Causes of venous thrombosis in fifty Chinese patients

Development and validation of a new risk assessment model for immunomodulatory drug-associated venous thrombosis among Chinese patients with multiple myeloma

BACKGROUND

Individuals with multiple myeloma (MM) receiving immunomodulatory drugs (IMiDs) are at risk of developing venous thromboembolism (VTE), a serious complication. There is no established clinical model for predicting VTE in the Chinese population. We develop a new risk assessment model (RAM) for IMiD-associated VTE in Chinese MM patients.

METHODS

We retrospectively selected 1334 consecutive MM patients receiving IMiDs from 16 medical centers in China and classified them randomly into the derivation and validation cohorts. A multivariate Cox regression model was used for analysis.

RESULTS

The overall incidence of IMiD-related VTE in Chinese MM patients was 6.1%. Independent predictive factors of VTE (diabetes, ECOG performance status, erythropoietin-stimulating agent use, dexamethasone use, and VTE history or family history of thrombosis) were identified and merged to develop the RAM. The model identified approximately 30% of the patients in each cohort at high risk for VTE. The hazard ratios (HRs) were 6.08 (P < 0.001) and 6.23 (P < 0.001) for the high-risk subcohort and the low-risk subcohort, respectively, within both the derivation and validation cohorts. The RAM achieved satisfactory discrimination with a C statistic of 0.64. The stratification approach of the IMWG guidelines yielded respective HRs of 1.77 (P = 0.053) and 1.81 (P = 0.063). The stratification approach of the SAVED score resulted in HRs of 3.23 (P = 0.248) and 1.65 (P = 0.622), respectively. The IMWG guideline and the SAVED score-based method yielded C statistics of 0.58 and 0.51, respectively.

CONCLUSIONS

The new RAM outperformed the IMWG guidelines and the SAVED score and could potentially guide the VTE prophylaxis strategy for Chinese MM patients.

Congenital thrombophilia in East-Asian venous thromboembolism population: a systematic review and meta-analysis

Background

Various inherited traits contribute to the overall risk of venous thromboembolism (VTE). In addition, the epidemiology of thrombophilia in the East-Asian VTE population remains unclear; thus, we aimed to assess the proportion of hereditary thrombophilia via a meta-analysis.

Methods

Publications from PubMed, EMBASE, web of science, and Cochrane before December 30, 2022, were searched. Studies from Japan, Korea, China, Hong Kong, Taiwan, Singapore, Thailand, Vietnam, Myanmar, and Cambodia were included. Congenital thrombophilia was described as diseases including protein C (PC) deficiency, protein S (PS) deficiency, antithrombin (AT) deficiency, factor (F)V Leiden (FVL), and prothrombin G20210A mutations. Studies were selected by 2 reviewers for methodological quality analysis. A random-effects model was used for the meta-analysis, assuming that estimated effects in the different studies are not identical.

Results

Forty-four studies involving 6453 patients from 7 counties/regions were included in the meta-analysis. The prevalence of PC, PS, and AT deficiencies were 7.1%, 8.3%, and 3.8%, respectively. Among 2924 patients from 22 studies, 5 patients were carriers of FVL mutation. Among 2196 patients from 10 studies, 2 patients were carriers of prothrombin G20210A mutation in a Thailand study.

Conclusion

The prevalence of PC, PS, and AT deficiencies was relatively high, while a much lower prevalence of FVL and prothrombin G20210A mutations were identified in East-Asian patients with VTE. Our data stress the relative higher prevalence of PC, PS, and AT deficiencies for thrombophilia in the East-Asian VTE population.

The Risk of Venous Thromboembolism after Thoracolumbar Spine Surgery: A Population-Based Cohort Study

Background: Although venous thromboembolism (VTE) is rare, including deep vein thrombosis (DVT) and pulmonary embolism (PE), it is a catastrophic complication after spinal surgery. This study was aimed to investigate the risk factors and incidence of VTE after thoracolumbar spine surgery (TLSS). Methods: We retrieved the data of 8697 patients >20 years old who underwent TLSS between 2000 and 2013 from Taiwan’s Longitudinal Health Insurance Database 2000. Each patient was randomly frequency-matched with four individuals who did not undergo TLSS by age, sex, and index year (the control group). Results: The incidence rates of VTE in the TLSS and control groups were 1.84 and 0.69 per 1000 person-years, respectively. The TLSS group had a higher VTE risk (adjusted HR (aHR): 2.13, 95% confidence interval [95%CI]: 1.41−3.21), DVT (aHR: 2.20, 95%CI: 1.40−3.46), and PE (aHR: 1.60, 95%CI: 0.68−3.78) than the control group. The correlated risk factors of VTE included older age (50−64 years: aHR: 2.16, 95%CI: 1.14−4.09; ≥65 years: aHR: 3.18, 95%CI: 1.65−6.13), a history of cancer (aHR: 2.96, 95%CI: 1.58−5.54), heart failure (aHR: 2.19, 95%CI: 1.27−3.78), and chronic kidney disease (aHR: 1.83, 95%CI: 1.18−2.83). Conclusions: The overall VTE risk following TLSS was less than 2% but correlated with certain risk factors. This information could help the spine surgeon help the patient prevent this fatal complication.

