The route to success – Transport network planning for acute ischaemic stroke
Comment Authors: Mónica Ferreira dos Santos, Diana Aguiar de Sousa, Department of Neurology, Hospital de Santa Maria, University of Lisbon, Portugal
Original Article: Holodinsky JK, Patel AB, Thornton J et al, 2018; Drip ´N ship versus direct to endovascular thrombectomy: The impact of treatment times on transport decision-making; European Stroke Journal; DOI: 10.1177/2396987318759362
Fast reperfusion with intravenous thrombolysis or endovascular treatment (EVT) is essential to improve disability free survival in ischaemic stroke care, but the latter is only available in selected centres. A small percentage of patients with suspected ischaemic stroke are eligible for EVT, but few patients with large vessel occlusion achieve recanalization with thrombolysis alone. And the question remains: does the direct transport to an EVT centre (mothership model) outweighs the benefits of early thrombolysis in a closer centre (drip-and-ship model)?
In this paper, the authors used conditional probability modelling techniques, applied to the Irish Healthcare System, to explore patient transport models in a geographic area and how changes in treatment times would impact transport decisions.
Using data from the National Stroke Register and a local EVT registry, the authors created models to assess in which conditions drip-and-ship and mothership are associated with greater probability of good outcome. They also investigated how an extra EVT centre in Ireland would influence outcome. The models included the probability of achieving reperfusion, time from onset to reperfusion and the probability of achieving a good outcome (mRS 0-2 at 90 days). Data from 699 patients treated with alteplase and 312 patients treated with EVT (258 of these patients were dripped and shipped) was used.
The median door-to-needle (DTN) time was 75 minutes. The median door-to-puncture (DTP) time was 100 minutes in the mothership patients, and only 10 minutes in the drip and ship patients. This study showed that, using real treatment times, drip-and-ship and mothership strategies were approximately equivalent in most of Ireland. The exceptions were regions where the thrombolysis centre was in the opposite direction of the EVT centre, and when another EVT centre was added to the models, making mothership the best choice for outcome.
However, when optimizing treatment times using the model, the best option varies. If we are fast enough at performing intravenous thrombolysis at the first centre (median DTN time=30min, median turnaround time=30min, median door-in-door-out time=60min), drip and ship model becomes the best choice in most regions.
On the other hand, using real intravenous thrombolysis times, if we are fast enough at achieving femoral puncture in the EVT centre (median DTP time=60min), mothership becomes the best model, even when there was only one operational EVT centre in the country. The same happens when the DTP and the turnaround time are decreased, leaving the DTN at baseline values. However, “mothershipping” all patients means that the EVT centre will receive a greater proportion of unselected patients not eligible for EVT, and the centre needs to be able to handle the additional workload without compromising the EVT treatment times. This may be why, if all treatment times are optimized, drip and ship model remains the best model in the majority of the country, as it allows for early imaging and specialist consultation, including quick treatment of patients who are not eligible for EVT (intravenous thrombolysis).
Although this can serve as a useful model for other major metropolitan areas, several assumptions may limit its generalizability: large vessel occlusions should be identified in the field; air transport is not considered; and the data source doesn’t capture all ischaemic strokes in the period of study.
We are still facing the beginning of a new era of advanced stroke treatment and medical infrastructures and stroke systems of care will continue to evolve and mature. Although the best organisational approach to improve stroke outcome is likely to differ according to health care systems and local geographic features, cooperation between stroke units and comprehensive centres should continue to play a pivotal role.
The original article “Drip ‘N ship versus direct to endovascular thrombectomy: The impact of treatment times on transport decision-making” is available in the Online First section of the European Stroke Journal.
References:
Holodinsky J, Patel AB, Thornton J et al. Drip ‘N ship versus direct to endovascular thrombectomy: The impact of treatment times on transport decision-making. European Stroke Journal 2018. doi: 10.1177/2396987318759362
