NICE updated their guidelines on the management of venous thromboembolism (VTE) in 2020. Some of the key changes include recommending the following:

• the use of direct oral anticoagulants (DOACs) as first-line treatment for most people with VTE
• the use of DOACs in patients with active cancer, as opposed to low-molecular weight heparin as was the previous recommendation
• outpatient treatment in low-risk pulmonary embolism (PE) patients
• routine cancer screening is no longer recommended following a VTE diagnosis

Outpatient treatment in low-risk PE patients

Deep vein thrombosis has for a long time been treated on an outpatient condition. In contrast, patients with any form of PE were typically admitted. However, in recent years patients with a new diagnosis of PE who are deemed low-risk are now increasingly managed as outpatients. NICE formally supported this approach in their latest guidance.

• NICE recommends using a 'validated risk stratification tool' to determine the suitability of outpatient treatment.
  • no guidance is given as to what tool should be used
  • the 2018 British Society guidelines support the use of the Pulmonary Embolism Severity Index (PESI) score
• key requirements would clearly be haemodynamic stability, lack of comorbidities and support at home

Anticogulant therapy

The cornerstone of VTE management is anticoagulant therapy. This was historically done with warfarin, often preceded by heparin until the INR was stable. However, the development of DOACs, and an evidence base supporting their efficacy, has changed modern management.

Choice of anticoagulant

• the big change in the 2020 guidelines was the increased use of DOACs
• apixaban or rivaroxaban (both DOACs) should be offered first-line following the diagnosis of a PE
  • instead of using low-molecular weight heparin (LMWH) until the diagnosis is confirmed, NICE now advocate using a DOAC once a diagnosis is suspected, with this continued if the diagnosis is confirmed
  • if neither apixaban or rivaroxaban are suitable then either LMWH followed by dabigatran or edoxaban OR LMWH followed by a vitamin K antagonist (VKA, i.e. warfarin)
• if the patient has active cancer
  • previously LMWH was recommended
  • the new guidelines now recommend using a DOAC, unless this is contraindicated
• if renal impairment is severe (e.g. < 15/min) then LMWH, unfractionated heparin or LMWH followed by a VKA
• if the patient has antiphospholipid syndrome (specifically 'triple positive' in the guidance) then LMWH followed by a VKA should be used

Length of anticoagulation

• all patients should have anticoagulation for at least 3 months
• continuing anticoagulation after this period is partly determined by whether the VTE was provoked or unprovoked
  • a provoked VTE is due to an obvious precipitating event e.g. immobilisation following major surgery. The implication is that this event was transient and the patient is no longer at increased risk
  • an unprovoked VTE occurs in the absence of an obvious precipitating event, i.e. there is a possibility that there are unknown factors (e.g. mild thrombophilia) making the patient more at risk from further clots