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Clin Infect Dis. Chickenpox and Risk of Stroke: A Self-controlled Case Series Analysis
[Source: Clinical Infectious Diseases, full page: (LINK). Abstract, edited.]
Chickenpox and Risk of Stroke: A Self-controlled Case Series Analysis
Sara L. Thomas 1, Caroline Minassian 1, Vijeya Ganesan 2, Sin?ad M. Langan 1, and Liam Smeeth 1
Author Affiliations: <SUP>1</SUP>Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine <SUP>2</SUP>Institute of Child Health, University College London, United Kingdom
Correspondence: Sara L. Thomas, MBBS, MSc, PhD, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK (sara.thomas@lshtm.ac.uk).
Abstract
Background.
There is good evidence that respiratory and other infections that cause systemic inflammation can trigger strokes; however, the role of specific infections is unclear. Case reports have highlighted chickenpox as a possible risk factor for arterial ischemic stroke, particularly in children, but rigorous studies are needed to determine and quantify any increased risk.
Methods.
We used anonymized electronic health records totaling >100 million person-years of observation from 4 UK primary care databases to identify individuals who had documented clinical chickenpox and a stroke or transient ischemic attack (TIA). Self-controlled case series methods were used to quantify any increased risk of first stroke or TIA in the 0?6 and 7?12 months following chickenpox compared to other observed time periods. We analyzed data within each database, and performed meta-analyses to obtain summary age-adjusted incidence ratios (IRs) separately for adults and children.
Results.
Five hundred sixty eligible individuals (including 60 children) were identified who experienced chickenpox and a stroke or TIA during follow-up. Among children, there was a 4-fold increased risk of stroke in the 0?6 months after chickenpox (summary IR = 4.07; 95% confidence interval [CI], 1.96?8.45; I<SUP>2</SUP> = 0%). Among adults, there was a less marked increased risk with moderate between-database heterogeneity (random-effects summary IR = 2.13; 95% CI, 1.05?4.36; I<SUP>2</SUP> = 51%). There was no significant increased risk of stroke in the 7?12 months after chickenpox in children or adults, nor was there evidence of increased risk of TIA in either time period.
Conclusions.
Our study provides new evidence that children who experience chickenpox are at increased risk of stroke in the subsequent 6 months.
Key words: chickenpox ? stroke ? child ? adult - risk factors
Received May 7, 2013. Accepted August 16, 2013.
? The Author 2013. Published by Oxford University Press on behalf of the Infectious Diseases Society of America.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License(http://creativecommons.org/licenses/by/3.0/ ), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
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Chickenpox and Risk of Stroke: A Self-controlled Case Series Analysis
Sara L. Thomas 1, Caroline Minassian 1, Vijeya Ganesan 2, Sin?ad M. Langan 1, and Liam Smeeth 1
Author Affiliations: <SUP>1</SUP>Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine <SUP>2</SUP>Institute of Child Health, University College London, United Kingdom
Correspondence: Sara L. Thomas, MBBS, MSc, PhD, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK (sara.thomas@lshtm.ac.uk).
Abstract
Background.
There is good evidence that respiratory and other infections that cause systemic inflammation can trigger strokes; however, the role of specific infections is unclear. Case reports have highlighted chickenpox as a possible risk factor for arterial ischemic stroke, particularly in children, but rigorous studies are needed to determine and quantify any increased risk.
Methods.
We used anonymized electronic health records totaling >100 million person-years of observation from 4 UK primary care databases to identify individuals who had documented clinical chickenpox and a stroke or transient ischemic attack (TIA). Self-controlled case series methods were used to quantify any increased risk of first stroke or TIA in the 0?6 and 7?12 months following chickenpox compared to other observed time periods. We analyzed data within each database, and performed meta-analyses to obtain summary age-adjusted incidence ratios (IRs) separately for adults and children.
Results.
Five hundred sixty eligible individuals (including 60 children) were identified who experienced chickenpox and a stroke or TIA during follow-up. Among children, there was a 4-fold increased risk of stroke in the 0?6 months after chickenpox (summary IR = 4.07; 95% confidence interval [CI], 1.96?8.45; I<SUP>2</SUP> = 0%). Among adults, there was a less marked increased risk with moderate between-database heterogeneity (random-effects summary IR = 2.13; 95% CI, 1.05?4.36; I<SUP>2</SUP> = 51%). There was no significant increased risk of stroke in the 7?12 months after chickenpox in children or adults, nor was there evidence of increased risk of TIA in either time period.
Conclusions.
Our study provides new evidence that children who experience chickenpox are at increased risk of stroke in the subsequent 6 months.
Key words: chickenpox ? stroke ? child ? adult - risk factors
Received May 7, 2013. Accepted August 16, 2013.
? The Author 2013. Published by Oxford University Press on behalf of the Infectious Diseases Society of America.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License(http://creativecommons.org/licenses/by/3.0/ ), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
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