Pre-diabetes a new risk factor for stroke in non-valvular atrial fibrillation

Background: Diabetes mellitus is a well-established independent risk factor for embolic complications in patients with non-valvular atrial fibrillation (NVAF). The association between prediabetes and risk of ischemic stroke, however, has not been studied separately in patients with NVAF.

Purpose: To evaluate whether pre-diabetes is associated with increased risk of stroke and death in patients with NVAF

Methods: We conducted a prospective, historical cohort study using the Clalit Health Services (CHS) electronic medical records database. The study population included all CHS members ≥ 21 years old, with a first diagnosis of NVAF between January 1 2010 to December 31 2016 and a minimal follow-up period of 1 year. We compared three groups of patients: prediabetes, those with established DM, and normoglycemic individuals

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 of stroke per 100 person-years in the three study groups was: 1.14 in non-diabetics, 1.40 in pre-diabetics and 2.15 in diabetics. In both univariate and multivariate analyses, pre-diabetes was associated with an increased risk of stroke compared with non-diabetics (Adjusted Hazard Ratio (HR) = 1.19 {95% CI 1.01-1.4}) even after adjusting for CHA₂DS₂-VASC individual risk factors and use of oral anti-coagulants while diabetes conferred an even higher risk (vs non-diabetics { HR = 1.56, 95% CI ;1.37 - 1.79}). The risk for mortality was higher for diabetics (HR =1.47, 95% CI ;1.41, 1.54}) but not for pre-diabetics (HR = 0.98 ,CI 95%; 0.92 - 1.03).

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