You are here

  • Home
  • Online First
  • Endovascular stroke therapy outside core working hours in a nationwide stroke system

Article Text

Article menu

other Versions

Ischemic stroke
Original research
Endovascular stroke therapy outside core working hours in a nationwide stroke system
  1. Simon Fandler-Höfler1,
  2. Dominika Mikšová2,
  3. Hannes Deutschmann3,
  4. Markus Kneihsl1,
  5. Sebastian Mutzenbach4,
  6. Monika Killer-Oberpfalzer4,5,
  7. Elke R Gizewski6,
  8. Michael Knoflach7,
  9. Stefan Kiechl7,
  10. Michael Sonnberger8,
  11. Milan R Vosko9,
  12. Jörg Weber10,
  13. Klaus A Hausegger11,
  14. Wolfgang Serles12,
  15. Philipp Werner13,
  16. Dimitre Staykov14,
  17. Marek Sykora15,
  18. Wilfried Lang15,
  19. Julia Ferrari15,
  20. Christian Enzinger1,
  21. Thomas Gattringer1,3
  22. on behalf of the Austrian EVT Study Group
    1. 1Department of Neurology, Medical University of Graz, Graz, Austria
    2. 2Austrian National Public Health Institute, Vienna, Austria
    3. 3Division of Neuroradiology, Vascular and Interventional Radiology, Department of Radiology, Medical University of Graz, Graz, Austria
    4. 4Department of Neurology, Christian Doppler Medical Center, Paracelsus Medical University Salzburg, Salzburg, Austria
    5. 5Institute of Neurointervention, Christian Doppler Medical Center, Paracelsus Medical University Salzburg, Salzburg, Austria
    6. 6Department of Neuroradiology, Medical University of Innsbruck, Innsbruck, Austria
    7. 7Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
    8. 8Institute of Neuroradiology, Kepler University Hospital Linz, Linz, Austria
    9. 9Department of Neurology, Kepler University Hospital Linz, Linz, Austria
    10. 10Department of Neurology, Klinikum Klagenfurt, Klagenfurt, Austria
    11. 11Institute of Diagnostic and Interventional Radiology, Klinikum Klagenfurt, Klagenfurt, Austria
    12. 12Department of Neurology, Medical University of Vienna, Vienna, Austria
    13. 13Department of Neurology, State Hospital of Feldkirch/Rankweil, Rankweil, Austria
    14. 14Department of Neurology, St. John’s Hospital, Eisenstadt, Austria
    15. 15Department of Neurology, St. John’s Hospital, Vienna, Austria
    1. Correspondence to Professor Thomas Gattringer, Department of Neurology, Medical University of Graz, Graz, Austria; thomas.gattringer{at}medunigraz.at

    Abstract

    Background Endovascular therapy (EVT) has been established as a major component in the acute treatment of large vessel occlusion stroke. However, it is unclear whether outcome and other treatment-related factors differ if patients are treated within or outside core working hours.

    Methods We analyzed data from the prospective nationwide Austrian Stroke Unit Registry capturing all consecutive stroke patients treated with EVT between 2016 and 2020. Patients were trichotomized according to the time of groin puncture into treatment within regular working hours (08:00–13:59), afternoon/evening (14:00–21:59) and night-time (22:00–07:59). Additionally, we analyzed 12 EVT treatment windows with equal patient numbers. Main outcome variables included favorable outcome (modified Rankin Scale scores of 0–2) 3 months post-stroke as well as procedural time metrics, recanalization status and complications.

    Results We analyzed 2916 patients (median age 74 years, 50.7% female) who underwent EVT. Patients treated within core working hours more frequently had a favorable outcome (42.6% vs 36.1% treated in the afternoon/evening vs 35.8% treated at night-time; p=0.007). Similar results were found when analyzing 12 treatment windows. All these differences remained significant in multivariable analysis adjusting for outcome-relevant co-factors. Onset-to-recanalization time was considerably longer outside core working hours, which was mainly explained by longer door-to-groin time (p<0.001). There was no difference in the number of passes, recanalization status, groin-to-recanalization time and EVT-related complications.

