DOAC - monitoring

Last edited 07/2019 and last reviewed 09/2023

• important to consider renal function (i.e. to 'think kidneys') when selecting the dose of any DOAC for each individual patient
  • usual measure of renal function (estimated Glomerular Filtration Rate (eGFR)) is not generally recommended for DOAC dosing decisions. In the major clinical trials of patients with non-valvular Atrial Fibrillation (AF) dosage was based on estimates of renal clearance based on the Cockcroft and Gault (CG) equation. This is not the same as the eGFR reported by most pathology services
    
    
  • where creatinine clearance is calculated to determine DOAC dose this should be done using the Cockcroft and Gault formula and ACTUAL body weight

Renal Clearance of DOACs

• Drug	Renal Clearance
  Apixaban	27%
  Dabigatran	80%
  Edoxaban	50%
  Rivaroxaban	35%

An incorrect DOAC dose may have important efficacy and safety implications:

• Using a lower dose when patients do not meet the criteria for dose reduction may increase the risk of embolic events and result in potentially preventable strokes.
• Using a higher dose where the renal function indicates that a dose reduction is necessary may increase the risk of bleeding

Notes (2):

• Anticoagulation is generally prescribed for older patents
  • an audit in primary care reported 4 in 5 patients taking anticoagulants were aged 65 or over and 1 in 2 were aged 75 or over. The risk of developing kidney disease also increases with age, so DOACs are likely to be prescribed for a substantial number of people who will require dosage adjustment. Regular monitoring to identify and address the consequences of any deterioration in kidney function over time is also important

Reference:

• Notts APC (July 2018). Direct Oral Anticoagulants (DOACs) for treatment of DVT or PE, or prevention against recurrent DVT or PE (in Adults).
• Specialist Pharmacy Service (July 2019). Direct Acting Oral Anticoagulants (DOACs) in Renal Impairment : Practice Guide To Dosing Issues.