title: Chlamydia pneumoniae IgG titres and coronary heart disease: prospective study and meta-analysis.
abstract: OBJECTIVE
  To examine the association between coronary heart disease and serum markers of chronic Chlamydia pneumoniae infection.
  
  
  METHODS
  "Nested" case-control analysis in a prospective cohort study and an updated meta-analysis of previous relevant studies.
  
  
  METHODS
  General practices in 18 towns in Britain.
  
  
  METHODS
  Of the 5661 men aged 40-59 who provided blood samples during 1978-80, 496 men who died from coronary heart disease or had non-fatal myocardial infarction and 989 men who had not developed coronary heart disease by 1996 were included.
  
  
  METHODS
  IgG serum antibodies to C pneumoniae in baseline samples; details of fatal and non-fatal coronary heart disease from medical records and death certificates.
  
  
  RESULTS
  200 (40%) of the 496 men with coronary heart disease were in the top third of C pneumoniae titres compared with 329 (33%) of the 989 controls. The corresponding odds ratio for coronary heart disease was 1.66 (95% confidence interval 1.25 to 2.21), which fell to 1.22 (0.82 to 1.82) after adjustment for smoking and indicators of socioeconomic status. No strong associations were observed between C pneumoniae IgG titres and blood lipid concentrations, blood pressure, or plasma homocysteine concentration. In aggregate, the present study and 14 other prospective studies of C pneumoniae IgG titres included 3169 cases, yielding a combined odds ratio of 1. 15 (0.97 to 1.36), with no significant heterogeneity among the separate studies (chi(2)=10.5, df=14; P>0.1).
  
  
  CONCLUSIONS
  This study, together with a meta-analysis of previous prospective studies, reliably excludes the existence of any strong association between C pneumoniae IgG titres and incident coronary heart disease. Further studies are required, however, to confirm or refute any modest association that may exist, particularly at younger ages.
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford OX2 6HE.
authors.forename: J
authors.initials: J
authors.lastname: Danesh
authors.forename: P
authors.initials: P
authors.lastname: Whincup
authors.forename: M
authors.initials: M
authors.lastname: Walker
authors.forename: L
authors.initials: L
authors.lastname: Lennon
authors.forename: A
authors.initials: A
authors.lastname: Thomson
authors.forename: P
authors.initials: P
authors.lastname: Appleby
authors.forename: Y
authors.initials: Y
authors.lastname: Wong
authors.forename: M
authors.initials: M
authors.lastname: Bernardes-Silva
authors.forename: M
authors.initials: M
authors.lastname: Ward
mesh_terms: D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002690:Chlamydia Infections / Q000150:complications* / Q000276:immunology; D016993:Chlamydophila pneumoniae / Q000276:immunology; D003327:Coronary Disease / Q000276:immunology / Q000382:microbiology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic
chemical_list: D000907:Antibodies, Bacterial; D015415:Biomarkers; D007074:Immunoglobulin G