Prescribing Warfarin in the Outpatient Dialysis Unit – Edinburgh Royal Infirmary
- INRs should only be checked on a Monday or Tuesday unless there are clinical concerns (eg: unusual bleeding at fistula site, prolonged nose bleeds, unusual extensive bruises, malaena etc) or when instructed by a prescriber
- Prescriptions should be completed and communicated to patients according to the following timings:
| HD Day | Session | INR reporting to prescriber | Time to contact patient |
| Monday | Morning | Monday morning before 11.00 | Monday afternoon before 16.00 |
| Afternoon | Tuesday morning before 11.00 | Tuesday afternoon before 16.00 | |
| Twilight | Tuesday morning before 11.00 | Tuesday afternoon before 16.00 | |
| Tuesday | Morning | Tuesday afternoon before 11.00 | Tuesday afternoon before 16.00 |
| Afternoon | Wednesday morning before 11.00 | Wednesday afternoon before 16.00 | |
| Twilight | Wednesday morning before 11.00 | Wednesday afternoon before 16.00 |
- The Yellow Warfarin book MUST be made available to the prescriber completing the prescriptions – understanding the patient’s anticoagulation history is key to safe prescribing
- All enquiries to Renal Registrar during the out-of-hours period or in the weekend MUST be done via the Nurse In-charge of the Dialysis Unit at the time. Junior doctors should NOT be routinely contacted for warfarin prescriptions except in unsafe situations as below:
- INR >4
- Active bleeding
- For sub-therapeutic INRs, please follow steps above except in the following situations where the prescriber should be contacted:
- Patients with a metallic heart valve when INR is <2.0
- Patients with lupus anticoagulant when INR is <1.5
- Patients with venous thromboembolism (PE/DVT) when INR is <1.5
- Patients with stable INRs will require less frequent monitoring. They should continue their usual warfarin dose unless it is unsafe (as described above)
- Unnecessary INR monitoring and frequent dose changes will lead to erratic anticoagulation which may be harmful to the patient
Written by: Jin Hah, Clinical Pharmacist
Reviewed by: Dr Iain MacIntyre, Consultant Nephrologist
Date written: September 2018
Review date: September 2020