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Is DVT prophylaxis warranted in the nonambulatory long-term care resident?

Caitilin Kelly, MD Bloomington, IN

------------------------------------------------------------------------ There are few data to support or refute the efficacy of prophylaxis for deep vein thrombosis (DVT) or venous thromboembolism (VTE) in the nonambulatory long-term care population without history of recent orthopedic surgery.

DVT formation is thought to occur due to vessel wall injury, venous stasis, and hypercoagulable state. Risk factors for venous thromboembolism were elucidated recently by Heit et al1 and include surgery, trauma, nursing home or hospital confinement, chemotherapy, central venous catheter, pacemaker, superficial vein thrombosis, and neurological disease with extremity paresis. The authors found that nursing home–acquired DVT or pulmonary embolism (PE) was associated with an odds ratio (OR) of 10.64, and hospital–acquired DVT or PE was associated with an OR of 464.95. However, patients and nursing home residents were grouped as “institutionalized” when the population was divided into those with and without surgery in the preceding 90 days. Separate results for nursing home residents with and without recent surgery were not reported. In the institutionalized group, the OR for those with history of surgery was 21.72, and the OR for those without surgery was 7.98.

While there are no studies that directly address the risk of DVT/PE in the nursing home, clinicians remain concerned for their long-term care patients. Two approaches for patients presumed at high risk have been devised, namely serial surveillance and prophylaxis. Regarding surveillance, impedance plethysmography and duplex ultrasonography have been studied in patients after orthopedic surgery. They have been shown to have only moderate sensitivity and positive predictive value in asymptomatic, high-risk patients.2

Prophylaxis for DVT has included graded compression stockings, intermittent pneumatic compression devices, warfarin, low-molecular-weight heparin (LMWH), and low-dose unfractionated heparin (LDUH). These agents have primarily been studied in the perioperative setting. With regard to nursing home residents, DVT prophylaxis studies with the above agents have exclusively looked at patients receiving rehabilitation post-hip or post-knee surgery,3-6 or following acute stroke.7 In these groups prophylaxis appears to be beneficial.

Additionally some studies have looked at DVT prophylaxis in those with acute medical illness in the hospital setting. Clagett et al2 reviewed this literature which looked at patients in the hospital for myocardial infarction (MI) or acute stroke. They concluded that for MI, low-dose unfractionated heparin or full anticoagulation reduced the incidence of VTE. They also recommended LDUH or LMWH for patients with acute stroke; however, the studies reviewed only maintained these regimens for 14 days.2 Samana and colleagues8 compared enoxaparin (LMWH) 40 mg/day or 20 mg/day to placebo in 1102 hospitalized patients with various acute medical illnesses. They found that enoxaparin 40 mg/day reduced the rate of proximal DVT.

To further complicate the issue, the recently published Pulmonary Embolism Prevention (PEP) trial provided some evidence that aspirin 160 mg daily may reduce the risk of PE and DVT in high-risk patients, specifically patients undergoing hip surgery or knee arthroplasty.9 Whether aspirin alone or the suggestions of any other studies evaluating antithrombotics in the rehabilitation setting can be extended to nonambulatory nursing home residents remains unclear. Further studies to answer this question are warranted given the size of this population.

An additional consideration is cost. While daily aspirin is inexpensive, unfractionated heparin, warfarin, and low-molecular-weight heparin are all relatively expensive when cost of medication and laboratory monitoring are combined. The Table indicates the monthly costs for the following prophylaxis medications. Figures do not include costs associated with nursing, laboratory monitoring, or adverse reactions. Graded compression stockings and intermittent compression devices are of significant cost as well. Should a pharmacologic or mechanical method for DVT prevention prove to be efficacious in the nursing home setting, cost analysis studies would also need to be completed.

Given the above considerations, our current practice is to provide DVT prophylaxis to nonambulatory nursing home residents without history of surgery in the preceding 90 days, who develop acute illness including but not limited to MI, pneumonia, and acute stroke. The primary agent used is unfractionated heparin 5000 units subcutaneously twice a day for the duration of the acute illness.

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References

1. Heit JA, Silverstein MD, Mohr DN, et al. Risk factors for deep vein thrombosis and pulmonary embolism: A population-based case control study. Arch Intern Med 2000;160(6):809-815.

2. Clagett GP, Anderson F, Geerts W, et al. Prevention of venous thromboembolism. Chest 1998;114:531S-560S.

3. Miric A, Lombardi P, Sculco TP. Deep vein thrombosis prophylaxis: A comprehensive approach for total hip and knee arthroplasty patient populations. Am J Orthop 2000;29(4):269-274.

4. Agu O, Hamilton G, Baker D. Graduated compression stockings in the prevention of venous thromboembolism. Br J Surg 1999;86(8):992-1004.

5. Imperiale TF, Speroff T. A meta-analysis of methods to prevent venous thromboembolism following total hip replacement. JAMA 1994;271(22):1780-1785.

6. Review: Heparin and mechanical devices reduce deep vein thrombosis in elderly patients having surgery for hip fracture. Evidence Based Medicine 1998;3:146.

7. Muir KW, Watt A, Baxter G, et al. Randomized trial of graded compression stockings for prevention of deep-vein thrombosis after acute stroke. QJM 2000;93(6):359-364.

8. Samana MM, Cohen AT, Darmon JY, et al. A comparison of enoxaparin with placebo for the prevention of venous thromboembolism in acutely ill medical patients. N Engl J Med 1999;341:793-800.

9. Prevention of Pulmonary Embolism Collaboration Group. Prevention of pulmonary embolism and deep vein thrombosis with low dose aspirin: Pulmonary Embolism Prevention (PEP) trial. Lancet 2000;355(9212):1295-1302.

Brian Heppard, MD, and Paul Katz, MD Monroe Community Hospital Rochester, NY

Annals of Long-Term Care - ISSN: 1524-7929 - Volume 9 - Issue 02 - February 2001