One-month versus six-month therapy with oral anticoagulants after symptomatic deep vein thrombosis

Efficacy and safety of non-vitamin K antagonist oral anticoagulants for venous thromboembolism: a meta-analysis

Objective

Several trials had compared the efficacy and safety between non-vitamin K antagonist oral anticoagulants and warfarin for acute venous thromboembolism, but the results were incomplete. This updated review comprehensively assessed the efficacy and safety of non-vitamin K antagonist oral anticoagulants for venous thromboembolism.

Design

Meta-analysis of randomised control trials. Six databases were searched from January 2000 to December 2018.

Setting

Adult patients had got non-vitamin K antagonist oral anticoagulants or warfarin for venous thromboembolism.

Participants

Randomised control trials that compared the efficacy and safety between non-vitamin K antagonist oral anticoagulants and warfarin.

Main outcome measures

The efficacy and safety of non-vitamin K antagonist oral anticoagulants .

Results

Seven studies involving 29,879 cases were included, among which 14,943 cases were assigned to non-vitamin K antagonist oral anticoagulants group and 14,936 cases to warfarin group. Meta-analysis showed that compared with warfarin, recurrent venous thromboembolism (odds ratio 0.94 [95% confidence interval 0.81 to 1.11]), death related to venous thromboembolism or fatal pulmonary embolism (odds ratio 1.00 [95% confidence interval 0.63 to 1.60]), symptomatic deep-vein thrombosis (odds ratio 0.88 [95% confidence interval 0.72 to 1.09]), symptomatic nonfatal pulmonary embolism (odds ratio 1.03 [(95% confidence interval 0.82 to 1.30]) and all deaths (odds ratio 0.92 [95% confidence interval 0.76 to 1.12]) are similar in non-vitamin K antagonist oral anticoagulants group, but major bleeding event (odds ratio 0.61 [95% confidence interval 0.50 to 0.75]) and clinically relevant non-major bleeding event (odds ratio [95% confidence interval 0.53 to 0.85]) are less in non-vitamin K antagonist oral anticoagulants group. .

Conclusions

For the treatment of venous thromboembolism, non-vitamin K antagonist oral anticoagulants is as effective as warfarin, and has a better safety profile than warfarin.

Thirty-day outcomes in patients with proximal deep vein thrombosis who discontinued anticoagulant therapy prematurely

INTRODUCTION

In patients receiving anticoagulation for deep vein thrombosis (DVT), a variety of reasons (including active bleeding or high-risk for bleeding) may lead into premature discontinuation of therapy (prior to completing 90 days). The relative frequency and clinical consequences of premature discontinuation in contemporary patients remain unknown.

METHODS

We used the data from RIETE, an international registry of patients with venous thromboembolism (VTE), to identify patients with proximal (above knee) lower limb DVT who prematurely discontinued anticoagulation. We assessed the incidence of the composite outcome: pulmonary embolism (PE)-related death, sudden death, or recurrent VTE within the subsequent 30 days after discontinuation and compared the risk of these events vs. the risk in patients without premature discontinuation, once adjusted for demographics and clinical factors.

RESULTS

Of 26,335 patients with proximal DVT recruited from 2001 to 2018, 1322 (5.02%) prematurely discontinued anticoagulation. Thirty days after discontinuation, 12 (0.91%) patients suffered fatal PE (n = 8) or sudden death (n = 4) and 33 (2.50%) had non-fatal recurrent VTE (PE = 15; recurrent DVT = 18). In patients with premature discontinuation, the 30-day incidence of the composite outcome was 1.62 per 1000 patient-days (95%CI: 0.00-3.80). During the first week after discontinuation, the incidence rate was 4.09 per 1000 patient-days (95%CI: 0.65-7.52). The adjusted odds of the composite outcome was 7.88 times (95%CI: 6.39-9.72) higher in patients who discontinued prematurely than in those without premature discontinuation.

CONCLUSION

Premature discontinuation of anticoagulation occurred in 5% of patients with proximal DVT, and was associated an 8-fold increased odds for the composite outcome.

Clinical presentation and therapeutic management of venous thrombosis in young children: a retrospective analysis

BACKGROUND

Venous thromboembolism (VTE) in young children is not well documented.

METHODS

Clinicians from 12 institutions retrospectively evaluated the presentation, therapeutic management, and outcome of VTE in children younger than 2 years seen in 2011-2016. Feasibility of recruiting these children in EINSTEIN-Jr. phase III, a randomized trial evaluating rivaroxaban versus standard anticoagulation for VTE, was assessed.

RESULTS

We identified 346 children with VTE, of whom 227 (65.6%) had central venous catheter-related thrombosis (CVC-VTE), 119 (34.4%) had non-CVC-VTE, and 156 (45.1%) were younger than 1 month. Of the 309 children who received anticoagulant therapy, 86 (27.8%) had a short duration of therapy (i.e. < 6 weeks for CVC-VTE and < 3 months for non-CVC-VTE) and 17 (5.5%) had recurrent VTE during anticoagulation (n = 8, 2.6%) or shortly after its discontinuation (n = 9, 2.9%). A total of 37 (10.7%) children did not receive anticoagulant therapy and 4 (10.5%) had recurrent VTE.The average number of children aged < 0.5 years and 0.5-2 years who would have been considered for enrolment in EINSTEIN-Jr is approximately 1.0 and 0.9 per year per site, respectively.

CONCLUSIONS

Young children with VTE most commonly have CVC-VTE and approximately one-tenth and one-fourth received no or only short durations of anticoagulant therapy, respectively. Recurrent VTE rates without anticoagulation, during anticoagulation or shortly after its discontinuation seem comparable to those observed in adults. Short and flexible treatment durations could potentially increase recruitment in EINSTEIN-Jr. phase III.

