Qualitative experiences, values, and decisional needs of patients with unprovoked venous thromboembolism who suffer bleeding-"This pill will keep you alive tonight".

Background: Contemporary guidelines recommend extended-duration anticoagulation among patients with a first unprovoked venous thromboembolism (VTE). Little is known about whether this recommendation aligns with patient values after a bleeding complication. Objectives: To explore the experiences, values, and decisional needs of patients with unprovoked VTE related to extended-duration treatment after an anticoagulant-associated bleed. Methods: In this descriptive, qualitative study, face to face online semistructured interviews were conducted with patients with unprovoked VTE who had experienced bleeding and continued anticoagulant treatment in one academic hospital in Canada. Data were analyzed using directed content analysis to identify themes. Themes were mapped onto the Ottawa Decisional Support Framework to identify decisional needs. Results: Between September and December 2021, 14 patients were interviewed (age 41-69 years; 9 females). Many patients were not aware of the option to stop anticoagulation and had limited understanding of the decision about treatment duration. Despite the negative quality-of-life impact of clinically relevant bleeding during VTE treatment, the majority continued anticoagulation due to emotional trauma of VTE diagnosis, a perception that bleeding would be more manageable than VTE recurrence, a desire to maintain a connection to subspecialty care or non-VTE related benefits (eg, cancer diagnosis, protection from COVID-19). Patients' decisional needs included lack of choice awareness, inadequate support for participation, lack of personalized risk stratification, and inadequate information on monitoring and managing heavy menstrual bleeding. Conclusion: Despite the impact of anticoagulant-associated bleeding on quality of life, patients preferred continuing with anticoagulation for reasons extending beyond secondary VTE prevention. Effective decision-support interventions are needed to address unmet decisional needs.

Thrombophilia gene mutations predict venous thromboembolism in ambulatory cancer patients receiving chemotherapy.

BACKGROUND: Inherited thrombophilia and cancer both independently increase the risk of venous thromboembolism (VTE). However, whether the increased VTE risk associated with inherited thrombophilia exists in cancer patients is less clear. OBJECTIVES: Our objective was to determine the influence of inherited thrombophilia on VTE and bleeding risk in moderate-to-high-risk ambulatory cancer patients receiving chemotherapy. METHODS: We conducted a post hoc analysis using blood samples from patients enrolled in the AVERT trial to determine if previously recognized thrombophilia gene mutations (prothrombin factor [F] II G20210A, FXI, fibrinogen gamma, serpin family A member 10, FV K858R, FXIII, FV Leiden [FVL], and ABO blood) were associated with VTE or bleeding during the 7-months after starting chemotherapy. Logistic regression was used to compare heterozygous and homozygous mutations (combined) to wild-type. VTE rates, bleeding rates, and risk differences for mutations stratified by prophylactic anticoagulation use were calculated. RESULTS: Of the 447 patients, there were 39 VTE and 39 bleeding events. The odds of VTE were significantly increased with FVL mutation and non-O blood type (odds ratio [OR]: 5.2; 95% CI: 1.9-14.7 and OR: 2.7; 95% CI: 1.2-6.1, respectively). The use of anticoagulation prophylaxis resulted in complete protection in FVL patients, whereas those not receiving anticoagulation had a VTE rate of 119 per 100 patient-years. Lower VTE rates were also observed in non-O blood type patients taking prophylactic anticoagulation. No other thrombophilia genes tested were significantly associated with VTE or bleeding. CONCLUSION: Our results indicate that FVL mutation and ABO blood type may be important VTE predictors in cancer patients starting chemotherapy.

Recurrent venous thromboembolism and bleeding with extended anticoagulation: the VTE-PREDICT risk score.

