Secondary transfer of emergency stroke patients eligible for mechanical thrombectomy by air in rural England: economic evaluation and considerations

The impact of large core and late treatment trials: An update on the modelled annual thrombectomy eligibility of UK stroke patients

INTRODUCTION

To support decisions about thrombectomy provision, we have previously estimated the annual UK population eligible for treatment as ∼10% of stroke admissions. Since then, eight further randomised trials that could alter the eligibility rate have reported in 2021-23. We updated our estimates of the eligible population from these trials and other recent studies.

PATIENTS AND METHODS

An updated decision tree describing the EVT eligible population for UK stroke admissions was produced. Decision criteria were derived from the highest level of evidence available. For nodes where no specific RCT data existed, evidence was obtained from the latest systematic review(s) or the highest quality observational data.

RESULTS

We estimate that 15,420 (approximately 15%) of admitted UK stroke patients are now eligible for thrombectomy, or 14,930 if advanced brain imaging using MRI/CT perfusion or collateral assessment were used in all patients. This is a 54% increase in our previous estimate in 2021. Over 50% of LAO strokes are now potentially eligible for thrombectomy. The increase in eligibility is principally due to a much larger cohort of later presenting and/or larger ischaemic core patients.

CONCLUSION

Most previously independent LAO stroke patients presenting within 24 h, even in the presence of a large ischaemic core on initial non-contrast CT, should be considered for thrombectomy with use of advanced brain imaging in those presenting beyond 12 h to identify salvageable penumbral brain tissue. Treatment in most patients remains critically time-dependent and our estimates should be interpreted with this in mind.

Air or Ground Transport to the Critical Care Resuscitation Unit: Does It Really Matter?

OBJECTIVE

Critically ill patients requiring urgent interventions or subspecialty care often require transport over significant distances to tertiary care centers. The optimal method of transportation (air vs. ground) is unknown. We investigated whether air transport was associated with lower mortality for patients being transferred to a specialized critical care resuscitation unit (CCRU).

METHODS

This was a retrospective study of all adult patients transferred to the CCRU at the University of Maryland Medical Center in 2018. Our primary outcome was hospital mortality. The secondary outcomes included the length of stay and the time to the operating room (OR) for patients undergoing urgent procedures. We performed optimal 1:2 propensity score matching for each patient's need for air transport.

RESULTS

We matched 198 patients transported by air to 382 patients transported by ground. There was no significant difference between demographics, the initial Sequential Organ Failure Assessment score, or hospital outcomes between groups. One hundred sixty-four (83%) of the patients transported via air survived to hospital discharge compared with 307 (80%) of those transported by ground (P = .46). Patients transported via air arrived at the CCRU more quickly (127 [100-178] vs. 223 [144-332] minutes, P < .001) and were more likely (60 patients, 30%) to undergo urgent surgical operation within 12 hours of CCRU arrival (30% vs. 17%, P < .001). For patients taken to the OR within 12 hours of arriving at the CCRU, patients transported by air were more likely to go to the OR after 200 minutes since the transfer request (P = .001).

CONCLUSION

The transportation mode used to facilitate interfacility transfer was not significantly associated with hospital mortality or the length of stay for critically ill patients.

Cost-effectiveness of improvement strategies for reperfusion treatments in acute ischemic stroke: a systematic review

BACKGROUND

Reducing delays along the acute stroke pathway significantly improves clinical outcomes for acute ischemic stroke patients eligible for reperfusion treatments. The economic impact of different strategies reducing onset to treatment (OTT) is crucial information for stakeholders in acute stroke management. This systematic review aimed to provide an overview on the cost-effectiveness of several strategies to reduce OTT.

METHODS

A comprehensive literature search was conducted in EMBASE, PubMed, and Web of Science until January 2022. Studies were included if they reported 1/ stroke patients treated with intravenous thrombolysis and/or endovascular thrombectomy, 2/ full economic evaluation, and 3/ strategies to reduce OTT. The Consolidated Health Economic Evaluation Reporting Standards statement was applied to assess the reporting quality.

