The association between red cell distribution width and stroke in patients with atrial fibrillation.

OBJECTIVE

Red cell distribution width is associated with increased risk of cardiovascular morbidity and mortality. We aimed to assess its association with stroke in patients with atrial fibrillation.

METHODS

By using the computerized database of the largest Health Maintenance Organization in Israel, we identified a cohort of adults with atrial fibrillation diagnosed before January 1, 2012. Eligible subjects were not taking anticoagulants at baseline and had at least 1 blood cell count performed in 2011 (41,140 subjects). The cohort was followed for the first occurrence of stroke until December 31, 2012.

RESULTS

Overall, 1692 subjects developed stroke during 38,024 person-years of follow-up (stroke rate, 4.45 per 100 person-years). Stroke incidence rate increased across red cell distribution width quartiles: 3.26, 3.71, 5.01, and 6.05 per 100 person-years in the lowest (≤ 13.4%), second (13.4%-14.1%), third (14.1%-15.0%), and highest (>15%) red cell distribution width quartiles, respectively. On multivariate analysis adjusting for Congestive heart failure, Hypertension, Age ≥ 75, Diabetes, and Prior Stroke or TIA (doubled) (CHADS2) score risk factors, the hazard ratio for stroke was 1.29 (95% confidence interval, 1.17-1.42) in subjects with red cell distribution width >14.5% compared with those with values ≤ 14.5% and was similar in subjects with and without anemia. When analyzed as quartiles, the hazard ratio for stroke was 1.33 (confidence interval, 1.15-1.53) in the highest quartile compared with the lowest quartile and was similar in subjects with and without anemia. The area under the receiver operating characteristic curve was 0.598 for (CHADS2) score and increased to 0.618 when red cell distribution width was included in the model (P < .001).

CONCLUSIONS

Red cell distribution width is directly associated with the risk of stroke regardless of anemia status and improves the predictive accuracy for stroke in patients with atrial fibrillation.