title: Differences in the distribution of stroke subtypes in a UK black stroke population - final results from the South London Ethnicity and Stroke Study.
abstract: BACKGROUND
  Stroke incidence is increased in Black individuals but the reasons for this are poorly understood. Exploring the differences in aetiological stroke subtypes, and the extent to which they are explained by conventional and novel risk factors, is an important step in elucidating the underlying mechanisms for this increased stroke risk.
  
  
  METHODS
  Between 1999 and 2010, 1200 black and 1200 white stroke patients were prospectively recruited from a contiguous geographical area in South London in the UK. The Trial of Org 10172 (TOAST) classification was used to classify stroke subtype. Age- and sex-adjusted comparisons of socio-demographics, traditional vascular risk factors and stroke subtypes were performed between black and white stroke patients and between Black Caribbean and Black African stroke patients using age-, sex-, and social deprivation-adjusted univariable and multivariable logistic regression analyses.
  
  
  RESULTS
  Black stroke patients were younger than white stroke patients (mean (SD) 65.1 (13.7) vs. 74.8 (13.7) years). There were significant differences in the distribution of stroke subtypes. Small vessel disease stroke was increased in black patients versus white patients (27 % vs. 12 %; OR, 2.74; 95 % CI, 2.19-3.44), whereas large vessel and cardioembolic stroke was less frequent in black patients (OR, 0.59; 95 % CI, 0.45-0.78 and OR, 0.61; 95 % CI, 0.50-0.74, respectively). These associations remained after controlling for traditional vascular risk factors and socio-demographics. Black Caribbean patients appeared to have an intermediate risk factor and stroke subtype profile between that found in Black African and white stroke patients. Cardioembolic stroke was more strongly associated with Black Caribbean ethnicity versus Black African ethnicity (OR, 1.48; 95 % CI, 1.04-2.10), whereas intracranial large vessel disease was less frequent in Black Caribbean patients versus Black African subjects (OR, 0.44; 95 % CI, 0.24-0.83).
  
  
  CONCLUSIONS
  Clear differences exist in stroke subtype distribution between black and white stroke patients, with a marked increase in small vessel stroke. These could not be explained by differences in the assessed traditional risk factors. Possible explanations for these differences might include variations in genetic susceptibility, differing rates of control of vascular risk factors, or as yet undetermined environmental risk factors.
authors.affiliation: Neurology, Frimley Park Hospital, Surrey, UK.
authors.forename: Giosue
authors.initials: G
authors.lastname: Gulli
authors.affiliation: Department of Clinical Neurosciences, Stroke Research group, University of Cambridge, Cambridge, UK. LR406@medschl.cam.ac.uk.
authors.forename: Loes C A
authors.initials: LC
authors.lastname: Rutten-Jacobs
authors.affiliation: Department of Basic and Clinical Neurosciences, Institute of Psychiatry, Psychology and Neurosciences, King's College London, London, UK.
authors.forename: Lalit
authors.initials: L
authors.lastname: Kalra
authors.affiliation: Division of Health and Social Care Research, King's College London, London, UK.|Stroke Unit, St. Thomas' Hospital, London, UK.
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Rudd
authors.affiliation: Division of Health and Social Care Research, King's College London, London, UK.|Guy's and St. Thomas' NHS Foundation Trust, National Institute for Health Research (NIHR) Biomedical Research Centre, London, UK.
authors.forename: Charles D A
authors.initials: CD
authors.lastname: Wolfe
authors.affiliation: Department of Clinical Neurosciences, Stroke Research group, University of Cambridge, Cambridge, UK.
authors.forename: Hugh S
authors.initials: HS
authors.lastname: Markus
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D044383:Black People / Q000706:statistics & numerical data*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000453:epidemiology; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D008131:London / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology* / Q000235:genetics / Q000517:prevention & control; D044465:White People / Q000706:statistics & numerical data*
keywords: Epidemiology; Ethnicity; Risk factors; Stroke