long-term care residents who die do not undergo autopsy, the true scope of VTE as a clinical problem in these patients is unknown. Consequently, the best way to diagnose, prevent, and treat VTE is also unclear.

WHY IS VTE PREVENTION SO OFTEN OVERLOOKED IN MEDICAL PATIENTS?

In general, nonsurgical patients receive suboptimal thromboprophylaxis. National and international chart audits and cross-sectional studies show that only 16% to 33% of hospitalized medical patients at risk for VTE receive appropriate anticoagulant prophylaxis.9 Though no audits in long-term care facilities have been published, the rate of appropriate prophylaxis is likely comparable to or possibly less than that in medical patients in the hospital. In contrast, in surgical patients the rate is much higher—up to 90%.10,11

Why is VTE prophylaxis so underused in medical patients?

One reason is that we do not really know the baseline risk of VTE in medical patients, particularly in those with chronic illness who require long-term care.12 This is relevant because, in the absence of data about patients’ baseline risk, anticoagulant prophylaxis should be ordered selectively, as it poses known risks of bleeding. The risk is greater in elderly people with comorbidities, as are the associated costs.

In addition, relatively few studies have assessed thromboprophylaxis in medical patients, especially in residents of long-term care facilities.

Another reason is that we lack practice guidelines for patients who need long-term care. The well-accepted guidelines from the American College of Chest Physicians (ACCP) cite advanced age and immobility as risk factors for VTE and strongly recommend prophylaxis in acutely ill medical patients who have limited mobility and an additional risk factor such as infection or cancer.13 Though elderly residents of long-term care facilities may share some of these risk factors, the ACCP guidelines make no specific recommendations for this group.

The attitudes of health care professionals may also pose a barrier. Lloyd et al (unpublished data, 2009) surveyed 1,601 health care professionals in Ontario, Canada, in 2007, to assess potential barriers to anticoagulant prophylaxis in hospitalized medical patients. Respondents cited concerns about the risk of bleeding from anticoagulants, lack of clear indications and contraindications for anticoagulant prophylaxis, and lack of time to consider VTE prophylaxis in every patient. (They did not, however, cite disagreement with guidelines or patient discomfort from subcutaneous anticoagulant injections as barriers.) It is reasonable to assume that these attitudes may also pose a problem in long-term care residents.

Finally, no randomized trials have evaluated the efficacy and safety of anticoagulant drugs or mechanical methods of prophylaxis in long-term care residents. Studies have shown that a short course (7–10 days) of an anticoagulant drug effectively prevents VTE in acutely ill patients, but the efficacy of an extended course in patients with chronic illness who require long-term care is not clear. Therefore, recommendations about thromboprophylaxis in long-term care residents should be made with the caveat that they are based on indirect evidence from other patient groups. This is a considerable limitation.

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