Implementation, Clinical Benefit and Safety of a D-Dimer-Focused Pulmonary Embolism Testing Pathway in the Emergency Department.

STUDY OBJECTIVE: Computed tomography pulmonary angiogram (CTPA) is overused during pulmonary embolism (PE) testing in the emergency department (ED), whereas prediction rules and D-dimer are underused. We report the adherence, clinical benefit, and safety of a D-dimer-only strategy to guide need for PE imaging in the ED. METHODS: This was a prospective multicenter implementation study in 2 EDs with historical and external controls. Patients with suspected PE underwent D-dimer testing and imaging (CTPA or ventilation-perfusion scan) when D-dimer levels were 500 ng/mL or more. PE was ruled out if D-dimer was less than 500 ng/mL or with negative imaging. The primary implementation outcome was the proportion of patients tested for PE in adherence with the pathway. The primary clinical benefit outcome was the proportion of patients tested for PE who received pulmonary imaging. The primary safety outcome was diagnosis of PE in the 30 days following negative PE testing postimplementation. RESULTS: Between January 2018 and June 2021, 16,155 patients were tested for PE, including 33.4% postimplementation, 30.7% preimplementation, and 35.9% in an external control site. Adherence with the D-dimer-only pathway was 97.6% (adjusted odds ratio (aOR) post- versus preimplementation 5.26 (95% confidence interval 1.70 to 16.26). There was no effect on the proportion undergoing PE imaging. Imaging yield increased aOR 4.89 (1.17 to 20.53). Two cases of PE (0.04%; 0.01% to 0.16%) were diagnosed within 30 days. CONCLUSION: In this Canadian ED study, the uptake of a D-dimer-only PE testing strategy was high. Implementation was associated with higher imaging yield and a D-dimer level of less than 500 ng/mL safely excluded PE.

The incidence of major bleeding in adult patients with urogenital and gynecological cancer being treated with direct oral anticoagulants (DOACs): a systematic review.

BACKGROUND: Direct oral anticoagulants (DOACs) are the mainstay of treatment for venous thromboembolism (VTE) and non-valvular atrial fibrillation (AF), with or without an underlying cancer. Patients with cancer have a 2-3-fold increase in risk for bleeding complications compared to non-cancer patients taking anticoagulant therapy, however the incidence of bleeding for urogenital and gynecological cancers on DOACs are uncertain. AIMS: To assess the bleeding risk associated with the use of DOACs in patients with urogenital and/or gynecological cancers. METHOD: We conducted a systematic review of randomized controlled trials (RCTs) and prospective cohort studies to address the safety of DOACs for VTE and AF when used in patients with urogenital and/or gynecological malignancy. The primary outcomes assessed were major and clinically relevant non-major (CRNMB) bleeding, with minor bleeding considered as a secondary outcome. MEDLINE, EMBASE and COCHRANE Central Registry of Controlled Trials were searched up to and including Oct 28, 2022. The study protocol was registered in PROSPERO (CRD42022370981). Studies were independently assessed for inclusion and data extracted in duplicate. RESULT: Seven studies met our inclusion criteria (Fig. 1): 2 RCTs and 5 prospective cohort studies. A total of 676 patients treated with DOACs were included, 628 (92.8%) had VTE and 48 (7.1%) had AF. In patients with VTE treated with DOACs, the pooled major bleeding rate was 2.1%, 95% confidence intervals (CI) 0.9-3.3% (Fig. 2). Pooled estimates could not be determined for AF patients given small event and patient numbers. CONCLUSION: Major bleeding rates in urogenital and/or gynecological cancer patients treated with DOACs are similar to that of the general cancer population.

Comparison of YEARS and Adjust-Unlikely D-dimer Testing for Pulmonary Embolism in the Emergency Department.

