Meta-Analysis of Emergency Embolectomy for Acute Thrombotic Stroke

Previous posts have reported positive results from a number of trials of intra-cranial, endovascular thrombectomy for acute stroke.[1] [2] One of the problems with individual trials is that they are powered to detect mean effects across a broad population, rather than more finely-grained effects in sub-groups. In total five high-quality trials of embolectomy have now been reported, thereby providing an opportunity to study effects by sub-group. Sub-groups are often defined differently across trials, but this problem can be overcome by pooling individual patient data across trials and applying a common definition for the sub-groups. This has now been done with respect to all 1,287 participants in the above five cerebral artery embolectomy trials.[3] The rather spectacular results in reducing the severity of disability at 90 days were replicated – only 2.6 patients would need to be tested to reduce the disability score by a clinically-relevant one point. Treatment was similarly effective across all sub-groups, including age over 80 and (perhaps surprisingly) a delay of over three hours between symptom onset and treatment. While the above study was based on five pivotal trials, a further meta-analysis, based on less stringent criteria for inclusion uncovered a total of ten trials, and reached similar conclusions.[4] This latter study combined aggregate data from the individual trials (i.e. it was not based on individual patient data).

It is proposed that the CLAHRC collaborate with the Commissioning Support Unit to model the service implications of these provocative findings.[1] [2]

— Richard Lilford, CLAHRC WM Director

References:

1. Lilford R. First the Heart, Now the Brain. NIHR CLAHRC WM News Blog. 10 April 2015.
2. Lilford R. Provocative Idea for Thrombectomy Services in Acute Stroke. NIHR CLAHRC West Midlands News Blog. 14 August 2015.
3. Goyal M, Menon BK,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.
4. Rodrigues FB, Neves JB, Caldeira D, et al. Endovascular treatment versus medical care alone for ischaemic stroke: systematic review and meta-analysis. BMJ. 2016; 353: i754.

Provocative Idea for Thrombectomy Services in Acute Stroke

In a previous post the CLAHRC WM Director argued that further rationalisation of acute stroke units would be necessary to provide rapid access to thrombectomy, not just clot busting therapy, for acute stroke. But another intriguing idea would be to integrate cardiac and neurological thrombolysis, cutting across tribal lines, as suggested by Apps and colleagues.[1] We think a modelling exercise is needed considering:

1. Likely patient demand as the number of centres increases or decreases across the country.
2. The costs of kitting up and staffing integrated versus independent units.

The model may show that more stroke thrombectomy units are cost-effective when they can be integrated with cardiac thrombectomy. Tim Jones, Director of Delivery at the University Hospitals Birmingham NHS Foundation Trust, goes further and thinks a general vascular intervention service should be considered. Our CLAHRC proposes such a modelling study to seek the most efficient and acceptable solution. We seek collaborators.

— Richard Lilford, CLAHRC WM Director

Reference:

1. Apps A, Firoozan S, Kabir T. Delivering thrombectomy for acute stroke using cardiology services. BMJ. 2015; 351: h3969.