Sean Yang

Risk of Bleeding With 2 Doses of Dabigatran Compared With Warfarin in Older and Younger Patients With Atrial Fibrillation An Analysis of the Randomized Evaluation of Long-Term Anticoagulant Therapy (RE-LY) Trial

Background— Dabigatran 150 and 110 mg twice a day and warfarin are effective for stroke prevention in atrial fibrillation. The purpose of this study was to compare their risks of bleeding in the Randomized Evaluation of Long-Term Anticoagulant Therapy (RE-LY) trial. Methods and Results— The RE-LY trial randomized 18 113 patients to receive dabigatran 110 or 150 mg twice a day or warfarin dose adjusted to an international normalized ratio of 2.0 to 3.0 for a median follow-up of 2.0 years. Compared with warfarin, dabigatran 110 mg twice a day was associated with a lower risk of major bleeding (2.87% versus 3.57%; P=0.002), whereas dabigatran 150 mg twice a day was associated with a similar risk of major bleeding (3.31% versus 3.57%; P=0.32). There was a significant treatment-by-age interaction, such that dabigatran 110 mg twice a day compared with warfarin was associated with a lower risk of major bleeding in patients aged <75 years (1.89% versus 3.04%; P<0.001) and a similar risk in those aged ≥75 years (4.43% versus 4.37%; P=0.89; P for interaction <0.001), whereas dabigatran 150 mg twice a day compared with warfarin was associated with a lower risk of major bleeding in those aged <75 years (2.12% versus 3.04%; P<0.001) and a trend toward higher risk of major bleeding in those aged ≥75 years (5.10% versus 4.37%; P=0.07; P for interaction <0.001). The interaction with age was evident for extracranial bleeding, but not for intracranial bleeding, with the risk of the latter being consistently reduced with dabigatran compared with warfarin irrespective of age. Conclusions— In patients with atrial fibrillation at risk for stroke, both doses of dabigatran compared with warfarin have lower risks of both intracranial and extracranial bleeding in patients aged <75 years. In those aged ≥75 years, intracranial bleeding risk is lower but extracranial bleeding risk is similar or higher with both doses of dabigatran compared with warfarin. Clinical Trial Registration— http://www.clinicaltrials.gov. Unique identifier: NCT00262600.

Risk of Bleeding With 2 Doses of Dabigatran Compared With Warfarin in Older and Younger Patients With Atrial Fibrillation

Background— Dabigatran 150 and 110 mg twice a day and warfarin are effective for stroke prevention in atrial fibrillation. The purpose of this study was to compare their risks of bleeding in the Randomized Evaluation of Long-Term Anticoagulant Therapy (RE-LY) trial. Methods and Results— The RE-LY trial randomized 18 113 patients to receive dabigatran 110 or 150 mg twice a day or warfarin dose adjusted to an international normalized ratio of 2.0 to 3.0 for a median follow-up of 2.0 years. Compared with warfarin, dabigatran 110 mg twice a day was associated with a lower risk of major bleeding (2.87% versus 3.57%; P=0.002), whereas dabigatran 150 mg twice a day was associated with a similar risk of major bleeding (3.31% versus 3.57%; P=0.32). There was a significant treatment-by-age interaction, such that dabigatran 110 mg twice a day compared with warfarin was associated with a lower risk of major bleeding in patients aged <75 years (1.89% versus 3.04%; P<0.001) and a similar risk in those aged ≥75 years (4.43% versus 4.37%; P=0.89; P for interaction <0.001), whereas dabigatran 150 mg twice a day compared with warfarin was associated with a lower risk of major bleeding in those aged <75 years (2.12% versus 3.04%; P<0.001) and a trend toward higher risk of major bleeding in those aged ≥75 years (5.10% versus 4.37%; P=0.07; P for interaction <0.001). The interaction with age was evident for extracranial bleeding, but not for intracranial bleeding, with the risk of the latter being consistently reduced with dabigatran compared with warfarin irrespective of age. Conclusions— In patients with atrial fibrillation at risk for stroke, both doses of dabigatran compared with warfarin have lower risks of both intracranial and extracranial bleeding in patients aged <75 years. In those aged ≥75 years, intracranial bleeding risk is lower but extracranial bleeding risk is similar or higher with both doses of dabigatran compared with warfarin. Clinical Trial Registration— http://www.clinicaltrials.gov. Unique identifier: NCT00262600.