STUDY OBJECTIVE: We prospectively assessed the diagnostic accuracy of YEARS and a modified age-adjusted clinical decision rule ("Adjust-Unlikely") for pulmonary embolism (PE) testing in the emergency department. METHODS: This study was conducted in tertiary care Canadian emergency departments. When the D-dimer was <500 ng/ml, PE was excluded. Pulmonary imaging for PE was performed when the D-dimer was ≥500 ng/ml. Patients were followed for 30 days, and PE outcomes were independently adjudicated. Physicians systematically recorded the presence or absence of YEARS items (PE most likely, hemoptysis, signs of deep venous thrombosis) prior to D-dimer testing and imaging. We analyzed the diagnostic accuracy of YEARS and the "Adjust-Unlikely" rule. Age adjustment (age x 10 in those >50 years old) was applied in patients where PE was not the most likely diagnosis and 500 ng/ml threshold when PE was most likely. RESULTS: One thousand seven hundred three patients were included, median age 62 (50, 74), 58% female, PE prevalence 8.0%. YEARS sensitivity for PE diagnosis was 92.6% (87.0, 96.0%) and specificity 45.0% (42.5, 47.5%). Adjust-Unlikely sensitivity was 100.0% (97.2, 100.0%) and specificity 32.4% (30.1, 34.8%). Posttest probability of PE in the group of patients with PE excluded by D-dimer between 500 ng/ml and the adjusted limit was 2.8% (1.6, 5.1%) for YEARS and 0.0% (0.0, 2.6%) for the "Adjust-Unlikely" rule. CONCLUSION: The "Adjust-Unlikely" rule would modestly reduce imaging and identify all cases of PE. YEARS would substantially reduce imaging but miss 1 in 14 cases of PE.

Adherence to apixaban for extended thromboprophylaxis after major abdominal or pelvic surgery for cancer: A prospective cohort study.

BACKGROUND: Due to lack of data, direct oral anticoagulants are not considered by guidelines for venous thromboembolism (VTE) prophylaxis after cancer surgery. Adherence to low-molecular-weight heparin injections in this setting is sometimes poor. AIM: Analysis of adherence to oral apixaban for extended thromboprophylaxis. METHODS: Consecutive patients discharged after major surgery for abdominal/pelvic cancer and considered eligible for extended prophylaxis were offered apixaban 2.5 mg twice daily. Primary outcomes were adherence metrics-proportion of prescriptions filled, persistence (not prematurely discontinued), proportion of days covered (PDC) based on apixaban pill counts, and modified Morisky medication adherence scale at Days 28-30. Secondary outcomes were bleeding, VTE, and serious adverse events until Day 90. RESULTS: We included 53 patients, 51 were analyzed. Of 45 patients with prescriptions all had it filled (95% confidence interval [CI], 92%-100%). Persistence was 98% (95% CI, 90%-100%). PDC was ≥80% for 48 patients (94%; 95% CI, 84%-99%). We found good adherence (0/6 answers "yes") in 75% and moderate (1/6 answers "yes") in 25%. No major bleed or VTE occurred while on apixaban. CONCLUSION: Our results support good adherence with apixaban for VTE prophylaxis up to 28 days after major abdominal or pelvic cancer surgery.

Efficacy and safety of pre-operative insertion of inferior vena cava filter in patients undergoing bariatric surgery: a systematic review.

Prophylactic placement of inferior vena cava (IVC) filters prior to performing bariatric surgery is an intervention of unclear safety and efficacy with disagreement between current practice guidelines. To better characterize the risk and benefit of IVC filter insertion prior to bariatric surgery based on the current evidence. A systematic review of the literature of patients with prophylactic IVC filter insertion prior to bariatric surgery was performed and 32 studies were identified for inclusion into the review, of which none were randomized controlled trials. Meta-analysis was performed including the high-quality included studies. Seven high quality studies reported thrombotic events in patients undergoing bariatric surgery who had an IVCF and a control group which allowed for meta-analysis. The pooled odds ratio of venous thrombotic events in the IVC filter population versus the group without IVC filters was 1.57 (95%CI 0.89, 2.76). Among high quality studies 5 reported major bleeding with a rate of 0.76% and 6 reported on IVC filter complications with a rate of 0.67%. Overall no significant reduction in the rate of venous thrombosis was found with prophylactic IVC filter insertion. Use of IVC filters for prophylaxis remains a concern given the lack of clear efficacy in this setting and a small but present complication risk.

