Risk of stroke and transient ischaemic attack in patients with a diagnosis of resolved atrial fibrillation: retrospective cohort studies
BMJ 2018; 361 doi: https://doi.org/10.1136/bmj.k1717 (Published 09 May 2018) Cite this as: BMJ 2018;361:k1717Opinion: The importance of asking the right research question
- Nicola J Adderley, research fellow,
- Krishnarajah Nirantharakumar, senior clinical lecturer,
- Tom Marshall, professor of public health and primary care
- Correspondence to: K Nirantharakumar K.Nirantharan{at}bham.ac.uk
- Accepted 2 April 2018
Abstract
Objectives To determine rates of stroke or transient ischaemic attack (TIA) and all cause mortality in patients with a diagnosis of “resolved” atrial fibrillation compared to patients with unresolved atrial fibrillation and without atrial fibrillation.
Design Two retrospective cohort studies.
Setting General practices contributing to The Health Improvement Network, 1 January 2000 to 15 May 2016.
Participants Adults aged 18 years or more with no previous stroke or TIA: 11 159 with resolved atrial fibrillation, 15 059 controls with atrial fibrillation, and 22 266 controls without atrial fibrillation.
Main outcome measures Primary outcome was incidence of stroke or TIA. Secondary outcome was all cause mortality.
Results Adjusted incidence rate ratios for stroke or TIA in patients with resolved atrial fibrillation were 0.76 (95% confidence interval 0.67 to 0.85, P<0.001) versus controls with atrial fibrillation and 1.63 (1.46 to 1.83, P<0.001) versus controls without atrial fibrillation. Adjusted incidence rate ratios for mortality in patients with resolved atrial fibrillation were 0.60 (0.56 to 0.65, P<0.001) versus controls with atrial fibrillation and 1.13 (1.06 to 1.21, P<0.001) versus controls without atrial fibrillation. When patients with resolved atrial fibrillation and documented recurrent atrial fibrillation were excluded the adjusted incidence rate ratio for stroke or TIA was 1.45 (1.26 to 1.67, P<0.001) versus controls without atrial fibrillation.
Conclusion Patients with resolved atrial fibrillation remain at higher risk of stroke or TIA than patients without atrial fibrillation. The risk is increased even in those in whom recurrent atrial fibrillation is not documented. Guidelines should be updated to advocate continued use of anticoagulants in patients with resolved atrial fibrillation.
Footnotes
Contributors: TM had the original idea for the study. NA, KN, and TM designed the study. KN undertook data extraction. NA designed and performed the analysis. NA wrote the first draft of the paper, which was revised in collaboration with TM and KN. NA acts as guarantor.
Competing interests: All authors have completed the ICMJE uniform disclosure form at http://www.icmje.org/coi_disclosure.pdf and declare: NA and TM report a grant from the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care West Midlands during the conduct of the study; KN reports personal fees from Sanofi, and grants from AstraZeneca, Health Data Research UK (Medical Research Council) and British Heart Foundation, outside the submitted work; authors declare no other financial relationships with any organisations that might have an interest in the submitted work in the previous three years; and no other relationships or activities that could appear to have influenced the submitted work.
Funding: NA and TM are funded by the NIHR Collaboration for Leadership in Applied Health Research and Care West Midlands initiative. This paper presents independent research and the views expressed are those of the authors and not necessarily those of the National Health Service, the NIHR, or the Department of Health. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Ethical approval: The THIN data collection scheme and research carried out using THIN data were approved by the NHS South-East Multicentre Research Ethics Committee in 2003; under the terms of this approval, studies must undergo independent scientific review. Approval for this analysis was obtained from the Scientific Review Committee (for the use of THIN data) in September 2017 (SRC reference No 17THIN082).
Data sharing: No additional data available.
Transparency: The lead author (NA) affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.
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