Dabigatran Versus Warfarin in Patients With Atrial Fibrillation An Analysis of Patients Undergoing Cardioversion

Background— The Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) trial compared dabigatran 110 mg BID (D110) and 150 mg BID (D150) with warfarin for stroke prevention in 18 113 patients with nonvalvular atrial fibrillation. Methods and Results— Cardioversion on randomized treatment was permitted. Precardioversion transesophageal echocardiography was encouraged, particularly in dabigatran-assigned patients. Data from before, during, and 30 days after cardioversion were analyzed. A total of 1983 cardioversions were performed in 1270 patients: 647, 672, and 664 in the D110, D150, and warfarin groups, respectively. For D110, D150, and warfarin, transesophageal echocardiography was performed before 25.5%, 24.1%, and 13.3% of cardioversions, of which 1.8%, 1.2%, and 1.1% were positive for left atrial thrombi. Continuous treatment with study drug for ≥3 weeks before cardioversion was lower in D110 (76.4%) and D150 (79.2%) compared with warfarin (85.5%; P<0.01 for both). Stroke and systemic embolism rates at 30 days were 0.8%, 0.3%, and 0.6% (D110 versus warfarin, P=0.71; D150 versus warfarin, P=0.40) and similar in patients with and without transesophageal echocardiography. Major bleeding rates were 1.7%, 0.6%, and 0.6% (D110 versus warfarin, P=0.06; D150 versus warfarin, P=0.99). Conclusions— This study is the largest cardioversion experience to date and the first to evaluate a novel anticoagulant in this setting. The frequencies of stroke and major bleeding within 30 days of cardioversion on the 2 doses of dabigatran were low and comparable to those on warfarin with or without transesophageal echocardiography guidance. Dabigatran is a reasonable alternative to warfarin in patients requiring cardioversion. Clinical Trial Registration— URL: http://www.ClinicalTrials.gov. Unique identifier: NCT00262600.Background– The Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) trial compared dabigatran 110 mg BID (D110) and 150 mg BID (D150) with warfarin for stroke prevention in 18 113 patients with nonvalvular atrial fibrillation. Methods and Results– Cardioversion on randomized treatment was permitted. Precardioversion transesophageal echocardiography was encouraged, particularly in dabigatran-assigned patients. Data from before, during, and 30 days after cardioversion were analyzed. A total of 1983 cardioversions were performed in 1270 patients: 647, 672, and 664 in the D110, D150, and warfarin groups, respectively. For D110, D150, and warfarin, transesophageal echocardiography was performed before 25.5%, 24.1%, and 13.3% of cardioversions, of which 1.8%, 1.2%, and 1.1% were positive for left atrial thrombi. Continuous treatment with study drug for ≥3 weeks before cardioversion was lower in D110 (76.4%) and D150 (79.2%) compared with warfarin (85.5%; P <0.01 for both). Stroke and systemic embolism rates at 30 days were 0.8%, 0.3%, and 0.6% (D110 versus warfarin, P =0.71; D150 versus warfarin, P =0.40) and similar in patients with and without transesophageal echocardiography. Major bleeding rates were 1.7%, 0.6%, and 0.6% (D110 versus warfarin, P =0.06; D150 versus warfarin, P =0.99). Conclusions– This study is the largest cardioversion experience to date and the first to evaluate a novel anticoagulant in this setting. The frequencies of stroke and major bleeding within 30 days of cardioversion on the 2 doses of dabigatran were low and comparable to those on warfarin with or without transesophageal echocardiography guidance. Dabigatran is a reasonable alternative to warfarin in patients requiring cardioversion. Clinical Trial Registration– URL: . Unique identifier: [NCT00262600][1]. # Clinical Perspective {#article-title-31} [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00262600&atom=%2Fcirculationaha%2F123%2F2%2F131.atom

Periprocedural bleeding and thromboembolic events with dabigatran compared with warfarin: results from the Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) randomized trial.

