Monitoring

There is no definitive schedule for the frequency of clinical visits after diagnosis and treatment initiation for DVT. Patients with good understanding of the disease and its management may not need an additional visit until reassessment at the conclusion of the treatment phase to determine whether to offer extended anticoagulant therapy. Patients at higher bleeding risk or with comorbidities may benefit from earlier follow-up.

Monitoring regimens related to anticoagulant therapy differ according to the agent being used.

There is no single, definitive approach to monitoring unfractionated heparin (UFH) for the management of venous thromboembolism (VTE). A suggested approach is to check activated partial thromboplastin time (aPTT) or anti-Xa level every 6 hours until two consecutive therapeutic results are obtained, following which monitoring frequency can be reduced to once daily.[262]​ Anti-Xa level monitoring may be preferred to aPTT in patients with heparin resistance, prolonged baseline aPTT, or altered heparin responsiveness.[262] A therapeutic range of 0.3 to 0.7 units/mL is suggested when anti-Xa monitoring is used.[262]

Patients treated with a vitamin K antagonist (usually warfarin) require frequent international normalized ratio (INR) monitoring, preferably at a specialized anticoagulant clinic. However, select patients may be candidates for self-monitoring using portable point-of-care units. Patients on oral anticoagulation who self-monitor or self-manage can improve the quality of their oral anticoagulation therapy.[263]

Direct oral anticoagulants (DOACs) do not require laboratory monitoring with coagulation assays. An assessment of renal function prior to initiating DOAC therapy, and renal and liver function monitoring during therapy, should be conducted as clinically indicated.

Consensus guidance recommends that patients (with VTE) receiving low molecular weight heparin (LMWH) should be monitored for signs and symptoms of bleeding and renal function change that necessitate dose adjustment.[262]​ Complete blood count, platelet count, and serum creatinine should be monitored periodically; routine anti-Xa monitoring is not recommended.[262]

Routine therapeutic drug monitoring of fondaparinux may not be necessary in the majority of patients; anti-Xa assay calibrated for fondaparinux may be considered if fondaparinux accumulation is suspected.[262]

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