The impact of stroke unit care on outcome in a Scottish stroke population, taking into account case mix and selection bias

Melanie Turner, Mark Barber, Hazel Dodds, Martin Dennis, Peter Langhorne, Mary Joan MacLeod

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Abstract

Background and aim Randomised trials indicate that stroke unit care reduces morbidity and mortality after stroke. Similar results have been seen in observational studies but many have not corrected for selection bias or independent predictors of outcome. We evaluated the effect of stroke unit compared with general ward care on outcomes after stroke in Scotland, adjusting for case mix by incorporating the six simple variables (SSV) model, also taking into account selection bias and stroke subtype.

Methods We used routine data from National Scottish datasets for acute stroke patients admitted between 2005 and 2011. Patients who died within 3 days of admission were excluded from analysis. The main outcome measures were survival and discharge home. Multivariable logistic regression was used to estimate the OR for survival, and adjustment was made for the effect of the SSV model and for early mortality. Cox proportional hazards model was used to estimate the hazard of death within 365 days.

Results There were 41 692 index stroke events; 79% were admitted to a stroke unit at some point during their hospital stay and 21% were cared for in a general ward. Using the SSV model, we obtained a receiver operated curve of 0.82 (SE 0.002) for mortality at 6 months. The adjusted OR for survival at 7 days was 3.11 (95% CI 2.71 to 3.56) and at 1 year 1.43 (95% CI 1.34 to 1.54) while the adjusted OR for being discharged home was 1.19 (95% CI 1.11 to 1.28) for stroke unit care.

Conclusions In routine practice, stroke unit admission is associated with a greater likelihood of discharge home and with lower mortality up to 1 year, after correcting for known independent predictors of outcome, and excluding early non-modifiable mortality.
Original languageEnglish
Pages (from-to)314-318
Number of pages5
JournalJournal of Neurology, Neurosurgery & Psychiatry
Volume86
Issue number3
Early online date25 Jun 2014
DOIs
Publication statusPublished - Mar 2015

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Selection Bias
Diagnosis-Related Groups
Stroke
Population
Mortality
Patients' Rooms
Survival
Scotland
Proportional Hazards Models
Observational Studies
Length of Stay
Logistic Models
Outcome Assessment (Health Care)
Morbidity

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The impact of stroke unit care on outcome in a Scottish stroke population, taking into account case mix and selection bias. / Turner, Melanie; Barber, Mark; Dodds, Hazel ; Dennis, Martin; Langhorne, Peter; MacLeod, Mary Joan.

In: Journal of Neurology, Neurosurgery & Psychiatry, Vol. 86, No. 3, 03.2015, p. 314-318.

Research output: Contribution to journalArticle

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title = "The impact of stroke unit care on outcome in a Scottish stroke population, taking into account case mix and selection bias",
abstract = "Background and aim Randomised trials indicate that stroke unit care reduces morbidity and mortality after stroke. Similar results have been seen in observational studies but many have not corrected for selection bias or independent predictors of outcome. We evaluated the effect of stroke unit compared with general ward care on outcomes after stroke in Scotland, adjusting for case mix by incorporating the six simple variables (SSV) model, also taking into account selection bias and stroke subtype.Methods We used routine data from National Scottish datasets for acute stroke patients admitted between 2005 and 2011. Patients who died within 3 days of admission were excluded from analysis. The main outcome measures were survival and discharge home. Multivariable logistic regression was used to estimate the OR for survival, and adjustment was made for the effect of the SSV model and for early mortality. Cox proportional hazards model was used to estimate the hazard of death within 365 days.Results There were 41 692 index stroke events; 79{\%} were admitted to a stroke unit at some point during their hospital stay and 21{\%} were cared for in a general ward. Using the SSV model, we obtained a receiver operated curve of 0.82 (SE 0.002) for mortality at 6 months. The adjusted OR for survival at 7 days was 3.11 (95{\%} CI 2.71 to 3.56) and at 1 year 1.43 (95{\%} CI 1.34 to 1.54) while the adjusted OR for being discharged home was 1.19 (95{\%} CI 1.11 to 1.28) for stroke unit care.Conclusions In routine practice, stroke unit admission is associated with a greater likelihood of discharge home and with lower mortality up to 1 year, after correcting for known independent predictors of outcome, and excluding early non-modifiable mortality.",
author = "Melanie Turner and Mark Barber and Hazel Dodds and Martin Dennis and Peter Langhorne and MacLeod, {Mary Joan}",
note = "Funding: This study was funded by Chest, Heart and Stroke Scotland (Grant no R11/A134). The SSCA is funded by NHS Scotland via ISD. Neither funder had any role in the analysis. Acknowledgments: We are grateful to David Murphy of the SSCA for providing data and to Lynsey Waugh of ISD Scotland for linking the SSCA data with General Register Office data. We also acknowledge the help of all who enter data into SSCA.",
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T1 - The impact of stroke unit care on outcome in a Scottish stroke population, taking into account case mix and selection bias