RESULTS

Twenty studies met the inclusion criteria, of which thirteen were based on cost-utility analysis with the incremental cost-effectiveness ratio per quality-adjusted life year gained as the primary outcome. Studies were performed in twelve countries focusing on four main strategies: educational interventions, organizational models, healthcare delivery infrastructure, and workflow improvements. Sixteen studies showed that the strategies concerning educational interventions, telemedicine between hospitals, mobile stroke units, and workflow improvements, were cost-effective in different settings. The healthcare perspective was predominantly used, and the most common types of models were decision trees, Markov models and simulation models. Overall, fourteen studies were rated as having high reporting quality (79%-94%).

CONCLUSIONS

A wide range of strategies aimed at reducing OTT is cost-effective in acute stroke care treatment. Existing pathways and local characteristics need to be taken along in assessing proposed improvements.

Health economic evaluation of the 'Flying Intervention Team' as a novel stroke care concept for rural areas: study protocol of the TEMPiS-GÖA study

INTRODUCTION

Providing comprehensive stroke care poses major organisational and financial challenges to the German healthcare system. The quasi-randomised TEMPiS-Flying Intervention Team (TEMPiS-FIT) study aims to close the gap in the treatment of patients who had ischaemic stroke in rural areas of Southeast Bavaria by flying a team of interventionalists via helicopter directly to patients in the regional TEMPiS hospitals instead of transporting the patients to the next comprehensive stroke centre. The objective of the present paper is to describe the methods for the economic evaluation (TEMPiS-Gesundheitsökonomische Analyse (TEMPiS-GÖA)) alongside the TEMPiS-FIT study to determine whether the new form of care is cost-effective compared with standard care.

METHODS AND ANALYSIS

The within-trial cost-effectiveness analysis (CEA) and cost-utility analysis (CUA) will be performed from a statutory health insurance perspective as well as from a societal perspective over the time horizon of 12 months after the patients' hospital discharge. Direct costs from outpatient and inpatient care are collected from routine data of the participating health insurance funds, while medical and non-medical costs from a patient's perspective are retrieved from primary data collected during the TEMPiS-FIT study and follow-up questionnaires. Results will be presented as incremental cost-effectiveness ratio and incremental cost-utility ratio quantifying the incremental costs and health benefits compared with standard care practice. The outcome of the CEA will be measured in costs per minute reduction in mean process time to thrombectomy. The outcome of the CUA will be presented as costs per quality-adjusted life year gained.

ETHICS AND DISSEMINATION

Ethical approval for the TEMPiS-FIT study was granted by the Bavarian State Medical Association Ethics Committee (# 17056). Results will be disseminated via reports, presentations of the results in publications and at conferences and on the TEMPiS website.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register DRKS00023885. Registered on 2 July 2021 - retrospectively registered.

Improving emergency treatment for patients with acute stroke: the PEARS research programme, including the PASTA cluster RCT

Background

Intravenous thrombolysis and intra-arterial thrombectomy are proven emergency treatments for acute ischaemic stroke, but they require rapid delivery to selected patients within specialist services. National audit data have shown that treatment provision is suboptimal.

Objectives

The aims were to (1) determine the content, clinical effectiveness and day 90 cost-effectiveness of an enhanced paramedic assessment designed to facilitate thrombolysis delivery in hospital and (2) model thrombectomy service configuration options with optimal activity and cost-effectiveness informed by expert and public views.

Design

A mixed-methods approach was employed between 2014 and 2019. Systematic reviews examined enhanced paramedic roles and thrombectomy effectiveness. Professional and service user groups developed a thrombolysis-focused Paramedic Acute Stroke Treatment Assessment, which was evaluated in a pragmatic multicentre cluster randomised controlled trial and parallel process evaluation. Clinicians, patients, carers and the public were surveyed regarding thrombectomy service configuration. A decision tree was constructed from published data to estimate thrombectomy eligibility of the UK stroke population. A matching discrete-event simulation predicted patient benefits and financial consequences from increasing the number of centres.

