Venous thromboembolism among United States soldiers deployed to Southwest Asia

INTRODUCTION: Military operations may represent a high-risk environment for venous thromboembolism (VTE). We sought to identify and describe cases of venous thromboembolism among US military personnel serving in Southwest Asia, and estimate relative disease rates compared to non-deployed personnel. MATERIALS AND METHODS: Retrospective review of imaging archives, hospital discharge codes, case logs and autopsy records for the diagnosis of deep vein thrombosis or pulmonary embolism occurring from 1 March 2003 through 29 February 2004 among U.S. military personnel deployed to Southwest Asia. Rates of disease in deployed and non-deployed active-duty soldiers were estimated using personnel data and deployment experience obtained from automated rosters. RESULTS: Forty cases of venous thromboembolism were identified. The case-fatality rate was 16% (3/19) among those with pulmonary embolism. Antecedent trauma followed by prolonged air evacuation was present in 55% (22/40). Compared to trauma-associated cases, non-trauma cases were more commonly over 40 years old (44% vs. 5%; p<0.05), assigned to a transportation or quartermaster company (56% vs. 14%; p<0.05), or had a history of remote venous thromboembolism (31% vs. 0%; p<0.05). The overall incidence among deployed active-duty soldiers was 22.1/100,000 person-years. Compared to non-deployed active-duty soldiers, the age-adjusted incidence rate ratio was 1.06 (CI(0.95) 0.68-1.67). CONCLUSIONS: VTE rates among deployed soldiers are relatively low compared to the general population, and are comparable to non-deployed soldiers. Fatalities from PE are not uncommon, and vigilance among clinicians remains warranted. Trauma followed by prolonged air evacuation or ground transport during military operations may represent unique interactive risk factors for venous thromboembolism.     

Prevalence of venous thromboembolism at a teaching hospital in Okinawa, Japan

Limited data suggest that Asian Americans may have a lower risk of venous thromboembolism (VTE) than Caucasians. However, the actual prevalence of VTE among Asians remains controversial, and has not been described in Japan. We studied all 131,060 patients hospitalized at a single medical centre in Japan (January 1987 - December 1999). Patients with VTE were identified through discharge diagnoses. Hospital records were reviewed for information on patient demographics, risk factors, and diagnostic modalities. VTE occurred in 0.11% of admissions (n=141, 95%CI 0.09-0.13%). Mean age (+/-SD) was 64+/-17 years, 70% were women, 91% had deep vein thrombosis, and 29% pulmonary embolism. Among hospitalized patients 50-69 years old, VTE was significantly more common among women than men (0.31% vs. 0.08%; OR 3.88; 95%CI 1.45-6.31). We found a low prevalence of VTE in Japan compared to that reported in the US. Future studies are needed to clarify the reasons for our findings.     

Seasonal and monthly variability in the incidence of venous thromboembolism. A systematic review and a meta-analysis of the literature

Many studies showed that the occurrence of cardiovascular and cerebrovascular events exhibits a seasonal and monthly variation. Evidences of a seasonal and monthly variation in the incidence of venous thromboembolism (VTE) are more conflicting. We conducted a systematic review and a meta-analysis of the literature to assess the presence of an infradian rhythm of this disease. MEDLINE and EMBASE databases were searched up to January 2010. Monthly and seasonal variation in the incidence of VTE were analysed. We included studies analysing seasonal or monthly aggregation in the incidence of deep-vein thrombosis (DVT) and/or pulmonary embolism (PE) with an objective diagnosis of VTE. Two authors independently reviewed and extracted data. Seventeen studies for a total of about 35,000 patients were included. Twelve studies analysed the seasonal variation and 10 studies the monthly variation of VTE. Our results showed a significantly increased incidence of VTE in winter (chi-square 146.04, p <0.001), with a relative risk (RR) of VTE of 1.143 (99% CI [1.141, 1.144]), and a significantly increased incidence of VTE in January (chi-square 232.57, p <0.001) with an RR of VTE of 1.194 (99% CI 1.186, 1.203). Subgroup analyses including only idiopathic venous thromboembolic events confirmed the results of principal analyses. In conclusion, our data support the presence of an infradian pattern in the incidence of venous thromboembolic events, with a significantly higher risk in Winter and in January. Future studies are needed to better clarify the mechanisms behind this pattern.     