    Conclusions The findings of delayed intrahospital EVT workflows and worse functional outcomes outside core working hours in this nationwide registry are relevant for optimization of stroke care, and might be applicable to other countries with similar settings.

    • Stroke
    • Thrombectomy

    Data availability statement

    Data are available upon reasonable request. The datasets generated during this study are available from the corresponding author upon reasonable request.

    https://doi.org/10.1136/jnis-2022-020044

    Statistics from Altmetric.com

      Request Permissions

      If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

      What is already known on this topic

      • Organization of endovascular stroke therapy (EVT) is challenging, particularly outside of core working hours. Limited data from previous studies have shown conflicting results regarding the influence of time of day on treatment workflows and patient outcome.

      What this study adds

      • This prospective nationwide study showed longer door-to-groin times and worse functional outcome in EVT patients treated outside core working hours. EVT procedural aspects (number of passes, recanalization status, groin-to-recanalization time and complications) were not different.

      How this study might affect research, practice or policy

      • Our results have clear implications for optimization of stroke care/EVT, indicating room for improvement mainly in workflows at the emergency department, at the intersection to neurointervention and between transferring hospitals.

      Background

      In 2015, endovascular therapy (EVT) was proven to be the most effective acute treatment strategy in patients with stroke due to large intracranial vessel occlusion,1 leading to a reorganization of stroke care systems at local, regional and national levels. Many healthcare systems have since established or improved 24/7/365 coverage of EVT, while others are still struggling with this endeavor.2–4 However, even when complete coverage has been achieved, the quality of EVT may differ across regions or in different time windows.5 6

      EVT during core working hours may have logistical advantages due to faster prehospital transfer times and better in-hospital treatment coordination. Furthermore, as the peri- and post-interventional care of patients with acute stroke is complex,7 8 increased availability of key personnel (stroke physicians, neurointerventionalists and anesthesiologists) may lead to optimized care, beyond difficult interventions. Previous studies have investigated the influence of treatment time of day on patient outcome in stroke with large vessel occlusion, but most of these studies were either small,9 focused on single specialized tertiary care centers10 11 and/or investigated cohorts before publication of large randomized controlled trials on EVT.12 Such variations likely explain the different results of these individual studies, although a meta-analysis found treatment delays and lower rates of successful recanalization in stroke patients treated with EVT outside core working hours.6 A recent study from the German Stroke Registry found worse outcomes in patients treated with EVT who had longer time intervals to recanalization, reporting longer door-to-groin time at night-time and weekends.13

      In Austria, nationwide coverage of EVT (including mandatory electronic documentation) was established in 2013.14 In the present study, we aimed to investigate the influence of time of day on procedural aspects (number of passes, recanalization success, treatment-related complications) and functional neurological outcome in a nationwide cohort of patients receiving EVT for acute large vessel occlusion stroke.

      Methods

      Study cohort

      The Austrian Stroke Unit Registry was federally mandated in 2002 and data are entered nationwide from all 38 acute stroke units. An expansion to the Registry was implemented in 2013 in order to capture data regarding EVT, which is currently provided in 12 stroke centers. Data collection and clinical ratings are performed by experienced stroke neurologists using standardized definitions of variables and scores. The registry contains epidemiological, clinical, diagnostic and therapeutic data, as well as clinical scores. A follow-up examination 3 months post-stroke including assessment of the modified Rankin Scale (mRS) is mandated to be performed by a neurologist; if an in-person visit is not possible, a telephone interview can be used instead.15 A more detailed description of the methodology of the Austrian Stroke Unit Registry is provided elsewhere.14 16

      For the present analysis, we included all patients with stroke due to acute large intracranial vessel occlusion treated with EVT over a 5-year study period (January 2016 to December 2020) who had available data regarding EVT time metrics. No clinical exclusion criteria were applied in order to consecutively capture patients recruited in ‘real-world’ scenarios (online supplemental figure 1).