Background— Dabigatran reduces ischemic stroke in comparison with warfarin; however, given the lack of antidote, there is concern that it might increase bleeding when surgery or invasive procedures are required. Methods and Results— The current analysis was undertaken to compare the periprocedural bleeding risk of patients in the Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) trial treated with dabigatran and warfarin. Bleeding rates were evaluated from 7 days before until 30 days after invasive procedures, considering only the first procedure for each patient. A total of 4591 patients underwent at least 1 invasive procedure: 24.7% of patients received dabigatran 110 mg, 25.4% received dabigatran 150 mg, and 25.9% received warfarin, P=0.34. Procedures included: pacemaker/defibrillator insertion (10.3%), dental procedures (10.0%), diagnostic procedures (10.0%), cataract removal (9.3%), colonoscopy (8.6%), and joint replacement (6.2%). Among patients assigned to either dabigatran dose, the last dose of study drug was given 49 (35–85) hours before the procedure on comparison with 114 (87–144) hours in patients receiving warfarin, P<0.001. There was no significant difference in the rates of periprocedural major bleeding between patients receiving dabigatran 110 mg (3.8%) or dabigatran 150 mg (5.1%) or warfarin (4.6%); dabigatran 110 mg versus warfarin: relative risk, 0.83; 95% CI, 0.59 to 1.17; P=0.28; dabigatran 150 mg versus warfarin: relative risk, 1.09; 95% CI, 0.80 to 1.49; P=0.58. Among patients having urgent surgery, major bleeding occurred in 17.8% with dabigatran 110 mg, 17.7% with dabigatran 150 mg, and 21.6% with warfarin: dabigatran 110 mg; relative risk, 0.82; 95% CI, 0.48 to 1.41; P=0.47; dabigatran 150 mg: relative risk, 0.82; 95% CI, 0.50 to 1.35; P=0.44. Conclusions— Dabigatran and warfarin were associated with similar rates of periprocedural bleeding, including patients having urgent surgery. Dabigatran facilitated a shorter interruption of oral anticoagulation. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00262600.Background —Dabigatran reduces ischemic stroke compared to warfarin; however, given the lack of antidote, there is concern that it might increase bleeding when surgery or invasive procedures are required. Methods and Results —The current analysis was undertaken to compare the peri-procedural bleeding risk of patients in the RE-LY trial treated with dabigatran and warfarin. Bleeding rates were evaluated from 7 days prior until 30 days following invasive procedures, considering only the first procedure for each patient. A total of 4591 patients underwent at least one invasive procedure: 24.7% of patients receiving dabigatran-110; 25.4% on dabigatran-150 and 25.9% on warfarin, p=0.34. Procedures included: pacemaker/ defibrillator insertion (10.3%), dental procedures (10.0%), diagnostic procedures (10.0%), cataract removal (9.3%), colonoscopy (8.6%) and joint replacement (6.2%). Among patients assigned to either dabigatran dose the last dose of study drug was given 49 (35-85) hours prior to the procedure; compared to 114 (87-144) hours in patients receiving warfarin, p<0.001. There was no significant difference in the rates of peri-procedural major bleeding between patients receiving dabigatran-110 (3.8%) or dabigatran-150 (5.1%) or warfarin (4.6%); dabigatran-110 vs. warfarin: RR=0.83, 95% CI: 0.59-1.17, p=0.28; dabigatran-150 vs. warfarin: RR=1.09, 95% CI: 0.80-1.49, p=0.58. Among patients having urgent surgery, major bleeding occurred in 17.8% with dabigatran-110, 17.7% with dabigatran-150 and 21.6% with warfarin: dabigatran-110: RR=0.82, 95% CI: 0.48-1.41, p=0.47; dabigatran-150: RR=0.82, 95% CI: 0.50-1.35, p=0.44. Conclusions —Dabigatran and warfarin were associated with similar rates of peri-procedural bleeding, including patients having urgent surgery. Dabigatran facilitated a shorter interruption of oral anticoagulation. Clinical Trial Registration Information —clinicaltrials.gov; Identifier: [NCT00262600][1]. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00262600&atom=%2Fcirculationaha%2Fearly%2F2012%2F06%2F11%2FCIRCULATIONAHA.111.090464.atom

