Time trends in stroke severity in the years 2005 to 2020: results from the Austrian Stroke Unit Registry

Background and purpose With aging population, there is an increase of atrial fibrillation (AF) and other vascular risk factors. We investigated trends in stroke severity at hospital admission with respect to AF and other risk factors in a prospective national stroke registry from 2005 to 2020. Methods Data from the prospective Austrian Stroke Unit Registry were used to study demographic and clinical factors associated with the change in admission stroke severity over years. Time trends in admission stroke severity of patients with pre-stroke modified Rankin Score <= 3 were investigated with respect to clinical variables and predefined age groups 18-54, 55-64, 65-74, 75-84 and >= 85 years. Time trends were studied using robust generalized linear models assuming normal distribution with a log link. Stroke severity on admission was assessed according to the National Institutes of Health Stroke Scale Score (NIHSS). Results In total, 140,312 patients with acute ischemic stroke were included in the analysis. Within the study period, mean patients' age increased from 70 to 72 years (p < 0.001) and median NIHSS at admission decreased from 4 to 3 (p < 0.001). The frequency of AF increased from 25 to 32% (p < 0.001). The decrease in median admission NIHSS was evident in all relevant subgroups but more pronounced in patients with risk factors including AF, diabetes, hypercholesterolemia, smoking, elderly patients and those with pre-stroke disability. Conclusion Despite an aging population and generally increasing AF frequency, we observed a consistent trend towards less disabling strokes on admission.