JOURNAL ARTICLE
MULTICENTER STUDY

Outcomes in a Warfarin-Treated Population With Atrial Fibrillation

Fredrik Björck, Henrik Renlund, Gregory Y H Lip, Per Wester, Peter J Svensson, Anders Själander
JAMA Cardiology 2016 May 1, 1 (2): 172-80
27437888

IMPORTANCE: Vitamin K antagonist (eg, warfarin) use is nowadays challenged by the non-vitamin K antagonist oral anticoagulants (NOACs) for stroke prevention in atrial fibrillation (AF). NOAC studies were based on comparisons with warfarin arms with times in therapeutic range (TTRs) of 55.2% to 64.9%, making the results less credible in health care systems with higher TTRs.

OBJECTIVES: To evaluate the efficacy and safety of well-managed warfarin therapy in patients with nonvalvular AF, the risk of complications, especially intracranial bleeding, in patients with concomitant use of aspirin, and the impact of international normalized ratio (INR) control.

DESIGN, SETTING, AND PARTICIPANTS: A retrospective, multicenter cohort study based on Swedish registries, especially AuriculA, a quality register for AF and oral anticoagulation, was conducted. The register contains nationwide data, including that from specialized anticoagulation clinics and primary health care centers. A total of 40 449 patients starting warfarin therapy owing to nonvalvular AF during the study period were monitored until treatment cessation, death, or the end of the study. The study was conducted from January 1, 2006, to December 31, 2011, and data were analyzed between February 1 and November 15, 2015. Associating complications with risk factors and individual INR control, we evaluated the efficacy and safety of warfarin treatment in patients with concomitant aspirin therapy and those with no additional antiplatelet medications.

EXPOSURES: Use of warfarin with and without concomitant therapy with aspirin.

MAIN OUTCOMES AND MEASURES: Annual incidence of complications in association with individual TTR (iTTR), INR variability, and aspirin use and identification of factors indicating the probability of intracranial bleeding.

RESULTS: Of the 40 449 patients included in the study, 16 201 (40.0%) were women; mean (SD) age of the cohort was 72.5 (10.1) years, and the mean CHA2DS2-VASc (cardiac failure or dysfunction, hypertension, age ≥75 years [doubled], diabetes mellitus, stroke [doubled]-vascular disease, age 65-74 years, and sex category [female]) score was 3.3 at baseline. The annual incidence, reported as percentage (95% CI) of all-cause mortality was 2.19% (2.07-2.31) and, for intracranial bleeding, 0.44% (0.39-0.49). Patients receiving concomitant aspirin had annual rates of any major bleeding of 3.07% (2.70-3.44) and thromboembolism of 4.90% (4.43-5.37), and those with renal failure were at higher risk of intracranial bleeding (hazard ratio, 2.25; 95% CI, 1.32-3.82). Annual rates of any major bleeding and any thromboembolism in iTTR less than 70% were 3.81% (3.51-4.11) and 4.41% (4.09-4.73), respectively, and, in high INR variability, were 3.04% (2.85-3.24) and 3.48% (3.27-3.69), respectively. For patients with iTTR 70% or greater, the level of INR variability did not alter event rates.

CONCLUSIONS AND RELEVANCE: Well-managed warfarin therapy is associated with a low risk of complications and is still a valid alternative for prophylaxis of AF-associated stroke. Therapy should be closely monitored for patients with renal failure, concomitant aspirin use, and poor INR control.

Full Text Links

Find Full Text Links for this Article

Discussion

You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read
27437888
×

Save your favorite articles in one place with a free QxMD account.

×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"