      Supplemental material

      All participating stroke centers have core working hours starting between 07:00 and 08:00 and ending between 14:00 and 16:00. After core working hours, a neurointerventionalist is on call either in the hospital or at home until next morning. Full coverage of EVT is available across the whole country. In most of Austria’s federal states (six out of nine), a single stroke center offers EVT for the respective region 24/7/365. In Vienna and the surrounding regions, on-call days are distributed between different hospitals.

      The start of EVT was defined as the time of groin puncture and was used to allocate patients to specific time windows in order to best compare the peri- and pre-interventional treatment of patients and to allow for comparison with previous studies which chose the same approach.10 In a first step, we allocated patients to three time windows according to clinical daily routine: morning/noon (08:00–13:59, encompassing the core working hours), afternoon/evening (14:00–21:59) and night-time (22:00–07:59). As larger numbers of EVTs were performed during core working hours and in order to avoid bias due to unequal group sizes, we further analyzed 12 time windows with equally sized patient numbers starting from 08:00, following previous studies.10

      We analyzed functional outcome according to the mRS at discharge from the stroke unit and at follow-up 3 months post-stroke, dichotomized as favorable (mRS 0–2) and unfavorable (mRS 3–6). Furthermore, we performed an ordinal shift analysis regarding mRS scores. Other target variables included treatment times (symptom onset-to-door, door-to-imaging, door-to-groin puncture, groin puncture-to-recanalization), recanalization status (dichotomized according to Thrombolysis in Cerebral Infarction (TICI) scores of 2b–3 vs 0–2a and 3 vs 0–2c), peri-interventional complications (dissection, reocclusion, hematoma and other complications related to groin puncture) and post-interventional symptomatic intracranial hemorrhage. Symptom onset-to-door time was defined as time of recognition of stroke symptoms until arrival at the primary hospital. In patients with stroke of unknown onset (including wake-up stroke), we only investigated in-hospital time metrics.

      Statistical analysis

      Comparison between categorical variables was performed using the χ2 test or Fisher exact test and presented as frequencies with percentages. The Kruskal–Wallis test was used for continuous variables and presented as median and IQR. Significance was set at p<0.05.

      Due to lack of having particular time cuts to determine 12 exact equally sized time windows, slight differences in sizes persisted. However, we tested the null hypothesis that sample proportions are equal in each time interval using the multiple proportional test and this was subsequently accepted.

      Multivariable proportional odds logistic regression models were conducted with mRS scores 3 months post-stroke as the target variable in an ordinal shift analysis. In these models we adjusted for age, sex, frequent comorbidities (hypertension, diabetes, hyperlipidemia, atrial fibrillation, coronary heart disease) and known factors associated with outcome (National Institutes of Health Stroke Scale (NIHSS) at admission, intravenous thrombolysis and stroke of unknown onset).17–19 We chose not to include reperfusion success and/or time metrics in the multivariable model as they are part of the treatment process we aimed to investigate. An additional sensitivity analysis was performed by including the variable secondary transfer to interventional center in the multivariable model.

      Statistical analysis was performed using R statistical software (R Foundation for Statistical Computing, Vienna, Austria), version 4.2.0, with the VGLM function from the ‘VGAM’ package.

      Results

      Of 2916 patients who underwent EVT included in this study, 50.7% were female and the median age was 74 years (IQR 63–82). The median NIHSS score at admission was 16 (IQR 10–20) and 53.9% of patients were additionally treated with intravenous thrombolysis. Most EVT procedures were performed for middle cerebral artery occlusions (61.9%) and successful recanalization (TICI 2b–3) was achieved in 84.9%.

      Patients treated in core working hours (08:00–13:59) or in the afternoon/evening (14:00–21:59) were slightly older than those treated at night-time (22:00–07:59); otherwise, no baseline differences were found including sex, stroke risk factors, history of stroke, type of vessel occlusion and NIHSS at admission. Intravenous thrombolysis was more frequently performed at night-time and strokes with unknown onset were more frequently treated in core working hours (table 1).

