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Optimizing prehospital acute stroke care in the presence of economic constraints
Linköping University, Department of Health, Medicine and Caring Sciences, Division of Society and Health. Linköping University, Faculty of Medicine and Health Sciences.ORCID iD: 0000-0002-1715-8862
2024 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Mechanical thrombectomy (MT) has become standard of care for acute anterior circulation ischaemic stroke due to large vessel occlusion since the launch of second-generation stent retrievers for clinical use nearly a decade ago. Up until recently, the treatment was exclusively performed at university hospitals in Sweden. Sundsvall Regional Hospital joined as the eighth treatment facility in late 2023. Scarce resources of healthcare systems across the world hamper the complete implementation of MT in acute stroke care. Hence, efforts to improve patients’ accessibility to and healthcare providers’ utilization of MT remain prioritized. Methods for determining the optimal number and locations of treatment facilities for MT in economically constrained healthcare systems remain unstudied. The optimal number and locations of ambulance helicopters for prehospital transportation of patients with presumed acute stroke too. The aim of the thesis is to solve constrained optimization problems within the framework of cost-effectiveness analysis for prehospital acute stroke care management of patients with AIS.   

To fill these knowledge gaps, this thesis takes on an interdisciplinary research approach, and combines health economics, operations research, and medicine to identify cost-effective solutions for location problems with respect to the implementation of MT in the Swedish healthcare system. A comprehensive set of consolidated data based on anonymized, patient-level, nation-wide registry data for a study period of six years underlies analyses. This thesis employs predictive modelling, geographic network analysis, optimization, and decision modelling for economic evaluation within the framework of cost-effectiveness analysis to identify the most cost-effective solutions to implement.    

The fitting of predictive generalized linear models to four treatment modalities in acute stroke care for patients with acute ischaemic stroke established the linear associations in absolute effect measures between the modified Rankin Scale score at 90 days post-stroke and the time from symptom onset to treatment start with intravenous thrombolysis only, MT only and intravenous thrombolysis plus MT, respectively. With imposed economic constraints, the analysis identified the optimal number and locations of thrombectomy centres for the Swedish healthcare system. Furthermore, it identified the optimal number and locations of ambulance helicopters too. Finally, it was possible to determine the combination of optimally located thrombectomy centres and ambulance helicopters that comprises the most cost-effective solution to implement into the Swedish stroke system of care.   

This thesis demonstrates that economically constrained optimization of thrombectomy centres and ambulance helicopters in acute stroke systems of care comprises highly cost-effective solutions that entail immense health gains in patients with acute ischaemic stroke. Health economics, operational research and medicine can be combined to create a powerful decision-modelling tool in the evaluation of implementation strategies for prehospital acute stroke systems of care. 

Abstract [sv]

Mekanisk trombektomi (MT) under det senaste decenniet etablerats som standardbehandling av patienter som drabbas av akut ischemisk stroke (AIS) till följd av blodpropp i ett av de större blodkärlen i hjärnans främre cirkulation. Den endovaskulära reperfusionsbehandlingen har fram tills nyligen enbart utförts på universitetssjukhus i Sverige. I slutet av år 2023 anslöt sig Sundsvalls sjukhus som det åttonde trombektomicentret i Sverige. Trots att trombektomi anses utgöra en kostnadseffektiv tilläggsintervention vid akut behandling av patient med AIS, har dess fullskaliga implementering i sjukvårdssystem världen över uteblivit; initiativ som syftar till att öka patienters tillgång till trombektomi kvarstår som ett prioriterat område, liksom dess rutinmässiga användning i klinisk praxis. Trots det saknas metoder för att fastställa antalet optimalt placerade trombektomicenter som utgör den mest kostnadseffektiva implementering av trombektomi i sjukvårdssystem som begränsas av knappa resurser.  Likaså saknas metoder för att fastställa antalet optimalt placerade ambulanshelikoptrar som utgör den mest kostnadseffektiva lösningen för patienttransporter vid prehospitalt omhändertagande av patient vid misstanke om akut stroke. Således syftar avhandlingen till att producera ekonomiskt begränsade lösningar på optimieringsproblem för prehospitalt akut omhändertagande av patient med AIS utifrån ett kostnadseffektivitetsperspektiv.   

