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Prediction of rates of thromboembolic and major bleeding outcomes with dabigatran or warfarin among patients with atrial fibrillation: new initiator cohort study.

ABSTRACT: To compare stratified event rates from randomized controlled trials with predicted event rates from models developed in observational data, and assess their ability to accurately capture observed rates of thromboembolism and major bleeding for patients treated with dabigatran or warfarin as part of routine care. New initiator cohort study. Data from United Health (October 2009 to June 2013), a commercial healthcare claims database in the United States. 21?934 adults with atrial fibrillation initiating dabigatran (150 mg dose only) or warfarin treatment as part of routine care. Predicted annual rates of thromboembolism or major bleeding, based on estimates from randomized controlled trials, models developed in routine care patients, and baseline risk scores (CHADS2, CHA2DS2-VASc, and HAS-BLED). Thromboembolism was a composite outcome, including primary inpatient diagnosis codes for ischemic or ill defined stroke, transient ischemic attack, pulmonary embolism, deep vein thrombosis, and systemic embolism. Major bleeding was a composite outcome including codes occurring in an inpatient setting for hemorrhagic stroke; major upper, lower, or unspecified gastrointestinal bleed; and major urogenital or other bleed. 6516 (30%) and 15?418 (70%) of patients initiated dabigatran and warfarin, respectively. Annual event rates per 100 patients were 1.7 for thromboembolism and 4.6 for major bleeding. For thromboembolism, calibration of estimates from randomized controlled trials was similar to calibration for model based predictions; however, trial estimates for major bleeding consistently underestimated the rate of bleeding among patients in routine care. Underestimation of bleeding rates was particularly pronounced in warfarin initiators with high HAS-BLED scores, where event rates were underestimated by up to 4.0 per 100 patient years. Harrell's c indices for discrimination for thromboembolism or major bleeding in dabigatran and warfarin initiators ranged between 0.59 and 0.66 for randomized controlled trial predictions, and between 0.52 and 0.70 for cross validated model based predictions. Estimated rates of thromboembolism under dabigatran or warfarin treatment in randomized controlled trials were close to observed rates in routine care patients. However, rates of major bleeding were underestimated. Models developed in routine care patients can provide accurate, tailored estimates of risk and benefit under alternative treatment to enhance patient centered care.

SUBMITTER: Wang SV

PROVIDER: S-EPMC4878389 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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Prediction of rates of thromboembolic and major bleeding outcomes with dabigatran or warfarin among patients with atrial fibrillation: new initiator cohort study.

Wang Shirley V SV Franklin Jessica M JM Glynn Robert J RJ Schneeweiss Sebastian S Eddings Wesley W Gagne Joshua J JJ

BMJ (Clinical research ed.) 20160524

<h4>Objectives</h4> To compare stratified event rates from randomized controlled trials with predicted event rates from models developed in observational data, and assess their ability to accurately capture observed rates of thromboembolism and major bleeding for patients treated with dabigatran or warfarin as part of routine care.<h4>Design</h4> New initiator cohort study.<h4>Setting</h4> Data from United Health (October 2009 to June 2013), a commercial healthcare claims database in the United ...[more]

