Ajay K. Kakkar

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.)

Rivaroxaban versus Enoxaparin for Thromboprophylaxis after Hip Arthroplasty

BACKGROUND This phase 3 trial compared the efficacy and safety of rivaroxaban, an oral direct inhibitor of factor Xa, with those of enoxaparin for extended thromboprophylaxis in patients undergoing total hip arthroplasty. METHODS In this randomized, double-blind study, we assigned 4541 patients to receive either 10 mg of oral rivaroxaban once daily, beginning after surgery, or 40 mg of enoxaparin subcutaneously once daily, beginning the evening before surgery, plus a placebo tablet or injection. The primary efficacy outcome was the composite of deep-vein thrombosis (either symptomatic or detected by bilateral venography if the patient was asymptomatic), nonfatal pulmonary embolism, or death from any cause at 36 days (range, 30 to 42). The main secondary efficacy outcome was major venous thromboembolism (proximal deep-vein thrombosis, nonfatal pulmonary embolism, or death from venous thromboembolism). The primary safety outcome was major bleeding. RESULTS A total of 3153 patients were included in the superiority analysis (after 1388 exclusions), and 4433 were included in the safety analysis (after 108 exclusions). The primary efficacy outcome occurred in 18 of 1595 patients (1.1%) in the rivaroxaban group and in 58 of 1558 patients (3.7%) in the enoxaparin group (absolute risk reduction, 2.6%; 95% confidence interval [CI], 1.5 to 3.7; P<0.001). Major venous thromboembolism occurred in 4 of 1686 patients (0.2%) in the rivaroxaban group and in 33 of 1678 patients (2.0%) in the enoxaparin group (absolute risk reduction, 1.7%; 95% CI, 1.0 to 2.5; P<0.001). Major bleeding occurred in 6 of 2209 patients (0.3%) in the rivaroxaban group and in 2 of 2224 patients (0.1%) in the enoxaparin group (P=0.18). CONCLUSIONS A once-daily, 10-mg oral dose of rivaroxaban was significantly more effective for extended thromboprophylaxis than a once-daily, 40-mg subcutaneous dose of enoxaparin in patients undergoing elective total hip arthroplasty. The two drugs had similar safety profiles. (ClinicalTrials.gov number, NCT00329628.)

Extended duration rivaroxaban versus short-term enoxaparin for the prevention of venous thromboembolism after total hip arthroplasty: a double-blind, randomised controlled trial

BACKGROUND The risk of venous thromboembolism is high after total hip arthroplasty and could persist after hospital discharge. Our aim was to compare the use of rivaroxaban for extended thromboprophylaxis with short-term thromboprophylaxis with enoxaparin. METHODS 2509 patients scheduled to undergo elective total hip arthroplasty were randomly assigned, stratified according to centre, with a computer-generated randomisation code, to receive oral rivaroxaban 10 mg once daily for 31-39 days (with placebo injection for 10-14 days; n=1252), or enoxaparin 40 mg once daily subcutaneously for 10-14 days (with placebo tablet for 31-39 days; n=1257). The primary efficacy outcome was the composite of deep-vein thrombosis (symptomatic or asymptomatic detected by mandatory, bilateral venography), non-fatal pulmonary embolism, and all-cause mortality up to day 30-42. Analyses were done in the modified intention-to-treat population, which consisted of all patients who had received at least one dose of study medication, had undergone planned surgery, and had adequate assessment of thromboembolism. This study is registered at ClinicalTrials.gov, number NCT00332020. FINDINGS The modified intention-to-treat population for the analysis of the primary efficacy outcome consisted of 864 patients in the rivaroxaban group and 869 in the enoxaparin group. The primary outcome occurred in 17 (2.0%) patients in the rivaroxaban group, compared with 81 (9.3%) in the enoxaparin group (absolute risk reduction 7.3%, 95% CI 5.2-9.4; p<0.0001). The incidence of any on-treatment bleeding was much the same in both groups (81 [6.6%] events in 1228 patients in the rivaroxaban safety population vs 68 [5.5%] of 1229 patients in the enoxaparin safety population; p=0.25). INTERPRETATION Extended thromboprophylaxis with rivaroxaban was significantly more effective than short-term enoxaparin plus placebo for the prevention of venous thromboembolism, including symptomatic events, in patients undergoing total hip arthroplasty.

