What is the best imaging strategy for acute stroke?

198 Pages·2004·0.91 MB·English

Health Technology Assessment 2004;Vol. 8: No. 1
Methodology
What is the best imaging strategy for
acute stroke?
JM Wardlaw, SL Keir, J Seymour, S Lewis,
PAG Sandercock, MS Dennis and J Cairns
January 2004
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What is the best imaging strategy for
acute stroke?
1* 1 2 1
JM Wardlaw, SL Keir, J Seymour, S Lewis,
1 1 2
PAG Sandercock, MS Dennis and J Cairns
1 Department of Clinical Neurosciences, Western General Hospital
(University of Edinburgh), Edinburgh, UK
2 Health Economics Research Unit, University of Aberdeen, UK
* Corresponding author
Declared competing interests of authors:see Appendix 11.
Published January 2004
This report should be referenced as follows:
Wardlaw JM, Keir SL, Seymour J, Lewis S, Sandercock PAG, Dennis MS, et al. What is the
best imaging strategy for acute stroke? Health Technol Assess2004;8(1).
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Health Technology Assessment2004; Vol. 8: No. 1
Abstract
What is the best imaging strategy for acute stroke?
JM Wardlaw,1* SL Keir,1 J Seymour,2 S Lewis,1 PAG Sandercock,1 MS Dennis1 and
J Cairns2
1Department of Clinical Neurosciences, Western General Hospital (University of Edinburgh), Edinburgh, UK
2Health Economics Research Unit, University of Aberdeen, Aberdeen, UK
* Corresponding author
Objectives: To determine the cost-effectiveness of suggests that the frequency of primary intracerebral
computed tomographic (CT) scanning after acute haemorrhage (PICH) has been underestimated. Aspirin
stroke. To assess the contribution of brain imaging to increases the risk of PICH. There were no reliable data
the diagnosis and management of stroke, and to on functional outcome or on the effect of
estimate the costs, benefits and risks of different antithrombotic treatment given long term after PICH.
imaging strategies in order to provide data to inform In 60% of patients with recurrent stroke after PICH,
national and local policy on the use of brain imaging in the cause is another PICH and mortality is high among
stroke. PICH patients. A specific MR sequence (gradient echo)
Design: A decision-analysis model was developed to is required to identify prior PICH reliably. CT scanners
represent the pathway of care in acute stroke using were distributed unevenly in Scotland, 65% provided
‘scan all patients within 48 hours’ as the comparator CT scanning within 48 hours of stroke, and 100%
against which to cost 12 alternative scan strategies. within 7 days for hospital-admitted patients, but access
Setting: Hospitals in Scotland. out of hours was very variable, and for outpatients was
Participants: Subjects were patients admitted to poor. The average cost of a CT brain scan for stroke
hospital with a first stroke and those managed as was £30.23 to £89.56 in normal working hours and
outpatients. £55.05 to £173.46 out of hours. Average length of stay
Interventions: The effect on functional outcome after was greatest for severe strokes and those who survived
ischaemic or haemorrhagic stroke, tumours or in a dependent state. For a cohort of 1000 patients
infections, of correctly administered antithrombotic or aged 70–74 years, the policy ‘scan all strokes within 48
other treatment; of time to scan and stroke severity on hours’, cost £10,279,728 and achieved 1982.3 QALYS.
diagnosis by CT or MRI; on management, including The most cost-effective strategy was ‘scan all
length of stay, functional outcome, and quality-adjusted immediately’ (£9,993,676 and 1982.4 QALYS). The
life years (QALYs), of the diagnostic information least cost-effective was to ‘scan patients on
provided by CT scanning; the cost-effectiveness (cost anticoagulants, in a life-threatening condition
versus QALYs) of different strategies for use of CT immediately and the rest within 14 days’.
after acute stroke. Conclusions: In general, strategies in which most
Main outcome measures: Death and functional patients were scanned immediately cost least and
outcome at long-term follow-up; accuracy of CT and achieved the most QALYs, as the cost of providing CT
MRI; cost of CT scanning by time of day and week; (even out of hours) was less than the cost of inpatient
effect of CT diagnosis on change in health outcome, care. Increasing independent survival by even a small
length of stay in hospital and QALYs; cost-effectiveness proportion through early use of aspirin in the majority
of various scanning strategies. with ischaemic stroke, avoiding aspirin in those with
Results: CT is very sensitive and specific for haemorrhagic stroke, and appropriate early
haemorrhage within the first 8 days of stroke only. management of those who have not had a stroke,
Suboptimal scanning used in epidemiology studies reduced costs and increased QALYs.