      View this table:
      Table 1

      Clinical characteristics, acute stroke treatment and outcome at different times of day in Austrian patients who underwent EVT

      Treatment times and peri-interventional data

      Compared with patients treated in core working hours, patients treated in the afternoon/evening or at night-time had comparable symptom onset-to-door times. However, patients treated outside of core working hours had significantly longer door-to-groin times (mean delay 8 min in the afternoon/evening and 18 min at night-time, p=0.004). There was no difference in door-to-imaging and groin-to-recanalization times. Overall, symptom-to-recanalization times were longer outside core working hours (mean delay 22 min in the afternoon/evening and 34 min at night-time compared with core working hours, p<0.001, table 1). Figure 1 shows procedural time metrics in relation to working hours. In a sub-analysis investigating time metrics in higher-volume (≥100 EVT performed per year) and lower-volume centers (<100 EVT performed per year), delays in door-to-groin and symptom onset-to-recanalization times outside of core working days were found to be similar (all p<0.01).

      Figure 1
      Figure 1

      Graphic depiction of treatment times in different time windows.

      Recanalization status was comparable between different treatment time windows. Furthermore, we found no difference in the number of passes or peri-interventional complications (table 1).

      Functional outcome

      At discharge from the stroke unit, median NIHSS scores were higher in patients treated outside core working hours (median 6 (core hours) vs 7 (afternoon/evening) vs 9 (night-time); p<0.001), while differences in dichotomized mRS proportions (0–2 vs 3–6) were not significant (p=0.13).

      Follow-up data at 3 months post-stroke were available in 2255 (77.3%) patients. Patients treated outside core working hours had a worse clinical outcome 3 months post-stroke in univariable analysis (mRS 0–2 in 42.6% of patients treated within core working hours compared with 36.1% and 35.8% in those treated in the afternoon/evening or at night-time; p=0.007, table 1).

      In multivariable ordinal shift analysis, patients treated at night-time had a higher risk for a worse outcome 3 months post-stroke according to the mRS (OR 1.28 for unfavorable outcome, 95% CI 1.05 to 1.50), while those treated within core working hours had a better outcome (OR 0.85, 95% CI 0.71 to 1.00, figure 2). A sensitivity analysis that further corrected for a secondary transfer to EVT did not change these results.

      Figure 2
      Figure 2

      Multivariable ordinal shift analysis model regarding common odds ratio (OR) for worse modified Rankin Scale scores 3 months post-stroke (ordinal logistic regression adjusted for age, sex, hypertension, diabetes, hyperlipidemia, atrial fibrillation, coronary heart disease, National Institutes of Health Stroke Scale score at admission, intravenous thrombolysis and stroke of unknown onset) across all EVT start time cohorts. EVT, endovascular therapy.

      Analysis of equally sized treatment time windows

      Compared with the investigation of the three pre-determined time windows, analysis of 12 time windows with an equal number of patients showed similar results.

      Door-to-groin times were shortest in the morning (median 66 and 67 min at 09:52–10:59 and 08:00–09:51) and significantly longer in the evening and at night-time (with median times between 81 and 91 min between different time windows), as was symptom-to-recanalization time (median 211 min at 08:00–09:51, median 267 min both at 20:40–22:39 and 01:34–07:59). Again, we found no differences in symptom onset-to-door time or groin-to-recanalization time (table 2).

      View this table:
      Table 2

      Clinical characteristics, acute stroke treatment and outcome in 12 time windows with equal patient numbers

      The highest rate of favorable outcome (mRS 0–2 3 months post-stroke) was found in patients treated at 08:00–09:51 (50.8%), followed by other time windows in the morning and early afternoon. Patients treated in the evening or at night-time had lower rates of favorable outcome (29% at 17:20–18:49, 31.4% at 18:50–20:39 and 33.3% at 01.34–07:59, table 2).

