Pre-Diabetes Increases Stroke Risk in Patients With Nonvalvular Atrial Fibrillation

Background: Diabetes mellitus (DM) increases the risk of embolism in nonvalvular atrial fibrillation (NVAF). The association between pre-diabetes and risk of ischemic stroke has not been studied separately in this population.

Objectives: The purpose of this study was to evaluate whether pre-diabetes is associated with increased risk of stroke and death in patients with NVAF.

Methods: We conducted a historical cohort study using the Clalit Health Services electronic medical records. The study population included all members aged ≥25 years, with a first diagnosis of NVAF between January 1, 2010, and December 31, 2016. We compared 3 groups of individuals: those with pre-diabetes, those with diabetes, and normoglycemic patients.

Results: A total of 44,451 cases were identified. The median age was 75 years, and 52.5% were women. During a mean follow-up of 38 months, the incidence rates of stroke (per 100 person-years) were: 1.14 in normoglycemic individuals, 1.40 in those with pre-diabetes, and 2.15 in those with diabetes. In both univariate and multivariate analyses, pre-diabetes was associated with an increased risk of stroke compared with normoglycemic persons (adjusted hazard ratio [adjHR]: 1.19; 95% confidence interval [CI]: 1.01 to 1.4) even after adjustment for CHA₂DS₂-Vasc risk factors and use of anticoagulants, while diabetes conferred an even higher risk (vs. normoglycemia (adjHR: 1.56; 95% CI: 1.37 to 1.79). The risk for mortality was higher for individuals with diabetes (adjHR: 1.47; 95% CI: 1.41 to 1.54) but not for those with pre-diabetes (adjHR: 0.98; 95% CI: 0.92 to 1.03).

Conclusions: In this cohort of patients with incident NVAF, pre-diabetes was associated with an increased risk of stroke even after accounting for other recognized risk factors.