Duration of anticoagulant therapy in pediatric venous thromboembolism: Current approaches and updates from randomized controlled trials

INTRODUCTION

Compared with the incidence of venous thromboembolism in the adult population, pediatric VTE is rare. Yet, recent data suggest that the incidence of VTE in children is increasing, and little is known about the optimal duration of anticoagulation in pediatrics. Areas covered: This review summarizes current evidence-based adult recommendations and associated clinical trials from which current guidelines on the duration of anticoagulation in children have been extrapolated. It also discusses pediatric expert consensus-based guidelines and current pediatric clinical trials on duration of therapy in pediatric VTE. Expert commentary: The vast majority of pediatric VTE are provoked, and evidence on duration of anticoagulation for pediatric VTE is highly limited, but suggests that a maximum duration of 3 months is reasonable for most patients with provoked VTE, whereas longer duration is likely appropriate for unprovoked VTE. Whether shorter duration than 3 months is optimal for pediatric provoked VTE is as yet unclear. Results from the multinational randomized controlled trial studying the duration of anticoagulant therapy for provoked VTE in patients <21 years old (Kids-DOTT) will be critical to inform the future standard of care in pediatric VTE treatment.

Tenecteplase compared with streptokinase and heparin in the treatment of pulmonary embolism: an observational study

Background: Thrombolytics are recommended in high risk patients with massive pulmonary embolism (PE). However, clinical practice seems to be far different and questions related to its utility in less severely affected patients remain the subject of investigation. The objective of this observational study was to compare the efficacy and safety of tenecteplase with streptokinase and heparin. Method: A total of 103 patients (tenecteplase: 62, streptokinase: 17, heparin: 24) diagnosed with PE (massive: 33 [32.04%], submassive: 50 [48.54%], and minor: 20 [19.42%]) were included. Results: Mean age was 50.04 years and major risk factors were immobilization due to hospitalization, history of deep vein thrombosis, and diabetes. Common clinical symptoms of dyspnoea, right ventricular dysfunction, and cough were found in 94.17%, 81.55%, and 77.67% patients, respectively. Between treatment and day 7, death occurred in 4.84%, 5.88%, and 8.33% patients in the tenecteplase, streptokinase, and heparin groups, respectively. The differences among treatment groups were non-significant (p > .05). All treatments have demonstrated significant alleviation of dyspnoea and heart rate (p < .05). Significant (p < .05) increase in oxygen saturation was seen and it was markedly higher in the tenecteplase-treated patients compared with the streptokinase- and heparin-treated patients. By day 7, there was 100% resolution of right bundle branch block only in the tenecteplase group. No intracranial bleeding or fatal bleeding episodes were found in any group. Conclusion: Tenecteplase was found to be effective in patients with PE irrespective of their clinical status and no major adverse events were noted.

Recurrence and Late Sequelae after First-Time Deep Vein Thrombosis: Relationship to Initial Signs

Objective:

To investigate the relation between initial symptoms and long-term sequelae in first-time deep venous thrombosis (DVT).

Design:

Follow-up study of patients 6 years after an episode of suspected symptomatic DVT.

Setting:

Vascular laboratory, University Hospital of Lund.

Patients:

66 patients, 19 with femoral DVT, 20 with calf DVT and 27 with normal phlebograms at initial investigation.

Main outcome measures:

Symptoms and signs of chronic venous insufficiency (CVI), foot volumetry and measurement of plasminogen activator inhibitor 1 (PAI-1) activity. Initial clinical signs and results at phlebography were compared with findings at follow-up.

Results:

Of patients with DVT, 11 (28%) had been treated for a recurrent DVT during follow-up. No relation was found between initial signs of DVT and late signs of CVI. Patients with DVT had significantly more signs of CVI but symptoms did not differ between the groups. Mean levels of PAI-1 activity were similar in the three groups, and patients with recurrent DVT did not differ. Refilling flow was related to the clinical CVI-score, and expelled volume was inversely related to the extension of DVT at phlebography.

Conclusion:

The recurrence rate is high in first-time DVT, but symptoms are mostly mild as long as after 6 years. There is a poor correlation between symptoms of CVI and objective findings. The late development of CVI cannot be predicted from the clinical signs in the acute phase. Levels of PAI-1 do not correlate with the degree of CVI.

Duration of treatment with vitamin K antagonists in symptomatic venous thromboembolism

BACKGROUND

Currently, the most frequently used secondary treatment for patients with venous thromboembolism (VTE) consists of vitamin K antagonists (VKA) targeted at an international normalized ratio (INR) of 2.5 (range 2.0 to 3.0). However, based on the continuing risk of bleeding and uncertainty regarding the risk of recurrent VTE, discussion on the proper duration of treatment with VKA for these patients is ongoing. Several studies have compared the risks and benefits of different durations of VKA in patients with VTE. This is the third update of a review first published in 2000.

OBJECTIVES

To evaluate the efficacy and safety of different durations of treatment with vitamin K antagonists in patients with symptomatic venous thromboembolism.

SEARCH METHODS

For this update, the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched October 2013) and the Cochrane Central Register of Controlled Trials (CENTRAL) 2013, Issue 9.

SELECTION CRITERIA

Randomized controlled clinical trials comparing different durations of treatment with vitamin K antagonists in patients with symptomatic venous thromboembolism.

DATA COLLECTION AND ANALYSIS

Three review authors (SM, MP, and BH) extracted the data and assessed the quality of the trials independently.

MAIN RESULTS

Eleven studies with a total of 3716 participants were included. A consistent and strong reduction in the risk of recurrent venous thromboembolic events was observed during prolonged treatment with VKA (risk ratio (RR) 0.20, 95% confidence interval (CI) 0.11 to 0.38) independent of the period elapsed since the index thrombotic event. A statistically significant "rebound" phenomenon (ie, an excess of recurrences shortly after cessation of prolonged treatment) was not found (RR 1.28, 95% CI 0.97 to 1.70). In addition, a substantial increase in bleeding complications was observed for patients receiving prolonged treatment during the entire period after randomization (RR 2.60, 95% CI 1.51 to 4.49). No reduction in mortality was noted during the entire study period (RR 0.89, 95% CI 0.66 to 1.21, P = 0.46).

AUTHORS' CONCLUSIONS

In conclusion, this review shows that treatment with VKA strongly reduces the risk of recurrent VTE for as long as they are used. However, the absolute risk of recurrent VTE declines over time, although the risk for major bleeding remains. Thus, the efficacy of VKA administration decreases over time since the index event.

