Thromb Haemost 2011; 106(04): 739-749
DOI: 10.1160/TH11-05-0364
New Technologies, Diagnostic Tools and Drugs
Schattauer GmbH

Risks of thromboembolism and bleeding with thromboprophylaxis in patients with atrial fibrillation: A net clinical benefit analysis using a ‘real world’ nationwide cohort study

Jonas Bjerring Olesen
1   Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark
2   University of Birmingham Centre for Cardiovascular Sciences, City Hospital, Birmingham, UK
,
Gregory Y. H. Lip
2   University of Birmingham Centre for Cardiovascular Sciences, City Hospital, Birmingham, UK
,
Jesper Lindhardsen
1   Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark
,
Deirdre A. Lane
2   University of Birmingham Centre for Cardiovascular Sciences, City Hospital, Birmingham, UK
,
Ole Ahlehoff
1   Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark
,
Morten Lock Hansen
1   Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark
,
Jakob Raunsø
1   Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark
,
Janne Schurmann Tolstrup
3   National Institute of Public Health, Copenhagen, Denmark
,
Peter Riis Hansen
1   Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark
,
Gunnar Hilmar Gislason
1   Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark
,
Christian Torp-Pedersen
1   Department of Cardiology, Copenhagen University Hospital Gentofte, Hellerup, Denmark
› Author Affiliations
Further Information

Publication History

Received: 30 May 2011

Accepted after major revision: 18 July 2011

Publication Date:
29 November 2017 (online)

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Summary

It was the aim of this study to determine the efficacy and safety of vitamin K antagonists (VKAs) and acetylsalicylic acid (ASA) in patients with non-valvular atrial fibrillation (AF), with separate analyses according to predicted thromboembolic and bleeding risk. By individual levellinkage of nationwide registries, we identified all patients discharged with non-valvular AF in Denmark (n=132,372). For every patient, the risk of stroke and bleeding was calculated by CHADS2, CHA2DS2-VASc, and HAS-BLED. During follow-up, treatment with VKA and ASA was determined time-dependently. VKA consistently lowered the risk of thromboembolism compared to ASA and no treatment; the combination of VKA+ASA did not yield any additional benefit. In patients at high thromboembolic risk, hazard ratios (95% confidence interval) for thromboembolism were: 1.81 (1.73–1.90), 1.14 (1.06–1.23), and 1.86 (1.78–1.95) for ASA, VKA+ASA, and no treatment, respectively, compared to VKA. The risk of bleeding was increased with VKA, ASA, and VKA+ASA compared to no treatment, the hazard ratios were: 1.0 (VKA; reference), 0.93 (ASA; 0.89–0.97), 1.64 (VKA+ASA; 1.55–1.74), and 0.84 (no treatment; 0.81–0.88), respectively. There was a neutral or positive net clinical benefit (ischaemic stroke vs. intracranial haemorrhage) with VKA alone in patients with a CHADS2 score of ≥ 0, and CHA2DS2-VASc score of ≥ 1. This large cohort study confirms the efficacy of VKA and no effect of ASA treatment on the risk of stroke/thromboembolism. Also, the risk of bleeding was increased with both VKA and ASA treatment, but the net clinical benefit was clearly positive, in favour of VKA in patients with increased risk of stroke/thromboembolism.