The diagnosis and treatment of venous thromboembolism in asian patients

Although the incidence of venous thromboembolism (VTE) in Asian populations is lower than in Western countries, the overall burden of VTE in Asia has been considerably underestimated. Factors that may explain the lower prevalence of VTE in Asian populations relative to Western populations include the limited availability of epidemiological data in Asia, ethnic differences in the genetic predisposition to VTE, underdiagnoses, low awareness toward thrombotic disease, and possibly less symptomatic VTE in Asian patients. The clinical assessment, diagnostic testing, and therapeutic considerations for VTE are, in general, the same in Asian populations as they are in Western populations. The management of VTE is based upon balancing the treatment benefits against the risk of bleeding. This is an especially important consideration for Asian populations because of increased risk of intracranial hemorrhage with vitamin K antagonists. Non-vitamin K antagonist oral anticoagulants have shown advantages over current treatment modalities with respect to bleeding outcomes in major phase 3 clinical trials, including in Asian populations. Although anticoagulant therapy has been shown to reduce the risk of postoperative VTE in Western populations, VTE prophylaxis is not administered routinely in Asian countries. Despite advances in the management of VTE, data in Asian populations on the incidence, prevalence, recurrence, risk factors, and management of bleeding complications are limited and there is need for increased awareness. To that end, this review summarizes the available data on the epidemiology, risk stratification, diagnosis, and treatment considerations in the management of VTE in Asia.

Bidirectional risk between venous thromboembolism and cancer in East Asian patients: synthesis of evidence from recent population-based epidemiological studies

BACKGROUND

Unprovoked (idiopathic) venous thromboembolism (VTE) with no obvious antecedent risk factors, is associated with a significant risk of subsequent occult cancer. Conversely, there is a heightened risk of VTE in cancer patients. This bidirectional risk can be estimated from population-based cohort studies conducted in East Asians.

METHODS

A literature search using medical subject heading terms and Boolean logic in PubMed and MedLine was performed in April 2017. Twenty-two papers reported from East Asia were retrieved for study and data synthesis. Proportional meta-analysis with a random-effects model was used to synthesize data with 95% confidence intervals (CIs) when appropriate.

RESULTS

Synthesis of data on VTE incidence in the East Asian population (I² = 76.2%) showed that pooled incidence was 20.3 (95% CI, 11.2-32) per 100,000 person-years. VTE incidence steadily increased with age. Unprovoked VTE accounted for 35% (95% CI, 24%-48%) of all cases of incident VTE (I² = 99.7%). The overall cancer risk was significantly higher (2.3-fold) in the VTE cohort than in comparators. Among the patients with unprovoked VTE, approximately 7% had a subsequent cancer diagnosis within 2 years of the first episode of idiopathic VTE. The risk of VTE recurrence was increased in cancer patients (adjusted odds ratio, 1.64; 95% CI, 1.26-1.99). VTE incidence was 9.9 per 1,000 person-years in cancer patients, particularly in liver, pancreas, and lung cancer patients.

CONCLUSION

Newly diagnosed VTE incidence is estimated at approximately 4,400 new cases annually in Taiwan and 7,100 in South Korea. Similar to the trend in VTE incidence among the general population, VTE risk in East Asian cancer patients is markedly lessened.

Review article: the aetiology of primary Budd-Chiari syndrome - differences between the West and China

BACKGROUND

China may have the largest number of Budd-Chiari syndrome (BCS) cases in the world (at least 1914 original papers were published, and at least 20 191 BCS patients were reported). Considering the discrepancy in the clinical profiles and preferred treatment selection of primary BCS between the West and China, understanding its aetiology in these two different regions is very important.

AIM

To review the data from large cohort studies and meta-analyses to illustrate the epidemiology of risk factors for BCS in the West and China.

METHODS

Relevant papers were identified by major English- and Chinese-language databases, conference abstracts, and by manual search.

RESULTS

Risk factors reviewed include myeloproliferative neoplasms (MPNs) and their related gene mutations, anti-phospholipid syndrome, paroxysmal nocturnal haemoglobinuria (PNH), hyperhomocysteinaemia and 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T mutation, factor V Leiden (FVL) and prothrombin G20210A mutations, inherited anti-thrombin, protein C and protein S deficiencies, pregnancy and puerperium, poverty, and family history.

