First Episode Of Venous Thromboembolism Research Articles

Arterial disease and venous thrombosis: are they related, and if so, what should we do about it?

Arterial disease and venous thrombosis: are they related, and if so, what should we do about it?

Risk of Recurrent Venous Thromboembolism in Patients With Common Thrombophilia

The 2 most common genetic polymorphisms that predispose to a first episode of venous thromboembolism (VTE) are factor V Leiden (FVL) and prothrombin G20210A. However, the effect of these polymorphisms on the risk of recurrent VTE is unclear. We performed a meta-analysis to obtain best estimates of the relative risk of recurrent VTE associated with these genetic polymorphisms. Electronic and manual searches were used to identify cohort studies of patients with a first episode of VTE that reported the incidence of objectively confirmed recurrence following discontinuation of anticoagulation among those with or without heterozygous FVL or prothrombin G20210A polymorphism. Thirteen reports fulfilled our criteria for inclusion. Pooled results from 10 studies involving 3104 patients with first-ever VTE revealed that FVL was present in 21.4% of patients (95% confidence interval [CI], 20%-23%) and associated with an increased odds of recurrent VTE of 1.41 (95% CI, 1.14-1.75; P = .08 for heterogeneity). Pooled results from 9 studies involving 2903 patients with first-ever VTE revealed that prothrombin G20210A was present in 9.7% of patients (95% CI, 9%-11%) and associated with an increased odds of recurrent VTE of 1.72 (95% CI, 1.27-2.31; P = .19). The estimated population-attributable risk of recurrence for FVL was 9.0% (95% CI, 4.5%-13.2%) and for prothrombin G20210A was 6.7% (95% CI, 3.4%-9.9%). Heterozygous FVL and prothrombin G20210A are each associated with a significantly increased risk of recurrent VTE after a first event, but the magnitude of the increase in risk is modest and by itself is unlikely to merit extended-duration anticoagulation. These data call into question the cost-effectiveness of routine testing for these common inherited thrombophilic polymorphisms among patients with a first episode of VTE.

Renal transplant recipients are at high risk for both symptomatic and asymptomatic deep vein thrombosis.

Venous thromboembolism (VTE) is one of the thrombotic complications that can occur in patients receiving renal transplantation (RT). The prevalence of VTE in RT patients is, however, undefined. To evaluate the rate of a first episode of VTE in a series of 538 consecutive RT recipients admitted to our institution, the timing of occurrence of the thromboembolic events after transplantation, and the rate of recurrence after thromboprophylaxis withdrawal. Risk factors for recurrence were also evaluated, particularly in relation to the type of the first event (symptomatic or asymptomatic). During follow-up, 47 of 518 patients (28 males, 19 females; 9.1%) developed a first episode of VTE at a median time of 17 months (range 1-165 months) after kidney transplantation. Cancer was associated with the occurrence of VTE (odds ratio 4.8). Seventeen of 43 patients (39.5%) with deep vein thrombosis were asymptomatic and the diagnosis was made during routine ultrasound examination. Twenty-two patients (46.8%) experienced a recurrence of VTE. A relevant rate of recurrence was documented amongst patients with a first episode of both symptomatic (53%) and asymptomatic (23.5%) VTE. This study confirms that RT patients are at high risk of symptomatic and asymptomatic VTE and that this risk persists even after several years. Patients who experience VTE are at high risk of recurrence after thromboprophylaxis withdrawal.

Post-thrombotic syndrome, recurrence, and death 10 years after the first episode of venous thromboembolism treated with warfarin for 6 weeks or 6 months.