PMID: 27221664

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Project description:ImportanceIt remains unclear whether dabigatran etexilate mesylate is associated with higher risk of bleeding than warfarin sodium in real-world clinical practice.ObjectiveTo compare the risk of bleeding associated with dabigatran and warfarin using Medicare data.Design, setting, and participantsIn this retrospective cohort study, we used pharmacy and medical claims in 2010 to 2011 from a 5% random sample of Medicare beneficiaries. We identified participants as those newly diagnosed as having atrial fibrillation from October 1, 2010, through October 31, 2011, and who initiated dabigatran or warfarin treatment within 60 days of initial diagnosis. We followed up patients until discontinued use or switch of anticoagulants, death, or December 31, 2011.ExposuresDabigatran users (n = 1302) and warfarin users (n = 8102).Main outcomes and measuresWe identified any bleeding events and categorized them as major and minor bleeding by anatomical site. Major bleeding events included intracranial hemorrhage, hemoperitoneum, and inpatient or emergency department stays for hematuria, gastrointestinal, or other hemorrhage. We used a propensity score weighting mechanism to balance patient characteristics between 2 groups and Cox proportional hazards regression models to evaluate the risk of bleeding. We further examined the risk of bleeding for 4 subgroups of high-risk patients: those 75 years or older, African Americans, those with chronic kidney disease, and those with more than 7 concomitant comorbidities.ResultsDabigatran was associated with a higher risk of bleeding relative to warfarin, with hazard ratios of 1.30 (95% CI, 1.20-1.41) for any bleeding event, 1.58 (95% CI, 1.36-1.83) for major bleeding, and 1.85 (95% CI, 1.64-2.07) for gastrointestinal bleeding. The risk of intracranial hemorrhage was higher among warfarin users, with a hazard ratio of 0.32 (95% CI, 0.20-0.50) for dabigatran compared with warfarin. Dabigatran was consistently associated with an increased risk of major bleeding and gastrointestinal hemorrhage for all subgroups analyzed. The risk of major bleeding among dabigatran users was especially high for African Americans and patients with chronic kidney disease.Conclusions and relevanceDabigatran was associated with a higher incidence of major bleeding (regardless of the anatomical site), a higher risk of gastrointestinal bleeding, but a lower risk of intracranial hemorrhage. Thus, dabigatran should be prescribed with caution, especially among high-risk patients.

Project description:BackgroundLimited data are available about the real-world safety of non-vitamin K antagonist oral anticoagulants (NOACs).ObjectivesTo compare the major bleeding risk among newly anticoagulated non-valvular atrial fibrillation (NVAF) patients initiating apixaban, warfarin, dabigatran or rivaroxaban in the United States.Methods and resultsA retrospective cohort study was conducted to compare the major bleeding risk among newly anticoagulated NVAF patients initiating warfarin, apixaban, dabigatran or rivaroxaban. The study used the Truven MarketScan(®) Commercial & Medicare supplemental US database from 1 January 2013 through 31 December 2013. Major bleeding was defined as bleeding requiring hospitalisation. Cox model estimated hazard ratios (HRs) of major bleeding were adjusted for age, gender, baseline comorbidities and co-medications. Among 29 338 newly anticoagulated NVAF patients, 2402 (8.19%) were on apixaban; 4173 (14.22%) on dabigatran; 10 050 (34.26%) on rivaroxaban; and 12 713 (43.33%) on warfarin. After adjusting for baseline characteristics, initiation on warfarin [adjusted HR (aHR): 1.93, 95% confidence interval (CI): 1.12-3.33, P=.018] or rivaroxaban (aHR: 2.19, 95% CI: 1.26-3.79, P=.005) had significantly greater risk of major bleeding vs apixaban. Dabigatran initiation (aHR: 1.71, 95% CI: 0.94-3.10, P=.079) had a non-significant major bleeding risk vs apixaban. When compared with warfarin, apixaban (aHR: 0.52, 95% CI: 0.30-0.89, P=.018) had significantly lower major bleeding risk. Patients initiating rivaroxaban (aHR: 1.13, 95% CI: 0.91-1.41, P=.262) or dabigatran (aHR: 0.88, 95% CI: 0.64-1.21, P=.446) had a non-significant major bleeding risk vs warfarin.ConclusionAmong newly anticoagulated NVAF patients in the real-world setting, initiation with rivaroxaban or warfarin was associated with a significantly greater risk of major bleeding compared with initiation on apixaban. When compared with warfarin, initiation with apixaban was associated with significantly lower risk of major bleeding. Additional observational studies are required to confirm these findings.

