title: Joint effects of Chlamydia pneumoniae infection and classic coronary risk factors on risk of acute myocardial infarction.
abstract: BACKGROUND
  Although not in itself strongly predictive of coronary heart disease, Chlamydia pneumoniae infection could interact with classic risk factors in determining risk of acute myocardial infarction (AMI).
  
  
  METHODS
  We assessed C pneumoniae immunoglobulin (Ig) G and IgA titers and classic risk factors in 618 patients with AMI and in 967 controls.
  
  
  RESULTS
  IgG titers were not related to AMI, but a significant association was seen between IgA titers and AMI. Excess risk of AMI was noted mainly among patients with the highest IgA titers, such as those beyond 2.88 (the 95th percentile cutoff point in control subjects), showing a 1.8-fold increase in risk (odds ratio 1.75, 95% CI 1.04-2.92). Classic risk factors did not differ between subjects with IgA titers above and below the 95th percentile cutoff. However, in multivariate analyses, models incorporating both IgA titers and a classic risk factor such as obesity, hypercholesterolemia, or smoking predicted risk more effectively than single-parameter models. For example, the odds ratio for AMI among subjects with the highest IgA titers plus hypercholesterolemia was greater than the product of individual risks associated with these high IgA titers and with hypercholesterolemia.
  
  
  CONCLUSIONS
  Interactions with classic risk factors (ie, obesity, hypercholesterolemia, and smoking), increased the predictive value of C pneumoniae IgA antibody titers in determining risk of AMI.
authors.affiliation: Department of Internal Medicine and Therapeutics, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Kinjo
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sato
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Sato
authors.forename: Yozo
authors.initials: Y
authors.lastname: Ohnishi
authors.forename: Eiji
authors.initials: E
authors.lastname: Hishida
authors.forename: Daisaku
authors.initials: D
authors.lastname: Nakatani
authors.forename: Hiroya
authors.initials: H
authors.lastname: Mizuno
authors.forename: Nobuhisa
authors.initials: N
authors.lastname: Ohgitani
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Kubo
authors.forename: Takashi
authors.initials: T
authors.lastname: Shimazu
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Akehi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takeda
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Hori
mesh_terms: D016022:Case-Control Studies; D002690:Chlamydia Infections / Q000150:complications*; D016993:Chlamydophila pneumoniae / Q000276:immunology*; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000209:etiology* / Q000382:microbiology; D016017:Odds Ratio; D011237:Predictive Value of Tests; D012307:Risk Factors
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G