Dabigatran compared with warfarin in patients with atrial fibrillation and previous transient ischaemic attack or stroke: a subgroup analysis of the RE-LY trial

BACKGROUND In the Randomised Evaluation of Long-Term Anticoagulation Therapy (RE-LY) trial, dabigatran reduced occurrence of both stroke and haemorrhage compared with warfarin in patients who had atrial fibrillation and were at increased risk of stroke. We aimed to assess the effects of dabigatran compared with warfarin in the subgroup of patients with previous stroke or transient ischaemic attack. METHODS In the RE-LY trial, 18,113 patients from 967 centres in 44 countries were randomly assigned to 110 mg or 150 mg dabigatran twice daily or to warfarin dose adjusted to international normalised ratio 2·0 to 3·0. Median follow-up was 2·0 years (IQR 1·14-2·86), and the primary outcome was stroke or systemic embolism. The primary safety outcome was major haemorrhage. Patients and investigators were aware of whether patients received warfarin or dabigatran, but not of dabigatran dose, and event adjudicators were masked to treatment. In a predefined analysis, we investigated the outcomes of the RE-LY trial in subgroups of patients with or without previous stroke or transient ischaemic attack. RE-LY is registered with ClinicalTrials.gov, NCT00262600. FINDINGS Within the subgroup of patients with previous stroke or transient ischaemic attack, 1195 patients were from the 110 mg dabigatran group, 1233 from the 150 mg dabigatran group, and 1195 from the warfarin group. Stroke or systemic embolism occurred in 65 patients (2·78% per year) on warfarin compared with 55 (2·32% per year) on 110 mg dabigatran (relative risk 0·84, 95% CI 0·58-1·20) and 51 (2·07% per year) on 150 mg dabigatran (0·75, 0·52-1·08). The rate of major bleeding was significantly lower in patients on 110 mg dabigatran (RR 0·66, 95% CI 0·48-0·90) and similar in those on 150 mg dabigatran (RR 1·01; 95% CI 0·77-1·34) compared with those on warfarin. The effects of both doses of dabigatran compared with warfarin were not significantly different between patients with previous stroke or transient ischaemic attack and those without for any of the outcomes from RE-LY apart from vascular death (110 mg group compared with warfarin group, interaction p=0·038). INTERPRETATION The effects of 110 mg dabigatran and 150 mg dabigatran twice daily in patients with previous stroke or transient ischaemic attack are consistent with those of other patients in RE-LY, for whom, compared with warfarin, 150 mg dabigatran reduced stroke or systemic embolism and 110 mg dabligatran was non-inferior. [corrected] Most effects of both dabigatran doses were consistent in patients with versus those without previous stroke or transient ischaemic attack. FUNDING Boehringer Ingelheim.