The influence of the duration of anticoagulant therapy after venous thromboembolism (VTE) on the long-term morbidity and mortality is unclear. To investigate the long-term sequelae of VTE in patients randomized to different duration of secondary prophylaxis. In a multicenter trial comparing secondary prophylaxis with vitamin K antagonists for 6 weeks or 6 months, we extended the originally planned 2 years follow-up to 10 years. The patients had annual visits and at the last visit clinical assessment of the post-thrombotic syndrome (PTS) was performed. Recurrent thromboembolism was adjudicated by a radiologist, blinded to treatment allocation. Causes of death were obtained from the Swedish Death Registry. Of the 897 patients randomized, 545 could be evaluated at the 10 years follow-up. The probability of developing severe PTS was 6% and any sign of PTS was seen in 56.3% of the evaluated patients. In multivariate analysis, old age and signs of impaired circulation at discharge from the hospital were independent risk factors at baseline for development of PTS after 10 years. Recurrent thromboembolism occurred in 29.1% of the patients with a higher rate among males, older patients, those with permanent triggering risk factor - especially with venous insufficiency at baseline - signs of impaired venous circulation at discharge, proximal deep vein thrombosis, or pulmonary embolism. Death occurred in 28.5%, which was a higher mortality than expected with a standardized incidence ratio (SIR) of 1.43 (95% CI 1.28-1.58), mainly because of a higher mortality than expected from cancer (SIR 1.83; 95% CI 1.44-2.23) or from myocardial infarction or stroke (SIR 1.28; 95% CI 1.00-1.56). The duration of anticoagulation did not have a statistically significant effect on any of the long-term outcomes. The morbidity and mortality during 10 years after the first episode of VTE is high and not reduced by extension of secondary prophylaxis from 6 weeks to 6 months. A strategy to reduce recurrence of VTE as well as mortality from arterial disease is needed.

Value of D-Dimer Testing for the Exclusion of Pulmonary Embolism in Patients With Previous Venous Thromboembolism

D-dimer levels remain elevated in many patients after completion of a 6-month anticoagulant drug course for a first episode of venous thromboembolism (VTE), which may limit the clinical usefulness of D-dimer testing for ruling out a possible recurrence. We assessed the safety and usefulness of D-dimer testing in patients with suspected pulmonary embolism (PE) who had experienced a previous VTE. We analyzed data from 2 outcome studies that enrolled 1721 consecutive emergency department patients with clinically suspected PE. Information on the existence of a previous episode of VTE was abstracted from the database. All the patients underwent a sequential diagnostic workup, including an enzyme-linked immunosorbent assay D-dimer test and a 3-month follow-up. The proportion of confirmed PE was 24.1% (415/1719); PE was ruled out by a negative D-dimer test result in 32.7% (462/1411) of the patients without previous VTE but in only 15.9% (49/308) of the patients with previous VTE (P<.001). The 3-month thromboembolic risk was 0% (95% confidence interval, 0.0%-7.9%) in patients with previous VTE and a negative D-dimer test result. The 2-fold lower chance of a negative D-dimer test result in patients with previous VTE was independent of older age, active malignancy, fever, and recent surgery. In patients with suspected PE and previous VTE, a negative D-dimer test result seems to allow safely ruling out a recurrent event. However, the proportion of negative results is lower in such patients, definitely reducing the clinical usefulness of the D-dimer test in that subgroup.

Guidelines on oral anticoagulation (warfarin): third edition – 2005 update

The British Committee for Standards in Haematology (BCSH) published its third edition of Guidelines on Oral Anticoagulation in 1998 (British Committee for Standards in Haematology, 1998). Most of the recommendations made in 1998 remain unchanged and a fourth edition of the guideline is considered unnecessary at the time of writing (June 2005). However, we draw attention to those areas where new informative data have been published. As in the original guideline, the term ‘oral anticoagulant’ used in this update refers to oral vitamin K antagonists (VKA), such as warfarin. New oral non-VKA are currently being evaluated in clinical trials but are not yet licensed for use in the UK. When these drugs become available new guidance will be issued specifically for the use of those drugs. The guideline group was selected to be representative of UKbased medical experts. The drafting group met and communicated by email. MEDLINE was searched systematically for publications in English from 1998. The writing group convenor (T. Baglin) produced the draft guidelines which were subsequently revised by consensus. The guideline was reviewed by a multidisciplinary sounding board, the BCSH and the British Society for Haematology (BSH) and comments incorporated where appropriate. Criteria used to quote levels and grades of evidence are as in Appendix 3 of the Procedure for Guidelines Commissioned by the BCSH (http://www.bcshguidelines.com/process1.asp#App3). The target audience for this guideline is healthcare professionals involved in the management of patients receiving oral anticoagulant therapy.

