title: Seropositivity to Chlamydia pneumoniae is associated with risk of first ischemic stroke.
abstract: OBJECTIVE
  Serologic evidence of infection with Chlamydia pneumoniae has been associated with cardiovascular disease, but its relationship with stroke risk remains uncertain. The objective of this study is to determine whether serological evidence of C pneumoniae infection is associated with risk of ischemic stroke.
  
  
  METHODS
  A population-based case-control study was performed in an urban, multiethnic population. Cases (n=246) had first ischemic stroke, and controls (n=474) matched for age, sex, and race-ethnicity were derived through random-digit dialing. Titers of C pneumoniae-specific IgG and IgA antibodies were measured using microimmunofluorescence, and positive titers were prospectively defined. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% CIs adjusting for medical, behavioral, and socioeconomic factors.
  
  
  RESULTS
  Mean age among cases was 72.3+/-9.7 years; 50.8% were women. Elevated C pneumoniae IgA titers were associated with increased risk of ischemic stroke after adjusting for hypertension, diabetes mellitus, current cigarette use, atrial fibrillation, and levels of high-density lipoprotein and low-density lipoprotein (adjusted OR, 1.5; 95% CI, 1.0 to 2.2). Elevated IgG titers were not associated with stroke risk (adjusted OR, 1.2; 95% CI, 0.8 to 1.8). There was a trend toward an association of elevated IgA titers with atherosclerotic and lacunar stroke but less so cardioembolic or cryptogenic subtypes.
  
  
  CONCLUSIONS
  Serologic evidence of C pneumoniae infection is associated with ischemic stroke risk. IgA titers may be a better marker of risk than IgG. This association is independent of other stroke risk factors and is present for atherosclerotic, lacunar, and cardioembolic subtypes. Further studies of the effect of C pneumoniae on stroke risk are warranted.
authors.affiliation: Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA. mse13@columbia.edu
authors.forename: Mitchell S V
authors.initials: MS
authors.lastname: Elkind
authors.forename: Maria Lucia C
authors.initials: ML
authors.lastname: Tondella
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Feikin
authors.forename: Barry S
authors.initials: BS
authors.lastname: Fields
authors.forename: Shunichi
authors.initials: S
authors.lastname: Homma
authors.forename: Marco R
authors.initials: MR
authors.lastname: Di Tullio
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000097:blood* / Q000382:microbiology / Q000473:pathology; D016022:Case-Control Studies; D023521:Chlamydophila Infections / Q000097:blood* / Q000150:complications*; D016993:Chlamydophila pneumoniae / Q000378:metabolism*; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008077:Lipoproteins, LDL / Q000378:metabolism; D016015:Logistic Models; D008297:Male; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D015233:Models, Statistical; D016017:Odds Ratio; D012044:Regression Analysis; D012306:Risk; D020521:Stroke / Q000097:blood* / Q000382:microbiology* / Q000473:pathology
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; D008077:Lipoproteins, LDL