CONCLUSIONS

We examined the differences in the aetiological distribution of BCS between the West and China. Several recommendations should be considered in Chinese BCS patients: (i) screening for hyperhomocysteinaemia and MTHFR mutation should be regularly performed; (ii) screening for MPNs, PNH, and anti-phospholipid syndrome should be selectively performed; (iii) inherited anti-thrombin, protein C, and protein S deficiencies should be actively explored; (iv) screening for FVL and prothrombin G20210A mutations may be unnecessary; and (v) the clinical significance of pregnancy and puerperium, poverty with bacterial infections and unsanitary environments, and family history as possible risk factors should never be neglected.

Management of Venous Thromboembolisms: Part I. The Consensus for Deep Vein Thrombosis

Deep vein thrombosis (DVT) is a potentially catastrophic condition because thrombosis, left untreated, can result in detrimental pulmonary embolism. Yet in the absence of thrombosis, anticoagulation increases the risk of bleeding. In the existing literature, knowledge about the epidemiology of DVT is primarily based on investigations among Caucasian populations. There has been little information available about the epidemiology of DVT in Taiwan, and it is generally believed that DVT is less common in Asian patients than in Caucasian patients. However, DVT is a multifactorial disease that represents the interaction between genetic and environmental factors, and the majority of patients with incident DVT have either inherited thrombophilia or acquired risk factors. Furthermore, DVT is often overlooked. Although symptomatic DVT commonly presents with lower extremity pain, swelling and tenderness, diagnosing DVT is a clinical challenge for physicians. Such a diagnosis of DVT requires a timely systematic assessment, including the use of the Wells score and a D-dimer test to exclude low-risk patients, and imaging modalities to confirm DVT. Compression ultrasound with high sensitivity and specificity is the front-line imaging modality in the diagnostic process for patients with suspected DVT in addition to conventional invasive contrast venography. Most patients require anticoagulation therapy, which typically consists of parenteral heparin bridged to a vitamin K antagonist, with variable duration. The development of non-vitamin K oral anticoagulants has revolutionized the landscape of venous thromboembolism treatment, with 4 agents available,including rivaroxaban, dabigatran, apixaban, and edoxaban. Presently, all 4 drugs have finished their large phase III clinical trial programs and come to the clinical uses in North America and Europe. It is encouraging to note that the published data to date regarding Asian patients indicates that such new therapies are safe and efficacious. Ultimately, our efforts to improve outcomes in patients with DVT rely on the awareness in the scientific and medical community regarding the importance of DVT.

KEY WORDS

Combination therapy; Hypertension; α1-blocker.

High Factor VIII and Von Willebrand Factor Levels Are Not Risk Factors of Cryptogenic Arterial Ischemic Stroke in Thai Children

High factor VIII levels and a risk factor of arterial ischemic stroke is controversial. Levels of factor VIII depend on ethnicity, age, and sex. This report included 24 Thai children with cryptogenic arterial ischemic stroke and 41 controls, with a mean (standard deviation) age of 11.5 (6.3) and 9.0 (4.7), respectively. The study was performed during the post-arterial ischemic stroke events to avoid acute phase reaction of factor VIII and von Willebrand factor. The levels of factor VIII activity and von Willebrand factor antigen in patients were not significantly different compared to controls (119.8 ± 41.3% vs 138.0 ± 48.7%, P = .29 and 92.8 ± 29.8% vs 103.7 ± 39.1%, P = .4, respectively). Therefore, high factor VIII and von Willebrand factor antigen levels were not risk factors of cryptogenic arterial ischemic stroke in Thai children.

Treating pulmonary embolism in Pacific Asia with direct oral anticoagulants

Pulmonary embolism (PE) is the principal preventable cause of in-hospital deaths. Prevalence of PE in Asians is uncertain but undoubtedly underestimated. Asians and Caucasians have similar non-genetic risk factors for PE, and there is mounting evidence that PE affects Asians much more commonly than previously supposed; incidence, especially among high-risk patients, may approach that in Caucasians. Furthermore, PE incidence in Asia is increasing, due to both increased ascertainment, and also population ageing and growing numbers of patients with predisposing risk factors. Despite being warranted, thromboprophylaxis for high-risk patients is not routine in Pacific Asian countries/regions. There also appears to be scope to implement venous thromboembolism (VTE) management guidelines more assiduously. Anticoagulants, primarily heparins and warfarin, have been the mainstays of VTE management for years; however, these agents have limitations that complicate routine use. The complexity of current guidelines has been another barrier to applying evidence-based recommendations in everyday practice. Updated management approaches have considerable potential to improve outcomes. New oral anticoagulants that are easier to administer, require no, or much less, monitoring or dose-adjustment and have a favourable risk/benefit profile compared with conventional modalities, may offer an alternative with the potential to simplify VTE management. However, more information is required on practical management and the occurrence and treatment of bleeding complications. Increasing recognition of the burden of PE and new therapeutic modalities are altering the VTE management landscape in Pacific Asia. Consequently, there is a need to further raise awareness and bridge gaps between the latest evidence and clinical practice.