Venous thromboembolism (VTE) in Europe. The number of VTE events and associated morbidity and mortality

Venous thromboembolism (VTE) is often asymptomatic, mis-diagnosed, and unrecognized at death, and there is a lack of routine postmortem examinations. These factors are thought to result in marked underestimates ofVTE incidence. The objective of our study was to estimate the total burden of VTE within the European Union (EU) per annum. An epidemiological model was constructed to estimate the number of community- and hospital-acquired incidents and recurrent cases (attack rate) of nonfatal VTE and VTE-related deaths, as well as incident and prevalent cases of post-thrombotic syndrome (PTS) and chronic thromboembolic pulmonary hypertension (PH) occurring in the EU per annum. Individual models were developed for six EU countries. The models were populated with data from published literature and, where necessary, expert opinions. The findings were tested using probabilistic sensitivity analyses. The estimated total number of symptomaticVTE events (range based on probabilistic sensitivity analysis) per annum within the six EU countries was 465,715 (404,664-538,189) cases of deep-vein thrombosis, 295,982 (242,450-360,363) cases of pulmonary embolism (PE), and 370,012 (300,193-483,108) VTE-related deaths. Of these deaths, an estimated 27,473 (7%) were diagnosed as being antemortem; 126,145 (34%) were sudden fatal PE, and 217,394 (59%) followed undiagnosed PE. Almost three-quarters of all VTE-related deaths were from hospital-acquired VTE. VTE is a major health problem in the EU, with over one million VTE events or deaths per annum in the six countries examined. Given the availability of effective VTE prophylaxis, many of these events and deaths could have been prevented. These results have important implications for the allocation of healthcare resources.     

Incidence of symptomatic venous thromboembolism after different elective or urgent surgical procedures

There have been no comprehensive studies that have compared the incidence of symptomatic VTE over a spectrum of different urgent or elective surgical procedures. In this study we determined the incidence of symptomatic venous thromboembolic events (VTE) within a 3 month period after 76 different surgical procedures. Using a large administrative data-base, we analyzed 1,653,275 cases that underwent one of 76 selected surgical procedures between January 1, 1992 and September 30, 1996. The principal outcomes were venous thrombosis or pulmonary embolism, during either the initial hospitalization or a re-hospitalization for VTE within 91 days of the date of surgery. Predictors of VTE were analyzed using logistic regression. Overall, VTE was diagnosed in 13,533 cases (0.8%, 95% CI = 0.7-0.9%) and of these, 5049 (37%, 95% CI = 36-38%) had pulmonary embolism. Predictors of VTE included: advancing age (OR=1.1 per 5 year increment in age, 95% CI =1.1-1.1), Latino ethnicity (OR = 0.9, 95% CI = 0.8-0.9), Asian/Pacific Islander ethnicity (OR = 0.5, 95% CI = 0.4-0.6), presence of a malignancy (OR = 1.7, 95% CI = 1.6-1.8) and prior VTE (OR = 6.2, 95% CI = 5.5-7.0). High-risk procedures that had an incidence of symptomatic VTE of approximately 2 to 3% included invasive neurosurgery, total hip arthroplasty, major vascular surgery and radical cystectomy. Fifty-six percent of all VTE events diagnosed within 91 days of surgery occurred after discharge. The findings of this study provide a basis for categorizing different surgical procedures as low, intermediate, high and very high risk for VTE. Because of the high incidence of VTE diagnosed after hospital discharge, further studies of extended thromboprophylaxis appear warranted.     