Concomitant Use of Antiplatelet Therapy with Dabigatran or Warfarin in the Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) Trial

Background— The Randomized Evaluation of Long-term Anticoagulation Therapy (RE-LY) trial showed that dabigatran etexilate 150 mg BID was superior and dabigatran etexilate 110 mg BID was noninferior to warfarin in preventing stroke and systemic embolism in patients with atrial fibrillation. In this subgroup analysis, we assess the efficacy and safety of dabigatran in patients who did and did not receive concomitant antiplatelets. Methods and Results— All comparisons used a Cox proportional hazards model with adjustments made for risk factors for bleeding. A time-dependent analysis was performed when comparing patients with concomitant antiplatelets with those without. Of 18 113 patients, 6952 (38.4%) received concomitant aspirin or clopidogrel at some time during the study. Dabigatran etexilate 110 mg BID was noninferior to warfarin in reducing stroke and systemic embolism, whether patients received antiplatelets (hazard ratio [HR], 0.93; 95% confidence interval [95% CI], 0.70–1.25) or not (HR, 0.87; 95% CI, 0.66–1.15; interaction P=0.738). There were fewer major bleeds than warfarin in both subgroups (HR, 0.82; 95% CI, 0.67–1.00 for patients who used antiplatelets; HR, 0.79; 95% CI, 0.64–0.96 for patients who did not; interaction P=0.794). Dabigatran etexilate 150 mg BID reduced the primary outcome of stroke and systemic embolism in comparison with warfarin. This effect seemed attenuated among patients who used antiplatelets (HR, 0.80; 95% CI, 0.59–1.08) in comparison with those who did not (HR, 0.52; 95% CI, 0.38–0.72; P for interaction=0.058). Major bleeding was similar to warfarin regardless of antiplatelet use (HR, 0.93; 95% CI, 0.76–1.12 for patients who used antiplatelets; HR, 0.94; 95% CI, 0.78–1.15 for patients who did not; P for interaction=0.875). In the time-dependent analysis, concomitant use of a single antiplatelet seemed to increase the risk of major bleeding (HR, 1.60; 95% CI, 1.42–1.82). Dual antiplatelet seemed to increased this even more (HR, 2.31; 95% CI, 1.79–2.98). The absolute risks were lowest on dabigatran etexilate 110 mg BID in comparison with dabigatran etexilate 150 mg BID or warfarin. Conclusions— Concomitant antiplatelet drugs appeared to increase the risk for major bleeding in RE-LY without affecting the advantages of dabigatran over warfarin. Choosing between dabigatran etexilate 110 mg BID and dabigatran etexilate 150 mg BID requires a careful assessment of characteristics that influence the balance between benefit and harm. Clinical Trial Registration— URL: http://clinicaltrials.gov. Unique identifier: NCT00262600.

Myocardial Ischemic Events in Patients With Atrial Fibrillation Treated With Dabigatran or Warfarin in the RE-LY (Randomized Evaluation of Long-Term Anticoagulation Therapy) Trial

Background— There is a modest risk of myocardial infarction (MI) and myocardial ischemic events in patients with atrial fibrillation. Methods and Results— Data from the RE-LY study (Randomized Evaluation of Long-Term Anticoagulation Therapy) were used to report rates of MI, unstable angina, cardiac arrest, and cardiac death and the prespecified net clinical benefit and treatment effects of dabigatran versus warfarin. MI occurred at annual rates of 0.82% and 0.81% with dabigatran 110 or 150 mg BID compared with 0.64% with warfarin (hazard ratio [HR] 1.29, 95% confidence interval [CI] 0.96–1.75, P=0.09 for dabigatran 110 mg; HR 1.27, 95% CI 0.94–1.71, P=0.12 for dabigatran 150 mg). Annual rates of a composite of MI, unstable angina, cardiac arrest, and cardiac death were 3.16% per year with dabigatran 110 mg, 3.33% per year with dabigatran 150 mg, and 3.41% per year with warfarin (HR versus warfarin 0.93, 95% CI 0.80–1.06, P=0.28 for dabigatran 110 mg and HR 0.98, 95% CI 0.85–1.12, P=0.77 for dabigatran 150 mg). Events prespecified as “net clinical benefit” (all strokes, systemic embolism, MI, pulmonary embolism, major bleeding, and all-cause death) occurred at a rate of 7.34% per year with dabigatran 110 mg, 7.11% per year with dabigatran 150 mg, and 7.91% per year with warfarin (HR 0.92, 95% CI 0.84–1.01, P=0.09 for dabigatran 110 mg and HR 0.90, 95% CI 0.82–0.99, P=0.02 for dabigatran 150 mg). The relative effects of dabigatran versus warfarin on myocardial ischemic events were consistent in patients with or without a baseline history of MI or coronary artery disease. Conclusions— There was a nonsignificant increase in MI with dabigatran compared with warfarin, but other myocardial ischemic events were not increased. Treatment effects of dabigatran were consistent in patients at higher and lower risk of myocardial ischemic events. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT 00262600.