AIMS: Deciding to stop or continue anticoagulation for venous thromboembolism (VTE) after initial treatment is challenging, as individual risks of recurrence and bleeding are heterogeneous. The present study aimed to develop and externally validate models for predicting 5-year risks of recurrence and bleeding in patients with VTE without cancer who completed at least 3 months of initial treatment, which can be used to estimate individual absolute benefits and harms of extended anticoagulation. METHODS AND RESULTS: Competing risk-adjusted models were derived to predict recurrent VTE and clinically relevant bleeding (non-major and major) using 14 readily available patient characteristics. The models were derived from combined individual patient data from the Bleeding Risk Study, Hokusai-VTE, PREFER-VTE, RE-MEDY, and RE-SONATE (n = 15,141, 220 recurrences, 189 bleeding events). External validity was assessed in the Danish VTE cohort, EINSTEIN-CHOICE, GARFIELD-VTE, MEGA, and Tromsø studies (n = 59 257, 2283 recurrences, 3335 bleeding events). Absolute treatment effects were estimated by combining the models with hazard ratios from trials and meta-analyses. External validation in different settings showed agreement between predicted and observed risks up to 5 years, with C-statistics ranging from 0.48-0.71 (recurrence) and 0.61-0.68 (bleeding). In the Danish VTE cohort, 5-year risks ranged from 4% to 19% for recurrent VTE and 1% -19% for bleeding. CONCLUSION: The VTE-PREDICT risk score can be applied to estimate the effect of extended anticoagulant treatment for individual patients with VTE and to support shared decision-making.

Redefining clinical venous thromboembolism phenotypes: a novel approach using latent class analysis.

BACKGROUND: Patients with venous thromboembolism (VTE) are commonly classified by the presence or absence of provoking factors at the time of VTE to guide treatment decisions. This approach may not capture the heterogeneity of the disease and its prognosis. OBJECTIVES: To evaluate clinically important novel phenotypic clusters among patients with VTE without cancer and to explore their association with anticoagulant treatment and clinical outcomes. METHODS: Latent class analysis was performed with 18 baseline clinical variables in 3062 adult patients with VTE without active cancer participating in PREFER in VTE, a noninterventional disease registry. The derived latent classes were externally validated in a post hoc analysis of Hokusai-VTE (n = 6593), a randomized trial comparing edoxaban with warfarin. The associations between cluster membership and anticoagulant treatment, recurrent VTE, bleeding, and mortality after initial treatment were studied. RESULTS: The following 5 clusters were identified: young men cluster (n = 1126, 37%), young women cluster (n = 215, 7%), older people cluster (n = 1106, 36%), comorbidity cluster (n = 447, 15%), and history of venous thromboembolism cluster (n = 168, 5%). Patient characteristics varied by age, sex, medical history, and treatment patterns. Consistent clusters were evident on external validation. In Cox proportional hazard models, recurrence risk was lower in the young women cluster (hazard ratio [HR], 0.27; 95% CI, 0.12-0.61) compared with the comorbidity cluster, after adjusting for extended anticoagulation. The risk of bleeding was lower in young men, young women, and older people clusters (HR, 0.50; 95% CI, 0.38-0.66; HR, 0.23; 95% CI, 0.11-0.46; and HR, 0.55; 95% CI 0.41-0.73, respectively). CONCLUSION: The heterogeneity of VTE cases extends beyond the distinction between provoked and unprovoked VTE.

Safety and efficacy of apixaban thromboprophylaxis in ambulatory cancer patients according to renal function: A subgroup analysis of the AVERT trial.

BACKGROUND: Apixaban was effective in preventing venous thromboembolism (VTE) in ambulatory cancer patients with Khorana score ≥2 initiating chemotherapy, but with an increased risk of bleeding. Patients with cancer have a higher risk of renal dysfunction, which may be associated with increased risks of thrombotic or bleeding complications. We sought to assess the efficacy and safety of apixaban thromboprophylaxis according to renal function in the AVERT trial. METHODS: AVERT trial was a randomized, double-blinded, placebo-controlled trial evaluating apixaban as primary thromboprophylaxis for ambulatory cancer patients. The primary efficacy outcome was objectively confirmed VTE within 180 days of randomization. The primary safety outcome was major bleeding events. RESULTS: Among 574 patients randomized, 66 (11.5%) patients had CrCl <60 mL/min and 508 (88.5%) had CrCl ≥60 mL/min. Patients with CrCl <60 mL/min were older, more likely to be female, had lower weight/body mass index, and poorer ECOG performance status. In patients with CrCl <60 mL/min, there were one VTE and one major bleeding event, with no differences in outcomes between apixaban and placebo. In patients with CrCl ≥60 mL/min, apixaban was associated with a significantly lower rate of VTE and overall mortality compared to placebo without an increased risk of bleeding events. The risk of VTE was significantly higher in patients with CrCl ≥60 mL/min. CONCLUSIONS: In the AVERT trial, patients with CrCl <60 mL/min did not have higher risk of thrombotic or bleeding complications compared to those with CrCl ≥60 mL/min. (Funded by the CIHR and Bristol-Myers Squibb-Pfizer Alliance; NCT02048865).