Dysfunction of protein C anticoagulant system, main genetic risk factor for venous thromboembolism in northeast Asians

Venous thromboembolism (VTE) is a life threatening medical disorder worldwide. A great deal of evidence suggests that prevalence of VTE varies significantly among ethnic populations, with consistently lower incidence found in Asians. While the distribution of genetic risk factors may vary among races, genetic risk factors can play a major role among individuals with different genetic backgrounds. Two clinically evaluated low-frequency genetic mutations that predispose to VTE--the factor V Leiden mutation and prothrombin G20210A mutation--are found predominantly in Caucasians, and virtually never in Asians. The findings of a recent genetic study of VTE in northeast Asians, which greatly advanced our knowledge in this area, indicate that the most frequent genetic risk factors for VTE in northeast Asians can be attributed to a dysfunction of the protein C anticoagulant system. Several low-frequency genetic mutations, PROS1 p.Lys196Glu in Japanese and PROC p.Arg189Trp and p.Lys193del in Chinese, are significantly associated with increased risk for VTE, with odds ratio more than 2 through the reduced protein C anticoagulant activity. Construction of a multifactorial model based on the genetic risk factors in the protein C anticoagulant system could facilitate genetic counseling for VTE risk in these populations. The influence of prevalent genetic mutations on the risk of VTE should be further investigated in Asian countries.

A Prospective Study of Venous Thromboembolic Prophylaxis using Foot Pumps following Total Knee Replacement in a Chinese Population

Purpose

The purpose of this study was to evaluate foot pumps as mechanical prophylaxis for deep vein thrombosis (DVT) following total knee replacement (TKR) in a Chinese population.

Methods

All consecutive patients following TKR during 2002–2006 received routine duplex ultrasound surveillance for DVT 9 days postoperatively. The demographic data and risk factors were recorded. No medication was given for DVT prophylaxis in all patients.

Results

We evaluated 91 consecutive TKRs in 85 patients. Although 44 knee replacements (Group 1) done before December 2004 were not given foot pumps, 47 knee replacements (Group 2) done afterwards were given foot pumps. All patients were followed up for more than 6 months. DVT was detected in three cases (6.8%) in Group 1 compared with four knees (8.5%) in Group 2. Proximal thrombosis was observed in two knees (4.5%) in Group 1 compared with two knees (4.3%) in Group 2. No patient had pulmonary embolism. Six out of 59 (10.2%) patients who underwent the operations under general anaesthesia suffered from DVT, whereas one in 28 (3.6%) patients operated under spinal anaesthesia had DVT. All had no statistical significance.

Conclusion

The rate of proximal DVT after TKR was low (4.5%) without pharmacological prophylaxis. We advise against the use of pharmacological prophylaxis in Chinese population for TKRs because of the low risk of proximal DVT and its possible bleeding complications. Foot pump did not lower the rate of DVTfurther, and its use for DVT prophylaxis in TKR is not necessary.

Cause of deep venous thrombosis and pulmonary embolism in young patients from India as compared with other ethnic groups

Venous thromboembolism (VTE), which consists of deep vein thrombosis (DVT) and pulmonary embolism, is a potentially fatal disease. The existing Asian literature has shown a wide variation in the prevalence of VTE, with very limited data from India. In the present study, the risk factors for VTE in Indian patients were compared with Caucasians and Blacks. We used data prospectively collected from total of 1396 Indian patients (716 males, 680 females) enrolled over a decade and compared with White (n = 2002) and Black (n = 395) patients objectively diagnosed with VTE. When compared with females, males had significantly higher episodes of pulmonary embolism and VTE (P = 0.0001). Amongst the known thrombophilia markers, only homocysteine was found to be significantly higher in males as compared with females (P = 0.006). Males had a higher proportion of rheumatic heart disease (RHD) and ischaemic heart disease (IHD) as compared with females. The prevalence of DVT amongst Indians was significantly higher as compared with Whites and Blacks. However, the rate of pulmonary embolism and VTE was lower in Indians as compared with both the races. Amongst the baseline characteristics identified as risk factors for VTE, Indians had a higher prevalence of infection as compared to both Whites and Blacks, but lower HIV infection as compared to Blacks. As compared to Whites, Indians had lower prevalence of idiopathic VTE (but similar to blacks) and had higher prevalence of idiopathic pulmonary embolism (P < 0.0001). This can be explained by different inherited and environment risk factors between these three populations.