Avhandlingen kombinerar hälsoekonomi, operationsanalys och medicinsk vetenskap i en interdisciplinär ansats för att fylla kvarstående kunskapsluckor och identifiera de mest kostnadseffektiva lösningarna på lokaliseringsproblem för en nationellt koordinerad implementering av trombektomi i det svenska hälso- och sjukvårdssystemet. Analyser baseras på konsoliderad, anonymiserade patientdata på individnivå som inhämtats från nationella patientregister och som omfattar en studieperiod på sex år.  

Avhandlingen tillämpar prediktiv modellering, geografisk nätverksanalys, optimering, och beslutsmodellering inom ramen för kostnadseffektivitetsanalys för att identifiera de mest kostnadseffektiva lösningarna att implementera i svensk hälso- och sjukvård.   

Anpassningen av prediktiva modeller till fyra olika behandlingsmodaliteter inom akutstrokesjukvård av patienter med akut ischemisk stroke kunde med absoluta effektmått formulera linjära samband mellan patienters hälsoutfall vid tre månader efter insjuknandet med tiden som förlöpt från insjuknande till behandlingsstart för respektive behandlingsmodalitet med akut reperfusionsterapi, det vill säga trombolys, trombektomi respektive kombinerad trombolys och trombektomi. I analys kunde det optimala antalet och placeringarna av trombektomicenter i Sverige givet ekonomiska restriktioner identifieras. På likande vis kunde även det optimala antalet och placeringarna av ambulanshelikoptrar identifieras. Slutligen kunde analysen fastställa det kombinerade antal optimalt placerade trombektomicenter och ambulanshelikoptrar som utgör den mest kostnadseffektiva implementeringslösningen för svensk akutstrokesjukvård.

Avhandlingen påvisar att det finns mycket kostnadseffektiva lösningar på optimeringsproblem med påförda ekonomiska restriktioner för lokalisering av trombektomicenter och ambulanshelikoptrar inom akutstrokesjukvård. Lösningarna medför även stora hälsovinster för patienter med AIS. Den interdisciplinära kombinationen av hälsoekonomi, operationsanalys, och medicin utgör ett kraftfullt modelleringsverktyg vid ekonomisk utvärdering av implementationsstrategier för prehospital akutstrokesjukvård.    

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2024. , p. 51
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1882
National Category
Cardiac and Cardiovascular Systems
Identifiers
URN: urn:nbn:se:liu:diva-201903DOI: 10.3384/9789180753982ISBN: 9789180753975 (print)ISBN: 9789180753982 (electronic)OAI: oai:DiVA.org:liu-201903DiVA, id: diva2:1847043
Public defence
2024-01-29, Campus US, Linköping, 09:00 (English)
Opponent
Supervisors
Available from: 2024-03-26 Created: 2024-03-26 Last updated: 2024-03-27Bibliographically approved
List of papers
1. Prediction modelling the impact of onset to treatment time on the modified Rankin Scale score at 90 days for patients with acute ischaemic stroke
Open this publication in new window or tab >>Prediction modelling the impact of onset to treatment time on the modified Rankin Scale score at 90 days for patients with acute ischaemic stroke
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2022 (English)In: BMJ Neurology Open, ISSN 2632-6140, Vol. 4, no 2, article id e000312Article in journal (Refereed) Published
Abstract [en]