Racial and gender differences in the incidence of recurrent venous thromboembolism

Men have been reported to have a higher incidence of recurrent venous thromboembolism than women. However, it is not known if this gender effect holds among different racial/ethnic groups and for both venous thrombosis and pulmonary embolism. We conducted a retrospective analysis of 18- to 65-year-old Caucasian, African-American and Hispanic cases hospitalized in California with unprovoked venous thromboembolism. The principal outcome was recurrent venous thromboembolism 7-60 months after the index event. Among 11,514 cases that were followed for a mean of 3.0 years, men had a significantly higher rate (events/100 patient-years) of recurrent venous thromboembolism than women for both venous thrombosis [rate ratio (RR) = 1.5, 95% confidence interval (CI):1.3-1.8] and pulmonary embolism [RR = 1.3, 95%CI:1.0-1.6]. Among men the recurrence rate did not vary significantly between the racial/ethnic groups (p > 0.05). However, the recurrence rate among Hispanic women with venous thrombosis was significantly higher than in Caucasian women (p < 0.001) and was comparable to the rate in men. Both Hispanic and African-American women with pulmonary embolism had a higher recurrence rate compared with Caucasian women (p < 0.02) that was comparable to the rate in men. We conclude that women in California had a 40% lower risk of recurrent venous thromboembolism compared to men. Rates were comparable among men of different races, but there were significant inter-racial differences among women, which also varied with the type of initial event. The effect of gender on the risk of recurrent venous thromboembolism can not be generalized because it varies between racial/ethnic groups and with the type of index event.     

Subarachnoid hemorrhage incidence among Whites, Blacks and Caribbean Hispanics: the Northern Manhattan Study

American blacks and Hispanics may have a greater incidence of subarachnoid hemorrhage (SAH) than whites, but incidence data are scant. We used an active hospital and community surveillance program and autopsy reports to identify incident SAH cases among white, black and Hispanic adults living in Northern Manhattan between July 1993 and June 1997. The annual incidence adjusted for age and sex to the 1990 US Census was 9.7 per 100,000 (95% CI 7.5-12.0). Compared with whites (9 cases, age- and sex-adjusted annual incidence 8.2 per 100,000), the rate ratio of SAH was 1.3 (95% CI 0.7-2.4) for Hispanics (34 cases, incidence 10.9), and 1.6 (95% CI 0.8-2.8) for blacks (9 cases, incidence 12.8). The 30-day case fatality rate was 26%. Risk of death increased significantly with age and severity at onset but was not influenced by gender or race-ethnicity.     

The allele frequency of mutations in four genes that confer enhanced susceptibility to venous thromboembolism in an unselected group of New York State newborns

The frequencies of Factor V G1691A (FVL), prothrombin (PT) G20210A, 5'10'methylenetetrahydrofolate reductase (MTHFR) C677T, and methionine synthase (MS) A2756G (four mutations associated with an increased risk of venous thromboembolism [VTE]) were determined in a sample of approximately 1500 New York State residents. Dried blood spots from approximately equal numbers of Caucasians, African-Americans and Hispanics were anonymously obtained from the New York State Department of Health Newborn Screening Program. Following PCR amplification of dried blood spot DNA, allele-specific oligonucleotide hybridization was used to detect mutant alleles. The total number of individuals at increased genetic risk for VTE was 271 (17.5%) of the 1553 persons tested. Increased genetic risk was defined as the heterozygous state for FVL or PT and the homozygous state for the MTHFR or MS polymorphisms. Sixteen individuals had more than one genetic risk factor. The MS gene variant allele frequencies for African-Americans and Hispanics are the first to be reported. This report also provides an estimate of the variant PT allele in the largest group of Hispanics studied to date.     

Death due to recurrent thromboembolism among younger healthier individuals hospitalized for idiopathic pulmonary embolism