A nation-wide analysis of venous thromboembolism in 497,180 cancer patients with the development and validation of a risk-stratification scoring system

The Asian population is thought to have a low risk of venous thromboembolism (VTE), but the epidemiology of VTE in cancer patients remains unclear. The National Health Insurance Research Database of Taiwan was used to find hospitalised patients newly-diagnosed with cancer to determine the incidence of VTE in cancer patients and to identify the risk factors for VTE. Between 1997 and 2005, 497,180 cancer patients were identified. During a median follow-up of 21.3 months (range 0-119.9 months), 5,296 patients developed VTE. The estimated incidence was 185 events per 100,000 person-years. Patients with a prior history of VTE and female patients between the ages of 40 and 80 carried high risk of VTE. The rate of VTE was relatively high in patients with myeloma, prostate cancer, lung cancer, gynaecologic cancers, sarcoma, and metastasis of unknown origin. We developed a risk-stratification scoring system to divide the cancer patients into four discrete risk groups (very low risk, low risk, intermediate, and high risk). The incidence of VTE in each group was 0.5%, 0.9%, 1.5%, and 8.7%, respectively (p < 0.001). This scoring system was validated in a separate patient cohort. In conclusion, VTE is a distinct burden for cancer patients in Taiwan. The risk scoring system could prove helpful in decision-making concerning thromboprophylaxis in cancer patients.

Thrombophilia among Chinese women with venous thromboembolism during pregnancy

AIMS

To assess the prevalence of thrombophilia among Chinese women with venous thromboembolism (VTE) developed during pregnancy.

METHODS

Based on information from a tertiary teaching unit, all recorded cases of deep vein thrombosis (DVT) and pulmonary embolism (PE) during pregnancy diagnosed between 1997 and 2005, were assessed for prevalence of thrombophilia. Fifty-five healthy women, who had at least one normal pregnancy but without any previous history of VTE, were recruited as controls.

RESULTS

A total of 44 subjects completed thrombophilia screening, of whom 5 (11%) were confirmed to have thrombophilia [protein C (PC) deficiency (2), protein S (PS) deficiency (1), combined PC & PS deficiency (1) and antithrombin III deficiency (1)]. Homozygous 5,10-methylenetetrahydrofolate reductase (C677T) gene mutation was found in 6 (14%) subjects but not in the controls. There was no antiphospholipid syndrome, activated PC resistance, factor V Leiden or prothrombin gene mutations.

CONCLUSION

In the Chinese population, PS and PC deficiencies are common thrombophilia for VTE during pregnancy and thrombophilia screening should be recommended in all pregnant women who suffer from VTE.

Low incidence of clinically apparent thromboembolism in Korean patients with multiple myeloma treated with thalidomide

The frequency of thromboembolic events (TE) in Caucasian patients with multiple myeloma (MM) receiving thalidomide as the initial treatment has been reported to be 10~58% without prophylactic anticoagulation. Korean MM patients treated with thalidomide were studied to determine the frequency of TE and associated risk factors. A retrospective medical record review of the Korean MM registry from 25 centers in Korea between 2003 and 2007 was performed. We assessed the incidence of arterial and venous TE and the associated clinical parameters. Three hundred and sixty MM patients (median age 61 years, range 32-88 years) received thalidomide treatment. Fourteen patients (3.9%) developed TE: 12 had venous and two had arterial locations. The sites for the venous TE included lungs (seven), lower extremities (four), upper extremities (one), and neck (one). Arterial TE developed in cerebral and peripheral arteries each. No single clinical parameter such as prerequisite for the metabolic syndrome, disease status, and treatment regimen were predictive for the development of TE. The frequency of TE in patients who received thalidomide as initial therapy (7/155) was not different from those who received thalidomide for progressive or relapsed disease (7/205, p = 0.592). The frequency of TE during thalidomide treatment in Korean patients with MM was low. No significant clinical factor was found to be a risk factor. The subgroup requiring thromboprophylaxis among the Korean patients with MM, receiving thalidomide, needs to be clarified.

Inherited thrombophilic factors do not increase central venous catheter blockage in children with malignancy

BACKGROUND

Central venous catheter (CVC) blockage is a common complication in pediatric oncology patients. We investigated whether inherited thrombophilic factors may predispose Chinese children with cancer to CVC blockage.

