This prospective observational study included 18,106 individuals with AF and available baseline hemoglobin (Hb) concentration measurements. All data were taken from the Chinese Atrial Fibrillation Registry Study, and patients were enrolled between August 2011 and December 2018.
Study participants reportedly had either no anemia (86.2%), mild anemia (9.9%), or moderate to severe anemia (3.9%). The 3 anemia groups were also stratified by sex (men vs women) for Hb levels: no anemia (Hb≥130 g/L and Hb≥120 g/L); mild anemia (110≤Hb<129 g/L and 110≤Hb<119 g/L); and moderate to severe anemia (Hb≤109 g/L and Hb≤109 g/L), respectively. Investigators used 3 stepwise models using Cox proportional hazards regressions to evaluate the associations between anemia and clinical outcomes, including CV mortality, all-cause mortality, and major bleeding with adjustments for confounders.
Among the 3 anemia groups (no anemia, mild anemia, and moderate to severe anemia), incidences of CV mortality (0.97, 2.85, and 4.47 per 100 person-years, respectively), all-cause mortality (1.78, 4.86, and 8.90 per 100 person-years, respectively), and major bleeding (0.51, 0.62, and 0.71 per 100 person-years, respectively) revealed significant associations between baseline anemia and increased risk for all-cause mortality and CV mortality.
When compared with patients without anemia in the fully adjusted model, the risk for all-cause mortality in patients with mild anemia was 1.22 times greater (95% CI, 1.08-1.38), and in patients with moderate to severe anemia it was 1.53 times greater (95% CI, 1.31-1.77) . Similarly, when compared to the no anemia group, the risk for CV mortality was 1.29 times greater (95% CI, 1.10-1.52) and 1.27 times greater (95% CI, 1.03-1.57) for the mild and moderate to severe anemia groups, respectively. The correlation between anemia and all-cause mortality persisted among subgroups categorized by ablation therapy, anticoagulant drugs, kidney function, and sex. No association was observed between anemia and major bleeding.
Limitations to this study include a lack of recorded Hb concentrations during follow-up, a lack of data on the cause of anemia in study patients, no age-matched control cohort of individuals without AF, and increased risk for bias due to the prospective observational study design.
The study found that anemia in AF patients was associated with increased risk for all-cause mortality and CV mortality, but did not affect major bleeding. The study authors noted, “Further studies are needed to further verify whether anemia correction could favorably affect outcomes in AF patients with anemia.”
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Zhang Z, Jiang C, He L, et al. Associations of anemia with death and major bleeding in patients with atrial fibrillation: a report from the Chinese Atrial Fibrillation Registry Study. Clin Cardiol. Published online December 28, 2021. doi:10.1002/clc.23764