The incidence of death due to recurrent pulmonary embolism (PE) after a first-time idiopathic PE is not well defined. We conducted a retrospective study of patients age 18 to 56 years who had idiopathic PE between 1994-2001. The incidence and cause of death within five years was determined using linked discharge records and a master death registry. A total of 3,456 patients had a first-time idiopathic PE. The rate of recurrent VTE 0-6 months after the index event was 13.1%/year, and 2.9%/year 6-60 months after the event. During the mean follow-up of 3.2 years 118 (3.4%, 95% confidence interval [CI] = 2.8-4.1%) patients died. Fifty-two (44%) deaths occurred <29 days after the index PE (case-fatality rate = 1.5%, 95%CI = 1.1-2.0%). Among the 66 cases (1.9%) that died after 28 days, 18 (0.52%) were due to recurrent PE or its sequelae: eight had recurrent PE alone, five had recurrent PE and a serious co-morbid illness, and five had thromboembolic pulmonary hypertension with or without acute PE. The person-time rate of death (deaths per 100 patient-years) attributed to any recurrent thromboembolism 6-60 months after the event was 0.16% (95%CI = 0.1-0.26%). Ten of the 18 (56%) late thromboembolic deaths reflected a first-time recurrent PE. The 28-day case-fatality rate for recurrent VTE was 2.8% (95%CI = 1.5-4.9%). In this cohort of younger patients with idiopathic PE, the rate of death due to recurrent VTE, particularly to first-time recurrent PE, was low. Among the patients who died of thromboembolism >28 days after the index PE, 28% had developed pulmonary hypertension.     

Risk of venous thromboembolism in relatives of symptomatic probands with thrombophilia: a systematic review

Clinical equipoise exists regarding whether relatives of individuals with venous thromboembolism (VTE) and thrombophilia should be screened for thrombophilia. There have been no systematic attempts to summarize studies that have assessed the incidence of VTE in relatives. The purpose of this review was to systematically identify and review observational studies with thrombophilic relatives and to summarize their findings with respect to their risk of VTE. We conducted a systematic literature review and included nine observational studies meeting a priori inclusion criteria. Potentially eligible studies evaluated VTE incidence in relatives of index patients (probands) with symptomatic thrombophilia. In the four prospective studies, the incidence of VTE for asymptomatic family members with factor V Leiden ranged from 0.58-0.67% per year, 1.0-2.5% for protein C deficiency, 0.7-2.2% for protein S deficiency, and 4% for antithrombin deficiency. About half of all VTEs occurred during well-known risk periods but incidence rates were decreased by use of prophylaxis. No deaths from pulmonary embolism or fatal hemorrhages from anticoagulants were reported. The incidence of VTE was generally lower in the retrospective studies. The pooled relative risk from four retrospective studies for factor V Leiden carriers was 3.69 (CI 2.27, 6.00) and from two studies the pooled relative risk for deficiencies of protein C, protein S, and antithrombin was 10.58 (CI 5.38, 20.81). In conclusion, the risk of VTE events in asymptomatic relatives is low, but this may be an underestimate. Anticoagulant prophylaxis during risk periods appears to be of benefit but further research in this area is required.     

Venous thromboembolism and fractured neck of femur

The post-operative incidence of venous thromboembolism (VTE) is high for patients undergoing hip fracture surgery. Proven prophylactic measures are available although underutilized due to concern on post-operative bleeding with use of anticoagulants. This study retrospectively reviewed the clinical incidence of VTE and utilisation of thromboprophylactic protocols over an eight year period. Demographic details, mechanism of injury, VTE risk factors, prophylactic modalities (mechanical and pharmacological), operation duration, mode of anaesthesia, hospital length of stay (LOS) and post-operative complications with particular attention to suspected deep vein thrombosis (DVT) and/or pulmonary embolism (PE) were analysed. Male to female ratio was 1:2.7 with a median age of 78 years (IQR: 70-86 years) and 83 years (IQR: 77-87 years) respectively (p<0.001). Median hospital LOS was 8 days (IQR: 5-13 days) and differed with mechanism of injury.The in-hospital incidence of VTE was 1.6% (95% CI: 1.1-2.5%) with a probably underestimated three month rate of 8.2% (95% CI: 5.3-12.4%). Non fatal PE was 0.5% (95% CI: 0.2-1.0%) in-hospital and 2.6% (95% CI: 1.2-5.5%) at three months. Fatal PE was 0.5% (95% CI: 0.2-1.0%) with a three month incidence of 0.4% (95% CI: 0.1-2.4%).The in-hospital VTE incidence was kept relatively low with use of prophylactic protocols with almost all patients receiving prophylaxis by the end of the study period. Given the five-fold out of hospital increase in incidence, consideration should be given to continue prophylaxis beyond hospital discharge in this high risk group of patients.     

