Routine home treatment of deep vein thrombosis

Heparin therapy for at least five days followed by long term oral anticoagulation has been the standard care for patients with acute deep vein thrombosis.¹ Initiation of treatment usually requires patients to be admitted to hospital for administration of intravenous unfractionated heparin and dose adjustment according to the results of the activated partial thromboplastin time. However, the emergence of low molecular weight heparin as a safe, effective, and convenient treatment for deep vein thrombosis has challenged the need for routine admission. A paper in this week's issue adds to the evidence that home treatment of deep vein thrombosis is now routinely feasible (p 1212).²

Aggregate data from a recent meta-analysis of randomised trials,³ also summarised in a Cochrane systematic review,⁴ show that low molecular weight heparin is at least as effective and safe as unfractionated heparin for the initial treatment of deep vein thrombosis. Unlike unfractionated heparin, which is usually given by continuous intravenous infusion, low molecular weight heparin can be given subcutaneously in a fixed, weight adjusted dose without the need for laboratory monitoring. This has simplified the initial management of deep vein thrombosis and facilitated the potential for home treatment. The safety and efficacy of low molecular weight heparin for home treatment of proximal deep vein thrombosis have subsequently been confirmed in several randomised trials.^5–8 Home treatment has the additional advantages of greater efficiency of healthcare delivery and improved quality of life for patients.⁹

Nevertheless, uncertainty remains about the optimal selection of patients for home treatment. In the randomised trials up to half of outpatients presenting with proximal deep vein thrombosis were ineligible for inclusion because of a history of recurrent venous thromboembolism, concomitant symptomatic pulmonary embolism, coexisting conditions requiring hospitalisation or associated with an increased risk of bleeding, or concerns about the feasibility of administering low molecular weight heparin at home.^5–8 Even among patients randomised to home treatment, up to half were initially admitted to hospital,⁵,⁶,⁸ and in one trial 25% of patients randomised to home treatment received all their low molecular weight heparin in hospital.⁵ This has led to questions about the generalisability of these trials to everyday clinical practice¹⁰ and may account for the reluctance of some centres to consider home treatment.

In this issue Schwarz et al report their recent experience with home treatment of acute deep vein thrombosis (p 1212).² In a cohort of 117 consecutive outpatients with confirmed proximal or distal deep vein thrombosis, three patients (2.6%; 95% confidence interval 0.9% to 7.1%) were excluded from home treatment based on their medical condition, while an additional 22 patients (18.8%; 12.2% to 27.1%) were admitted because they could not inject the heparin or undergo daily testing at home or presented outside working hours. In the 92 patients (78.6%; 70.1% to 85.7%) treated at home, no episodes of clinical pulmonary embolism or major bleeding were observed during three months of follow up.

These data add to a growing body of evidence supporting the safety and feasibility of routinely treating patients with acute deep vein thrombosis at home. In one of the first studies to evaluate this question outside a randomised trial, Lindmarker et al showed that about 80% of 434 consecutive patients could be safely treated at home for at least a part of the acute treatment phase.¹¹ These findings were confirmed in prospective cohort studies from Canada¹²,¹³ and the United Kingdom¹⁴ involving a combined total of 1693 consecutive patients, of whom about 80% were treated at home without ever being admitted. The incidences of recurrent venous thromboembolism (3.6-6.7%), major bleeding (0-2.2%), and death (0.9-8.7%) in these studies were comparable with those reported in the trials of highly selected patients.^5–8

Nevertheless, several caveats must be borne in mind when applying the results of these studies to everyday practice. Firstly, even though 80% of outpatients with acute deep vein thrombosis are eligible for home treatment, 20% remain who may be better treated in hospital, for medical or logistic reasons. There are four main groups of patients who seem to be unsuitable for home treatment. These are patients with high thrombotic load (massive leg thrombosis or symptomatic pulmonary embolism); those at increased risk of bleeding (active bleeding, recent surgery, active peptic ulcer disease, advanced liver disease, thrombocytopenia, or familial bleeding disorder); those for whom regimens of low molecular weight heparin are poorly defined (body weight <45 kg or >100 kg, children, pregnant women, people with renal impairment); and those with a medical disorder that requires admission.

Secondly, successful home treatment requires adequate resources to establish a multidisciplinary clinical service with expertise in diagnosing and managing venous thromboembolism. This service should be capable of providing rapid clinical assessment, including identifying patients unsuitable for home treatment; diagnostic testing to confirm or refute the diagnosis; and home support when required. Patients should also be educated about venous thromboembolism and its complications, self injection with low molecular weight heparin, the potential complications of anticoagulant therapy, and how to access help, particularly outside working hours. Thirdly, despite the availability of effective therapies, venous thromboembolism remains a potentially fatal disease, and some patients will inevitably die during home treatment. Although there is no evidence of an excess of adverse outcomes or death in patients treated at home, the safety and effectiveness of home treatment programmes in individual centres need to be monitored.

Papers p 1212