Efficacy of primary prevention of venous thromboembolism among subgroups of cancer patients undergoing chemotherapy: A post- hoc analysis of the AVERT trial.

BACKGROUND: Apixaban has been shown to significantly decrease the rate of VTE among intermediate-to-high risk patients starting chemotherapy compared to placebo. This investigation sought to determine the impact of apixaban among different subgroups of patients with cancer. METHODS: This is a pre-planned post-hoc analysis of the AVERT randomized controlled trial which compared apixaban to placebo for the primary prevention of VTE in ambulatory patients initiating chemotherapy. Subgroup analyses were performed based on different baseline characteristics. The primary efficacy outcome was objectively documented major VTE. Hazard ratios (HR) with 95% confidence intervals (CI) were calculated using the Cox proportional hazards model to compare the treatment effect accounting for clustering at study center level. RESULTS: During the study period, major VTE events occurred in 4.2% and 10.2% of the apixaban and placebo groups, respectively (HR 0.41; 95%CI, 0.26-0.65). Characteristics associated with decreased risk of major VTE among patients on apixaban included: male sex (HR 0.25, 95%CI 0.12-0.48); weight > 90Kg (HR 0.18, 95%CI, 0.06-0.52); no prior history of VTE (HR 0.41, 95%CI 0.26-0.64); solid cancers (HR 0.30; 95%CI, 0.19-0.47); metastatic disease (HR 0.45; 95%CI, 0.26-0.78); and concurrent use of antiplatelet therapy (HR 0.18, 95%CI 0.10-0.33). CONCLUSIONS: In the AVERT trial, while apixaban thromboprophylaxis reduced the risk of major VTE in most patients, patients with weight > 90 kg, solid cancers, or concurrent antiplatelet therapy experienced the greatest benefits.

Antithrombotic Therapy for VTE Disease: Second Update of the CHEST Guideline and Expert Panel Report.

BACKGROUND: This is the 2nd update to the 9th edition of these guidelines. We provide recommendations on 17 PICO (Population, Intervention, Comparator, Outcome) questions, four of which have not been addressed previously. METHODS: We generate strong and weak recommendations based on high-, moderate-, and low-certainty evidence, using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) methodology. RESULTS: The panel generated 29 guidance statements, 13 of which are graded as strong recommendations, covering aspects of antithrombotic management of VTE from initial management through secondary prevention and risk reduction of postthrombotic syndrome. Four new guidance statements have been added that did not appear in the 9th edition (2012) or 1st update (2016). Eight statements have been substantially modified from the 1st update. CONCLUSION: New evidence has emerged since 2016 that further informs the standard of care for patients with VTE. Substantial uncertainty remains regarding important management questions, particularly in limited disease and special patient populations.

Postoperative low molecular weight heparin bridging treatment for patients at high risk of arterial thromboembolism (PERIOP2): double blind randomised controlled trial.

OBJECTIVE: To determine the efficacy and safety of dalteparin postoperative bridging treatment versus placebo for patients with atrial fibrillation or mechanical heart valves when warfarin is temporarily interrupted for a planned procedure. DESIGN: Prospective, double blind, randomised controlled trial. SETTING: 10 thrombosis research sites in Canada and India between February 2007 and March 2016. PARTICIPANTS: 1471 patients aged 18 years or older with atrial fibrillation or mechanical heart valves who required temporary interruption of warfarin for a procedure. INTERVENTION: Random assignment to dalteparin (n=821; one patient withdrew consent immediately after randomisation) or placebo (n=650) after the procedure. MAIN OUTCOME MEASURES: Major thromboembolism (stroke, transient ischaemic attack, proximal deep vein thrombosis, pulmonary embolism, myocardial infarction, peripheral embolism, or vascular death) and major bleeding according to the International Society on Thrombosis and Haemostasis criteria within 90 days of the procedure. RESULTS: The rate of major thromboembolism within 90 days was 1.2% (eight events in 650 patients) for placebo and 1.0% (eight events in 820 patients) for dalteparin (P=0.64, risk difference -0.3%, 95% confidence interval -1.3 to 0.8). The rate of major bleeding was 2.0% (13 events in 650 patients) for placebo and 1.3% (11 events in 820 patients) for dalteparin (P=0.32, risk difference -0.7, 95% confidence interval -2.0 to 0.7). The results were consistent for the atrial fibrillation and mechanical heart valves groups. CONCLUSIONS: In patients with atrial fibrillation or mechanical heart valves who had warfarin interrupted for a procedure, no significant benefit was found for postoperative dalteparin bridging to prevent major thromboembolism. TRIAL REGISTRATION: Clinicaltrials.gov NCT00432796.

