Comparing stroke severity, subtype and treatment delivery by symptom onset time

<h3></h3> Stroke incidence peaks in the early morning, with worse outcomes associated with night-onset strokes. We aimed to determine differences in stroke severity, subtype and thrombolysis administration per stroke onset time at our centre. We searched our university hospital stroke registry (between 12/2021-10/2023) for patients diagnosed with stroke and had known onset time. Onset time was categorised into day-onset (06:00-18:00) and night-onset (18:00-06:00). Stroke severity was recorded on admission using the National Institutes of Health Stroke Scale (NIHSS) and stroke subtype using the Bamford classification. Significance differences were determined using χ² and Mann-Whitney tests. We used binary logistic regression to determine the odds of thrombolysis administration per onset category, adjusting for admission NIHSS, age and sex. 1488/3028 records met the inclusion criteria. Stroke subtype differed significantly between onset categories (p=0.022), with increased lacunar stroke in day-onset (321 (29.6%) vs 110 (27.2%)) and partial anterior circulation stroke in night-onset (275 (25.4%) vs 120 (29.6%)). Admission NIHSS was significantly increased in night-onset strokes (3 (IQR:1-7)) vs 4 (IQR:1-10), p=0.001). Odds of thrombolysis administration between onset categories did not differ in the adjusted analysis (p=0.848). Stroke subtype differed significantly with onset time. Night-onset strokes were associated with increased stroke severity.