American Society of Clinical Oncology Guideline: Recommendations for Venous Thromboembolism Prophylaxis and Treatment in Patients With Cancer

PURPOSE To develop guideline recommendations for the use of anticoagulation in the prevention and treatment of venous thromboembolism (VTE) in patients with cancer. METHODS A comprehensive systematic review of the medical literature on the prevention and treatment of VTE in cancer patients was conducted and reviewed by a panel of content and methodology experts. Following discussion of the results, the panel drafted recommendations for the use of anticoagulation in patients with malignant disease. RESULTS The results of randomized controlled trials of primary and secondary VTE medical prophylaxis, surgical prophylaxis, VTE treatment, and the impact of anticoagulation on survival of patients with cancer were reviewed. Recommendations were developed on the prevention of VTE in hospitalized, ambulatory, and surgical cancer patients as well as patients with established VTE, and for use of anticoagulants in cancer patients without VTE to improve survival. CONCLUSION Recommendations of the American Society of Clinical Oncology VTE Guideline Panel include (1) all hospitalized cancer patients should be considered for VTE prophylaxis with anticoagulants in the absence of bleeding or other contraindications; (2) routine prophylaxis of ambulatory cancer patients with anticoagulation is not recommended, with the exception of patients receiving thalidomide or lenalidomide; (3) patients undergoing major surgery for malignant disease should be considered for pharmacologic thromboprophylaxis; (4) low molecular weight heparin represents the preferred agent for both the initial and continuing treatment of cancer patients with established VTE; and (5) the impact of anticoagulants on cancer patient survival requires additional study and cannot be recommended at present.

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.

Venous Thromboembolism Prophylaxis and Treatment in Patients With Cancer: American Society of Clinical Oncology Clinical Practice Guideline Update 2014

PURPOSE To provide current recommendations about the prophylaxis and treatment of venous thromboembolism (VTE) in patients with cancer. METHODS PubMed and the Cochrane Library were searched for randomized controlled trials, systematic reviews, meta-analyses, and clinical practice guidelines from November 2012 through July 2014. An update committee reviewed the identified abstracts. RESULTS Of the 53 publications identified and reviewed, none prompted a change in the 2013 recommendations. RECOMMENDATIONS Most hospitalized patients with active cancer require thromboprophylaxis throughout hospitalization. Routine thromboprophylaxis is not recommended for patients with cancer in the outpatient setting. It may be considered for selected high-risk patients. Patients with multiple myeloma receiving antiangiogenesis agents with chemotherapy and/or dexamethasone should receive prophylaxis with either low-molecular weight heparin (LMWH) or low-dose aspirin. Patients undergoing major surgery should receive prophylaxis starting before surgery and continuing for at least 7 to 10 days. Extending prophylaxis up to 4 weeks should be considered in those undergoing major abdominal or pelvic surgery with high-risk features. LMWH is recommended for the initial 5 to 10 days of treatment for deep vein thrombosis and pulmonary embolism as well as for long-term secondary prophylaxis (at least 6 months). Use of novel oral anticoagulants is not currently recommended for patients with malignancy and VTE because of limited data in patients with cancer. Anticoagulation should not be used to extend survival of patients with cancer in the absence of other indications. Patients with cancer should be periodically assessed for VTE risk. Oncology professionals should educate patients about the signs and symptoms of VTE.

Extended Use of Da bi gat ran, Warfarin, or Placebo in Venous Thromboembolism

BACKGROUND Dabigatran, which is administered in a fixed dose and does not require laboratory monitoring, may be suitable for extended treatment of venous thromboembolism. METHODS In two double-blind, randomized trials, we compared dabigatran at a dose of 150 mg twice daily with warfarin (active-control study) or with placebo (placebo-control study) in patients with venous thromboembolism who had completed at least 3 initial months of therapy. RESULTS In the active-control study, recurrent venous thromboembolism occurred in 26 of 1430 patients in the dabigatran group (1.8%) and 18 of 1426 patients in the warfarin group (1.3%) (hazard ratio with dabigatran, 1.44; 95% confidence interval [CI], 0.78 to 2.64; P=0.01 for noninferiority). Major bleeding occurred in 13 patients in the dabigatran group (0.9%) and 25 patients in the warfarin group (1.8%) (hazard ratio, 0.52; 95% CI, 0.27 to 1.02). Major or clinically relevant bleeding was less frequent with dabigatran (hazard ratio, 0.54; 95% CI, 0.41 to 0.71). Acute coronary syndromes occurred in 13 patients in the dabigatran group (0.9%) and 3 patients in the warfarin group (0.2%) (P=0.02). In the placebo-control study, recurrent venous thromboembolism occurred in 3 of 681 patients in the dabigatran group (0.4%) and 37 of 662 patients in the placebo group (5.6%) (hazard ratio, 0.08; 95% CI, 0.02 to 0.25; P<0.001). Major bleeding occurred in 2 patients in the dabigatran group (0.3%) and 0 patients in the placebo group. Major or clinically relevant bleeding occurred in 36 patients in the dabigatran group (5.3%) and 12 patients in the placebo group (1.8%) (hazard ratio, 2.92; 95% CI, 1.52 to 5.60). Acute coronary syndromes occurred in 1 patient each in the dabigatran and placebo groups. CONCLUSIONS Dabigatran was effective in the extended treatment of venous thromboembolism and carried a lower risk of major or clinically relevant bleeding than warfarin but a higher risk than placebo. (Funded by Boehringer Ingelheim; RE-MEDY and RE-SONATE ClinicalTrials.gov numbers, NCT00329238 and NCT00558259, respectively.).