High Rate of Recurrence in Renal Transplant Recipients after a First Episode of Venous Thromboembolism

No data are available about the optimal duration of oral anticoagulant therapy (OAT) after an episode of venous thromboembolism (VTE) occurring in renal transplant (RT) recipients. Our study was undertaken to evaluate the risk of VTE recurrence in patients developing a first episode of VTE after RT. Among 484 RT patients, 34 (7%) developed a first VTE: 28/34 VTE patients (Group 1) were prospectively studied, after stopping OAT. Group 1 was compared with a group of 84 patients without history of renal disease who had suffered from a first episode of VTE matched for age, sex and type of thrombotic event (Group 2) and with a matched group of 84 RT recipients with no history of VTE (Group 3). After OAT withdrawal, blood samples were obtained for thrombophilia and clotting activation markers (prothrombin fragment 1+2 (F1+2) and D-dimer plasma levels). During follow-up, 14/28 patients of Group 1 and 8/84 patients of Group 2 experienced VTE recurrence (P < 0.0005). Homocysteine, F1+2 and D-dimer plasma levels were significantly higher in Group 1 than in Group 2 and 3 (P < 0.0001 and <0.05 respectively) for all the three parameters. Our data outline the high risk of VTE recurrence in RT recipients. Strategies for VTE recurrence prevention are needed; Prolonged OAT, in spite of the high bleeding risk of RT patients, should be considered in this respect.

Elevated levels of FVIII:C within families are associated with an increased risk for venous and arterial thrombosis

Elevated levels of coagulation factor VIII:C (FVIII:C) are associated with an increased risk for venous and arterial thromboembolism. Whether relatives of patients with elevated levels of FVIII:C are also at increased risk for thrombotic disease is unknown. The objective was to determine the annual incidences of both venous and arterial thrombotic events in first-degree relatives of patients with elevated levels of FVIII:C and venous thromboembolism (VTE) or premature atherosclerosis. A retrospective study with 584 first-degree relatives of 177 patients with elevated levels of FVIII:C was performed. The level of FVIII:C was determined and relatives with elevated and normal levels of FVIII:C were compared. Of the participants, 40% had elevated levels of FVIII:C. The annual incidence of a first episode of VTE was 0.34% and 0.13% in relatives with elevated levels of FVIII:C and those with normal levels, respectively [OR 3.7 (95% CI 1.9-7.5)]. The absolute annual incidence in the youngest age group with elevated levels of FVIII:C was 0.16% (0.05-0.37) and gradually increased to 0.99% (0.40-2.04) in those older than 60 years of age, although the odds ratios were not statistically significant. The annual incidences of a first arterial thrombotic event were 0.29% and 0.14% in relatives with and without elevated levels of FVIII:C, respectively [OR 3.1 (1.4-6.6)]. In particular the risks for a first myocardial infarction [OR 4.3 (1.0-18.1); P =0.046] and a first peripheral arterial thrombosis [OR 8.6 (1.6-47.6)] were increased. Within families of patients with elevated levels of FVIII:C and VTE or premature atherosclerosis, 40% of their first-degree relatives has elevated levels of FVIII:C as well, and they are at increased risk for both VTE and arterial thrombosis as compared with their relatives with normal levels.

High risk of recurrent venous thromboembolism in men

We have analyzed the influence of gender on risk of recurrence after a first episode of venous thromboembolism (VTE). The Cambridge Venous Thromboembolism Study (CVTE) is a single-center study of a cohort of unselected patients with a first episode of objectively proven VTE. Recurrence rates were significantly higher in men compared with women [log rank chi2=11.82; hazard ratio (HR) 2.66; 95% confidence interval (CI) 1.49, 4,77; P=0.0006]. The cumulative recurrence rate at 2 years was 19.2% in men and 7.7% in women. There was no evidence of a difference in recurrence between men with or without thrombophilia (log rank chi2=0.03; HR 1.08; 95% CI 0.49, 2.37; P=0.855). The high recurrence rate in men compared with women was still observed when only patients with idiopathic VTE were analyzed (log rank chi2=4.38; HR 2.31; 95% CI 1.027, 5.20; P=0.0363). The recurrence risk was highest in men with a first idiopathic event at 25.7% compared with 11.7% for women in the same category. The risk of recurrent VTE is higher in men than in women.