Setting

The paramedic assessment trial was hosted by three regional ambulance services (in north-east England, north-west England and Wales) serving 15 hospitals.

Participants

A total of 103 health-care representatives and 20 public representatives assisted in the development of the paramedic assessment. The trial enrolled 1214 stroke patients within 4 hours of symptom onset. Thrombectomy service provision was informed by a Delphi exercise with 64 stroke specialists and neuroradiologists, and surveys of 147 patients and 105 public respondents.

Interventions

The paramedic assessment comprised additional pre-hospital information collection, structured hospital handover, practical assistance up to 15 minutes post handover, a pre-departure care checklist and clinician feedback.

Main outcome measures

The primary outcome was the proportion of patients receiving thrombolysis. Secondary outcomes included day 90 health (poor status was a modified Rankin Scale score of > 2). Economic outputs reported the number of cases treated and cost-effectiveness using quality-adjusted life-years and Great British pounds.

Data sources

National registry data from the Sentinel Stroke National Audit Programme and the Scottish Stroke Care Audit were used.

Review methods

Systematic searches of electronic bibliographies were used to identify relevant literature. Study inclusion and data extraction processes were described using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

Results

The paramedic assessment trial found a clinically important but statistically non-significant reduction in thrombolysis among intervention patients, compared with standard care patients [197/500 (39.4%) vs. 319/714 (44.7%), respectively] (adjusted odds ratio 0.81, 95% confidence interval 0.61 to 1.08; p = 0.15). The rate of poor health outcomes was not significantly different, but was lower in the intervention group than in the standard care group [313/489 (64.0%) vs. 461/690 (66.8%), respectively] (adjusted odds ratio 0.86, 95% confidence interval 0.60 to 1.2; p = 0.39). There was no difference in the quality-adjusted life-years gained between the groups (0.005, 95% confidence interval –0.004 to 0.015), but total costs were significantly lower for patients in the intervention group than for those in the standard care group (–£1086, 95% confidence interval –£2236 to –£13). It has been estimated that, in the UK, 10,140–11,530 patients per year (i.e. 12% of stroke admissions) are eligible for thrombectomy. Meta-analysis of published data confirmed that thrombectomy-treated patients were significantly more likely to be functionally independent than patients receiving standard care (odds ratio 2.39, 95% confidence interval 1.88 to 3.04; n = 1841). Expert consensus and most public survey respondents favoured selective secondary transfer for accessing thrombectomy at regional neuroscience centres. The discrete-event simulation model suggested that six new English centres might generate 190 quality-adjusted life-years (95% confidence interval –6 to 399 quality-adjusted life-years) and a saving of £1,864,000 per year (95% confidence interval –£1,204,000 to £5,017,000 saving per year). The total mean thrombectomy cost up to 72 hours was £12,440, mostly attributable to the consumables. There was no significant cost difference between direct admission and secondary transfer (mean difference –£368, 95% confidence interval –£1016 to £279; p = 0.26).

Limitations

Evidence for paramedic assessment fidelity was limited and group allocation could not be masked. Thrombectomy surveys represented respondent views only. Simulation models assumed that populations were consistent with published meta-analyses, included limited parameters reflecting underlying data sets and did not consider the capital costs of setting up new services.

Conclusions

Paramedic assessment did not increase the proportion of patients receiving thrombolysis, but outcomes were consistent with improved cost-effectiveness at day 90, possibly reflecting better informed treatment decisions and/or adherence to clinical guidelines. However, the health difference was non-significant, small and short term. Approximately 12% of stroke patients are suitable for thrombectomy and widespread provision is likely to generate health and resource gains. Clinician and public views support secondary transfer to access treatment.

Future work

Further evaluation of emergency care pathways will determine whether or not enhanced paramedic assessment improves hospital guideline compliance. Validation of the simulation model post reconfiguration will improve precision and describe wider resource implications.

Trial registration

This trial is registered as ISRCTN12418919 and the systematic review protocols are registered as PROSPERO CRD42014010785 and PROSPERO CRD42015016649.