Project description:BackgroundAlthough warfarin has been extensively studied in clinical trials, little is known about rates of hemorrhage attributable to its use in routine clinical practice. Our objective was to examine incident hemorrhagic events in a large population-based cohort of patients with atrial fibrillation who were starting treatment with warfarin.MethodsWe conducted a population-based cohort study involving residents of Ontario (age ≥ 66 yr) with atrial fibrillation who started taking warfarin between Apr. 1, 1997, and Mar. 31, 2008. We defined a major hemorrhage as any visit to hospital for hemorrage. We determined crude rates of hemorrhage during warfarin treatment, overall and stratified by CHADS(2) score (congestive heart failure, hypertension, age ≥ 75 yr, diabetes mellitus and prior stroke, transient ischemic attack or thromboembolism).ResultsWe included 125 195 patients with atrial fibrillation who started treatment with warfarin during the study period. Overall, the rate of hemorrhage was 3.8% (95% confidence interval [CI] 3.8%-3.9%) per person-year. The risk of major hemorrhage was highest during the first 30 days of treatment. During this period, rates of hemorrhage were 11.8% (95% CI 11.1%-12.5%) per person-year in all patients and 16.7% (95% CI 14.3%-19.4%) per person-year among patients with a CHADS(2) scores of 4 or greater. Over the 5-year follow-up, 10 840 patients (8.7%) visited the hospital for hemorrhage; of these patients, 1963 (18.1%) died in hospital or within 7 days of being discharged.InterpretationIn this large cohort of older patients with atrial fibrillation, we found that rates of hemorrhage are highest within the first 30 days of warfarin therapy. These rates are considerably higher than the rates of 1%-3% reported in randomized controlled trials of warfarin therapy. Our study provides timely estimates of warfarin-related adverse events that may be useful to clinicians, patients and policy-makers as new options for treatment become available.

Project description:BackgroundWarfarin and similar vitamin K antagonists have been the standard therapy for patients with mechanical or biological valve prosthesis and atrial fibrillation (AF). Even with the appropriate use of therapy, some studies have reported that there is a high incidence of thromboembolic events, 1%-4% per year. Furthermore, a bleeding risk is significant, ranging from 2% to 9% per year, according to some studies.ObjectiveThe objective of our study was to examine the effect of dabigatran etexilate versus dose-adjusted warfarin for the prevention of intracardiac thrombus in persistent or permanent AF at least 3 months after aortic and/or mitral bioprosthesis replacement.MethodsDabigatran versus warfarin after bioprosthesis valve replacement for the management of atrial fibrillation postoperatively (DAWA) is a phase 2, prospective, open label, randomized exploratory pilot study. The main variable to be observed in this study is intracardiac thrombus. From August 2013 to April 2015, 100 patients, at least 3 months after aortic and/or mitral bioprosthesis replacement and permanent or persistent AF postoperatively, who match eligibility criteria will be selected from Ana Nery Hospital in Salvador-Bahia with a follow-up of three months. Patients were randomly assigned in a 1:1 ratio to receive either dabigatran etexilate or warfarin.ResultsAlthough the present study has no statistic power to proof non-inferiority, it is expected that the dabigatran etexilate group will be protected as well as the warfarin group from intracardiac thrombus, without increasing the bleeding rates, since we are using safer doses (110 mg bid). The lack of necessity of monitoring INR is also another factor that contributes to a better adherence to the new drug and it can make all the difference in the manner of doing anticoagulation for patients with similar clinical characteristics.ConclusionsThe study is in the recruitment phase. It is possible that dabigatran etexilate is as effective as warfarin in preventing the emergence of intracardiac thrombus in patients with AF and mitral and/or aortic bioprosthesis.Trial registrationClinicaltrials.gov NCT01868243; http://clinicaltrials.gov/ct2/show/NCT01868243 (Archived by WebCite at http://www.webcitation/6OABiuasd).

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Prediction of rates of thromboembolic and major bleeding outcomes with dabigatran or warfarin among patients with atrial fibrillation: new initiator cohort study.

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Prediction of rates of thromboembolic and major bleeding outcomes with dabigatran or warfarin among patients with atrial fibrillation: new initiator cohort study.

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