Men had greater risk of recurrent venous thromboembolism than women

Kyrle PA, Minar E, Bialonczyk C, et al . The risk of recurrent venous thromboembolism in men and women. N Engl J Med 2004;350:2558–63. [OpenUrl][1][CrossRef][2][PubMed][3][Web of Science][4] Q Does the...

Low intensity warfarin: is it clinically useful in venous thromboembolism management?

Therapy for a first episode of venous thromboembolism (VTE) typically includes a vitamin K antagonist, such as warfarin, for 3-6 months at an international normalized ratio (INR) of 2-3. After the cessation of warfarin therapy, unprovoked VTE is associated with a recurrence rate of 5-15% per year. Prolonging initial therapy does not reduce the recurrence risk once warfarin is discontinued and is not routinely recommended for such patients. The Prevention of Recurrent Venous Thromboembolism (PREVENT) and Extended Low-Intensity Anticoagulation for Thromboembolism (ELATE) trials were undertaken to evaluate the efficacy and safety of low-intensity warfarin (INR 5-2) in this population. While both trials demonstrated that low-intensity warfarin offers substantial protection against recurrent VTE, only the ELATE trial included a standard intensity arm; this arm showed a significantly lower recurrence rate and a major bleed rate that, surprisingly, was similar to the low-intensity arm. There still remains no consensus that long-term warfarin at an INR of 2-3 should be recommended for all patients who sustain a first unprovoked venous thromboembolic event, which largely stems from our current inability to reliably identify those patients most likely to develop recurrences. Given that an individualized approach is required in deciding the duration of anticoagulation, it is the author's belief that low-intensity warfarin, which the PREVENT trial demonstrated could be monitored every other month, is a useful option for some patients with a first episode of VTE.

Prothrombin 20210A mutation: a mild risk factor for venous thromboembolism but not for arterial thrombotic disease and pregnancy-related complications in a family study.

The prothrombin 20210A mutation has been associated with an increased risk of venous thromboembolism (VTE). Its relationship with arterial disease and pregnancy-related complications is, however, still uncertain. The aim of this study was to estimate the incidences of first venous and arterial thrombotic events and pregnancy-related complications in relatives of patients with the mutation. After clinical classification, the presence of the mutation was determined in first-degree relatives of consecutive patients with the mutation and a history of VTE or premature atherosclerosis. Relatives with and without the mutation were compared. Of all relatives, 204 (50%) were heterozygous, 5 were homozygous, and 198 had a normal genotype. The annual incidence of a first episode of VTE was 0.35% and 0.18% in carriers and noncarriers, respectively (odds ratio [OR], 1.9; 95% confidence interval [CI], 0.9-4.1); the annual incidence of a first arterial thrombosis was 0.22% and 0.15% in carriers and noncarriers, respectively (OR, 2.3; 95% CI, 0.8-6.3). The annual incidence of a first myocardial infarction was 0.14% (95% CI, 0.05%-0.23%) and 0.05% (0.01%-0.14%) in carriers and noncarriers, respectively (OR, 4.7; 95% CI, 1.0-22.5; P =.06). In particular, homozygous carriers were at increased risk of VTE (OR, 6.0; 95% CI, 1.3-27.2), whereas a history of VTE in the proband influenced the risk of VTE in the relatives. Women with the mutation did not experience significantly more pregnancy-related complications than their relatives with a normal genotype. The prothrombin mutation is a mild risk factor for VTE within families of carriers but does not seem to play an important role in arterial thrombotic disease, with the exception of myocardial infarction, or in pregnancy-related complications.

Has time come for screening for occult cancer in patients with venous thromboembolism?

