ORIGINAL RESEARCH article
Front. Stroke
Sec. Population Health and Risk Factors of Stroke
Interaction Between Age and Atrial Fibrillation on Ischemic Stroke Severity: A Cross-Sectional Analysis
Provisionally accepted
- 1MOH Holdings (Singapore), Singapore, Singapore
- 2Duke-NUS Medical School, Singapore, Singapore
- 3National Neuroscience Institute, Singapore, Singapore
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Background: While atrial fibrillation (AF) and older age are established independent risk factors for greater ischemic stroke severity, their interactive effect remains poorly characterised. This study aimed to evaluate the interaction between age and AF status on stroke severity, as measured by the National Institutes of Health Stroke Scale (NIHSS). Methods: We conducted a cross-sectional study using a prospectively collected institutional stroke registry comprising 5,044 patients with acute ischemic stroke from 2019–2023. The primary exposures were AF status and age, categorized as <65 and ≥65 years, while stroke severity at admission measured by the NIHSS served as the outcome. NIHSS was modelled using a negative binomial distribution within PROC GLIMMIX with a logarithmic link function to account for overdispersion in the NIHSS scores. Model included age, AF, and their interaction term, along with relevant co-variates such as gender, race and premorbid mRS. Results: AF was present in 17.3% of patients. Stroke severity was significantly greater in patients with AF across both age groups: IRR 1.88 (95% CI, 1.44–2.45; p<0.0001) in patients <65 years, and IRR 2.13 (95% CI, 1.89–2.39; p<0.0001) in patients ≥65 years. The interaction between AF and age on stroke severity was not statistically significant (p for interaction = 0.40). Conclusions: AF is associated with greater stroke severity in both younger and older adults. There was no statistically significant interaction between age and AF status on NIHSS scores, indicating no evidence of effect modification by age within limits of our data. These findings underscore the need to consider stroke severity in risk stratification, especially in younger AF patients who often experience greater treatment burden.
Keywords: age, Atrial Fibrillation, ischemic stroke, NIHSS (National Institue of Health Stroke Scale), stroke severity
Received: 16 Sep 2025; Accepted: 05 Jan 2026.
Copyright: © 2026 Hong, Sultana, Ibrahim, Chang and De Silva. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Daniel Zhihao Hong
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