Derivation of the non-inferiority margin for the evaluation of direct oral anticoagulants in the treatment of venous thromboembolism

BACKGROUND

Direct oral anticoagulants that target a single coagulation factor have been developed as an alternative to standard therapies with heparin and/or vitamin K antagonists. The purpose of this study was to derive non-inferiority margins suitable for randomised clinical studies designed to evaluate these agents for the treatment of venous thromboembolism (VTE).

METHODS

We performed a systematic review to derive non-inferiority margins suitable for use in studies evaluating direct oral anticoagulants for the treatment of VTE. A PubMed search identified publications that evaluated current standard treatment versus placebo, 'no treatment' or 'less intensive treatment' in patients with symptomatic deep vein thrombosis (DVT) and/or pulmonary embolism (PE). Publications were eligible if they had a randomised study design, included patients with symptomatic DVT and/or PE, used objective diagnostic methods to document the index event and reported objectively confirmed symptomatic recurrent VTE.

RESULTS

Fourteen publications were included in the analysis. Recurrent VTE occurred in 25 (1.5%) out of 1715 patients who received current standard of care and in 157 (9.2%) out of 1711 patients who received placebo, 'no treatment' or 'less intensive treatment', for an odds ratio of 0.18 (95% confidence interval, 0.14-0.25; test for heterogeneity, p=0.87). In order to preserve 50% or 75% of the established treatment effect using a linear scale, the corresponding thresholds for non-inferiority equalled 2.50 and 1.75, respectively.

CONCLUSIONS

This systematic review and statistical approach determined non-inferiority margins suitable for use in studies of direct oral anticoagulants for the treatment of DVT and/or PE.

Trial Protocol: a randomised controlled trial of extended anticoagulation treatment versus routine anticoagulation treatment for the prevention of recurrent VTE and post thrombotic syndrome in patients being treated for a first episode of unprovoked VTE (The ExACT Study)

Background

Venous thromboembolism comprising pulmonary embolism and deep vein thrombosis is a common condition with an incidence of approximately 1 per 1,000 per annum causing both mortality and serious morbidity. The principal aim of treatment of a venous thromboembolism with heparin and warfarin is to prevent extension or recurrence of clot. However, the recurrence rate following a deep vein thrombosis remains approximately 10% per annum following treatment cessation irrespective of the duration of anticoagulation therapy. Patients with raised D-dimer levels after discontinuing oral anticoagulation treatment have also been shown to be at high risk of recurrence.

Post thrombotic syndrome is a complication of a deep vein thrombosis which can lead to chronic venous insufficiency and ulceration. It has a cumulative incidence after 2 years of around 25% and it has been suggested that extended oral anticoagulation should be investigated as a possible preventative measure.

Methods/design

Patients with a first idiopathic venous thromboembolism will be recruited through anticoagulation clinics and randomly allocated to either continuing or discontinuing warfarin treatment for a further 2 years and followed up on a six monthly basis. At each visit D-dimer levels will be measured using a Roche Cobas h 232 POC device. In addition a venous sample will be taken for laboratory D-dimer analysis at the end of the study. Patients will be examined for signs and symptoms of PTS using the Villalta scale and complete VEINES and EQ5D quality of life questionnaires.

Discussion

The primary aim of the study is to investigate whether extending oral anticoagulation treatment (prior to discontinuing treatment) beyond 3–6 months for patients with a first unprovoked proximal deep vein thrombosis or pulmonary embolism prevents recurrence. The study will also determine the role of extending anticoagulation for patients with elevated D-dimer levels prior to discontinuing treatment and identify the potential of D-dimer point of care testing for identification of high risk patients within a primary care setting.

Trial registration

ISRCTN73819751

Influence of preceding length of anticoagulant treatment and initial presentation of venous thromboembolism on risk of recurrence after stopping treatment: analysis of individual participants' data from seven trials

OBJECTIVE

To determine how length of anticoagulation and clinical presentation of venous thromboembolism influence the risk of recurrence after anticoagulant treatment is stopped and to identify the shortest length of anticoagulation that reduces the risk of recurrence to its lowest level.

DESIGN

Pooled analysis of individual participants' data from seven randomised trials.

SETTING

Outpatient anticoagulant clinics in academic centres.

POPULATION

2925 men or women with a first venous thromboembolism who did not have cancer and received different durations of anticoagulant treatment.

MAIN OUTCOME MEASURE

First recurrent venous thromboembolism after stopping anticoagulant treatment during up to 24 months of follow-up.

RESULTS

Recurrence was lower after isolated distal deep vein thrombosis than after proximal deep vein thrombosis (hazard ratio 0.49, 95% confidence interval 0.34 to 0.71), similar after pulmonary embolism and proximal deep vein thrombosis (1.19, 0.87 to 1.63), and lower after thrombosis provoked by a temporary risk factor than after unprovoked thrombosis (0.55, 0.41 to 0.74). Recurrence was higher if anticoagulation was stopped at 1.0 or 1.5 months compared with at 3 months or later (hazard ratio 1.52, 1.14 to 2.02) and similar if treatment was stopped at 3 months compared with at 6 months or later (1.19, 0.86 to 1.65). High rates of recurrence associated with shorter durations of anticoagulation were confined to the first 6 months after stopping treatment.

CONCLUSION

Three months of treatment achieves a similar risk of recurrent venous thromboembolism after stopping anticoagulation to a longer course of treatment. Unprovoked proximal deep vein thrombosis and pulmonary embolism have a high risk of recurrence whenever treatment is stopped.

Dabigatran versus warfarin in the treatment of acute venous thromboembolism

BACKGROUND

The direct oral thrombin inhibitor dabigatran has a predictable anticoagulant effect and may be an alternative therapy to warfarin for patients who have acute venous thromboembolism.

METHODS

In a randomized, double-blind, noninferiority trial involving patients with acute venous thromboembolism who were initially given parenteral anticoagulation therapy for a median of 9 days (interquartile range, 8 to 11), we compared oral dabigatran, administered at a dose of 150 mg twice daily, with warfarin that was dose-adjusted to achieve an international normalized ratio of 2.0 to 3.0. The primary outcome was the 6-month incidence of recurrent symptomatic, objectively confirmed venous thromboembolism and related deaths. Safety end points included bleeding events, acute coronary syndromes, other adverse events, and results of liver-function tests.