METHOD

Newly diagnosed patients with CVC inserted were recruited during a 30-month period and prospectively followed until CVC removal, end of treatment or death. Protein C (PC), protein S (PS), anti-thrombin III (AT-III), Factor V Leiden (FVL), prothrombin 20210 variant (p20210), and methylenetetrahydrofolate reductase (MTHFR) polymorphism (C677T), were studied with other acquired factors. The primary endpoint was CVC blockage and symptomatic thromboembolic events (TE) were recorded.

RESULT

Thirty-six patients were recruited. CVC blockage was found in 3/36 (8.3%) and the incidence was 0.23 per 1,000 catheter-days. Among the 3 with CVC blockage, 2 were heterozygous for MTHFR polymorphism and 1 was heterozygous for PC deficiency. One with ALL developed superior saggital sinus thrombosis while on asparaginase and he was heterozygous for MTHFR polymorphism. One ALL patient with combined heterozygous MTHFR polymorphism, PC and PS deficiency did not develop any CVC blockage during a median follow-up of 3.8 years. AT-III deficiency, FVL and p20210 were not found in all patients.

CONCLUSION

Compared to previous studies, our cohort had a much lower incidence of CVC blockage. A different pattern of inherited thrombophilic factors was found with heterozygous MTHFR polymorphism being the most common. We concluded that inherited thrombophilic factors alone were not associated with CVC blockage in our pediatric cancer patient population.

Risk factors of venous thromboembolism in thai patients

Venous thromboembolism (VTE) has been reported to be less common among Thais than Caucasians. Whether this observation reflects genetic or environmental factors, or both, is uncertain. To identify genetic and acquired risk factors of Thai patients with VTE, we enrolled in the study 105 consecutive Thai patients (34 men, 71 women) who had an objectively confirmed history of VTE. A complete clinical summary was obtained from each patient, with emphasis on personal and family history of VTE, as well as circumstantial vascular risk factors (surgery, immobilization, pregnancy, postpartum condition, trauma, oral contraceptive use, and malignancy). Of the 105 patients, 19% were found to have a malignancy. The mean age at the time of the first thrombotic episode was 52.1 years (range, 29-76 years), compared with 42.6 years (range, 17-82 years) for the patients without malignancy. Of the 85 patients without malignancy, 12.3% had protein S deficiency, 8.9% had protein C deficiency, 4.7% had antithrombin deficiency, 10.4% had antiphospholipid antibody, 30.4% had an elevated factor VIII level, 26.8% had an elevated factor XI level, 5.3% had hyperhomocysteinemia, and 16.5% were on oral contraceptives before the thrombotic episode. Factor V Leiden, the G20210A prothrombin gene mutation, and homozygosity for the C677T methylenetetrahydrofolate reductase (MTHFR) gene variant were not found. The VTE in 7.1% of the patients was considered to be secondary to recent surgery, trauma, and/or immobilization. Compared with studies of Caucasian patients, there were significant differences in the risk factors for VTE, with protein S deficiency and protein C deficiency being more common in the Thai patients. In contrast, factor V Leiden, the G20210A prothrombin gene mutation, and the C677T MTHFR gene mutation are not genetic risk factors among Thai patients with VTE. Malignancy and the use of oral contraceptives were the most common acquired risk factors for VTE in the Thai patients.

Risk Factors and Presentation of Deep Venous Thrombosis among Asian Patients: A Hospital-Based Case-Control Study in Singapore

Deep venous thrombosis (DVT) is perceived to occur less frequently among Asians than Caucasians, although the reason for this has not been fully understood. Hence, there may be differences in risk factors and presentations among Asian patients compared to their Caucasian counterparts. This study examined the association of classical risk factors and presentations among Asian patients with DVT. We retrospectively reviewed 862 symptomatic patients referred to the vascular diagnostic laboratory in a hospital for suspected DVT over a 30-month period. Two hundred and seventy-seven patients (32.1%) tested positive for DVT on duplex ultrasound. After adjusting for age and gender, ethnicity was not a statistically significant demographic factor associated with DVT. Two hundred and seventy-one patients diagnosed as having DVT on ultrasound were matched for age, gender, and ethnicity to negative controls to study the significance of risk factors and presenting symptoms or signs. In multivariate analysis, independent risk factors for DVT included immobility (odds ratio [OR] = 2.61, 95% confidence interval [95% CI] 1.63-4.15], malignancy (OR = 1.77, 95% CI 1.01-3.10), and a history of thrombophilia (OR = 9.95, 95% CI 1.26-78.87). The significant forms of DVT presentation were limb swelling (OR = 2.53, 95% CI 1.41-4.54) and pulmonary embolism (OR = 11.45, 95% CI 3.23-40.59). Fever of more than 37.5 degrees C was a negative predictive factor (OR = 0.42, 95% CI 0.23-0.76). This study shows that the common risk factors of DVT such as surgery and fractures do not affect Asians as much as Caucasians. Instead, thrombophilia and underlying malignancy are prominent risk factors among Asians. Diagnosis of DVT in Asians based on clinical grounds can also be problematic as few presentations are specific.

