BACKGROUND: Nonrheumatic atrial fibrillation (AF) is a common cause of embolic stroke. Warfarin therapy can reduce stroke risk by two-thirds in patients with AF, but therapy may not always be used or always be used optimally. OBJECTIVES: This study sought to document the patterns of anticoagulant use and the determinants and incidence of stroke, intracranial hemorrhage, and arterial thromboembolism in US patients with AF. METHODS: Using health insurance claims and laboratory results, we examined events per unit of person-time and used Poisson regression to quantify the association of AF outcomes with the international normalized ratio (INR) and other covariates. RESULTS: In 116,969 patients age > or =40 years with an insurance claim for AF or atrial flutter between 1999 and 2005, warfarin was prescribed to 45%, and 48% had no claim for any anticoagulant or antiplatelet agent. Subtherapeutic INR levels (<2.0) raised the incidence of stroke (relative risk [RR]: 2.39, 95% confidence interval [CI]: 1.68 to 3.41) and arterial thromboembolism (RR: 5.68, 95% CI: 1.88 to 17.10) compared with therapeutic INR levels, whereas supratherapeutic INR levels (>3.0) doubled the incidence of intracranial hemorrhage (RR: 2.11, 95% CI: 1.16 to 3.84). Further covariate adjustment had little effect on these estimates. CONCLUSION: Warfarin remains underused within the outpatient setting. Nontherapeutic INR levels are associated with increased risk of stroke, bleeding, and thromboembolism compared with therapeutic INR levels.
BACKGROUND:Nonrheumatic atrial fibrillation (AF) is a common cause of embolic stroke. Warfarin therapy can reduce stroke risk by two-thirds in patients with AF, but therapy may not always be used or always be used optimally. OBJECTIVES: This study sought to document the patterns of anticoagulant use and the determinants and incidence of stroke, intracranial hemorrhage, and arterial thromboembolism in US patients with AF. METHODS: Using health insurance claims and laboratory results, we examined events per unit of person-time and used Poisson regression to quantify the association of AF outcomes with the international normalized ratio (INR) and other covariates. RESULTS: In 116,969 patients age > or =40 years with an insurance claim for AF or atrial flutter between 1999 and 2005, warfarin was prescribed to 45%, and 48% had no claim for any anticoagulant or antiplatelet agent. Subtherapeutic INR levels (<2.0) raised the incidence of stroke (relative risk [RR]: 2.39, 95% confidence interval [CI]: 1.68 to 3.41) and arterial thromboembolism (RR: 5.68, 95% CI: 1.88 to 17.10) compared with therapeutic INR levels, whereas supratherapeutic INR levels (>3.0) doubled the incidence of intracranial hemorrhage (RR: 2.11, 95% CI: 1.16 to 3.84). Further covariate adjustment had little effect on these estimates. CONCLUSION:Warfarin remains underused within the outpatient setting. Nontherapeutic INR levels are associated with increased risk of stroke, bleeding, and thromboembolism compared with therapeutic INR levels.
Authors: John J You; Daniel E Singer; Patricia A Howard; Deirdre A Lane; Mark H Eckman; Margaret C Fang; Elaine M Hylek; Sam Schulman; Alan S Go; Michael Hughes; Frederick A Spencer; Warren J Manning; Jonathan L Halperin; Gregory Y H Lip Journal: Chest Date: 2012-02 Impact factor: 9.410
Authors: Margaret C Fang; Alan S Go; Yuchiao Chang; Leila H Borowsky; Niela K Pomernacki; Natalia Udaltsova; Daniel E Singer Journal: Circ Cardiovasc Qual Outcomes Date: 2010-10-19
Authors: Gregory Y H Lip; Lars H Rasmussen; S Bertil Olsson; Eva C Jensen; Anders L Persson; Ulf Eriksson; Karin F C Wåhlander Journal: Eur Heart J Date: 2009-08-18 Impact factor: 29.983