RESULTS

A total of 30 of the 1274 patients randomly assigned to receive dabigatran (2.4%), as compared with 27 of the 1265 patients randomly assigned to warfarin (2.1%), had recurrent venous thromboembolism; the difference in risk was 0.4 percentage points (95% confidence interval [CI], -0.8 to 1.5; P<0.001 for the prespecified noninferiority margin). The hazard ratio with dabigatran was 1.10 (95% CI, 0.65 to 1.84). Major bleeding episodes occurred in 20 patients assigned to dabigatran (1.6%) and in 24 patients assigned to warfarin (1.9%) (hazard ratio with dabigatran, 0.82; 95% CI, 0.45 to 1.48), and episodes of any bleeding were observed in 205 patients assigned to dabigatran (16.1%) and 277 patients assigned to warfarin (21.9%; hazard ratio with dabigatran, 0.71; 95% CI, 0.59 to 0.85). The numbers of deaths, acute coronary syndromes, and abnormal liver-function tests were similar in the two groups. Adverse events leading to discontinuation of the study drug occurred in 9.0% of patients assigned to dabigatran and in 6.8% of patients assigned to warfarin (P=0.05).

CONCLUSIONS

For the treatment of acute venous thromboembolism, a fixed dose of dabigatran is as effective as warfarin, has a safety profile that is similar to that of warfarin, and does not require laboratory monitoring. (ClinicalTrials.gov number, NCT00291330.)

One-year sequential follow-up of venous emptying rate and leg temperature profiles after acute deep vein thrombosis

In order to study the natural course of venous flow and temperature reaction in the legs after symptomatic first episode of deep vein thrombosis (DVT), 65 patients (57 with proximal DVT) without further thromboembolic complications during the observation period were followed for 1 year by repeated plethysmography (PG) and thermography (TG). Regarding the non-invasive parameters substantial individual variations was observed during the observation period. After 1 year pathologic PG and TG were still demonstrated in 39% (I mu (95%) = /0.43 +/- 0.05/) and 65% (I mu (95%) = /1.18 +/- 0.11/), respectively, of the patients after proximal DVT. Only a minority of the patients were normalized permanently in both PG and TG during the first year. The high frequency of remaining venous obstruction and especially, persistent thermoactivity is notable and may be of clinical importance.

Antithrombotic therapy for venous thromboembolic disease: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This chapter about treatment for venous thromboembolic disease is part of the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh risks, burden, and costs. Grade 2 suggests that individual patient values may lead to different choices (for a full understanding of the grading, see "Grades of Recommendation" chapter). Among the key recommendations in this chapter are the following: for patients with objectively confirmed deep vein thrombosis (DVT) or pulmonary embolism (PE), we recommend anticoagulant therapy with subcutaneous (SC) low-molecular-weight heparin (LMWH), monitored IV, or SC unfractionated heparin (UFH), unmonitored weight-based SC UFH, or SC fondaparinux (all Grade 1A). For patients with a high clinical suspicion of DVT or PE, we recommend treatment with anticoagulants while awaiting the outcome of diagnostic tests (Grade 1C). For patients with confirmed PE, we recommend early evaluation of the risks to benefits of thrombolytic therapy (Grade 1C); for those with hemodynamic compromise, we recommend short-course thrombolytic therapy (Grade 1B); and for those with nonmassive PE, we recommend against the use of thrombolytic therapy (Grade 1B). In acute DVT or PE, we recommend initial treatment with LMWH, UFH or fondaparinux for at least 5 days rather than a shorter period (Grade 1C); and initiation of vitamin K antagonists (VKAs) together with LMWH, UFH, or fondaparinux on the first treatment day, and discontinuation of these heparin preparations when the international normalized ratio (INR) is > or = 2.0 for at least 24 h (Grade 1A). For patients with DVT or PE secondary to a transient (reversible) risk factor, we recommend treatment with a VKA for 3 months over treatment for shorter periods (Grade 1A). For patients with unprovoked DVT or PE, we recommend treatment with a VKA for at least 3 months (Grade 1A), and that all patients are then evaluated for the risks to benefits of indefinite therapy (Grade 1C). We recommend indefinite anticoagulant therapy for patients with a first unprovoked proximal DVT or PE and a low risk of bleeding when this is consistent with the patient's preference (Grade 1A), and for most patients with a second unprovoked DVT (Grade 1A). We recommend that the dose of VKA be adjusted to maintain a target INR of 2.5 (INR range, 2.0 to 3.0) for all treatment durations (Grade 1A). We recommend at least 3 months of treatment with LMWH for patients with VTE and cancer (Grade 1A), followed by treatment with LMWH or VKA as long as the cancer is active (Grade 1C). For prevention of postthrombotic syndrome (PTS) after proximal DVT, we recommend use of an elastic compression stocking (Grade 1A). For DVT of the upper extremity, we recommend similar treatment as for DVT of the leg (Grade 1C). Selected patients with lower-extremity (Grade 2B) and upper-extremity (Grade 2C). DVT may be considered for thrombus removal, generally using catheter-based thrombolytic techniques. For extensive superficial vein thrombosis, we recommend treatment with prophylactic or intermediate doses of LMWH or intermediate doses of UFH for 4 weeks (Grade 1B).

Anticoagulation for three versus six months in patients with deep vein thrombosis or pulmonary embolism, or both: randomised trial

OBJECTIVE

To determine the optimum duration of oral anticoagulant therapy after an episode of deep vein thrombosis or pulmonary embolism, or both.

DESIGN

Multicentre, prospective, randomised study with follow-up for one year.

SETTING

46 hospitals in United Kingdom.

PARTICIPANTS

Patients aged > or =18 with deep vein thrombosis or pulmonary embolism, or both.

INTERVENTIONS

Three (n=369) or six months (n=380) of anticoagulation with heparin for five days accompanied and followed by warfarin, with a target international normalised ratio of 2.0-3.5.

