Related Experiment Videos
Factors determining the maintenance dose of warfarin in Chinese patients
H C Yu1, T Y Chan, J A Critchley
1Department of Medicine, Chinese University of Hong Kong.
Insights
Chinese patients require lower warfarin doses than Caucasians due to increased sensitivity. Age is the primary factor influencing warfarin dosage, with body weight and underlying heart conditions also playing significant roles.
Area of Science:
- Pharmacology
- Internal Medicine
- Genetics
Background:
- Warfarin sensitivity varies across ethnic groups.
- Chinese patients may exhibit increased sensitivity to warfarin's anticoagulant effects compared to Caucasian populations.
Purpose of the Study:
- To investigate warfarin dose requirements in Chinese outpatients.
- To identify key determinants of warfarin dose variability in this population.
Main Methods:
- A study involving 151 Chinese outpatients on stable warfarin maintenance doses.
- Analysis of International Normalized Ratio (INR) and correlation with demographic and clinical factors.
Main Results:
- Mean daily warfarin requirement was 3.3 ± 1.4 mg, significantly lower than in Caucasian patients.
- Age was the most significant determinant (r = -0.43, p < 0.001), with higher age correlating with lower dose needs.
- Body weight (r = 0.20, p = 0.01) and underlying cardiac conditions (rheumatic heart disease vs. valve replacement) also influenced dosage.
Conclusions:
- Chinese patients require lower warfarin doses for equivalent anticoagulation.
- Age is the primary factor influencing warfarin dose, followed by body weight and specific cardiac conditions.
Abstract:
Chinese patients are reportedly more sensitive than Caucasians to the anticoagulant effect of warfarin. We examined warfarin dose requirements and their determinants in 151 Chinese out-patients on stable maintenance dose of warfarin with international normalized ratio of 2 to 2.5. Mean daily warfarin requirement was 3.3 +/- 1.4 mg, much lower than reported doses in Caucasian patients. The most important determinant was age (r = -0.43, p < 0.001), with progressively lower warfarin requirement with increasing age (p = 0.0001). There was a weaker association with body weight (r = 0.20, p = 0.01). Patients with chronic rheumatic heart disease tended to require a smaller dose than those with heart valve replacements (2.94 +/- 1.24 vs. 3.69 +/- 1.42 mg, p < 0.01). We confirm that Chinese patients require a smaller dose of warfarin for the same degree of anticoagulation. Age is the most important factor affecting dose requirement, although body weight and underlying disease also play a role.