      In multivariable ordinal shift analysis, patients treated after 15:30 had worse mRS scores 3 months post-stroke (most pronounced at 17:20–18:49, 18:50–20:39 and 01:34–07:59), while patients treated within core working hours tended to have a better outcome (figure 2).

      Weekdays versus weekend

      In an additional analysis we investigated differences between treatment on weekdays versus weekends. We identified no differences regarding clinical factors, treatment times, peri-interventional data and functional outcome (online supplemental table 1). While we found similar effects of time of day on weekdays compared with the overall study cohort (online supplemental table 2), these were not present on weekends (online supplemental table 3).

      Discussion

      In this nationwide analysis of the influence of time of day on outcome and procedural parameters in Austrian patients with stroke receiving EVT, we found that patients treated outside core working hours had slower in-hospital treatment workflows and worse functional neurological outcome. These two factors are probably directly related, as faster treatment times go along with better outcome in stroke patients treated with EVT.13 20

      While we found no significant differences in prehospital (time from symptom onset to hospital arrival), early in-hospital (time of arrival to first imaging) and EVT procedural (time from groin puncture to recanalization) time metrics, door-to-groin time was longer in patients outside core working hours, especially during night-time. Numerous reasons may be related to this, including workflow issues either in the emergency department, in interdisciplinary discussion of EVT indication as well as slower availability of anesthesiologic and neurointerventional specialists. Furthermore, slower communication or transfer times between and within hospitals if a secondary transfer to an EVT-capable center is necessary may contribute. While Austria has a tight stroke unit system enabling ready access to dedicated stroke treatment by ground or helicopter transport all over the mountainous country, helicopters—which may be used for secondary transfer of stroke patients in more rural regions21—are limited off-hours as only a few are capable of night flight. The need for a secondary transfer alone did not influence the outcome in a sensitivity analysis.

      Importantly, we found no differences in peri-interventional results including the number of passes, recanalization success, peri-/post-interventional complications and anesthesia technique between different treatment time windows. This indicates that the quality of the EVT procedure itself does not appear to be impaired outside core working hours. Previous studies on the influence of off-hours effects in patients with stroke treated with EVT showed variable results. While a meta-analysis showed delays in all treatment stages and lower recanalization rates in patients treated off-hours,6 these results need to be interpreted with caution as this analysis included studies of different methodologies and settings (eg, treatment in the pre-2015 EVT era, single high-volume centers opposed to regional registries, etc). Our study in the setting of a countrywide registry where EVT is established and available 24/7/365 is probably best comparable to a recently published study from two Swiss high-volume centers,10 which found better functional outcome in patients with stroke treated in the morning, similar to our results. This study actually identified longer time from symptom onset to recanalization in the morning, which can be explained by the different study methodology regarding patients with stroke of unknown onset, who are most frequently treated in this time window. While the Swiss study counted the time of last seen well10 (leading to much longer treatment times), we did not analyze the onset-to-treatment times in patients with unknown onset.

      A second recent Swiss study which investigated more general aspects of acute ischemic stroke treatment in a countrywide study population similarly found longer door-to-imaging, door-to-needle and door-to-groin times in patients with acute stroke outside core working hours. Corresponding to our results, patients admitted outside core working hours had worse functional outcome and higher mortality, although this referred to a general ischemic stroke cohort and was not focused on EVT, as our study.22

      The European Action Plan for Stroke defined a target of median onset-to-reperfusion times of <200 min in endovascular stroke treatment to be reached in 2030.23 Additional efforts will need to be taken to achieve this target and our study may help to point towards factors that have potential for improvement in order to reach it.