MAIN OUTCOME MEASURES

Death from deep vein thrombosis or pulmonary embolism; failure to resolve, extension, recurrence of during treatment; recurrence after treatment; and major haemorrhage during treatment.

RESULTS

In the patients allocated to three months' treatment two died from deep vein thrombosis or pulmonary embolism during or after treatment, compared with three in the six month group. During treatment deep vein thrombosis or pulmonary embolism failed to resolve, extended, or recurred in six patients in the three month group without fatal consequences, compared with 10 in the six month group. After treatment there were 23 non-fatal recurrences in the three month group and 16 in the six month group. Fatal and non-fatal deep vein thrombosis or pulmonary embolism during treatment, and after treatment thus occurred in 31(8%) of those who had received three months' anticoagulation compared with 29 (8%) of those who had received six months' (P=0.80, 95% confidence interval for difference -3.1% to 4.7%). There were no fatal haemorrhages during treatment but there were eight major haemorrhages in those treated for six months and none in those treated for three months (P=0.008, -3.5% to -0.7%). Thus 31 (8%) of the patients receiving three months' anticoagulation experienced adverse outcomes as a result of deep vein thrombosis or pulmonary embolism or its treatment compared with 35 (9%) of those receiving six months' (P=0.79, -4.9% to 3.2%).

CONCLUSION

For patients in the UK with deep vein thrombosis or pulmonary embolism and no known risk factors for recurrence, there seems to be little, if any, advantage in increasing the duration of anticoagulation from three to six months. Any possible advantage would be small and would need to be judged against the increased risk of haemorrhage associated with the longer duration of treatment with warfarin.

TRIAL REGISTRATION

Clinical Trials NCT00365950 [ClinicalTrials.gov].

Duration of treatment with vitamin K antagonists in symptomatic venous thromboembolism

BACKGROUND

Currently, the most frequently used secondary treatment for patients with venous thromboembolism is vitamin K antagonists targeted at an INR of 2.5 (range 2.0 to 3.0). However, based on the continuing risk of bleeding and uncertainty regarding the risk of recurrent venous thromboembolism, there is discussion on the proper duration of treatment with vitamin K antagonists for these patients. Recently, several studies were published in which the risk and benefits of different durations of oral anticoagulants were compared in patients with venous thromboembolism.

OBJECTIVES

The objective of this review was to evaluate efficacy and safety of different durations of treatment with vitamin K antagonists in patients with symptomatic venous thromboembolism.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Diseases Group searched their Specialised Register and the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library Issue 3, 2005). The Specialised Register is constructed from electronic searches of MEDLINE (from inception to October 2005) and EMBASE (inception to October 2005) and through handsearching relevant journals. In addition, we also contacted colleagues for details of trials. The last searches were carried out on 11 October 2005.

SELECTION CRITERIA

Randomized controlled clinical trials comparing different durations of treatment with vitamin K antagonists in patients with symptomatic venous thromboembolism.

DATA COLLECTION AND ANALYSIS

Two reviewers (BH and MP) extracted the data and assessed the quality of the trials independently.

MAIN RESULTS

Eight studies with a total of 2994 patients were included. A consistent reduction in the risk of recurrent events was observed during prolonged treatment with vitamin K antagonists (OR 0.18; 95% CI 0.13 to 0.26) independent of the period elapsed since the index thrombotic event. A 'rebound' phenomenon, i.e. an excess of recurrences shortly after cessation of the prolonged treatment was not observed (OR 1.24; 95% CI 0.91 to 1.69). In addition, a substantial increase in bleeding complications was found during the entire period after randomization (OR 2.62; 95% CI 1.48 to 4.61).

AUTHORS' CONCLUSIONS

In conclusion, this meta-analysis shows that treatment with vitamin K antagonists reduces the risk of recurrent venous thromboembolism for as long as it is used. However, the absolute risk of recurrent venous thromboembolism declines over time, while the risk for major bleeding remains. Thus, the efficacy of vitamin K antagonist administration decreases over time since the index event.

Duration of Anticoagulant Therapy after Initial Idiopathic Venous Thromboembolism

OBJECTIVE

To review the literature investigating the duration of oral anticoagulant therapy following a first event of idiopathic venous thromboembolism (VTE).

DATA SOURCE

MEDLINE (1967-April 2003) and bibliographic searches of the English-language literature pertaining to the duration of oral anticoagulant therapy following a first event of idiopathic VTE was conducted. Search terms included venous thromboembolism, anticoagulation, duration of treatment, warfarin, and idiopathic.

STUDY SELECTION AND DATA EXTRACTION

The results of all trials and meta-analyses that were obtained are reviewed and critiqued.

DATA SYNTHESIS

The risk of recurrent VTE following a first idiopathic event is similar to the risk in patients with a permanent risk factor. Conventional-intensity oral anticoagulant therapy reduces this risk by 80-90%, but at an annual risk of bleeding of approximately 2-3%. According to the PREVENT trial, low-intensity anticoagulation also affords protection against VTE recurrence, but at a lower risk of bleeding. Older trials indicated that longer therapy was superior to shorter therapy; however, data from recent trials have demonstrated that the benefit was maintained only while receiving therapy.

CONCLUSIONS

Patients with a first episode of idiopathic proximal VTE should be considered for indefinite anticoagulant therapy. The appropriate intensity of anticoagulation is still controversial; however, it appears that low-intensity treatment would be appropriate in most patients. For patients who will not continue therapy indefinitely, there does not appear to be any long-term benefit to extending the duration of therapy from 3 to 6 months.

The evolution and impact of the American College of Chest Physicians consensus statement on antithrombotic therapy

The evolution of the American College of Chest Physicians consensus on antithrombotic therapy is reviewed, specifically with regard to the prevention and treatment of venous thromboembolism and the rules of evidence applied. A perspective on the impact of the recommendations is offered.

Naltrexone maintenance treatment for opioid dependence

BACKGROUND

Despite widespread use of naltrexone maintenance in many countries for more than a decade, the evidence of its effects has not yet been systematically evaluated.

