7/21/2019 MRI Abstract

http://slidepdf.com/reader/full/mri-abstract 1/1

Cost-Effectiveness of Rapid Sequence MRI for Diagnosis of Acute Stroke

Sergios Gargalas, Bartolomiej Piechowski-Jozwiak, Lalit Kalra

King’s College Hospital, London

Purpose : To determine the cost-effectiveness of rapidsequence MRI of the head as additional imagingmodality used for diagnosis of acute stroke andelimination of stroke mimics within the NationalHealth Service in London.

Background:Stroke harbours a societal cost of £8.9 billion per

year and consumes up to 5% of total expenditureof the NHS in the UK. Diagnosis of acute strokeand initial inpatient care costs account for £890million per annum. Stroke mimics account for up to37% of admissions to hyper- acute stroke unit andunnecessarily consume expensive resourcesallocated for stroke care. MRI has been shown tohave clinical superiority over CT in excludingstroke mimics. Rapid sequence MRI that consistsof DWI, GRE, T2 and FLAIR sequences can beperformed in under 10 minutes on a 1.5 T scannerand could therefore be useful in identifying stroke

mimics within the setting of an A&E departmentwhen a CT has been inconclusive.

Should this approach be implemented, hospitalsare likely to require substantial nancialcommitment to meet the increased demand forMRI services.

Materials & Methods:A decision tree was designed to model the costsand effects of two separate strategies in patientspresenting with suspected acute stroke. A

conventional strategy included a CT scan of thehead in the A&E department followed by decisionto thrombolyse, admit for further investigations(when diagnosis of stroke is uncertain) ordischarge.

An alternative strategy included the addition of rapidsequence MRI scan of the head performed in A&E in thosepatients for whom diagnostic doubt exists and the CT hasbeen inconclusive, followed by decision to either admit astrue stroke or discharge as stroke mimic.

Probabilities required to analyse the model were derivedfrom a retrospective analysis of 207 patients admitted toKing’s College Hospital hyper-acute stroke unit betweenJanuary and March 2013.

This has been supplemented by data from publishedliterature and SINAP database. Costs were measured fromthe perspective of NHS London and derived from publiclyavailable National schedule for reference costs andrespective tariffs. Costs included length of stay, diagnosticcosts and other expenses embedded in the stroke tariff.Separate costs for inpatient imaging investigations wereobtained through consultations with the hospital’s nancialdepartment. Cost-effectiveness was measured with the helpof incremental cost effectiveness ratio (ICER). A short termoutcome of correct diagnosis on discharge was chosen for

this study as well as QALY.

Results : Case analysis included a hypothetical cohort of 5000 peoplewho presented in A&E department with suspected acutestroke. The end cost for the NHS if conventional diagnosticapproach (CT only) is used for this cohort would be£7,926,333 and would diagnose correctly 3374 of cases.The end cost if the alternative approach (CT and early MRI)is used would be £8,123,214 and would be diagnosticallycorrect in 4796 of cases. Incremental cost effectiveness ratiowould therefore be positive in the alternative subgroup, at

£136 per additional correct diagnosis of stroke. This fallswithin the limit of willingness to pay and is therefore cost-effective.

Conclusion : This study demonstrates that addition of rapidsequence MRI is not only clinically benecial, butalso cost-effective strategy for diagnosis of acutestroke and exclusion of stroke mimics. Thisapproach is likely to reduce costs associated withlength of stay and unnecessary investigations inpatients who did not have a stroke. It can also bebenecial and have long-lasting consequencesassociated with the rapid correct diagnosis, such ascost of follow up and avoidance of costs associatedwith unnecessary therapy in this misdiagnosed withstroke. Additional broader studies are needed toevaluate this approach from other perspectives, aswell as inclusion of long- term effects ofmisdiagnosis.

References : Saka, Ömer, Alistair McGuire, and Charles Wolfe. "Cost ofstroke in the United Kingdom." Age and ageing 38.1 (2009):27-32.

Lee, Sally, Anna CE Shafe, and Martin R. Cowie. "UK strokeincidence, mortality and cardio- vascular risk management1999–2008: time-trend analysis from the General PracticeResearch Database." BMJ open 1.2 (2011).

JM Wardlaw, Keir, S. L., et al. What is the best imaging strategyfor acute stroke?. Gray Pub- lishing, 2004

SINAP quarterly public report Oct-Dec 2012

Healthcare for London (2009) Stroke acute commissioning andtariff guidance. Healthcare for London. Available: http://www.londonhp.nhs.uk/wp-content/uploads/ 2011/03/Stroke-Commissioning-and-Tariff-Guidance.pdf.

2012-2013 National schedule for reference costs, Available athttps://www.gov.uk/ government/ publications/nhs-reference-costs-2012-to-2013