      Strengths of our study include the analysis of consecutively registered stroke patients from a nationwide well-established stroke unit/EVT network. However, we could not meaningfully correct for center effects and, although we were able to identify the broader pillar of the acute stroke treatment chain responsible for delays outside of core working hours, we were unable to investigate reasons for delayed treatment times in more detail (also with regard to the time neurointerventional specialists need to get to the hospital in case they are on call at home). About one-fifth of our study population had no 3-month follow-up data available, but differences in functional outcome were similarly found both at discharge from the stroke unit compared with after 3 months. Due to the study design, some variables of potential interest such as the Alberta Stroke Program Early CT Score or collateral circulation could not be investigated. Circadian biological factors might play a role in stroke pathophysiology and therefore different outcome at distinct times of day,24 and could not be investigated further apart from correcting for comorbidities, atrial fibrillation and stroke severity.

      Conclusion

      In this nationwide observational study we found significantly slower in-hospital treatment workflows translating into worse functional outcomes in patients treated with EVT in the evening and night-time. EVT treatment times outside core working hours need to be improved in order to reach equal treatment speed and functional outcome to that within regular working hours, with workflows within the emergency departments, at the intersection to neurointervention and between transferring hospitals being the main potential targets.

      Supplemental material

      Data availability statement

      Data are available upon reasonable request. The datasets generated during this study are available from the corresponding author upon reasonable request.

      Ethics statements

      Patient consent for publication

      Ethics approval

      The registry is part of a governmental quality assessment program for stroke care in Austria financed by the Federal Ministry of Social Affairs, Health, Care and Consumer Protection and based on federal law promoting quality in health. Anonymized data are centrally administered by the Austrian National Public Health Institute, and scientific analyses are approved and supervised by an academic review board (no reference ID system used). As this was a registry study based on federal law promoting quality in health, individual patient consent was waived.

      Acknowledgments

      We thank all Austrian stroke unit registry collaborators.

