Off-hour effect is not significant in endovascular treatment for anterior circulation large vessel occlusion in a multicentre registry

Background and purpose

Whether the off-hour effect has an impact on workflow and outcomes of endovascular treatment (EVT) for anterior circulation large vessel occlusion (AC-LVO) remains uncertain. This study aimed to compare the characteristics and outcomes of patients who presented or were treated during off-hour versus on-hour in a multi-center registry.


AC-LVO patients from 21 centres were categorised into the off-hour group and the on-hour group. Off-hour (weekends, holidays, and 18:00–7:59 on weekdays) and on-hour (8:00–17:59 on weekdays except for holidays) were defined according to arrival and groin-puncture time points, respectively. Subgroup comparisons between patients both arrived and treated during off-hour (true off-hour) and on-hour (true on-hour) were performed. The primary outcome was the 90-day modified Rankin Scale (mRS) score. Secondary outcomes included favourable outcome (mRS 0–2 at 90 days), EVT-related time metrics, and other clinical outcomes. Ordinary and binary logistic regression and linear regression were taken to adjust for confounding factors.


Of all 698 patients enrolled, 435 (62.3%) and 456 (65.3%) patients were categorised into the off-hour arrival and off-hour puncture group, respectively. Shorter onset to door time (adjusted ß coefficient: –21.56; 95% CI –39.96 to –3.16; p=0.022) was noted in the off-hour arrival group. Ordinal and dichotomous mRS scores at 90 days were comparable between the off-hour group and the on-hour group regardless of off-hour definitions. Other time metrics and outcomes were comparable between the two groups. Of 595 patients both presented and were treated during off-hour or on-hour, 394 patients were categorised into the true off-hour group and 201 into the true on-hour group. Time metrics and clinical outcomes were similar between the true off-hour and the true on-hour group.


The off-hour effect was not significant regarding clinical outcomes and in-hospital workflow in AC-LVO patients receiving EVT in this Chinese multicentre registry.

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