Can patients at elevated risk of stroke treated with anticoagulants be further risk stratified?
OBJECTIVE
Patients with atrial fibrillation have a varied risk of stroke, depending on age and comorbid conditions. The objective of this study was to assess the predictive value of stroke risk classification schemes and to identify patients with atrial fibrillation who are at substantial risk of stroke despite optimal anticoagulant therapy.


METHODS
Seven recognized classification schemes-the American College of Chest Physicians 2001, American College of Chest Physicians 2004, Stroke Prevention in Atrial Fibrillation (SPAF), Atrial Fibrillation Investigators, Framingham, van Walraven, and CHADS(2)-were compared for their ability to predict ischemic stroke in patients receiving anticoagulant therapy. Data came from the Stroke Prevention using an ORal Thrombin Inhibitor in atrial Fibrillation III and V trials, which compared the efficacy of adjusted-dose warfarin and the direct thrombin inhibitor ximelagatran (36 mg twice daily) in preventing thromboembolic events in 7329 patients with chronic or paroxysmal nonvalvular atrial fibrillation who were at moderate or high risk of ischemic stroke. The main outcome measure was ischemic stroke, as determined by a central event adjudication committee.


RESULTS
During 11 245 patient-years of follow-up, 159 patients had an ischemic stroke (1.4%/year). As indicated by c statistics and hazard ratios, 3 of the classification schemes predicted stroke significantly better than chance: Framingham (c=0.64), CHADS(2) (c=0.65), and SPAF (c=0.61).


CONCLUSIONS
In a large cohort of atrial fibrillation patients at moderate or high risk of ischemic stroke treated with warfarin or ximelagatran, the CHADS(2), SPAF, and Framingham schemes had greater predictive accuracy than chance. This predictive ability may allow clinicians to target high-risk patients for more aggressive intervention.
Baruch
Lawrence
L
Bronx VA Hospital, Bronx, NY 10468, USA. baruchlarry@att.net
Gage
Brian F
BF
Horrow
Jay
J
Juul-Möller
Steen
S
Labovitz
Arthur
A
Persson
Maria
M
Zabalgoitia
Miguel
M
D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000150:complications*; D001384:Azetidines / Q000627:therapeutic use; D001596:Benzylamines / Q000627:therapeutic use; D015331:Cohort Studies; D005500:Follow-Up Studies; D006801:Humans; D015337:Multicenter Studies as Topic; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D012307:Risk Factors; D020521:Stroke / Q000188:drug therapy / Q000209:etiology / Q000517:prevention & control; D014859:Warfarin / Q000627:therapeutic use
D000925:Anticoagulants; D001384:Azetidines; D001596:Benzylamines; C426686:ximelagatran; D014859:Warfarin