Identifying patients at high risk for stroke despite anticoagulation: A comparison of contemporary stroke risk stratification schemes in an anticoagulated atrial fibrillation cohort

Gregory Y.H. Lip, Lars Frison, Jonathan L. Halperin, Deirdre A. Lane

Research output: Contribution to journalArticlepeer-review

437 Scopus citations

Abstract

Background and Purpose- The risk of stroke in patients with atrial fibrillation (AF) is not homogeneous, and various clinical risk factors have informed the development of stroke risk stratification schemes (RSS). Among anticoagulated cohorts, the emphasis should be on the identification of patients who remain at high risk for stroke despite anticoagulation. Methods- We investigated predictors of thromboembolism (TE) risk in an anticoagulated AF clinical trial cohort (n=7329 subjects) and tested the predictive value of contemporary RSS in this cohort: CHADS2, Framingham, NICE 2006, American College of Cardiology/American Heart Association/European Society of Cardiology 2006, the 8th American College of Chest Physicians guidelines and the CHA2DS2-VASc schemes. Results- On multivariate analysis, significant predictors of TE were stroke/TIA (hazard ratio [HR], 2.24; P<0.001), age 75 years or older (HR, 1.77; P=0.0002), coronary artery disease (HR, 1.52; P=0.0047), and smoking (HR, 2.10; P=0.0005), whereas reported alcohol use (HR, 0.70; P=0.02) was protective. Comparison of contemporary RSS demonstrated variable classification of AF patients into risk strata, although c-statistics for TE were broadly similar among the RSS tested and varied between 0.575 (NICE 2006) and 0.647 (CHA 2DS2-VASc). CHA2DS2-VASc classified 94.2% as being at high risk, whereas most other RSS categorized two-thirds as being at high risk. Of the 184 TE events, 181 (98.4%) occurred in patients identified as being at high risk by the CHA2DS2-VASc schema. There was a stepwise increase in TE with increasing CHA 2DS2-VASc score (Ptrend<0.0001), which had the highest HR (3.75) among the tested schemes. The negative predictive value (ie, the percent categorized as "not high risk" actually being free from TE) for CHA2DS2-VASc was 99.5%. Conclusion- Coronary artery disease and smoking are additional risk factors for TE in anticoagulated AF patients, whereas alcohol use appears protective. Of the contemporary stroke RSS, the CHA2DS2-VASc scheme correctly identified the greatest proportion of AF patients at high risk, despite the similar predictive ability of most RSS evidenced by the c-statistic.

Original languageEnglish
Pages (from-to)2731-2738
Number of pages8
JournalStroke
Volume41
Issue number12
DOIs
StatePublished - Dec 2010

Keywords

  • trial fibrillation
  • warfarin

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