Prothrombin complex concentrate for emergency surgery in patients on oral Xa-inhibitors.

BACKGROUND: It is uncertain whether prothrombin complex concentrate (PCC) improves hemostasis in patients on treatment with oral factor Xa-inhibitors (XaI) who require emergency surgery. OBJECTIVES: To evaluate whether, in patients with therapeutic levels of oral XaI, preoperative PCC prevents excessive bleeding during and after emergency surgery and is not associated with thrombotic complications. METHODS: We conducted a prospective cohort study wherein a fixed 2000 IU dose of 4-factor PCC was given to patients taking oral XaI with plasma XaI levels of at least 75 ng/mL before the emergency surgery with an expected blood loss of at least 50 mL. Patients were followed for 30 days. The primary efficacy outcome was the incidence of normal or mildly abnormal surgical hemostasis, as assessed by the surgeon; primary safety outcome was the incidence of thromboembolic events within 7 days. RESULTS: We included 20 patients, of which 50% were female, on apixaban (75%) or rivaroxaban (25%) with median XaI level of 128 ng/mL (range, 77-497 ng/mL). The median duration of surgery was 2 hours 42 minutes (range, 15 minutes to 8 hours 17 minutes). Normal or mildly abnormal hemostasis was observed in 16 patients (80%); 2 patients had moderately abnormal and 2 had severely abnormal hemostasis, 1 each of those was considered due to local or technical factors. There were 4 deaths (20%) secondary to underlying disease and 1 incidental pulmonary embolism in a patient with cancer. CONCLUSION: A fixed dose of PCC appears to control hemostasis in patients with therapeutic plasma levels of apixaban or rivaroxaban requiring emergency surgery.

Thromboprophylaxis with rivaroxaban in patients with malignancy and central venous lines (TRIM-Line): A two-center open-label pilot randomized controlled trial.

BACKGROUND: Central venous catheter (CVC) insertion is an important risk factor for venous thromboembolism (VTE) among patients with cancer. Routine use of primary thromboprophylaxis in this patient population is not currently recommended. We sought to assess the feasibility of conducting a randomized controlled trial (RCT) assessing the safety and efficacy of rivaroxaban (10 mg daily) to prevent VTE complications in this patient population. METHODS: This is a two-center prospective, randomized, open blinded end point pilot trial including patients with active cancer and a newly inserted CVC. Patients were randomly assigned 1:1 to rivaroxaban or observation for 90 days. The primary feasibility outcome of this pilot study was the number of participants recruited per month. Secondary clinical outcomes included thrombotic complications, major VTE, and major bleeding episodes. RESULTS: Overall, 105 patients were enrolled over 11 months. The average enrollment rates were 7.5 and 2 patients per month at the two participating centers, respectively. Overall, thrombotic complications occurred in 3 patients in the rivaroxaban group (5.8%; 95% confidence interval [CI], 1.2-16.0) compared with 5 patients in the control group (9.4%; 95% CI, 3.1-20.7) (HR, 0.58; 95% CI, 0.14-2.5). Major VTE occurred in 2 (3.9%; 95% CI, 0.5-13.2) and 3 (5.7%; 95% CI, 1.2-15.7) patients in the rivaroxaban and control group, respectively (HR, 0.66; 95% CI, 0.11-3.9). One patient (1.9%) receiving rivaroxaban had a major bleeding event. CONCLUSIONS: Thrombotic complications are common in patients with cancer and a newly inserted CVC. The pilot trial achieved its enrollment targets and supports that a large multicenter RCT is feasible in this area. ClinicalTrials.gov (NCT03506815).

