Venous thromboembolism in ischaemic stroke in Asia

Background: There are extensive studies indicating that deep venous thrombosis and pulmonary embolism contributes to significant morbidity and mortality after acute ischaemic stroke in the West, with established guidelines for prophylaxis. The situation is less clear in Asia. Accordingly, a literature search was performed to review the available evidence. Methods: A search was performed with all published materials in PubMed, Directory of Open Access Journals and BioMed Central, using the following keywords “venous thromboembolism”, “Asia”, “stroke”, “deep venous thrombosis” and “pulmonary embolism”. Systematic and non-systematic studies, previous review articles with their related references were also reviewed. Results: Wide ranging prevalence of venous thromboembolism has been reported after acute ischaemic stroke in Asia, 1% or less in clinical studies, 4.8% to 45% with imaging studies. The prevalence is lower as compared to Caucasian populations, 1.5% to 5.6% in clinical studies, 11% to 80% with imaging studies. Conclusion: The problem of venous thromboembolism is not negligible in Asia. There is a need for future studies in Asia with larger sample sizes. Antiplatelet drugs should be routinely used as prophylaxis while compression stockings applied for those with significant limb weakness. Prophylactic anticoagulation may be considered in those with additional risk factors. Neurology Asia 2008; 13 : 95 – 101 Address correspondence to: Dr KS Tan, c/o Neurology Laboratory, University of Malaya Medical Centre, Kuala Lumpur 59100, Malaysia. E-mail: tanks@ ummc.edu.my INTRODUCTION A review of the evidence available for venous thromboembolism after acute ischaemic stroke in Asian patients have not been performed to date despite the continuing controversy that venous thromboembolism in stroke patients was less frequent among Asians compared to Caucasians. Accordingly, this review aims to assemble and interpret the accumulated evidence of venous thromboembolism among stroke patients in Asia, compare the current evidence with the Western literature on the background of recent therapeutic trials and to make clinical recommendations. Previous studies have suggested that venous thromboembolism in stroke patients was likely to be less frequent among Asians compared to Caucasians. Evidence for this came indirectly from various studies. A comparative study within multi-ethnic California revealed that the risk ratio for annual venous thromboembolism for Asians was 0.2 compared with Caucasians.1 Autopsy studies were also noted to be lower in Japanese (0.7%) compared with North Americans (15%).2 The annual incidence of venous thromboembolism in Hong Kong Chinese was estimated at 16.6 events per 100,000 population. This incidence was 10 to 20% of the rates found in Western populations.3 In addition, other studies in Asia noted that venous thromboembolism incidence in multi-ethnic Singapore among hospitalized patients was 15.8 per 10,000 admissions4 while its prevalence in post operative conditions in Malaysia and Singapore such as hip surgery5, colorectal surgery6, cranial procedures7 and general surgery8 were 14%, 3%, 5% and 2.2% respectively. A previous review in Asia9 noted a similar wide ranging prevalence in post-operative settings with ranges between 3%-63%. Overall, these rates were lower compared with Western data, which routinely showed prevalence of between 28-80% in similar clinical situations. However, no previous critical evaluation has been performed among stroke patients in Asia and to our knowledge, this is the first of such a review.