The association between symptomatic venous thromboembolism (VTE) and the presence of a still asymptomatic malignancy has fascinated the medical community for almost 70 years. Over and over again the name of Armand Trousseau is quoted when reference is made to this association. However, upon careful reading of the original Trousseau lessons nothing is mentioned about occult cancer [1, 2]. In fact, he describes the other well-known association: patients with overt cancer often suffer from (recurrent) episodes of deep venous thrombosis, as well as superficial phlebitis. Two British physicians, James and Matheson, have the honour to be the first ones. They reported in 1935 the subsequent development of cancer in a patient who experienced a venous thrombosis 2 months earlier and speculated about the role of occult cancer as a possible cause of the thrombosis [3]. Subsequent retrospective and prospective studies have confirmed that the incidence of new cancers in patients with idiopathic VTE in the next 2–3 years is approximately 7.5%, while in those with secondary VTE this rate is around 1.6%[4-9]. There is also, in part from these studies, suggestive evidence that when these cancers are detected earlier they are predominantly at an early stage. The major challenge is whether we can diagnose these occult cancers and whether if detected the balance between good and harm is positive. In this issue of the Journal, Monreal and colleagues [10] present their interesting findings of a two-step approach to detect asymptomatic malignancies in a cohort of VTE patients. They included 1089 consecutive patients with a first episode of VTE (80% had deep vein thrombosis). At entry 17% had known cancer and they were excluded. The remaining 864 patients (40% with idiopathic VTE) underwent what the authors called a routine examination, including a thorough history taking, physical examination and laboratory investigation. Upon careful reading it is obvious that this ‘routine examination’ was quite extensive, with clear guidelines about subsequent investigations based on the findings. The relevance of this approach is that in less dedicated centers this examination may be less thorough and therefore less effective. Nevertheless, the authors identified 167 patients (19%) who based on this routine examination had a suspicion of an occult cancer, the majority (58%) based on careful history taking. The presence of cancer was confirmed in 34 patients, i.e. in a fifth of those suspected of having cancer, and 3.9% of all patients investigated. The remaining patients, i.e. those with a normal routine examination, as well as those with normal findings despite the initial suspicion of cancer raised during routine examination, underwent what the authors called a ‘limited diagnostic work-up’. This consisted of ultrasonography of the abdomino-pelvic region and several cancer laboratory markers. Of the 830 patients who underwent this testing, 13 (1.6%) were diagnosed as having cancer of which 60% were early stage. During the 1-year follow-up an additional 14 (1.7%) cases of cancer became apparent. Which questions are answered by this study and which are raised? The most impressive finding is the high yield of the initial, albeit quite standardized routine examination. Thirty-four of the total of 61 cancers seen in this study with a follow-up of 1 year were detected with this initial step. This is 56% of all cancers. The limited diagnostic work-up found another 21%, whereas 23% were missed. The second conclusion therefore is that the limited diagnostic work-up strategy needs to be improved. Other studies partly by the same investigators suggested that spiral computed tomography or other imaging modalities might increase the sensitivity of this step to above 90%[10]. Finally, although this study provides additional evidence that those cancers detected by screening are often early stage, we lack evidence that the overall benefit–risk ratio is positive. All investigators worldwide interested in this topic should cooperate in answering this question, only than time has come to include screening for occult cancer in patients with idiopathic VTE.

Comparison of 1 month with 3 months of anticoagulation for a first episode of venous thromboembolism associated with a transient risk factor

The risk of recurrence is lower after treatment of an episode of venous thromboembolism associated with a transient risk factor, such as recent surgery, than after an episode associated with a permanent, or no, risk factor. Retrospective analyses suggest that 1 month of anticoagulation is adequate for patients whose venous thromboembolic event was provoked by a transient risk factor. In this double-blind study, patients who had completed 1 month of anticoagulant therapy for a first episode of venous thromboembolism provoked by a transient risk factor were randomly assigned to continue warfarin or to placebo for an additional 2 months. Our goal was to determine if the duration of treatment could be reduced without increasing the rate of recurrent venous thromboembolism during 11 months of follow-up. Of 84 patients assigned to placebo, five (6.0%) had recurrent venous thromboembolism, compared with three of 81 (3.7%) assigned to warfarin, resulting in an absolute risk difference of 2.3%[95% confidence interval (CI) - 5.2, 10.0]. The incidence of recurrent venous thromboembolism after discontinuation of warfarin was 6.8% per patient-year in those who received warfarin for 1 month and 3.2% per patient-year in those who received warfarin for 3 months (rate difference of 3.6% per patient-year; 95% CI - 3.8, 11.0). There were no major bleeds in either group. Duration of anticoagulant therapy for venous thromboembolism provoked by a transient risk factor should not be reduced from 3 months to 1 month as this is likely to increase recurrent venous thromboembolism without achieving a clinically important decrease in bleeding.