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Health Technology Assessment2004; Vol. 8: No. 1
Contents
List of abbreviations .................................. vii 5 Cost-effectiveness of CT in stroke:
a systematic review of the available
Executive summary .................................... ix evidence, detailed costings and decision
modelling analysis ...................................... 71
1 Background ................................................ 1 Systematic review of previous studies
The burden of stroke: death, disability and of the cost-effectiveness of CT
loss of quality of life ................................... 1 in stroke ...................................................... 71
The cost of stroke ....................................... 1 Development of the cost-effectiveness
Incidence of types of stroke and outcomes .. 2 model and decision tree, including devising
Current primary treatment and secondary a menu of representative scanning
prevention of stroke ................................... 3 strategies ..................................................... 73
The need for brain imaging ...................... 4 Data for the model: probability table,
Reasons for the controversy over CT outcomes and costs .................................... 78
scanning ..................................................... 5 Current provision of CT scanning for
Current standards of care and stroke: questionnaire survey of CT scanning
guidelines ................................................... 7 departments in Scotland linked to
The questions posed in this project ........... 8 population distribution .............................. 100
What information is required to determine Results of the analysis of the
whether CT is cost-effective or not? .......... 8 cost-effectiveness model for CT scanning,
Potential applications of these results ........ 9 and sensitivity analyses ............................... 109
2 The contribution of brain imaging to the 6 Discussion ................................................... 113
diagnosis of stroke: a systematic review of Robustness of the conclusions .................... 113
the accuracy of the clinical diagnosis of Difficulties in undertaking this work ......... 114
stroke ......................................................... 11 Limitations ................................................. 116
Background ................................................ 11 Generalisability of the results ..................... 116
Methods ...................................................... 12 Implications for healthcare ........................ 117
Details of included studies ......................... 13 Implications for research ........................... 118
Details of excluded studies ......................... 15
Results ........................................................ 15 Acknowledgements .................................... 121
Discussion ................................................... 18
Conclusions ................................................ 20 References .................................................. 123
3 The reliability of imaging in the diagnosis Appendix 1 Definitions ............................. 137
of haemorrhage and infarction .................. 21
Systematic descriptive study of the diagnostic Appendix 2 Tables of information sought
accuracy of CT and MR in stroke .............. 21 at start of project, likely sources and
Primary study comparing CT with information contained therein ................... 139
MRI ............................................................ 39
Discussion ................................................... 54 Appendix 3 ICD-9 and ICD-10 codes ...... 143
Conclusions ................................................ 56
Appendix 4 Search strategies for imaging
4 Contribution of brain imaging to and epidemiology ...................................... 145
therapeutic decision-making in stroke ..... 59
Background ................................................ 59 Appendix 5 Search strategies: systematic
Methods ...................................................... 61 review of cost-effectiveness of CT scanning
Details of the included trials ...................... 62 for stroke .................................................... 149
Results ........................................................ 65
Discussion ................................................... 68 Appendix 6 Questionnaire for Scottish CT
Conclusions ................................................ 69 scanning departments ................................ 151 v
Contents
Appendix 7 Current provision of CT Appendix 10 Publications and
scanners in Scotland .................................. 165 presentations .............................................. 177
Appendix 8 Costings of CT scanning Appendix 11 Authors’ declared conflicts of
interest ............................................................ 179
services from three hospitals in Scotland
within normal working hours and out Health Technology Assessment reports
of hours ...................................................... 167 published to date ....................................... 181
Appendix 9 Results of the sensitivity Health Technology Assessment
analysis ....................................................... 173 Programme ................................................ 189
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Health Technology Assessment2004; Vol. 8: No. 1
List of abbreviations
ABN Association of British Neurologists HRQoL health-related quality of life
ACCP American College of Chest HTI haemorrhagic transformation of an
Physicians infarct
AF atrial fibrillation ICH intracerebral haemorrhage
ANOVA analysis of variance ISD Information and Statistics Division
of the Scottish Office
APTT activated partial thromboplastin
time IST International Stroke Trial
ARI Aberdeen Royal Infirmary LACI lacunar infarction
ATT Antithrombotic Trialists’ LACS lacunar syndrome
Collaboration
LOS length of stay
BG basal ganglia
LSR Lothian Stroke Register
BGH Borders General Hospital
MCA middle cerebral artery
CAST Chinese Acute Stroke Trial
MI myocardial infarction
CCTR Cochrane Controlled Trials Register
MR magnetic resonance
CHD coronary heart disease
MRI magnetic resonance imaging
CI confidence interval
mRS modified Rankin scale
CMA Canadian Medical Association
NINDS National Institutes of Neurological
CT computed tomography Diseases and Stroke
DGH district general hospital NSAID non-steroidal anti-inflammatory
drug
DWI diffusion-weighted imaging
OCSP Oxfordshire Community Stroke
DVT deep vein thrombosis
Project
EAC equivalent annual cost
OR odds ratio
ECG electrocardiogram
PACI partial anterior circulation
FLAIR fluid-attenuated inversion recovery infarction
magnetic resonance imaging
PACS partial anterior circulation
FSE T2 T2-weighted fast spin-echo syndrome
FSE fast spin-echo PD proton density-weighted magnetic
resonance imaging
GIS Geographical Information Service
PE pulmonary embolism
GRE gradient echo magnetic resonance
imaging PHV prosthetic heart valve
GROS General Registers Office of Scotland PICH primary intracerebral
haemorrhage
HI haemorrhagic infarction
PMV prosthetic mitral valve
HMCAS hyperdense middle cerebral artery
sign continued
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© Queen’s Printer and Controller of HMSO 2004. All rights reserved.
List of abbreviations
List of abbreviations continued
POCI posterior circulation infarction SRI Stirling Royal Infirmary
POCS posterior circulation syndrome STICH surgical treatment of intracerebral
haemorrhage
QALY quality-adjusted life year
T1 T1-weighted magnetic resonance
RCR Royal College of Radiologists
imaging
RCT randomised controlled trial
T2 T2-weighted magnetic resonance
rt-PA recombinant tissue plasminogen imaging
activator
TACI total anterior circulation
SAH subarachnoid haemorrhage
infarction
SDH subdural haematoma
TACS total anterior circulation
SHPIC Scottish Health Purchasing syndrome
Information Centre
TIA transient ischaemic attack
SIGN Scottish Intercollegiate Guidelines
TTO time trade-off
Network
WHO World Health Organization
SPECT single-photon emission computed
tomography WMHI white matter hyperintensities
All abbreviations that have been used in this report are listed here unless the abbreviation is well known (e.g. NHS), or
it has been used only once, or it is a non-standard abbreviation used only in figures/tables/appendices in which case
the abbreviation is defined in the figure legend or at the end of the table.
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