Warfarin
Conditions
Keywords
Warfarin, dosage adjustment, therapeutic range, linear regression model
Brief summary
Despite the wide availability of Direct oral anticoagulation (DOAC), warfarin remains an important oral anticoagulant1 especially in patients with mechanical valve replacement or chronic renal failure where the evidence of DOAC is limited. However, the dosing of warfarin is challenging as it has a narrow therapeutic index and is highly influenced by dietary vitamin K intake and drugs that interacts with cytochrome (CYP) P4501. The time outside therapeutic range will carry the risk of adverse events such as thrombosis and bleeding. Numerous algorithms have been proposed that utilized either clinical or pharmacogenetics factors. The Clinical Pharmacogenetics Implementation Consortium (CPIC) has recommended the use of 4 dosing algorithms. However, these algorithms require the input of genetic information such as CYP2C9 and VKORC1 type which are not widely available locally and are less relevant in maintenance phase. Furthermore, these algorithms target mainly at predicting the initiation and the maintenance dose of warfarin. This has provided us with the opportunities to explore the Prediction model for on-treatment warfarin dose titration for outside therapeutic range.
Detailed description
Despite the wide availability of Direct oral anticoagulation (DOAC), warfarin remains an important oral anticoagulant1 especially in patients with mechanical valve replacement or chronic renal failure where the evidence of DOAC is limited. However, the dosing of warfarin is challenging as it has a narrow therapeutic index and is highly influenced by dietary vitamin K intake and drugs that interacts with cytochrome (CYP) P4501. The time outside therapeutic range will carry the risk of adverse events such as thrombosis and bleeding. Numerous algorithms have been proposed that utilized either clinical or pharmacogenetics factors. The Clinical Pharmacogenetics Implementation Consortium (CPIC) has recommended the use of 4 dosing algorithms. However, these algorithms require the input of genetic information such as CYP2C9 and VKORC1 type which are not widely available locally and are less relevant in maintenance phase. Furthermore, these algorithms target mainly at predicting the initiation and the maintenance dose of warfarin. This has provided us with the opportunities to explore the Prediction model for on-treatment warfarin dose titration for outside therapeutic range.
Interventions
BEHAVIORALWarfarin dosage adjustment model
Warfarin dosage adjustment model use to predict the initiation and the maintenance dose of warfarin. Variation of warfarin dose during stable maintenance phase for the same patient might be influenced more by temporal factors such as modification of drug regimens that utilize the CYP450 pathway, or dietary vitamin K intake
Sponsors
Professor Bryan Ping Yen YAN (byan)
Chinese University of Hong Kong
Study design
Observational model
CASE_ONLY
Time perspective
CROSS_SECTIONAL
Eligibility
Sex/Gender
ALL
Healthy volunteers
No
Inclusion criteria
1. Patients who have been on maintenance warfarin treatment 2. Patients whose INR have fallen outside therapeutic range will be identified using CDARS enquiry
Exclusion criteria
1\. No
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| extreme outside therapeutic range | 1 year | INR\<1.5 or INR\>3.5 on two consecutive blood checking |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| the time needed to achieve within therapeutic range | 1 year | It is calculated by the time interval from the outside therapeutic range INR to final within therapeutic range INR, the number of INRs checking between the initial outside therapeutic range and the final within therapeutic range |
Countries
Hong Kong
Contacts
Primary ContactDaniel Xu
Outcome results
None listed