      References

      1. ↵
        1. Goyal M,
        2. Menon BK,
        3. van Zwam WH, et al
        . Endovascular thrombectomy after large-vessel ischaemic stroke: a meta-analysis of individual patient data from five randomised trials. Lancet 2016;387:1723–31. doi:10.1016/S0140-6736(16)00163-X
        OpenUrlCrossRefPubMed
      2. ↵
        1. Abilleira S,
        2. de Sousa DA,
        3. Gattringer T, et al
        . Planning of stroke care and urgent prehospital care across Europe: results of the ESO/ESMINT/EAN/SAFE survey. Eur Stroke J 2019;4:329–36. doi:10.1177/2396987319837106
        OpenUrl
      3. ↵
        1. Aguiar de Sousa D,
        2. von Martial R,
        3. Abilleira S, et al
        . Access to and delivery of acute ischaemic stroke treatments: a survey of national scientific societies and stroke experts in 44 European countries. Eur Stroke J 2019;4:13–28. doi:10.1177/2396987318786023
        OpenUrlCrossRefPubMed
      4. ↵
        1. Weddell J,
        2. Parr E,
        3. Knight S, et al
        . Mechanical thrombectomy: can it be safely delivered out of hours in the UK? BMC Neurol 2020;20:326. doi:10.1186/s12883-020-01909-8
      5. ↵
        1. Yan Y,
        2. Hu K,
        3. Alcock S, et al
        . Access to endovascular thrombectomy for stroke in rural versus urban regions. Can J Neurol Sci 2022;49:70–5. doi:10.1017/cjn.2021.35
        OpenUrl
      6. ↵
        1. Zha M,
        2. Yang Q,
        3. Liu S, et al
        . Off-hour effect on time metrics and clinical outcomes in endovascular treatment for large vessel occlusion: a systematic review and meta-analysis. Int J Stroke 2022;17:669–80. doi:10.1177/17474930211012545
        OpenUrl
      7. ↵
        1. Simonsen CZ,
        2. Bösel J,
        3. Rasmussen M
        . Periprocedural management during stroke thrombectomy. Neurology 2021;97(20 Suppl 2):S105–14. doi:10.1212/WNL.0000000000012798
        OpenUrl
      8. ↵
        1. Jadhav AP,
        2. Molyneaux BJ,
        3. Hill MD, et al
        . Care of the post-thrombectomy patient. Stroke 2018;49:2801–7. doi:10.1161/STROKEAHA.118.021640
        OpenUrlCrossRefPubMed
      9. ↵
        1. Potts MB,
        2. Abdalla RN,
        3. Golnari P, et al
        . Analysis of mechanical thrombectomy for acute ischemic stroke on nights and weekends versus weekdays at comprehensive stroke centers. J Stroke Cerebrovasc Dis 2021;30:105632. doi:10.1016/j.jstrokecerebrovasdis.2021.105632
        OpenUrlPubMed
      10. ↵
        1. Hajdu SD,
        2. Kaesmacher J,
        3. Michel PP, et al
        . Association of time of day when endovascular therapy for stroke starts and functional outcome. Neurology 2021;96:e1124–36. doi:10.1212/WNL.0000000000011449
        OpenUrlCrossRefPubMed
      11. ↵
        1. Kaaouana O,
        2. Bricout N,
        3. Casolla B, et al
        . Mechanical thrombectomy for ischaemic stroke in the anterior circulation: off-hours effect. J Neurol 2020;267:2910–6. doi:10.1007/s00415-020-09946-6
        OpenUrlPubMed
      12. ↵
        1. Hinsenveld WH,
        2. de Ridder IR,
        3. van Oostenbrugge RJ, et al
        . Workflow intervals of endovascular acute stroke therapy during on- versus off-hours: the MR CLEAN Registry. Stroke 2019;50:2842–50. doi:10.1161/STROKEAHA.119.025381
        OpenUrlCrossRefPubMed
      13. ↵
        1. Herm J,
        2. Schlemm L,
        3. Siebert E, et al
        . How do treatment times impact on functional outcome in stroke patients undergoing thrombectomy in Germany? results from the German Stroke Registry. Int J Stroke 2021;16:953–61. doi:10.1177/1747493020985260
        OpenUrl
      14. ↵
        1. Serles W,
        2. Gattringer T,
        3. Mutzenbach S, et al
        . Endovascular stroke therapy in Austria: a nationwide 1-year experience. Eur J Neurol 2016;23:906–11. doi:10.1111/ene.12958
        OpenUrlCrossRefPubMed
      15. ↵
        1. Sommer P,
        2. Scharer S,
        3. Posekany A, et al
        . Thrombectomy in basilar artery occlusion. Int J Stroke 2022;17:1006–12. doi:10.1177/17474930211069859
        OpenUrl
      16. ↵
        1. Ferrari J,
        2. Knoflach M,
        3. Kiechl S, et al
        . Early clinical worsening in patients with TIA or minor stroke: the Austrian Stroke Unit Registry. Neurology 2010;74:136–41. doi:10.1212/WNL.0b013e3181c9188b
        OpenUrlCrossRefPubMed
      17. ↵
        1. Stösser S,
        2. Bode FJ,
        3. Meissner JN, et al
        . Outcome of stroke patients with unknown onset and unknown time last known well undergoing endovascular therapy. Clin Neuroradiol July 7, 2022. doi:10.1007/s00062-022-01188-5
      18. ↵
        1. Fischer U,
        2. Kaesmacher J,
        3. Strbian D, et al
        . Thrombectomy alone versus intravenous alteplase plus thrombectomy in patients with stroke: an open-label, blinded-outcome, randomised non-inferiority trial. Lancet 2022;400:104–15. doi:10.1016/S0140-6736(22)00537-2
        OpenUrlPubMed
      19. ↵
        1. Fandler-Höfler S,
        2. Odler B,
        3. Kneihsl M, et al
        . Acute and chronic kidney dysfunction and outcome after stroke thrombectomy. Transl Stroke Res 2021;12:791–8. doi:10.1007/s12975-020-00881-2
        OpenUrl
      20. ↵
        1. Saver JL,
        2. Goyal M,
        3. van der Lugt A, et al
        . Time to treatment with endovascular thrombectomy and outcomes from ischemic stroke: a meta-analysis. JAMA 2016;316:1279–88. doi:10.1001/jama.2016.13647
        OpenUrlCrossRefPubMed
      21. ↵
        1. Reiner-Deitemyer V,
        2. Teuschl Y,
        3. Matz K, et al
        . Helicopter transport of stroke patients and its influence on thrombolysis rates: data from the Austrian Stroke Unit Registry. Stroke 2011;42:1295–300. doi:10.1161/STROKEAHA.110.604710
        OpenUrlAbstract/FREE Full Text
      22. ↵
        1. Altersberger VL,
        2. Wright PR,
        3. Schaedelin SA, et al
        . Effect of admission time on provision of acute stroke treatment at stroke units and stroke centers-an analysis of the Swiss Stroke Registry. Eur Stroke J 2022;7:117–25. doi:10.1177/23969873221094408
        OpenUrl
      23. ↵
        1. Norrving B,
        2. Barrick J,
        3. Davalos A, et al
        . Action plan for stroke in Europe 2018-2030. Eur Stroke J 2018;3:309–36. doi:10.1177/2396987318808719
        OpenUrlPubMed
      24. ↵
        1. Lo EH,
        2. Albers GW,
        3. Dichgans M, et al
        . Circadian biology and stroke. Stroke 2021;52:2180–90. doi:10.1161/STROKEAHA.120.031742
        OpenUrl