Direct oral anticoagulant use in special populations.

PURPOSE OF REVIEW: The pivotal phase III trials demonstrating efficacy and safety of direct oral anticoagulants (DOACs) in the treatment of venous thromboembolism (VTE) or nonvalvular atrial fibrillation (NVAF) excluded patients with important and common comorbidities, including obesity, advanced chronic kidney disease, cirrhosis, cancer and antiphospholipid antibody syndrome. Despite the lack of large prospective randomized control trials in these patient populations, the use of DOACs has led to a wealth of efficacy and safety data within these groups. RECENT FINDINGS: Retrospective studies, meta-analyses, national databases and pharmacokinetic data have shed light on the efficacy and safety of DOACs in these patient populations. Although DOACs should be avoided in those with high-risk triple positive antiphospholipid antibody syndrome, advanced cirrhosis, advanced kidney disease and intact gastrointestinal cancers, and used with caution in genitourinary cancers, their use extends beyond the inclusion criteria of the initial randomized control trials. SUMMARY: DOACs have revolutionized anticoagulant management and have become the cornerstone for VTE treatment and stroke prevention in NVAF. The decision to use DOACs must be individualized. Patient preference, underlying comorbidities and informed consent must always be considered when selecting the most appropriate anticoagulant.

Efficacy and safety of apixaban for primary prevention in gastrointestinal cancers: A post-hoc analysis of the AVERT trial.

BACKGROUND: Recent trials have demonstrated that thromboprophylaxis using direct oral anticoagulants is effective but associated with a higher rate of major bleeding in intermediate-to-high risk (Khorana score ≥ 2) patients with cancer initiating systemic chemotherapy. Patients with gastrointestinal cancer may be at higher risk of major bleeding complications. We sought to assess the efficacy and safety of using thromboprophylaxis with apixaban in this patient population. METHODS: This is a post-hoc analysis of the AVERT trial, which was a randomized, placebo-controlled, double-blind clinical trial. The primary efficacy outcome was objectively documented venous thromboembolism within 180 days of randomization. The primary safety outcome was a major bleeding episode. Time-to-event analyses were performed in patients with gastrointestinal cancers (upper gastrointestinal, pancreatic/hepatobiliary and colorectal cancers). RESULTS: A total of 130 patients from the original AVERT trial were included, with 65 patients allocated to each of the apixaban and placebo groups. VTE occurred in 3 (4.6%) patients in the apixaban group and 13 (20%) patients in the placebo group (HR: 0.27; 95% CI: 0.13-0.54; p = 0.0002). Major bleeding occurred in 2 (3.1%) patients in the apixaban group and 1 (1.5%) patient in the placebo group (HR 2.39, 95% CI 0.29-19.78, p = 0.42). None of the major bleeding events occurred in patients with upper gastrointestinal or colorectal cancers. CONCLUSION: Primary thromboprophylaxis with apixaban therapy seems to be safe and effective in patients with gastrointestinal cancers. Major bleeding complications are uncommon in our cohort. (Funded by the CIHR and Bristol-Myers Squibb-Pfizer Alliance; NCT02048865).

Long-term risk of recurrent venous thromboembolism after a first contraceptive-related event: Data from REVERSE cohort study.