Incidence of post-thrombotic syndrome in patients with previous pulmonary embolism. A retrospective cohort study

There is little information available about the true incidence of post-thrombotic syndrome (PTS) after pulmonary embolism (PE). The aim of this study was to investigate the incidence of PTS in patients with previous pulmonary embolism without concomitant ultrasonographically-detectable deep vein thrombosis (DVT). A retrospective cohort study was conducted at a single tertiary care centre, Cosenza, Italy. Forty-seven consecutive patients with proved PE without DVT within the previous 2 to 6 years, 45 patients with previous DVT in the same years, and 45 patients with diseases unrelated to venous thromboembolism (VTE) underwent a blind assessment for PTS using a clinical score. Two of 47 (4.2%, 95%CI: 0.01-9.9) patients with PE, 2 of 45 (4.4%, 95%CI: 0.01-10.4) patients with diseases unrelated to VTE, and 23 of 45 (53.3%, 95%CI: 38.7-67.9) patients with DVT showed signs and symptoms of PTS. The difference between the first two groups was not statistically significant (p = 0.7). In conclusion, the incidence of PTS after pulmonary embolism without DVT is low, and no different from that of patients without previous VTE.     

Moyamoya disease in Washington State and California

The authors identified 298 diagnoses of moyamoya in California and Washington from hospital discharge databases during the period 1987 to 1998. The incidence was 0.086/100,000 persons. The ethnicity-specific incidence rate ratios compared to whites were 4.6 (95% CI: 3.4 to 6.3) for Asian Americans, 2.2 (95% CI: 1.3 to 2.4) for African Americans, and 0.5 (95% CI: 0.3 to 0.8) for Hispanics. The incidence of moyamoya in Washington and California was lower than reported in Japan, but the rate among US Asians is similar.     

Incidence, risk factors and clinical features of venous thromboembolism in newly diagnosed lymphoma patients: Results from a prospective cohort study with Asian population

Introduction

Venous thromboembolism (VTE) may be associated with treatment failure rate and quality of life deterioration in lymphoma patients. However, the majority of data regarding VTE has come from retrospective studies done in Western countries.

Materials and methods

We analyzed VTE, including pulmonary embolism and deep vein thrombosis, from Asian patients enrolled a prospective cohort study. All patients were newly diagnosed Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma (NHL).

Results

A total of 686 patients were analyzed, and the median follow-up duration was 21.8 months. There were 54 cases of VTE including deep vein thrombosis alone (33/54, 61.1%) and pulmonary embolism (21/54, 38.9%). The median time to VTE was 1.97 months, and the one-year actuarial incidence was 7.9%. The global incidence of VTE was higher in patients with NHL (51/641, 8.0%) than HL (3/45, 6.7%). All cases of VTE occurred in patients receiving chemotherapy whereas no VTE in patients without chemotherapy. VTE was also independently associated with age older than 60 years and primary central nervous system (CNS) lymphoma. No VTE-related deaths were reported among all cases of VTE. Thus, overall survival was not different between patients with and without VTE. The subgroup analysis of patients with diffuse large B-cell lymphoma showed 8.9% of one-year actuarial incidence, but the occurrence of VTE did not influence its overall survival, either.

Conclusions

The incidence of VTE in our study population was comparable to that of Western countries, and VTE was associated with chemotherapy, brain involvement and old age.     

Clinical presentation and time-course of postoperative venous thromboembolism: Results from the RIETE Registry