OBJECTIVES

To evaluate the effects of naltrexone maintenance treatment in preventing relapse in opioid addicts after detoxification.

SEARCH STRATEGY

We searched MEDLINE (1973-first year of naltrexone use in humans-July 2000), EMBASE (1974-July 2000), Cochrane Controlled Trials Register (Cochrane Library issue 2001.4) and handsearched the "Bolletino per le Farmacodipendenze e l'Alcolismo" (1978 to 1997) and reference lists of relevant articles. We contacted pharmaceutical producers of naltrexone, authors and other Cochrane review groups. Date of most recent searches: February 2003.

SELECTION CRITERIA

All controlled studies of naltrexone; treatment of heroin addicts after detoxification.

DATA COLLECTION AND ANALYSIS

Reviewers evaluated data independently and analysed outcome measures taking into consideration adherence to and success of the study intervention. Data were extracted and analysed stratifying for the three categories of study quality. Where possible, meta-analysis was performed.

MAIN RESULTS

Eleven studies met the criteria for inclusion in this review, even if not all of them were randomised. The methodological quality of the included studies varied, but was generally poor. Meta-analysis could be performed to a very low degree only, because the studies and their outcome measures were very heterogeneous. A statistically significant reduction of (re-)incarcerations was found for patients treated with naltrexone and behaviour therapy in respect to those treated with behaviour therapy only. The other outcomes considered in the meta-analysis did not yield any significant results. Final conclusions on whether naltrexone treatment may be considered effective in maintenance therapy cannot be drawn from the clinical trials available so far.

REVIEWER'S CONCLUSIONS

The available trials do not allow a final evaluation of naltrexone maintenance treatment yet. A trend in favour of treatment with naltrexone was observed for certain target groups (particularly people who are highly motivated), as has been previously described in the literature.

[Duration of oral anticoagulant therapy in deep venous thrombosis of the lower limbs]

The optimal duration of oral anticoagulant therapy is a matter of debate. It is essential to balance the desired effect of the anticoagulants in reducing recurrences against the risk of major bleeding. Recent data suggest that it is necessary to tailor the duration of anticoagulation individually according to the topography of deep vein thrombosis (DVT) and the presence of risk factors. A six-week treatment for patients with isolated calf DVT is sufficient. For proximal DVT and/or pulmonary embolism, a short anticoagulant course seems sufficient in patients with temporary risk factors (three months) and a longer anticoagulant course (six months at least) is recommended for cases with permanent risk factors or idiopathic DVT. The inherited or acquired hypercoagulable states can be divides into those that are common and associated with a modest risk of recurrence (i.e. isolated factor V Leiden or G20210A prothrombin gene) and those are uncommon but associated with a high risk of recurrence (i.e. antithrombin, protein C or S deficiencies and anticardiolipin antibodies). Thus, the presence of one of these last abnormalities favours more prolonged anticoagulant therapy. For the high-risk of recurrence patients, there is a paucity of evidence based medicine particularly for patients with biological thrombophilia, and randomised controlled trials in this population are required. An assessment of low- or fixed-dose oral anticoagulation is also necessary in order to reduce the bleeding risk.

[Duration of oral anticoagulant therapy in venous thromboembolism]

PURPOSE

The optimal duration of oral anticoagulant therapy after a first episode of venous thromboembolism is still a matter of debate. It is essential to balance the desired effect of the anticoagulants in reducing recurrences against the risk of major bleeding. The aims of this paper are to describe the current concepts in this field.

CURRENT KNOWLEDGE AND KEY POINTS

Recent data, based on randomised controlled trials, suggest that it is necessary to tailor the duration of anticoagulation individually according to the topography of venous thromboembolism and the presence of risk factors. A 6-week treatment for patients with isolated calf vein thrombosis is sufficient. For proximal thrombosis and/or pulmonary embolism, a short anticoagulant course seems sufficient in patients with temporary risk factors (3 months) and a longer anticoagulant course (6 months at least) is recommended for cases with permanent risk factors or idiopathic venous thromboembolism. The inherited or acquired hypercoagulable states can be divided into those that are common and associated with a modest risk of recurrence (i.e., isolated factor V Leiden or G20210A prothrombin gene) and those that are uncommon but associated with a high risk of recurrence (i.e., antithrombin, protein C or S deficiencies and anticardiolipin antibodies). Thus, the presence of one of these last abnormalities favours more prolonged anticoagulant therapy.

FUTURE PROSPECTS AND PROJECTS

1) For patients at high risk of recurrence, there is a paucity of evidence-based medicine, particularly for patients with biological thrombophilia, and randomised controlled trials in this population are required. An assessment of low- or fixed-dose oral anticoagulation is also necessary in order to reduce the bleeding risk. 2) It is not always possible to precisely determine the optimal duration with the available data. We have performed a meta-analysis on summary data which suggests that a long course of oral anticoagulant therapy is superior to a short course. An individual meta-analytic approach is needed to draw more precise conclusions on an interesting and important clinical topic and we propose to perform this analysis in a international collaborative group.

Comparison of 3 and 6 months of oral anticoagulant therapy after a first episode of proximal deep vein thrombosis or pulmonary embolism and comparison of 6 and 12 weeks of therapy after isolated calf deep vein thrombosis

BACKGROUND

The optimal duration of oral anticoagulant therapy after a first episode of venous thromboembolism remains controversial.

METHODS AND RESULTS

We performed an open-label, randomized trial comparing a short oral anticoagulant course (3 months for proximal deep vein thrombosis [P-DVT] and/or pulmonary embolism [PE]; 6 weeks for isolated calf DVT [C-DVT]) with a long course of therapy (6 months for P-DVT/PE; 12 weeks for C-DVT). The outcome events were recurrences and major, minor, or fatal bleeding complications. A total of 736 patients were enrolled. There were 23 recurrences of venous thromboembolism in the short treatment group (6.4%) and 26 in the long treatment group (7.4%); the 2 treatment regimens had an equivalent effect. For the hemorrhage end point, the difference between the short and the long treatment groups was not significant: 15.5% versus 18.4% for all events (P=0.302), 1.7% versus 2.8% (P=0.291) for major events, and 13.9% versus 15.3% for minor bleeding. Subgroup analysis demonstrated that the rate of recurrence was lower for C-DVT than for P-DVT or PE.