Introduction Shortening the time from stroke onset to treatment increases the effectiveness of endovascular stroke therapies. Aim This study aimed to predict the modified Rankin Scale score at 90 days post-stroke (mRS-90d score) in patients with acute ischaemic stroke (AIS) with respect to four types of treatment: conservative therapy (CVT), intravenous thrombolysis only (IVT), mechanical thrombectomy only (MT) and pretreatment with IVT before MT (IVT+MT). Patients and methods This nationwide observational study included 124 484 confirmed cases of acute stroke in Sweden over 6 years (2012-2017). The associations between onset-to-treatment time (OTT), patient age and hospital admission National Institutes of Health Stroke Scale (NIHSS) score with the five-levelled mRS-90d score were retrospectively studied. A generalised linear model (GLM) was fitted to predict the mRS-90d scores for each patient group. Results The fitted GLM for CVT patients is a function of age and NIHSS score. For IVT, MT and IVT+MT patients, GLMs additionally employed OTT variables. By reducing the mean OTTs by 15 min, the number needed-to-treat (NNT) for one patient to make a favourable one-step shift in the mRS was 30 for IVT, 48 for MT and 21 for IVT+MT. Discussion and conclusion This study demonstrates linear associations of mRS-90d score with OTT for IVT, MT and IVT+MT, and shows in absolute effects measures that OTT reductions for IVT and/or MT produces substantial health gains for patients with AIS. Even moderate OTT reductions led to sharp drops in the NNT.

Place, publisher, year, edition, pages
BMJ Publishing Group, 2022
Keywords
statistics; stroke; interventional; MRS
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:liu:diva-188152 (URN)10.1136/bmjno-2022-000312 (DOI)000844209800003 ()
Note

Funding Agencies|Center for Advanced Research in Emergency Response (CARER) at Linkoping University, Sweden; Region Ostergotland, Sweden

Available from: 2022-09-06 Created: 2022-09-06 Last updated: 2024-03-26
2. Optimized density and locations of stroke centers for improved cost effectiveness of mechanical thrombectomy in patients with acute ischemic stroke
Open this publication in new window or tab >>Optimized density and locations of stroke centers for improved cost effectiveness of mechanical thrombectomy in patients with acute ischemic stroke
2024 (English)In: JOURNAL OF NEUROINTERVENTIONAL SURGERY, ISSN 1759-8478, Vol. 16, p. 156-162Article in journal (Refereed) Published
Abstract [en]

BackgroundDespite the proven cost effectiveness of mechanical thrombectomy (MT) in patients with acute ischemic stroke (AIS) due to large vessel occlusion, treatment within 6 hours from symptom onset remains inaccessible for many patients. We aimed to find the optimal number and location of treatment facilities with respect to the cost effectiveness of MT in patients with AIS, first by the most cost effective implementation of comprehensive stroke centers (CSCs), and second by the most cost effective addition of complementary thrombectomy capable stroke centers (TSCs). MethodsThis study was based on nationwide observational data comprising 18 793 patients with suspected AIS potentially eligible for treatment with MT. The most cost effective solutions were attained by solving the p median facility location-allocation problem with the objective function of maximizing the incremental net monetary benefit (INMB) of MT compared with no MT in patients with AIS. Deterministic sensitivity analysis (DSA) was used as the basis of the results analysis. ResultsThe implementation strategy with seven CSCs produced the highest annual INMB per patient of all possible solutions in the base case scenario. The most cost effective implementation strategy of the extended scenario comprised seven CSCs and four TSCs. DSA revealed sensitivity to variability in MT rate and the maximum willingness to pay per quality adjusted life year gained. ConclusionThe combination of optimization modeling and cost effectiveness analysis provides a powerful tool for configuring the extent and locations of CSCs (and TSCs). The most cost effective implementation of CSCs in Sweden entails 24/7 MT services at all seven university hospitals.

Place, publisher, year, edition, pages
BMJ PUBLISHING GROUP, 2024
Keywords
intervention; stroke; thrombectomy; thrombolysis; economics
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:liu:diva-194182 (URN)10.1136/jnis-2023-020299 (DOI)000981480100001 ()37072170 (PubMedID)2-s2.0-85160234118 (Scopus ID)
Note

Funding Agencies|Center for Advanced Research in Emergency Response (CARER) at Linkoeping University, Sweden; Region Ostergotland, Sweden

Available from: 2023-05-31 Created: 2023-05-31 Last updated: 2024-04-11

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Ennab Vogel, Nicklas

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