Intracranial Hemorrhage in Atrial Fibrillation Patients During Anticoagulation With Warfarin or Dabigatran: The RE-LY Trial

Background and Purpose— Intracranial hemorrhage is the most devastating complication of anticoagulation. Outcomes associated with different sites of intracranial bleeding occurring with warfarin versus dabigatran have not been defined. Methods— Analysis of 18 113 participants with atrial fibrillation in the Randomized Evaluation of Long-term anticoagulant therapY (RE-LY) trial assigned to adjusted-dose warfarin (target international normalized ratio, 2–3) or dabigatran (150 mg or 110 mg, both twice daily). Results— During a mean of 2.0 years of follow-up, 154 intracranial hemorrhages occurred in 153 participants: 46% intracerebral (49% mortality), 45% subdural (24% mortality), and 8% subarachnoid (31% mortality). The rates of intracranial hemorrhage were 0.76%, 0.31%, and 0.23% per year among those assigned to warfarin, dabigatran 150 mg, and dabigatran 110 mg, respectively (P<0.001 for either dabigatran dose versus warfarin). Fewer fatal intracranial hemorrhages occurred among those assigned dabigatran 150 mg and 110 mg (n=13 and n=11, respectively) versus warfarin (n=32; P<0.01 for both). Fewer traumatic intracranial hemorrhages occurred among those assigned to dabigatran (11 patients with each dose) compared with warfarin (24 patients; P<0.05 for both dabigatran doses versus warfarin). Independent predictors of intracranial hemorrhage were assignment to warfarin (relative risk, 2.9; P<0.001), aspirin use (relative risk, 1.6; P=0.01), age (relative risk, 1.1 per year; P<0.001), and previous stroke/transient ischemic attack (relative risk, 1.8; P=0.001). Conclusions— The clinical spectrum of intracranial hemorrhage was similar for patients given warfarin and dabigatran. Absolute rates at all sites and both fatal and traumatic intracranial hemorrhages were lower with dabigatran than with warfarin. Concomitant aspirin use was the most important modifiable independent risk factor for intracranial hemorrhage.

Myocardial Ischemic Events in Patients with Atrial Fibrillation Treated with Dabigatran or Warfarin in the RE-LY Trial