Thrombosis and bleeding disorders outside Western countries

The rapidly developing countries of Asia are witnessing substantial progress in the awareness of bleeding and thrombotic disorders as important health care problems. It has been thought for a long time that venous thromboembolism is very rare in Asia. Recent large studies that involved the majority of Asian countries demonstrated that this is not true, so that the practice of not using thromboprophylaxis in high-risk medical and surgical cases should be abandoned. The management of hemophilia and allied coagulation disorders has also dramatically improved in several Asian countries, due to the increased availability of blood products for replacement therapy coupled with the leadership role exerted by a few charismatic physicians, particularly in India and Thailand. As to the future, countries such as China and India have the capacity and expertise in biotechnology to consider the production of recombinant factors and gene transfer as the best strategies to tackle the management of persons with hemophilia in these densely populated and huge countries.

Factor VIII levels in children with thrombosis

BACKGROUND

A number of coagulation defects have been implicated as risk factors in thrombo-embolic disease. Of these, high levels of clotting factor VIII have been shown to be associated with a five- to six-fold increased risk of thrombosis, compared to levels < 100 IU/dL in adults. The objective of this study was to investigate the prevalence of elevated plasma levels of factor VIII in a pediatric population with thrombo-embolism (TE).

METHODS

Forty-two children (17 female, 25 male) with TE and 165 healthy controls without familial history of thrombosis or stroke were included in the present study. Doppler ultrasonography with or without angiography, computed tomography, magnetic resonance imaging or echocardiography was utilized to establish the diagnosis. One-stage clotting assay with factor VIII-deficient plasma for measurement of factor VIII and immunoturbidometric assay for von Willebrand factor (vWF) levels were utilized. All measurements were performed in duplicate. Plasma levels of factor VIII were assessed in parents of nine patients to establish whether high levels of factor VIII were genetically determined.

RESULTS

The median age at onset of TE was 7 years (range 0-17 years). Among patients with TE compared to controls, the prevalence of high factor VIII levels was 59.5% versus 12.1% (odds ratio 10.6, 95% CI: 4.9-23.1). The prevalence of high factor VIII levels was detected in at least one of nine families.

CONCLUSION

The data in the present study provide evidence that elevated plasma factor VIII levels are associated with increased risk of thrombosis in children: thus, plasma concentration of factor VIII should be measured in all children with TE.

Heparin cofactor II deficiency

OBJECTIVES

To review of the state of the art relating to congenital heparin cofactor II deficiency as a potential risk factor for thrombosis, as reflected by the medical literature and the consensus opinion of recognized experts in the field, and to make recommendations for the use of laboratory assays for assessing this thrombotic risk in individual patients.

DATA SOURCES

Review of the medical literature, primarily from the last 10 years.

DATA EXTRACTION AND SYNTHESIS

After an initial assessment of the literature, including review of clinical study design and laboratory methods, a draft manuscript was prepared and circulated to participants in the College of American Pathologists Conference XXXVI: Diagnostic Issues in Thrombophilia. Recommendations were accepted if a consensus of experts attending the conference was reached. The results of the discussion were used to revise the manuscript into its final form.

CONCLUSIONS

Consensus was reached that there is insufficient evidence to recommend testing for heparin cofactor II deficiency in patients with thromboembolic disease.

Factor V gene G1691A mutation, prothrombin gene G20210A mutation, and MTHFR gene C677T mutation are not risk factors for pulmonary thromboembolism in Chinese population

A mutation in coagulant factor V gene, a substitution in the 3' untranslated region of prothrombin gene, and a variant in 5,10-methylenetetrahydrofolate reductase (MTHFR) gene have been reported to be related to venous thromboembolism in Caucasians, but this relationship remains in debate in other populations. In this case-control study, we aimed to determine the prevalence of these three mutations in the Chinese population and investigate whether they are associated with pulmonary thromboembolism. The subjects consisted of 90 patients with pulmonary thromboembolism and 143 age- and sex-matched healthy controls. Traditional risk factors for venous thrombosis and pulmonary thromboembolism were investigated as well. We found that the frequencies of varicose vein, phlebitis, trauma, and surgery were significantly higher in cases than in controls. Of all subjects, none was a carrier of coagulant factor V gene G1691A mutation or prothrombin gene G 20210A mutation, which are common point mutations in Caucasians, while the frequency of MTHFR gene 677T allele exceeded 55% in cases (56.7%), controls (55.2%), and all subjects (55.8%) studied. The homozygous mutation rate of MTHFR gene was over 30% in both cases (33.3%) and controls (32.2%), but no significant difference was found in genotype distribution (chi(2)=0.100, P=0.951). Model fitting using logistic regression did not find that MTHFR gene C677T mutation was associated with pulmonary thromboembolism, consistent with the results of stratification analysis. In conclusion, coagulant factor V gene G1691A mutation and prothrombin G20210A mutation are very rare, while MTHFR C677T mutation is very common, and all of them are not associated with pulmonary thromboembolism in the Chinese population.

