Red blood cell distribution width is associated with incidence of atrial fibrillation

Objectives: Red blood cell distribution width (RDW), a measure of variation in erythrocyte volume, has been associated with several cardiovascular disorders, but the relationship with atrial fibrillation (AF) remains unclear. We investigated the association between RDW and incidence of first hospitalization due to AF in a population-based cohort. Design: Red blood cell distribution width was measured in 27 124 subjects from the general population (age 45-73 years, 62% women) with no history of AF, heart failure, myocardial infarction or stroke. The association between baseline RDW and incidence of AF identified from the Swedish Hospital Discharge Register was evaluated. Results: During a mean follow-up of 13.6 years, 1894 subjects (53% men) were hospitalized with a diagnosis of AF. After adjustment for potential confounding factors, including cardiovascular disease risk factors, nutrient intake (iron, vitamin B12 and folate) and several haematological parameters (haemoglobin concentration, mean corpuscular volume and corpuscular haemoglobin content), the hazard ratio (HR) for incidence of AF was 1.33 [95% confidence interval (CI) 1.16-1.53] for the fourth versus first quartile of RDW (P for trend <0.001). The results were essentially unchanged when subjects with incident myocardial infarction or hospitalizations because of heart failure were censored from the analysis (HR 1.30, 95% CI 1.13-1.51; P for trend = 0.001). Conclusion: Red blood cell distribution width was associated with incidence of AF independently of several cardiovascular, nutritional and haematological factors in this study of middle-aged subjects from the general population. © 2013 The Association for the Publication of the Journal of Internal Medicine.