Can extended anticoagulation prophylaxis after discharge prevent thromboembolism?

ILLUSTRATIVE CASE

A 67-year-old man with a history of type 2 diabetes, hypertension, and chronic congestive heart failure (ejection fraction = 30%) was admitted to the intensive care unit with a diagnosis of acute hypoxic respiratory failure. He was discharged after 10 days of inpatient treatment that included daily VTE prophylaxis with low-molecular-weight heparin (LMWH). Should he go home on VTE prophylaxis?

Patients hospitalized with nonsurgical conditions such as congestive heart failure, chronic obstructive pulmonary disease, sepsis, inflammatory bowel disease, or active cancers are at increased risk for VTE due to inflammation and immobility. In a US study of 158,325 hospitalized nonsurgical patients, including those with cancer, infections, congestive heart failure, or respiratory failure, 4% of patients developed deep vein thrombosis (DVT), 1.5% developed pulmonary embolism (PE), and 0.2% developed both DVT and PE, at a median time of 74 days after discharge.² Prophylaxis in medical inpatients reduces VTE incidence in the hospital by 50% to 75%, but the period of increased VTE risk after discharge is not well understood in medical patients.³ American College of Chest Physicians guidelines provide recommendations for the duration of prophylactic anticoagulation after major orthopedic surgeries but make no recommendation for medical patients.³ American Society of Hematology 2018 guidelines recommend against extending VTE prophylaxis after hospital discharge, including for patients with risk factors or chronic immobility.⁴

However, use of DOACs for short-term VTE prophylaxis as an alternative to LMWH in hospitalized patients is supported by a meta-analysis showing equivalent efficacy, safety, and cost-effectiveness.¹ The current study examined DOACs for extended postdischarge use.¹

STUDY SUMMARY

Significant benefit of DOACs demonstrated across 4 large trials

This meta-analysis of 4 large randomized controlled trials examined the safety and efficacy of 6 weeks of postdischarge DOAC thromboprophylaxis compared with placebo in 26,408 high-risk nonsurgical hospitalized patients.¹ Patients at least 40 years old were admitted with diagnoses that included New York Heart Association (NYHA) class III or IV congestive heart failure, active cancer, acute ischemic stroke, acute respiratory failure, or infectious or inflammatory disease. Study patients also had risk factors for VTE, including age 75 and older, obesity, chronic venous insufficiency, history of VTE, history of NYHA class III or IV congestive heart failure, history of cancer, thrombophilia, hormone replacement therapy, or major surgery within the 6 to 12 weeks before current medical hospitalization.

A recent meta-analysis sheds light on the benefits of extended postdischarge thromboprophylaxis in nonsurgical patients at high risk for VTE.

Patients were excluded if DOACs were contraindicated or if they had active or recent bleeding, renal failure, abnormal liver values, an upcoming need for surgery, or an indication for ongoing anticoagulation. Patients in 3 studies received 6 to 10 days of enoxaparin as prophylaxis during their inpatient stay. (The fourth study did not specify length of inpatient prophylaxis or drug used.) After discharge, patients were assigned to placebo or a regimen of rivaroxaban 10 mg daily, apixaban 2.5 mg twice daily, or betrixaban 80 mg daily for a range of 30 to 45 days. The primary outcome was the composite of total VTE and VTE-related death. A secondary outcome was the occurrence of nonfatal symptomatic VTE, and the primary safety outcome was the incidence of major bleeding.

The primary outcome occurred in 2.9% of the patients in the DOAC group compared with 3.6% of patients in the placebo group (odds ratio [OR] = 0.79; 95% CI, 0.69-0.91; number needed to treat [NNT] = 143). The secondary outcome occurred in 0.48% of patients in the DOAC group compared with 0.77% of patients in the placebo group (OR = 0.62; 95% CI, 0.47-0.83; NNT = 345). Major bleeding resulting in a decrease in hemoglobin concentration of more than 2 g/L, requiring transfusion of at least 2 units of packed red blood cells, reintervention at a previous surgical site, or bleeding in a critical organ or that was fatal, occurred in 0.58% of patients in the DOAC group compared with 0.3% of patients in the placebo group (OR = 1.9; 95% CI, 1.4-2.7; number needed to harm [NNH] = 357). Nonmajor bleeding was increased in the DOAC group compared with placebo (2.2% vs 1.2%; OR = 1.8; 95% CI, 1.5-2.1; NNH = 110).

The NNT to prevent a fatal VTE was 899 patients. After extrapolating original data on fatal PE and major bleeding to a national level, cost-benefit analysis preferred extended DOAC use, with a direct medical cost balance of $1.2 million per life saved.

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