Associations of Anaemia with Stroke, Bleeding, and Mortality in Atrial Fibrillation: A Systematic Review and Meta-Analysis.

BACKGROUND: Anaemia frequently co-exists with atrial fibrillation (AF) and has been variably associated with worse outcomes. We performed a systematic review and meta-analysis to comprehensively assess the effect of anaemia on mortality, stroke/systemic thromboembolism and bleeding events in patients with AF.

METHODS: MEDLINE and Embase were searched from inception until May 2020. Studies examining associations of anaemia with the above outcomes in AF patients were included, and maximally adjusted hazard ratios (HRs) meta-analysed. PROSPERO registration number CRD42020171113.

RESULTS: Twenty-eight studies involving 365,484 patients (41% female, mean age 74.7 years) were included. The average study follow-up ranged from 0.2 to 4.0 years, and prevalence of anaemia was 16%. Anaemia was associated with a 78% increase in all-cause mortality (HR 1.78, 95% CI 1.44-2.20), 60% increase in cardiovascular mortality (HR 1.60, 95% CI 1.17-2.19), 134% increase in non-cardiovascular mortality (HR 2.34, 95% CI 1.58-3.47) 15% increase in stroke/systemic thromboembolism (HR 1.15, 95% CI 1.01-1.31), 78% increase in major bleeding (HR 1.78, 95% CI 1.54-2.05), and 77% increase in gastrointestinal bleeding (HR 1.77, 95% CI 1.23-2.55). Sensitivity analyses including studies that reported odds ratios did not result in any material change.

CONCLUSION: Anaemia is a frequently observed comorbidity in patients with AF, and is associated with an increased risk of all-cause, cardiovascular and non-cardiovascular mortality, stroke/systemic thromboembolism, and major and gastrointestinal bleeding. Future studies are required to explore the causes of anaemia in AF, and whether investigation and treatment may be clinically beneficial in affected individuals. This article is protected by copyright. All rights reserved.