Diana Aguiar de Sousa

Comment Authors: Daniela Pimenta Silva, Diana Aguiar de Sousa, Department of Neurology, Hospital de Santa Maria, University of Lisbon, Portugal

Original Article: McMeekin P., White P., Martin AJ., et al 2017. Estimating the number of UK stroke patients eligible for endovascular thrombectomy. European Stroke Journal. doi: 10.1177/2396987317733343

Implementation of mechanical thrombectomy in clinical practice: defining the target

Growing evidence has shown the effectiveness of endovascular thrombectomy (EVT) in reducing disability in patients presenting with acute ischemic stroke. However, major changes are often required in order to routinely provide this treatment, including a more centralised model of hyperacute stroke care and additional infrastructures and workforce.

In this paper published in the European Stroke Journal, McMeekin and colleagues estimated the proportion of all stroke patients eligible for EVT in order to anticipate the annual demand for this treatment in the UK.

 After assessing the number of patients hospitalised annually with acute stroke, the authors constructed a decision tree model to estimate the proportion of patients eligible to EVT, based upon inclusion and exclusion criteria from published trials. The number of stroke admissions was estimated using the prospective Sentinel Stroke National Audit Programme (SNNAP) and the Scottish Stroke Care Audit (SSCA) for that purpose.

The annual estimate for stroke admissions in the UK is 95,500. The proportion of ischemic strokes caused by large artery occlusion (LAO) was approximately 41%, with 80% of these patients having moderate or severe neurologic deficit (NIHSS 6 or more). These patients would be considered eligible for EVT according to three recent trials (ESCAPE, SWIFT PRIME and MR CLEAN).

Considering time of onset only, the decision tree estimated 24,750 patients (25% of stroke admissions) potentially suitable for EVT. This group included patients with a known time of onset or last seen well within 12 hours (20,740 of admissions) and those with stroke unknown time of onset (SUTO) but last seen well within 12 hours (4,010). At this point, patients were excluded if CT ASPECTS (Alberta Stroke Programme Early CT Score) was less than 6 and a pre-stroke modified Rankin Scale (mRS) was more than 2. Additionally, according to the EXTEND-IA trial and the SONIIA registry, advanced imaging would exclude further 5% of patients because of large volume core and small penumbra. This leaves an EVT eligible population of 9,620 and 2,340 patients per year, amongst the early presenting intravenous thrombolysis (IVT) eligible population and the late presenting/SUTO population, respectively. Finally, 540 patients were excluded because of expected recanalization prior to EVT.

Based on the available evidence from intervention trials and prospective registries in EVT, the authors estimated that 9,140-10,920 patients with acute ischemic stroke in the UK were eligible for EVT annually, i.e. approximately 10% of strokes admitted to hospital. The selection of patients by advanced imaging based upon current best evidence would exclude 5% of the patients presenting early, but would include 56% of late presenters. Although the little impact on the overall requirement for EVT, it would affect EVT treatment decisions in approximately 15% of cases.

According to the results of this study, as well as the benefits estimated in a recent meta-analysis1, an EVT national coverage in the UK could provide independent functional outcomes to more 2420 patients annually. This means over £22 million (€27 million at 2014 exchange rates) savings over the 12 months post-stroke, considering the mean monthly cost of £790 (980€ at 2014 exchange rates) to the UK National Health Service and social care providers of caring for people who lose their independence because of stroke. Therefore, despite the higher costs of providing EVT, the annual saving in the UK are estimated in £73 million over patient’s lifetimes.

Given the magnitude of the potential clinical and wider economic benefits from EVT, widespread implementation of this treatment must be a key priority. The robust estimates of this study should contribute to an accurate planning of stroke care in the UK and across Europe.

The original article “Estimating the number of UK stroke patients eligible for endovascular thrombectomy” is available in the Online First section of the European Stroke Journal.

McMeekin P., White P., Martin AJ., et al 2017. Estimating the number of UK stroke patients eligible for endovascular thrombectomy. European Stroke Journal. doi: 10.1177/2396987317733343

1Campbell BCV, Hill MD, Rubiera M, et al. Safety and efficacy of solitaire stent thrombectomy individual patient data meta-analysis of randomized trials. Stroke 2016; 47: 798–806.