There is little literature about the clinical presentation and time-course of postoperative venous thromboembolism (VTE) in different surgical procedures. RIETE is an ongoing, prospective registry of consecutive patients with objectively confirmed, symptomatic acute VTE. In this analysis, we analysed the baseline characteristics, thromboprophylaxis and therapeutic patterns, time-course, and three-month outcome of all patients with postoperative VTE. As of January 2006, there were 1,602 patients with postoperative VTE in RIETE: 393 (25%) after major orthopaedic surgery (145 elective hip arthroplasty, 126 knee arthroplasty, 122 hip fracture); 207 (13%) after cancer surgery; 1,002 (63%) after other procedures. The percentage of patients presenting with clinically overt pulmonary embolism (PE) (48%, 48%, and 50% respectively), the average time elapsed from surgery to VTE (22 +/- 16, 24 +/- 16, and 21 +/- 15 days, respectively), and the three-month incidence of fatal PE (1.3%, 1.4%, and 0.8%, respectively), fatal bleeding (0.8%, 1.0%, and 0.2%, respectively), or major bleeding (2.3%, 2.9%, and 2.8%, respectively) were similar in the three groups. However, the percentage of patients who had received thromboprophylaxis (96%, 76% and 52%, respectively), the duration of prophylaxis (17 +/- 9.6, 13 +/- 8.9, and 12 +/- 11 days, respectively) and the mean daily doses of low-molecular-weight heparin (4,252 +/- 1,016, 3,260 +/- 1,141, and 3,769 +/- 1,650 IU, respectively), were significantly lower in those undergoing cancer surgery or other procedures. In conclusion, the clinical presentation, time-course, and three-month outcome of VTE was similar among the different subgroups of patients, but the use of prophylaxis in patients undergoing cancer surgery or other procedures was suboptimal.     

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.     

Risk factors for intracerebral and subarachnoid hemorrhage among Hispanics and non-Hispanic whites in a New Mexico community

BACKGROUND AND OBJECTIVE: A higher incidence of spontaneous intracerebral and subarachnoid hemorrhage among Hispanics than non-Hispanic whites has been measured in Bernalillo County, New Mexico. In an attempt to explain these differences, we compared historical vascular risk factors between Hispanics and non-Hispanic whites living in this community. METHODS: An ongoing telephone survey, the Behavioral Risk Factor Surveillance System, collected annual data about vascular risk factors among non-institutionalized, randomly selected adults. Data covering 6 years, 1988-1993, were analyzed. RESULTS: There were 843 Hispanic and 1,635 non-Hispanic white residents of Bernalillo County, New Mexico, who participated in this survey. Because Hispanics were significantly younger than non-Hispanic whites (37.7 vs. 43.4 years, p < 0.001), all other comparisons were adjusted for age. Prevalence of hypertension was similar between these ethnic groups (15-17%). Prevalence of alcohol drinking considered risky for abuse was similar between these ethnic groups (5-6%), but was significantly higher among Hispanic men than women (8.5 vs. 1.6%, p < 0.001). The quantity of alcohol consumption among those at risk for abuse was similar between these ethnic groups. Prevalence of current cigarette smoking was similar between these ethnic groups (22-23%), but Hispanics smoked significantly less than non-Hispanic whites (11.4 vs. 15.2 cigarettes per day, p < 0.001) and among non-Hispanic whites, men smoked significantly more than women (17.0 vs. 13.4 cigarettes per day, p = 0.001). CONCLUSION: The vascular risk factors which we compared between Hispanics and non-Hispanic whites do not help to explain the higher incidence of hemorrhagic strokes among the Hispanics in Bernalillo County, New Mexico. Additional risk factors for hemorrhagic strokes in these two ethnic groups should be studied.     

Oral dabigatran versus enoxaparin for thromboprophylaxis after primary total hip arthroplasty (RE-NOVATE II*). A randomised, double-blind, non-inferiority trial