Background— There is a modest risk of myocardial infarction (MI) and myocardial ischemic events in patients with atrial fibrillation. Methods and Results— Data from the RE-LY study (Randomized Evaluation of Long-Term Anticoagulation Therapy) were used to report rates of MI, unstable angina, cardiac arrest, and cardiac death and the prespecified net clinical benefit and treatment effects of dabigatran versus warfarin. MI occurred at annual rates of 0.82% and 0.81% with dabigatran 110 or 150 mg BID compared with 0.64% with warfarin (hazard ratio [HR] 1.29, 95% confidence interval [CI] 0.96–1.75, P=0.09 for dabigatran 110 mg; HR 1.27, 95% CI 0.94–1.71, P=0.12 for dabigatran 150 mg). Annual rates of a composite of MI, unstable angina, cardiac arrest, and cardiac death were 3.16% per year with dabigatran 110 mg, 3.33% per year with dabigatran 150 mg, and 3.41% per year with warfarin (HR versus warfarin 0.93, 95% CI 0.80–1.06, P=0.28 for dabigatran 110 mg and HR 0.98, 95% CI 0.85–1.12, P=0.77 for dabigatran 150 mg). Events prespecified as “net clinical benefit” (all strokes, systemic embolism, MI, pulmonary embolism, major bleeding, and all-cause death) occurred at a rate of 7.34% per year with dabigatran 110 mg, 7.11% per year with dabigatran 150 mg, and 7.91% per year with warfarin (HR 0.92, 95% CI 0.84–1.01, P=0.09 for dabigatran 110 mg and HR 0.90, 95% CI 0.82–0.99, P=0.02 for dabigatran 150 mg). The relative effects of dabigatran versus warfarin on myocardial ischemic events were consistent in patients with or without a baseline history of MI or coronary artery disease. Conclusions— There was a nonsignificant increase in MI with dabigatran compared with warfarin, but other myocardial ischemic events were not increased. Treatment effects of dabigatran were consistent in patients at higher and lower risk of myocardial ischemic events. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT 00262600.

Risks for stroke, bleeding, and death in patients with atrial fibrillation receiving dabigatran or warfarin in relation to the CHADS2 score: a subgroup analysis of the RE-LY trial.

BACKGROUND CHADS(2) is a simple, validated risk score for predicting the risk for stroke in patients with atrial fibrillation not treated with anticoagulants. There are sparse data on the risk for thrombotic and bleeding complications according to the CHADS(2) score in patients receiving anticoagulant therapy. OBJECTIVE To evaluate the prognostic importance of CHADS(2) risk score in patients with atrial fibrillation receiving oral anticoagulants, including the vitamin K antagonist warfarin and the direct thrombin inhibitor dabigatran. DESIGN Subgroup analysis of a randomized, controlled trial. (ClinicalTrials.gov registration number: NCT00262600) SETTING: Multinational study setting. PATIENTS 18 112 patients with atrial fibrillation who were receiving oral anticoagulants. MEASUREMENTS Baseline CHADS(2) score, which assigns 1 point each for congestive heart failure, hypertension, age 75 years or older, and diabetes mellitus and 2 points for stroke. RESULTS Distribution of CHADS(2) scores were as follows: 0 to 1-5775 patients; 2-6455 patients; and 3 to 6-5882 patients. Annual rates of the primary outcome of stroke or systemic embolism among all participants were 0.93% in patients with a CHADS(2) score of 0 to 1, 1.22% in those with a score of 2, and 2.24% in those with a score of 3 to 6. Annual rates of other outcomes among all participants with CHADS(2) scores of 0 to 1, 2, and 3 to 6, respectively, were the following: major bleeding, 2.26%, 3.11%, and 4.42%; intracranial bleeding, 0.31%, 0.40%, and 0.61%; and vascular mortality, 1.35%, 2.39%, and 3.68% (P < 0.001 for all comparisons). Rates of stroke or systemic embolism, major and intracranial bleeding, and vascular and total mortality each increased in the warfarin and dabigatran groups as CHADS(2) score increased. The rates of stroke or systemic embolism with dabigatran, 150 mg twice daily, and of intracranial bleeding with dabigatran, 150 mg or 110 mg twice daily, were lower than those with warfarin; there was no significant heterogeneity in subgroups defined by CHADS(2) scores. LIMITATION These analyses were not prespecified and should be deemed exploratory. CONCLUSION Higher CHADS(2) scores were associated with increased risks for stroke or systemic embolism, bleeding, and death in patients with atrial fibrillation receiving oral anticoagulants. PRIMARY FUNDING SOURCE Boehringer Ingelheim.