Thrombophilia and New Anticoagulant Drugs

Venous thromboembolism, which includes deep vein thrombosis and pulmonary embolism, is the result of an imbalance among procoagulant, anticoagulant and profibrinolytic processes. This imbalance reflects a complex interplay between genetic and environmental or acquired risk factors. Genetic thrombophilic defects influence the risk of a first episode of thrombosis. How these defects influence the risk of recurrence in patients whose first episode of venous thromboembolism was unprovoked is less certain. Thus, when anticoagulants are stopped, patients with unprovoked venous thromboembolism have a risk of recurrence of at least 7% to 10% per year, even in the absence of an underlying thrombophilic defect. Consequently, there is a trend toward longer durations of anticoagulation therapy for these patients, which is problematic given the limitation of existing anticoagulants. This chapter provides an overview of the thrombophilic defects and how they influence the risk of venous thromboembolism. The chapter also details advances in anticoagulant therapy, focusing on new inhibitors of factor Xa and thrombin. In Section I, Dr. Saskia Middeldorp describes the various thrombophilic defects and reviews their relative importance in the pathogenesis of a first episode of venous thromboembolism. She then discusses the influence of these defects on the risk of recurrent thrombotic events in patients with unprovoked venous thromboembolism and in those whose thrombosis occurred in association with a known risk factor, such as surgery. In Section II, Dr. William Geerts reviews the pharmacology of new parenteral and oral factor Xa inhibitors and describes the results of the Phase II and III clinical trials with these agents. He then provides perspective on the potential advantages and drawbacks of these drugs for the prevention and treatment of venous thromboembolism. In Section III, Dr. John Heit focuses on direct thrombin inhibitors. He discusses their mechanism of action and compares and contrasts their pharmacological profiles prior to describing the results of Phase II and III clinical trials. Dr. Heit then provides perspective on the potential advantages and limitations of these drugs relative to existing anticoagulants.

Assessment of the Risk and Prophylactic Treatment of Venous Thromboembolism in the Elderly

Numerous large randomized controlled trials have assessed the benefit of prophylactic anticoagulation for venous thromboembolism in selected patients. However, few trials were conducted in elderly patients, as this issue was not addressed in this specific population,or as elderly patients were excluded of these studies. Therefore, as the risk of a first episode of venous thromboembolism (in surgical and in medical setting) and the risk of a major anticoagulant-related bleeding are both increased in elderly subjects, the results of the main available studies can not be extrapolated to this population. Consequently, in practice, the balance between expected benefit and risk of prophylactic anticoagulation should be carefully assessed for each individual elderly patient taking in account the specific risk of venous thromboembolism in elderly in the absence of anticoagulation, the risk of anticoagulant related bleeding according to the type of anticoagulant treatment and the intrinsic risk of bleeding of elderly subjects and, lastly, the available guideline recommendations. In order to improve such evaluation, it is anticipated that further prophylactic studies are needed in elderly patients. In addition, the development of anticoagulation clinics and new oral anticoagulants should help to reduce anticoagulant related bleeding for an equivalent, or an increased, benefit.

Therapy and secondary prevention of venous thromboembolism with vitamin K antagonists

Oral anticoagulation with vitamin-K-antagonists is very effective in secondary prevention of venous thromboembolism. In Germany, most commonly Phenprocoumon is used, while most of the evidence-based data are available for Warfarin. The initial treatment of acute venous thromboembolism requires immediate anticoagulation with heparin and a subsequent overlapping treatment with oral anticoagulants. During this phase, anticoagulation may be unstable with increased risk for bleeding. An INR target range between 2 and 3 provides effective protection with minimal risk for major bleeding. The individual risk for bleeding may be estimated by a clinical score. Six months of oral anticoagulation is the standard duration for a first episode of venous thromboembolism, while recurrencies are treated for at least one to two years. The duration may be tailored to the individual patient according to underlying risk factors for recurrencies and for bleeding. Because of a plethora of practical problems and the narrow therapeutic window, there is a need for new antithrombotic agents. These may allow a longer duration of secondary prevention with improved protection against recurrencies without sacrificing safety.