INTRODUCTION: The risk of recurrent venous thromboembolism (VTE) after combined oral contraceptive (COC) use is variably reported. We assessed the long-term risk of recurrent VTE in women on COC at the time of a first VTE, in comparison to women without COC use. Our secondary aim assessed the impact of COC use on the recurrent VTE risk in high-risk and low-risk hyperpigmentation, edema, or redness in either leg; D-dimer level ≥250 µg/L; obesity with body mass index ≥30; or older age, ≥65 years (HERDOO2) subgroups. METHODS: The REVERSE cohort study derived the HERDOO2 clinical decision rule to predict recurrent VTE in patients who discontinued anticoagulation after 5-7 months for a first unprovoked VTE. Incidence rates of recurrent VTE among women with and without COC exposure were calculated as the number of recurrent VTE over the number of person-years of follow-up, and Cox proportional hazards model was used to compare risks between groups. RESULTS: The risk of recurrent VTE among COC users was 1.1% (95% confidence interval [CI] 0.3-2.9) per patient-year as compared with 3.2% per patient-year (95% CI 2.4-4.3) among nonusers (hazard ratio 0.37; 95% CI 0.1-1.0). Women who were COC users and high risk by HERDOO2 score had a recurrence rate of 3.5% (95% CI 0.4-12.5) compared with 6.1% (95% CI 4.3-8.5) among women who were non-COC users and at high risk by HERDOO2 score (HR 0.6, 95% CI 0.1-2.5). CONCLUSIONS: Women who were COC users at the time of an otherwise unprovoked VTE event had a lower VTE recurrence rate during long-term follow-up, compared with nonusers. The use of HERDOO2 rule may help identify higher risk women with COC use.

Cost-utility analysis of apixaban compared with usual care for primary thromboprophylaxis in ambulatory patients with cancer.

BACKGROUND: Apixaban (2.5 mg) taken twice daily has been shown to substantially reduce the risk of venous thromboembolism (VTE) compared with placebo for the primary thromboprophylaxis of ambulatory patients with cancer who are starting chemotherapy and are at intermediate-to-high risk of VTE. We aimed to compare the health system costs and health benefits associated with primary thromboprophylaxis using apixaban with those associated with the current standard of care (where no primary thromboprophylaxis is given), from the perspective of Canada's publicly funded health care system in this subpopulation of patients with cancer over a lifetime horizon. METHODS: We performed a cost-utility analysis to estimate the incremental cost per quality-adjusted life-year (QALY) gained with primary thromboprophylaxis using apixaban. We obtained baseline event rates and the efficacy of apixaban from the Apixaban for the Prevention of Venous Thromboembolism in High-Risk Ambulatory Cancer Patients (AVERT) trial on apixaban prophylaxis. We estimated relative risk for bleeding, risk of complications associated with VTE treatment, mortality rates, costs and utilities from other published sources. RESULTS: Over a lifetime horizon, apixaban resulted in lower costs to the health system (Can$7902.98 v. Can$14 875.82) and an improvement in QALYs (9.089 v. 9.006). The key driver of cost-effectiveness results was the relative risk of VTE as a result of apixaban. Results from the probabilistic analysis showed that at a willingness to pay of Can$50 000 per QALY, the strategy with the highest probability of being most cost-effective was apixaban, with a probability of 99.87%. INTERPRETATION: We found that apixaban is a cost-saving option for the primary thromboprophylaxis of ambulatory patients with cancer who are starting chemotherapy and are at intermediate-to-high risk of VTE.

Safety and efficacy of apixaban thromboprophylaxis in cancer patients with metastatic disease: A post-hoc analysis of the AVERT trial.

BACKGROUND: The risk of venous thromboembolism (VTE) is increased in patients with active cancer and the risk is highest in those with metastatic disease. The risks and benefits of thromboprophylaxis among cancer patients with metastatic disease initiating chemotherapy treatment are unknown. To address this important knowledge gap, we evaluated the efficacy and safety of apixaban thromboprophylaxis in patients with and without metastatic disease. METHODS: Post-hoc analysis of the AVERT trial, which was a randomized, placebo-controlled, double-blind trial comparing apixaban therapy to placebo for VTE prophylaxis among cancer patients who were intermediate-to-high risk for VTE and who were initiating chemotherapy. The hazards ratios (HRs) for VTE and major bleeding episodes in patients with and without metastatic disease were calculated using a Cox regression model controlling for age, gender, and center. RESULTS: A total of 574 patients underwent randomization and 365 patients could be stratified according to the presence (n = 138) or absence (n = 227) of metastatic disease. In patients with metastatic disease, those receiving apixaban had a significantly lower risk of VTE (HR 0.55; 95% CI 0.32 to 0.97) without a significant increase in major bleeding complications (HR 1.36 95% CI 0.27 to 6.93) compared to those on placebo. In patients without metastatic disease, the use of apixaban was also associated with a significantly lower risk of VTE (HR 0.34 95% CI 0.19 to 0.60) without a significant increase in major bleeding complications (HR 1.14 95% CI 0.08 to 15.91). CONCLUSIONS: In patients with and without metastatic disease, apixaban thromboprophylaxis was associated with a significantly lower rate of VTE compared to placebo.