      Supplementary materials

      • Supplementary Data

        This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.

      Footnotes

      • Collaborators Austrian EVT Study Group: Wolfgang Serles, Stefan Greisenegger, Martha Marko, Florian Wolf, Christian Kinstner (Medical University of Vienna); Elisabeth Fertl, Peter Sommer, Sandrina Steiner, Rüdiger Schernthaner, Dominic Schauer (Klinik Landstraße, Vienna); Julia Ferrari, Marek Sykora, Stefan Krebs, Siegfried Thurnher, Christian Neumann (Hospital St John of God Vienna); Walter Struhal, Cornelia Brunner, Nilguen Yilmaz-Kaymaz, Christian Našel, Christian Filip (Universitätsklinikum Tulln); Christoph Waiß, Alexander Tinchon, Anna Fischer, Matthias Schilling, Michael Schwarz (Universitätsklinikum St Pölten); Mirja Wallner-Blazek, Thomas Wolf, Peter Schnider, Joachim Kettenbach, Wolfgang Krizmanich (Landesklinikum Wiener Neustadt); Milan R Vosko, Judith Wagner, Tim J von Oertzen, Franz A Fellner, Michael Sonnberger (Kepler University Hospital Linz); Johannes Sebastian Mutzenbach, Nele Bubel, Thomas Zellner, Monika Killer-Oberpfalzer, Erasmia Broussalis (Christian-Doppler-Clinic, Salzburg); Michael Knoflach, Christian Böhme, Lukas Mayer, Elke R Gizewski, Astrid E Grams (Medical University of Innsbruck); Elmar Höfner, Stephan Seiler, Jörg R Weber, Klaus Hausegger, Luca De Paoli (Klinikum Klagenfurt); Christian Enzinger, Thomas Gattringer, Birgit Poltrum, Hannes Deutschmann, Michael Augustin (Medical University of Graz); Dimitre Staykov, Almin Halilovic, Michael Frattner, Martin Wehrschütz, Patrick Kinsberger (St John’s of God Hospital, Eisenstadt); Philipp Werner, Andrea Mayr, Benjamin Matosevic, Manfred Cejna, Thomas Haglmüller (State Hospital of Feldkirch/Rankweil).

      • Contributors SF-H and TG conceived the study design, acquired data, interpreted the data and drafted the manuscript. DM performed the statistical analysis and revised the manuscript for important intellectual content. All other authors acquired data and revised the manuscript for important intellectual content. SF-H acts as the guarantor of this article.

      • Funding Research funding was provided by the Austrian Neurological Society and the Austrian Stroke Society.

      • Competing interests None declared.

      • Provenance and peer review Not commissioned; externally peer reviewed.

      • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.