Anaemia and incidence of post stroke dementia

Phyo K. Myint*, Mary Joan Macleod, Allan B. Clark, Toby O. Smith, Joao H. Bettencourt-Silva, Anthony Kneale Metcalf, John F. Potter

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Objectives: To assess the impact of anaemia on incidence of post-stroke dementia.

Patients and Methods: We used data from a UK regional stroke register. To be eligible, patient must have survived to discharge and had anaemia by WHO criteria. Dementia status and other prevalent co-morbidities were assessed using ICD-10 codes. Patients were followed till May 2015 (mean follow-up 3.7 years, total person years = 27,769). Hazard Ratio for incident dementia was calculated using Cox-proportional hazards model controlling for potential confounders. Fine and Gray model was additionally constructed using mortality as the competing risk.

Results: A total of 7,454 stroke patients were included with mean age (SD) of 75.9(12.3) years (50.2% men). Those with anaemia were older, has higher disability and co-morbidity burden prior to stroke. We observed a large amount of variation in the dementia incidence rates over time and that the hazard ratio increased every year. The significant association between anaemia and dementia incidence was lost after controlling for pre-stroke Modified Rankin score (HR1.17(0.97,1.40)). With every 20g/dL increase in Hb was associated with a significant reduction in the risk of dementia after adjustment for age, sex, stroke factors and disability but lost significance after adjustment for vascular risk factors. Competing risk analyses showed similar results.

Conclusion: Whilst we found no evidence of anaemia as a risk factor for post-stroke dementia, the findings may be limited by potential under recognition of post stroke dementia.
Original languageEnglish
Article number105688
JournalClinical Neurology and Neurosurgery
Volume191
Early online date23 Jan 2020
DOIs
Publication statusE-pub ahead of print - 23 Jan 2020

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Dementia
Anemia
Stroke
Incidence
International Classification of Diseases
Morbidity
Sex Factors
Risk Reduction Behavior
Proportional Hazards Models
Mortality

Keywords

  • dementia
  • post-stroke
  • prognosis
  • incidence

Cite this

Myint, P. K., Macleod, M. J., Clark, A. B., Smith, T. O., Bettencourt-Silva, J. H., Metcalf, A. K., & Potter, J. F. (2020). Anaemia and incidence of post stroke dementia. Clinical Neurology and Neurosurgery, 191, [105688]. https://doi.org/10.1016/j.clineuro.2020.105688

Anaemia and incidence of post stroke dementia. / Myint, Phyo K.; Macleod, Mary Joan; Clark, Allan B.; Smith, Toby O.; Bettencourt-Silva, Joao H.; Metcalf, Anthony Kneale; Potter, John F.

In: Clinical Neurology and Neurosurgery, Vol. 191, 105688, 04.2020.

Research output: Contribution to journalArticle

Myint, PK, Macleod, MJ, Clark, AB, Smith, TO, Bettencourt-Silva, JH, Metcalf, AK & Potter, JF 2020, 'Anaemia and incidence of post stroke dementia', Clinical Neurology and Neurosurgery, vol. 191, 105688. https://doi.org/10.1016/j.clineuro.2020.105688
Myint, Phyo K. ; Macleod, Mary Joan ; Clark, Allan B. ; Smith, Toby O. ; Bettencourt-Silva, Joao H. ; Metcalf, Anthony Kneale ; Potter, John F. / Anaemia and incidence of post stroke dementia. In: Clinical Neurology and Neurosurgery. 2020 ; Vol. 191.
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abstract = "Objectives: To assess the impact of anaemia on incidence of post-stroke dementia.Patients and Methods: We used data from a UK regional stroke register. To be eligible, patient must have survived to discharge and had anaemia by WHO criteria. Dementia status and other prevalent co-morbidities were assessed using ICD-10 codes. Patients were followed till May 2015 (mean follow-up 3.7 years, total person years = 27,769). Hazard Ratio for incident dementia was calculated using Cox-proportional hazards model controlling for potential confounders. Fine and Gray model was additionally constructed using mortality as the competing risk.Results: A total of 7,454 stroke patients were included with mean age (SD) of 75.9(12.3) years (50.2{\%} men). Those with anaemia were older, has higher disability and co-morbidity burden prior to stroke. We observed a large amount of variation in the dementia incidence rates over time and that the hazard ratio increased every year. The significant association between anaemia and dementia incidence was lost after controlling for pre-stroke Modified Rankin score (HR1.17(0.97,1.40)). With every 20g/dL increase in Hb was associated with a significant reduction in the risk of dementia after adjustment for age, sex, stroke factors and disability but lost significance after adjustment for vascular risk factors. Competing risk analyses showed similar results.Conclusion: Whilst we found no evidence of anaemia as a risk factor for post-stroke dementia, the findings may be limited by potential under recognition of post stroke dementia.",
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note = "Acknowledgements We gratefully acknowledge the stroke data team at the NNUH Foundation NHS Trust. We gratefully acknowledge Professor Bowles who is one of the steering committee members of the NNUH Stroke and TIA register. Source of Funding Declarations Dr Toby Smith is supported by funding from the National Institute for Health Research (NIHR) Oxford Health Biomedical Research Centre. The views expressed are those of the author(s) and not necessarily those of the NIHR.",
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AU - Macleod, Mary Joan