Thromboprophylaxis for patients with newly diagnosed vs. recurrent cancers: a post-hoc analysis of the avert trial.

Venous thromboembolic disease (VTE) is a common complication among patients with cancer. Data reporting risk of VTE among patients receiving chemotherapy for recurrent cancer compared to those with newly diagnosed tumors is scarce. Furthermore, it is unclear if thromboprophylaxis is beneficial and safe in these specific patient populations. Post-hoc analysis of the AVERT trial which was a randomized, placebo-controlled, double-blind trial comparing apixaban therapy to placebo for VTE prophylaxis among cancer patients who were intermediate-to-high risk for VTE and who were initiating chemotherapy. The HRs for recurrent VTE and major bleeding episodes in patients with newly diagnosed and recurrent cancers were calculated using a Cox regression model controlling for age, gender, and center. Of the 563 included patients 469 and 93 patients had newly diagnosed and recurrent cancers, respectively. Patients with recurrent cancer have a higher risk of VTE (Hazard ratio (HR): 1.53 (95% CI 1.0 to 2.33; p = 0.047) and major bleeding episodes (HR 2.89 (95% CI 1.52 to 5.49; p = 0.001) compared to those with newly diagnosed cancer. In patients with newly diagnosed cancers, the use of apixaban was associated with a significantly lower risk of VTE (HR 0.45; 95% CI 0.27-0.76; p = 0.002) and a higher rate of major bleeding (HR 2.10; 95% CI 1.09-4.08; p = 0.028). In patients with recurrent cancer, apixaban was associated with a significant lower rate of VTE (HR 0.26; 95% CI 0.13-0.53; p < 0.001) without an associated significantly increased risk of major bleeding (HR 1.82; 95% CI 0.36-9.15; p = 0.466). Patients with recurrent cancer seem to be at higher risk of recurrent VTE and major bleeding complications compared to those with newly diagnosed tumors. Apixaban appears to be safe and effective in these patient populations.

Association of Splanchnic Vein Thrombosis on Survival: 15-Year Institutional Experience With 1561 Cases.

Background Previous studies regarding survival in patients with splanchnic vein thrombosis (SVT) are limited. This study measured overall survival in a large cohort of SVTs through linkage to population-based data. Methods and Results Using a previously derived text-search algorithm, we screened the reports of all abdominal ultrasound and contrast-enhanced computed tomography studies at The Ottawa Hospital over 14 years. Screen-positive reports were manually reviewed by at least 2 authors to identify definite SVT cases by consensus. Images of uncertain studies were independently reviewed by 2 radiologists. One thousand five hundred sixty-one adults with SVT (annual incidence ranging from 2.8 to 5.9 cases/10 000 patients) were linked with population-based data sets to measure the presence of concomitant cancer and survival status. Thrombosis involved multiple veins in 314 patients (20.1%), most commonly the portal vein (n=1410, 90.3%). Compared with an age-sex-year matched population, patients with SVT had significantly reduced survival in particular with local cancer (adjusted relative excess risk for recent cases 12.0 [95% CI, 9.8-14.6] and for remote cases 9.7 [7.7-12.2]), distant cancer (relative excess risk for recent cases 5.7 [4.5-7.3] and for remote cases 5.4 [4.4-6.6]), cirrhosis (relative excess risk 8.2 [5.3-12.7]), and previous venous thromboembolism (relative excess risk 3.8 [2.4-6.0]). One hundred fifty (23.9%) of patients >65 years of age were anticoagulated within 1 month of diagnosis. Conclusions SVT is more common than expected. Most patients have cancer and the portal vein is by far the most common vein involved. Compared with the general population, patients with SVT had significantly reduced survival, particularly in patients with concomitant cancer, cirrhosis, and previous venous thromboembolic disease. Most elderly patients did not receive anticoagulant therapy.