This trial compared the efficacy and safety of oral dabigatran, a direct thrombin inhibitor, versus subcutaneous enoxaparin for extended thromboprophylaxis in patients undergoing total hip arthroplasty. A total of 2,055 patients were randomised to 28-35 days treatment with oral dabigatran, 220 mg once-daily, starting with a half-dose 1-4 hours after surgery, or subcutaneous enoxaparin 40 mg once-daily, starting the evening before surgery. The primary efficacy outcome was a composite of total venous thromboembolism [VTE] (venographic or symptomatic) and death from all-causes. The main secondary composite outcome was major VTE (proximal deep-vein thrombosis or non-fatal pulmonary embolism) plus VTE-related death. The main safety outcome was major bleeding. In total, 2,013 were treated, of whom 1,577 operated patients were included in the primary efficacy analysis. The primary efficacy outcome occurred in 7.7% of the dabigatran group versus 8.8% of the enoxaparin group, risk difference (RD) -1.1% (95%CI -3.8 to 1.6%); p<0.0001 for the pre-specified non-inferiority margin. Major VTE plus VTE-related death occurred in 2.2% of the dabigatran group versus 4.2% of the enoxaparin group, RD -1.9% (-3.6% to -0.2%); p=0.03. Major bleeding occurred in 1.4% of the dabigatran group and 0.9% of the enoxaparin group (p=0.40). The incidence of adverse events, including liver enzyme elevations and cardiac events, during treatment was similar between the groups. Extended prophylaxis with oral dabigatran 220 mg once-daily was as effective as subcutaneous enoxaparin 40 mg once-daily in reducing the risk of VTE after total hip arthroplasty, and superior to enoxaparin for reducing the risk of major VTE. The risk of bleeding and safety profiles were similar.     

Incidence of arterial cardiovascular events in patients with idiopathic venous thromboembolism. A retrospective cohort study

Recent data have shown a higher incidence of arterial events in patients with venous thromboembolism (VTE) of unknown origin than in those with the secondary form of disease. Whether patients with idiopathic VTE have a higher risk of subsequent arterial events than the general population is unknown. The aim was to evaluate the rates of subsequent arterial events in patients with idiopathic VTE and control subjects. In a retrospective cohort study we compared the rates of subsequent arterial events (i.e. acute myocardial infarction, ischemic stroke and peripheral arterial disease) in 151 consecutive patients with objectively confirmed spontaneous VTE and 151 control subjects randomly selected from the database of two family physicians. We collected information about cardiovascular risk-factors (hypertension, hypercholesterolemia, diabetes, obesity and smoke) at the time of VTE episode, or corresponding date for the controls, and considered the follow-up from this time. Patients and controls who had suffered from arterial events before the index date were excluded. During a mean follow-up of 43.1 (+/- 21.7) months there were 16 arterial events in the VTE patients and six in the control group (HR, 2.84;95% CI,1.11 to 7.27; p = 0.03). The difference remained significant after adjusting for age and other cardiovascular risk factors (HR 2.86;95% CI,1.07 to 7.62). Overall mortality was also higher in the VTE patients (12 vs.4 deaths). In conclusion, arterial events are more common in patients with previous idiopathic VTE than in the general population. These findings may have practical implications.     

Population-based epidemiology of postoperative venous thromboembolism in Taiwanese patients receiving hip or knee arthroplasty without pharmacological thromboprophylaxis

Introduction

Population-based evaluation on the incidence of postoperative venous thromboembolism (VTE) has not yet been reported for Asians receiving arthroplasty. In Taiwan, thromboprophylaxis was not commonly applied for patients. The population-based cohort study aimed to investigate the epidemiology, and to determine the risk factors VTE for patients receiving hip or knee replacement without pharmacological thromboprophylaxis in Taiwan.

Materials and Methods

We retrospectively acquired patients’ data from National Health Insurance databases representing more than 99% of about 23 million Taiwanese citizens. The primary outcome was the incidence of composite symptomatic VTE within 28 days after receiving hip or knee replacement surgery.

Results

During 2002 to 2006, there were 114,026 patients undergoing hip (n = 61,460) or knee (n = 52,566) replacement surgery. The occurrence rate of overall postoperative VTE was 0.44%. The incidence of pulmonary embolism was four in 10,000 patients receiving hip replacement or seven in 10,000 individuals undergoing knee replacement. The weekly cumulative incidence of VTE was persistently rising up to 28 days after surgery. Dramatic increase in risk of post-surgical VTE was associated with prior disease history of PE (p < 0.001 for hip replacement, p = 0.01 for knee replacement) or DVT (p = 0.004 for hip replacement, p < 0.001 for knee replacement). Prior claim of congestive heart failure was an independent risk factor associated with patients receiving knee arthroplasty (p = 0.01).

Conclusion

Life-threatening PE occurred and increased cumulatively up to 28 days after hip or knee arthroplasty in Asians. Proper prophylaxis for patients with the exposure of high risks needs to be scrutinized.