Efficacy and safety of primary thromboprophylaxis for the prevention of venous thromboembolism in patients with cancer and a central venous catheter: A systematic review and meta-analysis.

BACKGROUND: Venous thromboembolism (VTE) is a leading cause of mortality in patients with cancer and is associated with significant morbidity and healthcare expenditure. The risk of VTE is increased following the insertion of a central venous catheter (CVC) for chemotherapy delivery and supportive care. The risks and benefits of primary thromboprophylaxis in patients with cancer and CVC are unclear. OBJECTIVE: We sought to assess the rates of VTE and bleeding complications and to determine the efficacy and safety of primary thromboprophylaxis in adult patients with cancer and a CVC. METHODS: A systematic search of MEDLINE, EMBASE, and all EBM was conducted. Randomized controlled trials (RCTs) of adult patients with cancer and a CVC receiving primary thromboprophylaxis compared to observation/placebo were included. The primary efficacy and safety outcomes were total VTE and major bleeding episodes, respectively. RESULTS: A total of 12 RCTs (3545 patients) were included in the analysis. The total rates of VTE were significantly lower in patients receiving thromboprophylaxis compared to those not receiving primary prevention (7.6% vs. 13%; Odds Ratio (OR) 0.51, 95% CI 0.32-0.82, p < 0.01). The rates of major bleeding complications were not higher in patients receiving thromboprophylaxis (0.9% vs. 0.6%; OR 1.12, 95% CI 0.29-4.40, p = 0.87). CONCLUSIONS: Primary thromboprophylaxis significantly reduced the risk of VTE without increasing the risk of major bleeding complications in patients with cancer and CVC. Future studies are needed to confirm these findings.

Comparing low-molecular-weight heparin dosing for treatment of venous thromboembolism in patients with obesity (RIETE registry).

Because of the absence of comparative evidence, current guidelines and product monographs diverge in the dosing of low-molecular-weight heparin (LMWH) for obese patients with venous thromboembolism (VTE). We used the RIETE registry to compare the primary composite outcomes (VTE recurrence, major bleeding, or death) in patients with VTE who weighed >100 kg during LMWH therapy with capped doses of LMWH (18 000 IU/d) vs uncapped doses (>18 000 IU/d). Multivariable logistic regression analysis was used to account for possible confounders. A total of 2846 patients who weighed >100 kg were included: 454 (16%) received capped doses of LMWH, and the remaining 2392 received uncapped doses. Mean (standard deviation) LMWH treatment duration was 14.8 (20.6) and 14.3 (32.3) days, respectively. Thirty-one patients (1.9%) had VTE recurrences, 38 (1.3%) had bleeding episodes, 65 (2.3%) died, and 122 (4.3%) had at least 1 of the composite outcomes. Unadjusted outcome rates revealed that capped dosing was associated with a decrease in the composite outcome (rate ratio, 0.22; 95% confidence interval [CI], 0.04-0.75). Multivariable analysis confirmed that patients who received capped doses had significantly lower rates of the composite outcome (odds ratio, 0.16; 95% CI, 0.04-0.68) while receiving LMWH. These retrospective observational data suggest that capped dosing of LMWH is an acceptable alternative to uncapped dosing based on body weight, given the significantly lower composite event rate of VTE recurrence, major bleeding, and all-cause death.

Pilot trials in thrombosis: Purpose and pitfalls.

