title: U-curve relation between cholesterol and prior ischemic stroke.
abstract: Previous prospective studies on ischemic stroke patients have shown conflicting results concerning the association between cholesterol level and patient outcome. We aimed to investigate the relation between cholesterol level and prior ischemic stroke. We hypothesized that acute ischemic stroke patients with increased cholesterol on admission more frequently had experienced prior ischemic stroke.
  
  
  
  All consecutive patients with acute ischemic stroke (the index stroke) admitted to the Stroke Unit, Department of Neurology, Haukeland University Hospital between February 2006 and October 2013 were prospectively registered in The Bergen NORSTROKE Registry. On admission, cholesterol, low-density lipoprotein, and high-density lipoprotein levels were measured and prior ischemic stroke, risk factors, and medication were registered. Patients with prior versus no prior ischemic stroke were compared regarding risk factors, cholesterol levels, and use of statins on admission for the index stroke. Only patients with available cholesterol values measured on admission were included in the analyses.
  
  
  
  Of the 2,514 included patients admitted with acute ischemic stroke, 429 (17%) patients had prior ischemic stroke. We found a U-curve relationship between the relative frequency of prior ischemic stroke and cholesterol level. Lower frequency of prior ischemic stroke was associated with high cholesterol level on admission up to 5.5 mmol/L. For cholesterol levels higher than this, the opposite was true. These associations included all patients and statin-naive patients. For patients using statin there was a declining relative frequency of prior ischemic stroke from low to high cholesterol levels.
  
  
  
  Our hypothesis was falsified. The association between lower cholesterol levels and higher frequency of prior ischemic stroke in patients with cholesterol <5.5 mmol/L cannot be solely an effect of aggressive statin treatment in patients with prior ischemic stroke, as the association pertained also to patients who did not use statin.
authors.affiliation: Department of Neurology Haukeland University Hospital Bergen Norway.
authors.forename: Gerd Haga
authors.initials: GH
authors.lastname: Bringeland
authors.affiliation: Department of Neurology Haukeland University Hospital Bergen Norway; Institute of Clinical Medicine University of Bergen Bergen Norway.
authors.forename: Aliona
authors.initials: A
authors.lastname: Nacu
authors.affiliation: Department of Neurology Haukeland University Hospital Bergen Norway; Institute of Biological and Medical Psychology University of Bergen Bergen Norway.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Waje-Andreassen
authors.affiliation: Department of Neurology Haukeland University Hospital Bergen Norway; Institute of Clinical Medicine University of Bergen Bergen Norway.
authors.forename: Lars
authors.initials: L
authors.lastname: Thomassen
authors.affiliation: Department of Neurology Haukeland University Hospital Bergen Norway; Institute of Clinical Medicine University of Bergen Bergen Norway; Centre for Age-Related Medicine Stavanger University Hospital Stavanger Norway.
authors.forename: Halvor
authors.initials: H
authors.lastname: Naess
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000097:blood* / Q000453:epidemiology; D002784:Cholesterol / Q000097:blood*; D005260:Female; D006801:Humans; D008075:Lipoproteins, HDL / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood; D016015:Logistic Models; D008297:Male; D009664:Norway / Q000453:epidemiology; D012042:Registries; D020521:Stroke / Q000097:blood* / Q000453:epidemiology
chemical_list: D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D002784:Cholesterol
keywords: cholesterol; ischemic stroke; reverse epidemiology; statin; stroke recurrence; vascular risk factors