title: Combined effects of socioeconomic position, smoking, and hypertension on risk of ischemic and hemorrhagic stroke.
abstract: OBJECTIVE
  Combined effects of socioeconomic position and well-established risk factors on stroke incidence have not been formally investigated.
  
  
  METHODS
  In a pooled cohort study of 68 643 men and women aged 30 to 70 years in Denmark, we examined the combined effect and interaction between socioeconomic position (ie, education), smoking, and hypertension on ischemic and hemorrhagic stroke incidence by the use of the additive hazards model.
  
  
  RESULTS
  During 14 years of follow-up, 3613 ischemic strokes and 776 hemorrhagic strokes were observed. Current smoking and hypertension were more prevalent among those with low education. Low versus high education was associated with greater ischemic, but not hemorrhagic, stroke incidence. The combined effect of low education and current smoking was more than expected by the sum of their separate effects on ischemic stroke incidence, particularly among men: 134 (95% confidence interval, 49-219) extra cases per 100 000 person-years because of interaction, adjusted for age, cohort study, and birth cohort. There was no clear evidence of interaction between low education and hypertension. The combined effect of current smoking and hypertension was more than expected by the sum of their separate effects on ischemic and hemorrhagic stroke incidence. This effect was most pronounced for ischemic stroke among women: 178 (95% confidence interval, 103-253) extra cases per 100 000 person-years because of interaction, adjusted for age, cohort study, and birth cohort.
  
  
  CONCLUSIONS
  Reducing smoking in those with low socioeconomic position and in those with hypertension could potentially reduce social inequality stroke incidence.
authors.affiliation: From the Section of Social Medicine, Department of Public Health, University of Copenhagen, Copenhagen, Denmark (H.N., I.A., F.D., N.H.R.); Research Center for Prevention and Health, Glostrup University Hospital, Glostrup, Denmark (M.O.); Clinical Research Centre, Hvidovre University Hospital, Copenhagen, Denmark (B.L.F.); Department of Cardiology, Bispebjerg University Hospital and the Copenhagen City Heart Study, Bispebjerg, Denmark (E.P.); and Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark, and Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark (K.O.). henor@sund.ku.dk.
authors.forename: Helene
authors.initials: H
authors.lastname: Nordahl
authors.affiliation: From the Section of Social Medicine, Department of Public Health, University of Copenhagen, Copenhagen, Denmark (H.N., I.A., F.D., N.H.R.); Research Center for Prevention and Health, Glostrup University Hospital, Glostrup, Denmark (M.O.); Clinical Research Centre, Hvidovre University Hospital, Copenhagen, Denmark (B.L.F.); Department of Cardiology, Bispebjerg University Hospital and the Copenhagen City Heart Study, Bispebjerg, Denmark (E.P.); and Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark, and Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark (K.O.).
authors.forename: Merete
authors.initials: M
authors.lastname: Osler
authors.affiliation: From the Section of Social Medicine, Department of Public Health, University of Copenhagen, Copenhagen, Denmark (H.N., I.A., F.D., N.H.R.); Research Center for Prevention and Health, Glostrup University Hospital, Glostrup, Denmark (M.O.); Clinical Research Centre, Hvidovre University Hospital, Copenhagen, Denmark (B.L.F.); Department of Cardiology, Bispebjerg University Hospital and the Copenhagen City Heart Study, Bispebjerg, Denmark (E.P.); and Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark, and Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark (K.O.).
authors.forename: Birgitte Lidegaard
authors.initials: BL
authors.lastname: Frederiksen
authors.affiliation: From the Section of Social Medicine, Department of Public Health, University of Copenhagen, Copenhagen, Denmark (H.N., I.A., F.D., N.H.R.); Research Center for Prevention and Health, Glostrup University Hospital, Glostrup, Denmark (M.O.); Clinical Research Centre, Hvidovre University Hospital, Copenhagen, Denmark (B.L.F.); Department of Cardiology, Bispebjerg University Hospital and the Copenhagen City Heart Study, Bispebjerg, Denmark (E.P.); and Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark, and Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark (K.O.).
authors.forename: Ingelise
authors.initials: I
authors.lastname: Andersen
authors.affiliation: From the Section of Social Medicine, Department of Public Health, University of Copenhagen, Copenhagen, Denmark (H.N., I.A., F.D., N.H.R.); Research Center for Prevention and Health, Glostrup University Hospital, Glostrup, Denmark (M.O.); Clinical Research Centre, Hvidovre University Hospital, Copenhagen, Denmark (B.L.F.); Department of Cardiology, Bispebjerg University Hospital and the Copenhagen City Heart Study, Bispebjerg, Denmark (E.P.); and Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark, and Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark (K.O.).
authors.forename: Eva
authors.initials: E
authors.lastname: Prescott
authors.affiliation: From the Section of Social Medicine, Department of Public Health, University of Copenhagen, Copenhagen, Denmark (H.N., I.A., F.D., N.H.R.); Research Center for Prevention and Health, Glostrup University Hospital, Glostrup, Denmark (M.O.); Clinical Research Centre, Hvidovre University Hospital, Copenhagen, Denmark (B.L.F.); Department of Cardiology, Bispebjerg University Hospital and the Copenhagen City Heart Study, Bispebjerg, Denmark (E.P.); and Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark, and Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark (K.O.).
authors.forename: Kim
authors.initials: K
authors.lastname: Overvad
authors.affiliation: From the Section of Social Medicine, Department of Public Health, University of Copenhagen, Copenhagen, Denmark (H.N., I.A., F.D., N.H.R.); Research Center for Prevention and Health, Glostrup University Hospital, Glostrup, Denmark (M.O.); Clinical Research Centre, Hvidovre University Hospital, Copenhagen, Denmark (B.L.F.); Department of Cardiology, Bispebjerg University Hospital and the Copenhagen City Heart Study, Bispebjerg, Denmark (E.P.); and Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark, and Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark (K.O.).
authors.forename: Finn
authors.initials: F
authors.lastname: Diderichsen
authors.affiliation: From the Section of Social Medicine, Department of Public Health, University of Copenhagen, Copenhagen, Denmark (H.N., I.A., F.D., N.H.R.); Research Center for Prevention and Health, Glostrup University Hospital, Glostrup, Denmark (M.O.); Clinical Research Centre, Hvidovre University Hospital, Copenhagen, Denmark (B.L.F.); Department of Cardiology, Bispebjerg University Hospital and the Copenhagen City Heart Study, Bispebjerg, Denmark (E.P.); and Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark, and Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark (K.O.).
authors.forename: Naja Hulvej
authors.initials: NH
authors.lastname: Rod
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure; D002545:Brain Ischemia / Q000150:complications / Q000453:epidemiology*; D015331:Cohort Studies; D003718:Denmark; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000453:epidemiology* / Q000503:physiopathology; D015994:Incidence; D020300:Intracranial Hemorrhages / Q000150:complications / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology*; D012923:Social Class; D020521:Stroke / Q000150:complications / Q000453:epidemiology*
keywords: hypertension; smoking; socioeconomic position; stroke