Author + information
- Thure Filskov Overvad, MD,
- Peter Brønnum Nielsen, MSc, PhD and
- Torben Bjerregaard Larsen, MD, PhD∗ ()
- ↵∗Aalborg Thrombosis Research Unit, Department of Clinical Medicine, Faculty of Health, Aalborg University, Aalborg Hospital Science and Innovation Center, Søndre Skovvej 15, DK-9100 Aalborg, Denmark
We read with interest the study by Ashburner et al. (1), investigating associations between duration of diabetes, glycemic control, and risk of ischemic stroke in patients with atrial fibrillation (AF) in the ATRIA (Anticoagulation and Risk Factors in Atrial Fibrillation) cohort.
They found that duration of diabetes is an important predictor of ischemic stroke in patients with AF, suggesting that an arbitrary duration threshold of ≥3 years may be a useful cut-off. These findings serve partly as valuable confirmation of observations from another recent analysis including >17,000 patients with AF and concomitant diabetes that investigated a similar issue (2). Here, the risk of a composite outcome of ischemic stroke or systemic embolism according to diabetes duration exhibited a linear dose-response relationship, with the highest risk observed among patients with diabetes duration ≥15 years. These previous data do not support a risk threshold at 3 years of duration as observed in the ATRIA study.
The ATRIA study also used glycemic control as exposure. Perhaps surprisingly, no clear positive associations between hemoglobin A1c (HbA1c) levels and ischemic stroke were observed. Suggested explanations included the unique stroke etiology inflicted by AF that may be unaffected by HbA1c, and the short follow-up period of ≈2.5 years (1,3). However, another recent report including >11,000 patients opposes these explanations, in which a clear dose-response relationship between HbA1c and risk of incident stroke or transient ischemic attack was observed, despite a mean follow-up of <1 year (4). The relatively smaller ATRIA sample size and the exclusion of follow-up time without HbA1c information may have limited the possibility of detecting a similar signal.
In summary, the results from the ATRIA study should be interpreted with caution and in light of the pre-existing evidence investigating similar matters. Nonetheless, the results re-emphasize the important observation that the dichotomization of diabetes in many available AF risk scores is simplistic, and that subdividing existing score components would provide new avenues for more accurate and individualized risk calculations.
Please note: Dr. Brønnum Nielsen has served on the speakers bureau for Boehringer Ingelheim. Dr. Bjerregaard Larsen has served as an investigator for Janssen Scientific Affairs, LLC, and Boehringer Ingelheim; and has served on the speakers bureau for Bayer, Bristol-Myers Squibb/Pfizer, Janssen Pharmaceuticals, Takeda, Roche Diagnostics, and Boehringer Ingelheim. Dr. Filskov Overvad has reported that he has no relationships relevant to the contents of this paper to disclose.
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