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AU - Smith, Toby O.

AU - Bettencourt-Silva, Joao H.

AU - Metcalf, Anthony Kneale

AU - Potter, John F.

N1 - Acknowledgements We gratefully acknowledge the stroke data team at the NNUH Foundation NHS Trust. We gratefully acknowledge Professor Bowles who is one of the steering committee members of the NNUH Stroke and TIA register. Source of Funding Declarations Dr Toby Smith is supported by funding from the National Institute for Health Research (NIHR) Oxford Health Biomedical Research Centre. The views expressed are those of the author(s) and not necessarily those of the NIHR.

PY - 2020/1/23

Y1 - 2020/1/23

N2 - Objectives: To assess the impact of anaemia on incidence of post-stroke dementia.Patients and Methods: We used data from a UK regional stroke register. To be eligible, patient must have survived to discharge and had anaemia by WHO criteria. Dementia status and other prevalent co-morbidities were assessed using ICD-10 codes. Patients were followed till May 2015 (mean follow-up 3.7 years, total person years = 27,769). Hazard Ratio for incident dementia was calculated using Cox-proportional hazards model controlling for potential confounders. Fine and Gray model was additionally constructed using mortality as the competing risk.Results: A total of 7,454 stroke patients were included with mean age (SD) of 75.9(12.3) years (50.2% men). Those with anaemia were older, has higher disability and co-morbidity burden prior to stroke. We observed a large amount of variation in the dementia incidence rates over time and that the hazard ratio increased every year. The significant association between anaemia and dementia incidence was lost after controlling for pre-stroke Modified Rankin score (HR1.17(0.97,1.40)). With every 20g/dL increase in Hb was associated with a significant reduction in the risk of dementia after adjustment for age, sex, stroke factors and disability but lost significance after adjustment for vascular risk factors. Competing risk analyses showed similar results.Conclusion: Whilst we found no evidence of anaemia as a risk factor for post-stroke dementia, the findings may be limited by potential under recognition of post stroke dementia.

AB - Objectives: To assess the impact of anaemia on incidence of post-stroke dementia.Patients and Methods: We used data from a UK regional stroke register. To be eligible, patient must have survived to discharge and had anaemia by WHO criteria. Dementia status and other prevalent co-morbidities were assessed using ICD-10 codes. Patients were followed till May 2015 (mean follow-up 3.7 years, total person years = 27,769). Hazard Ratio for incident dementia was calculated using Cox-proportional hazards model controlling for potential confounders. Fine and Gray model was additionally constructed using mortality as the competing risk.Results: A total of 7,454 stroke patients were included with mean age (SD) of 75.9(12.3) years (50.2% men). Those with anaemia were older, has higher disability and co-morbidity burden prior to stroke. We observed a large amount of variation in the dementia incidence rates over time and that the hazard ratio increased every year. The significant association between anaemia and dementia incidence was lost after controlling for pre-stroke Modified Rankin score (HR1.17(0.97,1.40)). With every 20g/dL increase in Hb was associated with a significant reduction in the risk of dementia after adjustment for age, sex, stroke factors and disability but lost significance after adjustment for vascular risk factors. Competing risk analyses showed similar results.Conclusion: Whilst we found no evidence of anaemia as a risk factor for post-stroke dementia, the findings may be limited by potential under recognition of post stroke dementia.

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KW - post-stroke

KW - prognosis

KW - incidence

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SN - 0303-8467

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