Low Molecular Weight Heparin, Therapy With Dalteparin, and Survival in Advanced Cancer: The Fragmin Advanced Malignancy Outcome Study (FAMOUS)

PURPOSE In experimental systems, interference with coagulation can affect tumor biology. Furthermore, it has been suggested that low molecular weight heparin therapy may prolong survival in patients with cancer. The primary aim of this study was to assess survival at 1 year of patients with advanced cancer. PATIENTS AND METHODS Patients with advanced malignancy (N = 385) were randomly assigned to receive either a once-daily subcutaneous injection of dalteparin (5,000 IU), a low molecular weight heparin, or placebo for 1 year. RESULTS The Kaplan-Meier survival estimates at 1, 2, and 3 years after randomization for patients receiving dalteparin were 46%, 27%, and 21%, respectively, compared with 41%, 18%, and 12%, respectively, for patients receiving placebo (P =.19). In an analysis not specified a priori, survival was examined in a subgroup of patients (dalteparin, n = 55; and placebo, n = 47) who had a better prognosis and who were alive 17 months after randomization. In these patients, Kaplan-Meier survival estimates at 2 and 3 years from randomization were significantly improved for patients receiving dalteparin versus placebo (78% v 55% and 60% v 36%, respectively, P =.03). The rates of symptomatic venous thromboembolism were 2.4% and 3.3% for dalteparin and placebo, respectively, with bleeding rates of 4.7% and 2.7%, respectively. CONCLUSION Dalteparin administration did not significantly improve 1-year survival rates in patients with advanced malignancy. However, the observed improved survival in a subgroup of patients with a better prognosis suggests a potential modifying effect of dalteparin on tumor biology.

Treatment of Acute Venous Thromboembolism With Dabigatran or Warfarin and Pooled Analysis

Background— Dabigatran and warfarin have been compared for the treatment of acute venous thromboembolism (VTE) in a previous trial. We undertook this study to extend those findings. Methods and Results— In a randomized, double-blind, double-dummy trial of 2589 patients with acute VTE treated with low-molecular-weight or unfractionated heparin for 5 to 11 days, we compared dabigatran 150 mg twice daily with warfarin. The primary outcome, recurrent symptomatic, objectively confirmed VTE and related deaths during 6 months of treatment occurred in 30 of the 1279 dabigatran patients (2.3%) compared with 28 of the 1289 warfarin patients (2.2%; hazard ratio, 1.08; 95% confidence interval [CI], 0.64–1.80; absolute risk difference, 0.2%; 95% CI, −1.0 to 1.3; P<0.001 for the prespecified noninferiority margin for both criteria). The safety end point, major bleeding, occurred in 15 patients receiving dabigatran (1.2%) and in 22 receiving warfarin (1.7%; hazard ratio, 0.69; 95% CI, 0.36–1.32). Any bleeding occurred in 200 dabigatran (15.6%) and 285 warfarin (22.1%; hazard ratio, 0.67; 95% CI, 0.56–0.81) patients. Deaths, adverse events, and acute coronary syndromes were similar in both groups. Pooled analysis of this study RE-COVER II and the RE-COVER trial gave hazard ratios for recurrent VTE of 1.09 (95% CI, 0.76–1.57), for major bleeding of 0.73 (95% CI, 0.48–1.11), and for any bleeding of 0.70 (95% CI, 0.61–0.79). Conclusion— Dabigatran has similar effects on VTE recurrence and a lower risk of bleeding compared with warfarin for the treatment of acute VTE. Clinical Trial Registration— URL: www.clinicaltrials.gov. Unique identifiers: NCT00680186 and NCT00291330.

Randomized Comparison of Low Molecular Weight Heparin and Coumarin Derivatives on the Survival of Patients With Cancer and Venous Thromboembolism

PURPOSE Experimental studies and indirect clinical evidence suggest that low molecular weight heparins may have antineoplastic effects. We investigated the influence of a low molecular weight heparin dalteparin on the survival of patients with active cancer and acute venous thromboembolism. PATIENTS AND METHODS Survival data were examined in a posthoc analysis in patients with solid tumors and venous thromboembolism who were randomly assigned to dalteparin or a coumarin derivative for 6 months in a multicenter, open-label, randomized, controlled trial. All-cause mortality at 12 months was compared between treatment groups in patients with and without metastatic malignancy. The effect of dalteparin on survival was compared between the two patient subgroups. RESULTS During the 12-month follow-up period, 356 of 602 patients with solid tumors and acute venous thromboembolism died. Among patients without metastatic disease, the probability of death at 12 months was 20% in the dalteparin group, as compared with 36% in the oral anticoagulant group (hazard ratio, 0.50; 95% CI, 0.27 to 0.95; P = .03). In patients with metastatic cancer, no difference in mortality between the treatment groups was observed (72% and 69%, respectively; hazard ratio, 1.1; 95% CI, 0.87 to 1.4; P = .46). The observed effects of dalteparin on survival were statistically significantly different between patients with and without metastatic disease (P = .02). CONCLUSION The use of dalteparin relative to coumarin derivatives was associated with improved survival in patients with solid tumors who did not have metastatic disease at the time of an acute venous thromboembolic event. Additional studies are warranted to investigate these findings.