Extensive mesenteric vein and portal vein thrombosis successfully treated by thrombolysis and anticoagulation

Mesenteric vein thrombosis is generally difficult to diagnose and can be fatal. A case of extensive thrombosis of the mesenteric and portal veins was diagnosed early and successfully treated in a 26-year-old man with Down syndrome who was admitted to hospital because of abdominal pain, severe nausea and high fever. Ultrasonography revealed moderate ascites, and there was minimal flow in the portal vein (PV) on the Doppler examination. Computed tomography (CT) showed remarkable thickening of the walls of the small intestine and extensive thrombosis of the mesenteric, portal and splenic veins. Because neither intestinal infarction nor peritonitis was seen, combined thrombolysis and anticoagulation therapy without surgical treatment was chosen. Urokinase was administered intravenously and later through a catheter in the superior mesenteric artery. Heparin and antibiotics were given concomitantly. The patient's symptoms and clinical data improved gradually. After 10 days, CT revealed that collateral veins had developed and the thrombi in the distal portions of the mesenteric veins had dissolved, although the main trunk of the PV had not recanalized. The only risk factor of thrombosis that was detected was decreased protein S activity.

Two common genetic thrombotic risk factors: factor V Leiden and prothrombin G20210A in adult Turkish patients with thrombosis

The prevalence of genetic risk factors for thrombosis varies greatly in different parts of the world, both in patients with thrombosis and in the general population. Factor V Leiden (FVL) and prothrombin G20210A (PT G20210A) mutations are the most common genetic defects leading to thrombosis. We have previously reported that those two thrombotic risk alleles are frequently found in Turkish children with thrombosis. The aim of the present study was to investigate the frequency of FVL and PT G20210A and their clinical manifestations in adult Turkish patients with thrombosis. Between January 1997 and February 2000, 146 patients with documented thrombosis were investigated in our center for the presence of the FVL and PT G20210A mutations. Forty-five of 146 patients with thrombosis (30.8%) were detected to have FVL mutation. Among those cases with the FVL mutation, seven (4.8%) had homozygote and 38 (26%) had heterozygote mutation. The PT G20210A mutation was detected in 10 of the 146 patients with thrombosis (6.8%). Another six cases (4.1%) had both FVL and PT G20210A mutations. The overall frequency of these two common risk alleles in our adult population with thrombosis was 41.6%. Our findings reveal that FVL and PT G20210A mutations are significant genetic risk factors contributing to the pathophysiology of thrombosis in the Turkish population.

Importance of hyperhomocysteinemia as a risk factor for venous thromboembolism in a Taiwanese population. A case-control study

OBJECTIVE

To determine the current status of hyperhomocysteinemia, which is a known risk for venous thrombosis (DVT), in Taiwan.

SUBJECTS

101 unselected patients with a minimum of one episode of deep leg DVT, either initial inpatients or current compliant outpatients in a teaching hospital.

METHODS

Various thrombophilic risks, gene polymorphism and clinical predisposition were evaluated.

RESULTS AND CONCLUSIONS

Patients presented higher fast total plasma homocysteine (hcy) levels than age- and sex-matched controls did (14.1 vs. 9.94 microM). Based on the 95th percentile of control values, hyperhomocysteinemia had a four- to nine-fold risk for DVT, irrespective of clinical predisposition, as well as other thrombophilic risks surveyed. Polymorphism of a metabolizing enzyme, methylenetetrahydrofolate reductase (MTHFR), was not associated with DVT, although homozygous thermolabile mutation tended to have higher plasma hcy levels. Factor V Leiden was absent in analysis of 80 patients. In complete evaluation (hcy, antithrombin (AT), protein S (PS), protein C (PC), lupus anticoagulant (LA), anticardiolipin antibody) of a subset of 83 patients hyperhomocysteinemia was the most prevalent risk (33.7%), with PC or PS deficiencies following (22.9%). Thus, hyperhomocysteinemia is a prominent risk for DVT in Taiwan.