CONCLUSIONS

After isolated C-DVT, 6 weeks of oral anticoagulation is sufficient. For P-DVT or PE, we demonstrated an equivalence between 3 and 6 months of anticoagulant therapy. For patients with temporary risk factors who have a low risk of recurrence, 3 months of treatment seems to be sufficient. For patients with idiopathic venous thromboembolism or permanent risk factors who have a high risk of recurrence, other trials are necessary to assess prolonged therapy beyond 6 months.

Management of oral anticoagulants in the treatment of venous thromboembolism

Venous thromboembolism still represents a major public health problem. After initial heparin therapy, oral anticoagulants are the treatment most often used. Bleeding is the major risk of such a therapy. This review of the literature emphasises the practical aspects of the clinical management of oral anticoagulant therapy, such as initiation, monitoring, interaction, withdrawal, optimal duration, bleeding complications and non-haemorrhagic adverse reactions.

Looking forward in the treatment of deep-vein thrombosis

Clinical guidelines developed by the American College of Chest Physicians (ACCP) for the management of venous thromboembolism (VTE) are based on current evidence from randomized clinical trials and amended in response to emerging results. The standard treatment for VTE comprises in-hospital treatment with dose-adjusted unfractionated heparin (UFH) for a minimum of 5 days and oral anticoagulants for at least 3 months. Recent clinical studies show that subcutaneous low-molecular-weight heparins (LMWHs) in fixed doses according to body weight are as effective and safe as intravenous UFH in the initial treatment of deep-vein thrombosis, with or without pulmonary embolism. There is also evidence that the optimal duration of secondary thromboprophylaxis depends on assessable thromboembolic risk factors. The 1998 ACCP guidelines take account of this new evidence by advocating LMWHs as an alternative to standard UFH for the initial treatment of VTE and risk stratification of patients to guide duration of secondary thromboprophylaxis. Outpatient treatment of VTE with LMWHs has been shown to be feasible and is increasingly used in clinical practice, offering substantial economic benefits. Certain LMWHs appear to be effective at a once-daily dose. Evidence is now emerging that may clarify the role of inferior vena cava filters and thrombolysis in VTE management. Future versions of the ACCP guidelines may be expected to reflect new data from ongoing trials.

Optimal duration of anticoagulant therapy after an episode of venous thromboembolism

The optimal duration of oral anticoagulant therapy after a first episode of venous thromboembolism (VTE) is still a matter of debate. It is essential to balance the desired effect of the anticoagulants in reducing recurrences against the risk of major bleeding. The aims of this paper are to describe the current concepts in this field. Recent data, based on randomized controlled trials, suggest that it is necessary to tailor the duration of anticoagulation individually according to the topography of VTE and the presence of risk factors. A 6-week treatment for patients with isolated calf vein thrombosis is sufficient. For proximal thrombosis and/or pulmonary embolism, a short anticoagulant course is sufficient in patients with temporary risk factors (3 months), and a longer anticoagulant course (6 months at least) is recommended for cases with permanent risk factors or idiopathic VTE. For these high-risk of recurrence patients, an assessment of low- or fixed-dose oral anticoagulation is necessary in order to reduce the bleeding risk. It is not possible to precisely determine the optimal duration with the available data. We have already performed a meta-analysis on summary data that suggests a long course of oral anticoagulant therapy is superior to a short course. An individual meta-analytic approach is needed to draw more precise conclusions on an interesting and important clinical topic.

Duration of anticoagulants in acute or recurrent venous thromboembolism

While the most recent trend in secondary prophylaxis after venous thromboembolism has been toward a prolonged duration, it has become obvious that individualization according to risk factors is crucial. Subgroup analyses in a long-term follow-up of a previous trial, as well as new trials on patients with idiopathic thromboembolism, have now improved our base of evidence. Many studies on the influence of biochemical factors in the risk of recurrence have also been published recently. This review should be helpful in-the individual decision on how to tailor the duration of anticoagulation.

Comparison of long versus short duration of anticoagulant therapy after a first episode of venous thromboembolism: a meta-analysis of randomized, controlled trials

OBJECTIVE

To assess the length of oral anticoagulant therapy (short versus long duration) after a first episode of venous thromboembolism (VTE).

DESIGN

Meta-analysis of randomized controlled trials, comparing two durations of anticoagulation, identified in 1999 by a computerized search of the Cochrane Controlled Trial Register, Medline and Embase, completed by an extensive review of the references of pertinent articles.

SETTING AND SUBJECTS

The meta-analysis was performed on literature data. Seven published controlled trials were included. Relative risks with 95% confidence intervals were computed using the relative risk logarithm method. Statistical significance was set up at 0.01 for the test of association.

MAIN OUTCOME MEASURES

Outcomes are major haemorrhage and recurrence after a 12-month follow-up.

RESULTS

For the recurrence end-point (sample size of 2304 patients), a duration treatment of 12-24 weeks seems preferable to a 3-6 week regimen, with a relative risk (RR) of 0.60 (95% CI: 0.45-0.79, P < 0.001). For the major haemorrhage end-point (1823 patients), the RR is not significantly different from 1 (RR = 1.43, 95% CI: 0.51-4.01, P = 0. 5). The results were similar for the subgroup 'permanent risk factors' or 'idiopathic VTE' (RR for recurrence = 0.48, 95% CI: 0. 34-0.68, P < 0.001). The tendency was similar, although not reaching statistical significance, for the 'temporary risk factors' subgroup (RR for recurrence = 0.34, 95% CI: 0.13-0.93, P = 0.035).

CONCLUSIONS

After a first episode of VTE, a long-term treatment regimen allows a significant reduction in the incidence of recurrences without increasing the incidence of bleeding events.

