Determinants of door-in-door-out time in patients with ischaemic stroke transferred for endovascular thrombectomy

Background: Long door-in-door-out (DIDO) times are an important cause of treatment delay in patients transferred for endovascular thrombectomy (EVT) from primary stroke centres (PSC) to an intervention centre. Insight in causes of prolonged DIDO times may facilitate process improvement interventions. We aimed to quantify different components of DIDO time and to identify determinants of DIDO time. Methods: We performed a retrospective cohort study in a Dutch ambulance region consisting of six PSCs and one intervention centre. We included consecutive adult patients with anterior circulation large vessel occlusion, transferred from a PSC for EVT between October 1, 2019 and November 31, 2020. We subdivided DIDO into several time components and quantified contribution of these components to DIDO time. We used univariable and multivariable linear regression models to explore associations between potential determinants and DIDO time. Results: We included 133 patients. Median (IQR) DIDO time was 66 (52–83) min. The longest component was CTA-to-ambulance notification time with a median (IQR) of 24 (16–37) min. DIDO time increased with age (6 min per 10 years, 95% CI: 2–9), onset-to-door time outside 6 h (20 min, 95% CI: 5–35), M2-segment occlusion (15 min, 95% CI: 4–26) and right-sided ischaemia (12 min, 95% CI: 2–21). Conclusions: The CTA-to-ambulance notification time is the largest contributor to DIDO time. Higher age, onset-to-door time longer than 6 h, M2-segment occlusion and right-sided occlusions are independently associated with a longer DIDO time. Future interventions that aim to decrease DIDO time should take these findings into account.