Funding

The project was funded by the National Institute for Health and Care Research (NIHR) Programme Grants for Applied Research programme and will be published in full in Programme Grants for Applied Research; Vol. 10, No. 4. See the NIHR Journals Library website for further project information.

Anterior circulation large vessel occlusion outcomes in patients transferred from a peripheral primary stroke centre

OBJECTIVES

To identify predictors of functional outcome in patients with an anterior circulation large-vessel occlusion (LVO) in a setting of long transfer distances.

METHODS

Outcomes of LVO patients transferred for an endovascular thrombectomy (EVT) from North Karelia Central Hospital to Kuopio University Hospital between January 2018 and October 2019 were analysed using retrospective patient chart review.

RESULTS

Three months after the stroke, modified Rankin Scale (mRS) was 0-2 in 20 of the 41 transferred patients. They were younger (66.7 vs. 74.2 years, p = 0.032) and had less severe stroke symptoms (National Institutes of Health Stroke Scale, NIHSS, 11.5 vs. 16.5, p = 0.029) than those with mRS 3-6. They also had the occlusion less often in M1 and more often in M2. EVT was performed in 32 patients (no differences between those treated with EVT and those not treated with EVT). Their median age was 73.0 years (interquartile range 65.5, 79.8; range 32-86; 25% over 80), mean NIHSS score 14.0 (standard deviation 5.9) and mRS eventually 0-2 in 44%. Only NIHSS was associated with mRS (OR = 1.16; p = 0.016) in the EVT-treated patients. mRS was 0 in 38% of all EVT-treated octogenarians but 4-6 in 83% of those with an internal carotid artery and/or M1 occlusion.

DISCUSSION

Outcomes depended on stroke severity, age and vessel of occlusion. Prognosis was worse if the occlusion included M1, especially in octogenarians. Mothership and Drip-n-ship strategies should be compared in patients from remote locations stratified by stroke severity and patient age.

National implementation of reperfusion for acute ischaemic stroke in England: How should services be configured? A modelling study

Objectives

To guide policy when planning thrombolysis (IVT) and thrombectomy (MT) services for acute stroke in England, focussing on the choice between ‘mothership’ (direct conveyance to an MT centre) and ‘drip-and-ship’ (secondary transfer) provision and the impact of bypassing local acute stroke centres.

Design

Outcome-based modelling study.

Setting

107 acute stroke centres in England, 24 of which provide IVT and MT (IVT/MT centres) and 83 provide only IVT (IVT-only units).

Participants

242,874 emergency admissions with acute stroke over 3 years (2015–2017).

Intervention

Reperfusion delivered by drip-and-ship, mothership or ‘hybrid’ models; impact of additional travel time to directly access an IVT/MT centre by bypassing a more local IVT-only unit; effect of pre-hospital selection for large artery occlusion (LAO).

Main outcome measures

Population benefit from reperfusion, time to IVT and MT, admission numbers to IVT-only units and IVT/MT centres.

Results

Without pre-hospital selection for LAO, 94% of the population of England live in areas where the greatest clinical benefit, assuming unknown patient status, accrues from direct conveyance to an IVT/MT centre. However, this policy produces unsustainable admission numbers at these centres, with 78 out of 83 IVT-only units receiving fewer than 300 admissions per year (compared to 3 with drip-and-ship). Implementing a maximum permitted additional travel time to bypass an IVT-only unit, using a pre-hospital test for LAO, and selecting patients based on stroke onset time, all help to mitigate the destabilising effect but there is still some significant disruption to admission numbers, and improved selection of patients suitable for MT selectively reduces the number of patients who would receive IVT at IVT-only centres, challenging the sustainability of IVT expertise in IVT-only centres.

Conclusions

Implementation of reperfusion for acute stroke based solely on achieving the maximum population benefit potentially leads to destabilisation of the emergency stroke care system. Careful planning is required to create a sustainable system, and modelling may be used to help planners maximise benefit from reperfusion while creating a sustainable emergency stroke care system.