Incidence of recurrent venous thromboembolism in relation to clinical and thrombophilic risk factors: prospective cohort study

Stratification for risk of recurrence after a first episode of venous thromboembolism (VTE) would affect the duration of anticoagulant therapy. We aimed to determine the incidence of recurrence of VTE in relation to clinical risk factors and standard laboratory testing for heritable thrombophilic defects. We established a database to prospectively follow-up a cohort of unselected patients who had had a first episode of objectively proven VTE. We excluded patients with malignant disease and antiphospholipid syndrome. All patients were offered testing for heritable thrombophilia. At 2 years, the cumulative recurrence rate in 570 patients was 11%. Incidence was lowest after surgery-related VTE (0%) and highest after unprecipitated VTE (19.4%) (p<0.001). 85% of patients were tested for heritable thrombophilic defects. Recurrence rates were not related to presence or absence of laboratory evidence of heritable thrombophilia (hazard ratio 1.50 [95% CI 0.82-2.77]; p=0.187). In patients with a first event that was unprecipitated or was associated with a non-surgical trigger, recurrence rates did not differ in patients with or without thrombophilia (1.34 [0.73-2.46]; p=0.351). In unselected patients who have had a first episode of VTE, testing for heritable thrombophilia does not allow prediction of recurrent VTE in the first 2 years after anticoagulant therapy is stopped. However, assessment of clinical risk factors associated with the first episode of VTE does predict risk of recurrence. Patients with postoperative VTE have a very low rate of recurrence.

The incidence of recurrent venous thromboembolism after treatment with vitamin K antagonists in relation to time since first event: a meta-analysis.

After a first episode of venous thromboembolism, patients are treated with vitamin K (phytonadione) antagonists. There are indications that the risk of recurrence after treatment with vitamin K antagonists decreases relative to the time since the first event. The aim of the present meta-analysis is to describe the risk of recurrent venous thromboembolism after treatment with vitamin K antagonist in relation to the time since the index event. Computerized searches in MEDLINE and EMBASE databases; reference checks of pertinent articles; personal communication with colleagues to find randomized clinical trials and cohort studies in which patients with venous thromboembolism were treated with vitamin K antagonists. Per treatment arm, 2 reviewers independently extracted data on the number of recurrent events and the duration of follow-up per time period of 3 months. A total of 135 potentially eligible studies were identified. Of these, 18 studies could be included, comprising 25 treatment arms that could be analyzed. Treatment arms were divided into 3 groups based on treatment duration (short, medium, and long). For all 3 groups, the monthly incidence immediately after discontinuation of treatment was high and declined rapidly thereafter. The monthly incidence after 9 months seemed independent of the treatment duration. There is a diminishing risk of recurrent venous thromboembolism over time and a stabilization after 9 months independent of the duration of the initial treatment with vitamin K antagonists. These findings have important implications for decision making about the optimal duration of treatment with vitamin K antagonists.

Screening for the risk for bleeding or thrombosis.

Numerous tests are available to assess patient risk for bleeding or thrombosis. Appropriate use of these tests must involve consideration of the clinical setting, disease prevalence, performance characteristics of the tests, cost, and consequences of false-positive and false-negative results. To summarize information about coagulation testing in three common clinical settings: nonsurgical hospitalized patients, surgical patients, and patients having a first venous thromboembolic event. All English-language studies identified in searches of MEDLINE (1966 to April 2002) and reference lists of key articles. All published studies of blood coagulation testing as routine diagnostic tests or in the preoperative care of patients reporting postoperative bleeding complications, and all published studies of patients with the factor V Leiden mutation reporting venous thromboembolic outcomes. 5 observational studies of routine coagulation testing in nonsurgical hospitalized patients and 12 observational studies of preoperative coagulation testing, from which both sensitivity and specificity could be calculated. Test performance characteristics for the partial thromboplastin time in predicting postoperative hemorrhage were pooled by type of surgery. Likelihood ratios for positive and negative results were calculated for each group; 95% confidence intervals were calculated. Patients with prolonged partial thromboplastin times did not have a statistically significantly increased risk for postoperative complications. For nonsurgical and surgical patients without synthetic liver dysfunction or a history of oral anticoagulant use, routine testing has no benefit in assessment of bleeding risk. Routine testing after a first episode of venous thromboembolism is not recommended for most patients.