Rates of initial and recurrent thromboembolic disease among patients with malignancy versus those without malignancy. Risk analysis using Medicare claims data

Although the association between malignancy and thromboembolic disease is well established, the relative risk of developing initial and recurrent deep vein thrombosis (DVT) or pulmonary embolism (PE) among patients with malignancy versus those without malignancy has not been clearly defined. The Medicare Provider Analysis and Review Record (MEDPAR) database was used for this analysis. Patients hospitalized during 1988-1990 with DVT/PE alone, DVT/PE and malignancy, malignancy alone, or 1 of several nonmalignant diseases (other than DVT/PE) were studied. The association of malignancy and nonmalignant disease with an initial episode of DVT/PE, recurrent DVT/PE, and mortality were analyzed. The percentage of patients with DVT/PE at the initial hospitalization was higher for those with malignancy compared with those with nonmalignant disease (0.6% versus 0.57%, p = 0.001). The probability of readmission within 183 days of initial hospitalization with recurrent thromboembolic disease was 0.22 for patients with prior DVT/PE and malignancy compared with 0.065 for patients with prior DVT/PE and no malignancy (p = 0.001). Among those patients with DVT/PE and malignant disease, the probability of death within 183 days of initial hospitalization was 0.94 versus 0.29 among those with DVT/PE and no malignancy (p = 0.001). The relative risk of DVT/PE among patients with specific types of malignancy is described. This study demonstrates that patients with concurrent DVT/PE and malignancy have a more than threefold higher risk of recurrent thromboembolic disease and death (from and cause) than patients with DVT/PE without malignancy. An alternative management strategy may be indicated for such patients.

Oral anticoagulants for the treatment of venous thromboembolism

Oral anticoagulation has been the mainstay of therapy for the long-term treatment of venous thromboembolism since the 1940s. The rationale for the use of oral anticoagulation is based on the results of both empirical clinical evidence and animal models of thrombosis in the 1950s and 1960s. Higher-quality studies emerged in the 1970s and 1980s demonstrating the benefit of initial heparinization for venous thromboembolism followed by long-term oral anticoagulation. Good clinical outcomes with oral anticoagulation are highly dependent on the quality of dose management. Excellent management is best achieved in a programme of focused and co-ordinated care, often referred to as an anticoagulation clinic. Such programmes achieve better outcomes at reduced costs because of fewer adverse events. New models of anticoagulation management are emerging with the development of point-of-care testing that enables patients to do their own prothrombin time monitoring and anticoagulation dose adjustment. These models have the potential to improve care further, to increase patient satisfaction and to reduce costs.

Low recurrence rate after deep calf-vein thrombosis with 6 weeks of oral anticoagulation

OBJECTIVES

To evaluate the recurrence rate after deep calf-vein thrombosis treated with 6 weeks of oral anticoagulation.

DESIGN AND SUBJECTS

A 2 year follow-up of 126 consecutive patients admitted to the Department of Internal Medicine with venographically verified deep calf-vein thrombosis.

RESULTS

One hundred and twenty-six patients were treated with warfarin for 6 weeks, 18 of them having had a previous episode of venous thrombosis (DVT). Eleven patients (8.7%) suffered a recurrent thromboembolic episode within 2 years, four of which were within the first 3 months. Eight of those without a history of DVT had a recurrence (7.4%). Three of these were activated protein C (APC)-resistant, one was protein C-deficient and one had malignant melanoma. Eight patients (6.3%) reported minor haemorrhagic complications, but no major bleeding was seen.

CONCLUSION

Our data support the use of a 6 week regimen of secondary oral prophylaxis after a first episode of deep calf-vein thrombosis in patients without a permanent risk factor. Whether individuals with inherited thrombophilia require prolonged treatment remains to be evaluated.

[Current data on the treatment of venous thromboembolic disease]

Venous thromboembolism disease is frequently seen in medical practice. Its morbidity, mortality and long-term sequels, as well as its haemorrhagic iatrogenic complications, represent a major problem of public health. For therapeutic management, we can usually use in medical practice non-fractionated heparin or low molecular weight heparin, sometimes substituted by antivitamin K therapy. Vena cava filter, surgical thrombectomy or thrombolytic therapy are rarely used. Elastic contention should by systematically prescribed. Therapeutic guidelines have been published on the recommendation furnished by randomised controlled trials. Low molecular weight heparin and early substitution by antivitamin K permitted an ambulatory treatment for deep vein thrombosis. The optimal duration of anticoagulant therapy is still controversial. Adequate biological survey causes decreasing incidence of haemorrhagic complications.

A comparison of six weeks with six months of oral anticoagulant therapy after a first episode of venous thromboembolism. Duration of Anticoagulation Trial Study Group

BACKGROUND

The optimal duration of oral anticoagulant therapy after a first episode of venous thromboembolism is still a matter of debate.

METHODS

We performed a multicenter trial comparing six weeks of oral anticoagulant treatment with six months of such therapy in patients who had a first episode of venous thromboembolism. Anticoagulant therapy consisted of warfarin or dicumarol. Of the 902 patients enrolled, 5 were later excluded because they had congenital protein C deficiency; 443 were randomly assigned to receive six weeks of oral anticoagulant therapy with a targeted international normalized ratio (INR) of 2.0 to 2.85, and 454 were randomly assigned to receive six months of such therapy. The initial diagnoses were confirmed by means of venography in cases of deep-vein thromboses (n = 790) and with perfusion-ventilation scanning or angiography in cases of pulmonary embolism (n = 107); recurrences were confirmed in the same way.

RESULTS

After two years of follow-up, there had been 123 recurrences of venous thromboembolism that met the diagnostic criteria, 80 in the six-week group (18.1 percent; 95 percent confidence interval, 14.5 to 21.6) and 43 in the six-month group (9.5 percent; 95 percent confidence interval, 6.8 to 12.2). The odds ratio for recurrence in the six-week group was 2.1 (95 percent confidence interval, 1.4 to 3.1). There was no difference in mortality or the rate of major hemorrhage between the six-week and six-month groups.

CONCLUSIONS

Six months of prophylactic oral anticoagulation after a first episode of venous thromboembolism led to a lower recurrence rate than did treatment lasting for six weeks. The difference between the two groups occurred between 6 weeks and 6 months after the start of treatment, and the rates of recurrence remained nearly parallel for 1 1/2 years thereafter.