AU - Turner, Melanie

AU - Barber, Mark

AU - Dodds, Hazel

AU - Dennis, Martin

AU - Langhorne, Peter

AU - MacLeod, Mary Joan

N1 - Funding: This study was funded by Chest, Heart and Stroke Scotland (Grant no R11/A134). The SSCA is funded by NHS Scotland via ISD. Neither funder had any role in the analysis. Acknowledgments: We are grateful to David Murphy of the SSCA for providing data and to Lynsey Waugh of ISD Scotland for linking the SSCA data with General Register Office data. We also acknowledge the help of all who enter data into SSCA.

PY - 2015/3

Y1 - 2015/3

N2 - Background and aim Randomised trials indicate that stroke unit care reduces morbidity and mortality after stroke. Similar results have been seen in observational studies but many have not corrected for selection bias or independent predictors of outcome. We evaluated the effect of stroke unit compared with general ward care on outcomes after stroke in Scotland, adjusting for case mix by incorporating the six simple variables (SSV) model, also taking into account selection bias and stroke subtype.Methods We used routine data from National Scottish datasets for acute stroke patients admitted between 2005 and 2011. Patients who died within 3 days of admission were excluded from analysis. The main outcome measures were survival and discharge home. Multivariable logistic regression was used to estimate the OR for survival, and adjustment was made for the effect of the SSV model and for early mortality. Cox proportional hazards model was used to estimate the hazard of death within 365 days.Results There were 41 692 index stroke events; 79% were admitted to a stroke unit at some point during their hospital stay and 21% were cared for in a general ward. Using the SSV model, we obtained a receiver operated curve of 0.82 (SE 0.002) for mortality at 6 months. The adjusted OR for survival at 7 days was 3.11 (95% CI 2.71 to 3.56) and at 1 year 1.43 (95% CI 1.34 to 1.54) while the adjusted OR for being discharged home was 1.19 (95% CI 1.11 to 1.28) for stroke unit care.Conclusions In routine practice, stroke unit admission is associated with a greater likelihood of discharge home and with lower mortality up to 1 year, after correcting for known independent predictors of outcome, and excluding early non-modifiable mortality.

AB - Background and aim Randomised trials indicate that stroke unit care reduces morbidity and mortality after stroke. Similar results have been seen in observational studies but many have not corrected for selection bias or independent predictors of outcome. We evaluated the effect of stroke unit compared with general ward care on outcomes after stroke in Scotland, adjusting for case mix by incorporating the six simple variables (SSV) model, also taking into account selection bias and stroke subtype.Methods We used routine data from National Scottish datasets for acute stroke patients admitted between 2005 and 2011. Patients who died within 3 days of admission were excluded from analysis. The main outcome measures were survival and discharge home. Multivariable logistic regression was used to estimate the OR for survival, and adjustment was made for the effect of the SSV model and for early mortality. Cox proportional hazards model was used to estimate the hazard of death within 365 days.Results There were 41 692 index stroke events; 79% were admitted to a stroke unit at some point during their hospital stay and 21% were cared for in a general ward. Using the SSV model, we obtained a receiver operated curve of 0.82 (SE 0.002) for mortality at 6 months. The adjusted OR for survival at 7 days was 3.11 (95% CI 2.71 to 3.56) and at 1 year 1.43 (95% CI 1.34 to 1.54) while the adjusted OR for being discharged home was 1.19 (95% CI 1.11 to 1.28) for stroke unit care.Conclusions In routine practice, stroke unit admission is associated with a greater likelihood of discharge home and with lower mortality up to 1 year, after correcting for known independent predictors of outcome, and excluding early non-modifiable mortality.

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DO - 10.1136/jnnp-2013-307478

M3 - Article

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SP - 314

EP - 318

JO - Journal of Neurology, Neurosurgery & Psychiatry

JF - Journal of Neurology, Neurosurgery & Psychiatry

SN - 0022-3050

IS - 3

ER -