Author + information
- Jeffrey M. Ashburner, PhD, MPH∗ ( and )
- Daniel E. Singer, MD
- ↵∗Division of General Internal Medicine, Massachusetts General Hospital, 50 Staniford Street, 9th Floor, Boston, Massachusetts 02114
We are delighted to recognize the thoughtful work by Overvad et al. (1) and Saliba et al. (2). The association of diabetes and ischemic stroke risk in patients with atrial fibrillation (AF) was first observed more than 20 years ago (3). Yet, there is scant published data analyzing this association by the core epidemiological components of diabetes duration and glycemic control.
We (4) and Overvad et al. (1) both found a moderately increased stroke risk with increased diabetes duration. However, Overvad et al. (1) observed a linear relationship, whereas we found a threshold for increased risk at 3 years duration, an effect that remained constant over longer durations. There were notable differences in our methods. Overvad et al. (1) assembled their cohort from hospitalized patients, whereas we also included patients first diagnosed in the outpatient setting. We updated diabetes duration over the multiyear follow-up, whereas Overvad et al. (1) used duration at baseline. We focused on periods during which patients were not receiving oral anticoagulants (OAC), whereas Overvad et al. (1) included patients taking OAC and adjusted for OAC use in their models. Also, we clinically validated all stroke events. These differences notwithstanding, our results are quite consistent: AF-related stroke risk increases with duration of diabetes.
Our results are not consistent with those of Saliba et al. (2). We (4) did not observe an association between hemoglobin A1c and ischemic stroke, whereas Saliba et al. (2) observed a dose-response relationship between glycated hemoglobin and stroke. Again, there are clear methodological differences. For example, Saliba et al. (2) used glycated hemoglobin measured within the 2 years preceding the start of their 1-year follow-up, whereas we used time-updated hemoglobin A1c values over a maximum follow-up of 7 years (mean: 2 years). Still, it is not clear why our results are so different. Further studies of the effect of glycemic control are needed.
Diabetes is a consistently identified but moderately weak risk factor for ischemic stroke in patients with AF. The aforementioned studies sought aspects of diabetes more proximal to the cause of stroke to better inform the use of OAC for AF. For now, patients with longer-duration diabetes should be viewed as being at higher risk than those with a relatively recent onset.
Please note: Dr. Singer serves as a consultant/advisory board member for Boehringer Ingelheim, Bristol-Myers Squibb, Daiichi-Sankyo, CVS Heath, Johnson & Johnson, Medtronic, Pfizer, and St. Jude Medical on matters related to preventing stroke in atrial fibrillation; and has research contracts with Medtronic, Inc. related to atrial fibrillation and risk of stroke, with Johnson & Johnson related to stroke prevention in atrial fibrillation, and with Bristol-Myers Squibb related to atrial fibrillation and risk of stroke. Dr. Ashburner has reported that he has no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation
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