Full Length ArticleFactors influencing warfarin control in Australia and Singapore

- Warfarin control is significantly higher in Australia (TTR 82%) than Singapore (58%).
- A reduced TTR was associated with chronic kidney disease at both sites.
- Anaemia and age < 60 years was associated with reduced TTR in Australia.
- In Singapore, vascular disease, CHA2DS2-VASc 6, and antiplatelets reduced TTR.

IntroductionWarfarin is widely used for patients with non-valvular atrial fibrillation (NVAF). Variations in warfarin control, as measured by time in therapeutic range (TTR), have been reported across different regions and ethnicities, particularly between Western and Asian countries. However, there is limited data on comparative factors influencing warfarin control in Caucasian and Asian patients. Therefore, the aim of this study was to determine warfarin control and potential factors influencing this in patients with NVAF in Australia and Singapore.MethodsRetrospective data was collected for patients receiving warfarin for January to June 2014 in Australia and Singapore. TTR was calculated for individuals with mean patient TTR used for analysis. Possible influential factors on TTR were analysed including age, gender, concurrent co-morbidities, and concurrent medication.ResultsThe mean TTR was significantly higher in Australia (82%) than Singapore (58%). At both sites, chronic kidney disease significantly lowered this TTR. Further factors influencing control were anaemia and age < 60 years in Australia, and vascular disease, CHA2DS2-VASc score of 6, and concurrent platelet inhibitor therapy in Singapore.DiscussionWarfarin control was significantly higher in Australia compared to Singapore, however chronic kidney disease reduced control at both sites. The different levels of control in these two countries, together with patient factors further reducing control may impact on anticoagulant choice in these countries with better outcomes from warfarin in Australia compared to Singapore.