Investigating a new approach to re-starting Warfarin after Surgery

Phase 3

• Conditions: Re-commencing post-operative warfarin; elective surgery; Surgery - Other surgery; Blood - Other blood disorders

• Registration Number: ACTRN12613001376730
• Lead Sponsor: Flinders Medical Centre

Brief Summary

Not available

Detailed Description

Not available

Study Timeline

• Results First Posted: 1900-01-01
• Study Start: 2013-12-16
• Last Update Posted: 13 January 2020

Recruitment & Eligibility

• Status: ot yet recruiting
• Sex: All
• Target Recruitment: 186

Inclusion Criteria

> 18 years old, receiving ongoing warfarin therapy, undergoing elective surgery, able to provide written, informed consent, and followed-up by Hospital-at-Home services for INR monitoring

Exclusion Criteria

Unable to provide written, informed consent
Not followed-up by Hospital-at-Home until a stable therapeutic INR is achieved
Undergoing cardiac surgery (note – patients with pre-existing artificial mitral or aortic valves are eligible as long as the surgery is not cardiac)
Surgery expected to grossly prevent normal oral intake in the week post-operatively eg colon resection
Use of more than 2 mg of vitamin K, fresh frozen plasma, or Prothrombinex-VT for INR reversal immediately pre-operatively
Use of any vitamin K, fresh frozen plasma, or Prothrombinex for INR reversal in the week after surgery, prior to a stable therapeutic INR being achieved. Normal blood transfusions are permissible and will be considered as a sub-group.
Commencement of regular therapy with drugs known to interact with warfarin in the period between the most recently measured maintenance INR and the commencement of surgery, excluding routine drugs administered immediately prior to surgery, such as antibiotic prophylaxis. This includes, imidazole antifungals, macrolide antibiotics, fluoroquinolones, amiodarone, omeprazole, metronidazole, cholestyramine, carbamazepine, phenytoin, barbiturates, rifampicin, sulfamethoxizole/trimpethoprim, SSRI’s, thyroxine, NSAIDs.
Lack of reliable INR results with corresponding maintenance dose
Most recent routine maintenance dose INR below 1.5 or above 3.5 for patients with a therapeutic range of 2-3, or above 4.0 for patients with a therapeutic range of 2.5-3.5
Warfarin reversed during warfarin re-commencement period due to unexpected return to theatre

Study & Design

• Study Type: Interventional
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Time to achieve a stable therapeutic INR (range 2-3) where a stable INR is the first INR of two consecutive daily INRs in the therapeutic range or the first INR in the therapeutic range where the previous INR was within 0.5[achievement of stable therapeutic INR ]

Secondary Outcome Measures

Name	Time	Method
episodes of overanticoagulation (INR>=4) prior to achieving a stable therapeutic INR[ achievement of a stable therapeutic INR];Length of stay under Hospital at Home care[achievement of a stable therapeutic INR];Subgroups analysis of patients commenced on drugs known to interact with warfarin that are commenced during the induction period. This will be separated into two groups - interacting drugs known to increase the response to warfarin (elevate the INR) and drugs known to decrease the efficacy of warfarin. All new post-operative drug use during warfarin re-commencement will be recorded. [achievement of a stable therapeutic INR];Sub-group analysis of patients maintained on daily doses (measured as the Standardised Maintenance Dose) of <2mg[achievement of a stable therapeutic INR];Sub-group analysis of patients maintained on daily doses (measured as the Standardised Maintenance Dose) of >7.5mg[achievement of a stable therapeutic INR]