title: Antibiotics active against Chlamydia do not reduce the risk of myocardial infarction.
abstract: OBJECTIVE
  There is evidence that Chlamydia pneumoniae (CP) is involved in the aetiology of myocardial infarction (MI). Randomised trials do not support a beneficial effect of antibiotics in secondary prevention of MI, but the evidence for an effect on primary prevention is conflicting. We investigated if past use of antibiotics active against CP is associated with a decreased risk of developing MI.
  
  
  METHODS
  We conducted a population-based case-control study of 4166 patients hospitalised due to MI from 1 January 1994 to 1 September 1999 in the County of Funen, Denmark. Controls (n=16,664) were a random sample of inhabitants, matched for age and sex. Confounders controlled for in the analysis were gender, age, obstructive pulmonary disease, diabetes, previous MI and known atherosclerotic antecedents. Previous use of antibiotics active against CP (macrolides, tetracyclines and quinolones) and of antibiotics not active against CP (penicillins) was analysed among the cases and controls.
  
  
  RESULTS
  The risk of MI was not associated with previous exposure to macrolides (OR: 1.0; CI: 0.9-1.1), tetracyclines (OR: 1.0; CI: 0.9-1.2) or quinolones (OR: 1.0; CI: 0.9-1.2) or combinations of the three drugs (OR: 1.0; CI: 0.9-1.1). There was no sign of a protective effect in subgroups defined by high cumulative doses of antibiotics, various time-windows of exposure, risk factors of MI or other co-morbidity. OR was 1.1 (0.9-1.3) in persons with no atherosclerotic antecedents.
  
  
  CONCLUSIONS
  The study does not support the hypothesis of a decreased risk of MI in patients exposed to antibiotics active against CP.
authors.affiliation: Research Unit of General Practice, University of Southern Denmark, J.B. Winslows Vej 9, 5000, Odense C, Denmark. lbjerrum@health.sdu.dk
authors.forename: Lars
authors.initials: L
authors.lastname: Bjerrum
authors.forename: Morten
authors.initials: M
authors.lastname: Andersen
authors.forename: Jesper
authors.initials: J
authors.lastname: Hallas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D016022:Case-Control Studies; D023521:Chlamydophila Infections / Q000150:complications / Q000188:drug therapy*; D016993:Chlamydophila pneumoniae; D004363:Drug Utilization; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000209:etiology / Q000517:prevention & control*; D012307:Risk Factors
chemical_list: D000900:Anti-Bacterial Agents