D-Dimer Enhances Risk-Targeted Thromboprophylaxis in Ambulatory Patients with Cancer.

BACKGROUND: Thromboprophylaxis for ambulatory patients with cancer is effective, although uncertainties remain on who should be targeted. Using D-dimer values from individuals enrolled to the AVERT trial, we sought to identify and validate a more efficient venous thromboembolism (VTE) risk threshold for thromboprophylaxis. MATERIALS AND METHODS: The AVERT trial compared thromboprophylaxis with apixaban with placebo among patients with cancer with a Khorana Risk Score ≥2. The D-dimer measured at randomization was used to calculate an individualized 6-month VTE risk using the validated CATScore. A modified intention-to-treat analysis was used to assess efficacy (VTE) and safety (major and overall bleeding) in the (a) complete cohort and (b) ≥8% and < 8% 6-month VTE risk thresholds. RESULTS: Five hundred seventy-four patients were randomized in the AVERT trial; 466 (81%) with baseline D-dimer were included in the study. Two hundred thirty-seven subjects received apixaban; 229 received placebo. In the complete cohort, there were 13 (5.5%) VTE events in the apixaban arm compared with 26 (11.4%) events in the placebo arm (adjusted hazard ratio [aHR] 0.49 [0.25-0.95], p < .05). Number needed to treat (NNT) to prevent one VTE = 17. Eighty-two (35%) and 72 (31%) patients in the apixaban and placebo arms, respectively, had a 6-month VTE risk ≥8%. In this subgroup, 7 (8.4%) VTE events occurred with apixaban and 19 (26.3%) events with placebo (aHR 0.33 [0.14-0.81], p < .05), NNT = 6. Individuals with a VTE risk <8% derived no benefit from apixaban thromboprophylaxis (aHR 0.89 [0.30-2.65), p = .84). Increased rates of overall bleeding were observed with apixaban in both the complete (aHR 2.11 [1.09-4.09], p < .05) and ≥ 8% predicted risk cohorts (aHR 2.87 [0.91-9.13], p = .07). CONCLUSION: A 6-month VTE risk threshold of ≥8% increases the efficiency of risk-targeted thromboprophylaxis in ambulatory patients with cancer. IMPLICATIONS FOR PRACTICE: Ambulatory patients with cancer receiving chemotherapy have an increased risk of venous thromboembolism (VTE). A Khorana Risk Score (KRS) ≥2 is currently the suggested threshold for thromboprophylaxis. Using baseline D-dimer values from individuals enrolled to the AVERT trial, this retrospective validation study identifies a 6-month VTE risk of ≥8% as a more efficient threshold for thromboprophylaxis. At this threshold, the number needed to treat to prevent one VTE is 6, compared with 17 when using a KRS ≥2. Conversely, individuals with a predicted risk of <8% derive no clinical benefit from thromboprophylaxis. Future prospective studies should validate this threshold for outpatient thromboprophylaxis.

Accuracy of the Ottawa score in risk stratification of recurrent venous thromboembolism in patients with cancer-associated venous thromboembolism: a systematic review and meta-analysis.

In patients with cancer-associated venous thromboembolism, knowledge of the estimated rate of recurrent events is important for clinical decision-making regarding anticoagulant therapy. The Ottawa score is a clinical prediction rule designed for this purpose, stratifying patients according to their risk of recurrent venous thromboembolism during the first six months of anticoagulation. We conducted a systematic review and meta-analysis of studies validating either the Ottawa score in its original or modified versions. Two investigators independently reviewed the relevant articles published from 1st June 2012 to 15th December 2018 and indexed in MEDLINE and EMBASE. Nine eligible studies were identified; these included a total of 14,963 patients. The original score classified 49.3% of the patients as high-risk, with a sensitivity of 0.7 [95% confidence interval (CI): 0.6-0.8], a 6-month pooled rate of recurrent venous thromboembolism of 18.6% (95%CI: 13.9-23.9). In the low-risk group, the recurrence rate was 7.4% (95%CI: 3.4-12.5). The modified score classified 19.8% of the patients as low-risk, with a sensitivity of 0.9 (95%CI: 0.4-1.0) and a 6-month pooled rate of recurrent venous thromboembolism of 2.2% (95%CI: 1.6-2.9). In the high-risk group, recurrence rate was 10.2% (95%CI: 6.4-14.6). Limitations of our analysis included type and dosing of anticoagulant therapy. We conclude that new therapeutic strategies are needed in patients at high risk for recurrent cancer-associated venous thromboembolism. Low-risk patients, as per the modified score, could be good candidates for oral anticoagulation. (This systematic review was registered with the International Prospective Registry of Systematic Reviews as: PROSPERO CRD42018099506).