Randomized controlled trials provide important evidence to guide clinical practice. These full-scale trials are expensive, time consuming and many are never successfully completed. Well conducted pilot studies help with full-scale trial design, assessment and optimization of feasibility, and can avoid the waste of resources associated with starting a full-scale trial that will not succeed. They also provide an opportunity for capacity growth and mentorship of new investigators. It is important to appreciate that the usual goal of a pilot trial is assessment of feasibility and refinement of trial design rather than to gain preliminary evidence of efficacy. Indeed, using event rates from a pilot trial to calculate sample sizes can be misleading in therapeutic trials. Misconceptions exist that pilot trials are just "small trials," are easy to perform, and are not worthy of publication. While, in the past, many pilot trials were poorly conducted and not followed by a full-scale trial, by following the recommendations in the "CONSORT 2010 statement: extension to randomized pilot and feasibility trials," high-quality pilot trials can be performed and reported that will greatly improve the chances of successfully completing a practice-changing trial. We propose that pilot trials are a valuable investment and describe the TRIM-Line pilot trial (NCT03506815), a pilot study assessing the feasibility of a randomized controlled trial investigating primary thromboprophylaxis with rivaroxaban in patients with malignancy and central venous catheters, as an illustrative example of how a pilot trial in the area of thrombosis should be designed.

The importance of post thrombotic syndrome as an outcome after deep venous thrombosis: A survey of Canadian thrombosis clinicians.

OBJECTIVES: The development of post thrombotic syndrome (PTS) is a major source of morbidity and reduced quality of life. We sought to determine the value assigned by clinicians to post thrombotic syndrome and whether clinicians believe that any post thrombotic syndrome or severe post thrombotic syndrome are important outcomes to assess after deep vein thrombosis (DVT) as compared to other outcomes. DESIGN: The design of the study was a self-responded electronic survey. Questions for the online survey were designed by two authors (R.I. and E.G.). METHODS: The survey was distributed to 233 members of Thrombosis Canada and the Canadian Society for Vascular Surgery between August 2014 and October 2014. RESULTS: There were 84 responses to the survey with complete responses were obtained from 71 respondents for a response rate of 36%. PTS was ranked as a significantly less important outcome after DVT than recurrent DVT, pulmonary embolism during treatment, major bleeding, death, quality of life, venous ulceration and severe post thrombotic syndrome (all comparisons p<0.05 by two sample t-test). CONCLUSIONS: Our survey determined that "any post thrombotic syndrome" is perceived by physicians as less important than other DVT outcomes. Thus, "Severe PTS" and not "Any PTS" should be included as an outcome measure in studies investigating acute DVT.

Efficacy and safety of weight-adjusted heparin prophylaxis for the prevention of acute venous thromboembolism among obese patients undergoing bariatric surgery: a systematic review and meta-analysis.

BACKGROUND: The bariatric surgical population is a particularly high risk population for VTE. It is unclear if standard (i.e. non-adjusted) thromboprophylaxis doses of low-molecular weight or unfractionated heparin provide adequate protection for obese patients undergoing bariatric surgery, or if higher doses are required. We sought to determine whether a weight based thromboprophylactic dosing regimen is safe and effective in the post-operative period for obese patients undergoing bariatric surgery. METHODS: A systematic literature search strategy was conducted using MEDLINE, EMBASE, the Cochrane Register of Controlled Trials and all EBM Reviews. Pooled proportions for the different outcomes were calculated. RESULTS: A total of 6 studies (1 RCT, 4 cohort studies and one quasi experimental trial) containing 1,858 patients were include in the systematic review. Post bariatric surgery patients receiving weight-adjusted prophylactic doses of heparin products, had an in hospital rate of VTE of 0.54% (95% CI: 0.2 to 1.0%) compared to 2.0% (95% CI: 0.1 to 6.4%) for those that did not weight adjust doses. Rates of major bleeding were similar for both groups: 1.6% (95% CI: 0.6 to 3.0%) for patients receiving weight-adjusted dosing compared to 2.3% (95% CI: 1.1% to 3.9%) for those receiving standard doses of heparin products. CONCLUSIONS: Adjusting the dose of heparin products for thromboprophylaxis post-bariatric surgery seems to be associated with a lower rate of in hospital VTE compared to a strategy of not adjusting the dose, although this did not reach statistical significance. This practice does not lead to an increase in adverse major bleeding events.