Direct oral anticoagulant for the prevention of thrombosis in ambulatory patients with cancer: A systematic review and meta-analysis.

BACKGROUND: It is unclear if direct oral anticoagulant (DOAC) is efficacious and safe for prophylaxis of venous thromboembolism (VTE) in ambulatory patients with cancer. METHODS: We performed a systematic review using EMBASE, MEDLINE, and CENTRAL. Inclusion criteria included adult ambulatory patients with cancer, prophylactic use of DOAC, and randomized controlled trials. Exclusion criteria included pediatric patients, inpatient or postoperative setting, therapeutic indication of DOAC, or non-phase III randomized controlled trial. Two authors screened/reviewed articles and abstracted the data. Meta-analysis was performed using random-effects model. Efficacy outcome included overall and symptomatic VTE incidence during the first 6 months. Safety outcomes included major bleeding and clinically relevant non-major bleeding (CRNMB) incidence during the on-treatment period. Subgroup analysis was performed for intermediate- and high-risk Khorana score. RESULTS: A total of 202 records were identified and 28 full-text articles were assessed. Two studies with 1415 participants were included for meta-analysis. For DOAC vs placebo, the relative risks for overall and symptomatic VTE incidence by 6 months were 0.56 (0.35-0.89) and 0.58 (0.29-1.13), respectively. The relative risks for major bleeding and CRNMB while on-treatment were 1.96 (0.80-4.82) and 1.28 (0.74-2.20), respectively. Patients with high-risk Khorana score (3+) derived the largest absolute risk reduction of VTE. CONCLUSIONS: Low-dose DOAC reduces the rate of overall VTE in higher risk cancer patients starting systemic chemotherapy. It may reduce the rate of symptomatic VTE but increase the likelihood of bleeding.

Apixaban to Prevent Venous Thromboembolism in Patients with Cancer.

BACKGROUND: Patients with active cancer have an increased risk of venous thromboembolism, which results in substantial morbidity, mortality, and health care expenditures. The Khorana score (range, 0 to 6, with higher scores indicating a higher risk of venous thromboembolism) has been validated to identify patients with cancer at elevated risk for this complication and may help select those who could benefit from thromboprophylaxis. METHODS: We conducted a randomized, placebo-controlled, double-blind clinical trial assessing the efficacy and safety of apixaban (2.5 mg twice daily) for thromboprophylaxis in ambulatory patients with cancer who were at intermediate-to-high risk for venous thromboembolism (Khorana score, ≥2) and were initiating chemotherapy. The primary efficacy outcome was objectively documented venous thromboembolism over a follow-up period of 180 days. The main safety outcome was a major bleeding episode. RESULTS: Of the 574 patients who underwent randomization, 563 were included in the modified intention-to-treat analysis. Venous thromboembolism occurred in 12 of 288 patients (4.2%) in the apixaban group and in 28 of 275 patients (10.2%) in the placebo group (hazard ratio, 0.41; 95% confidence interval [CI], 0.26 to 0.65; P<0.001). In the modified intention-to-treat analysis, major bleeding occurred in 10 patients (3.5%) in the apixaban group and in 5 patients (1.8%) in the placebo group (hazard ratio, 2.00; 95% CI, 1.01 to 3.95; P = 0.046). During the treatment period, major bleeding occurred in 6 patients (2.1%) in the apixaban group and in 3 patients (1.1%) in the placebo group (hazard ratio, 1.89; 95% CI, 0.39 to 9.24). CONCLUSIONS: Apixaban therapy resulted in a significantly lower rate of venous thromboembolism than did placebo among intermediate-to-high-risk ambulatory patients with cancer who were starting chemotherapy. The rate of major bleeding episodes was higher with apixaban than with placebo. (Funded by the Canadian Institutes of Health Research and Bristol-Myers Squibb-Pfizer Alliance; AVERT ClinicalTrials.gov number, NCT02048865.).