Objective: It has been suggested that Chlamydia pneumoniae, a Gram-negative intracellular bacterium, is a risk factor for both myocardial infarction and chronic coronary heart disease. Previous studies have been done predominantly in non-diabetic subjects and thus the effect of diabetes on the association between C. pneumoniae antibodies and coronary heart disease has not been analysed. The aim of our study was to investigate the association between prior chlamydial infection and the risk of serious coronary heart disease events (myocardial infarction or coronary death) in a 7-year prospective study of cohorts of diabetic and non-diabetic subjects in two areas of Finland.
Results: It was found that the prevalence of elevated chlamydial antibodies at baseline was higher in nondiabetic subjects who had serious coronary heart disease events during the follow-up than in subjects without coronary heart disease events (32 vs 15%, relative risk 2.56, P = 0.013) in East Finland. In non-diabetic subjects living in West Finland we did not find this association. The association between the C. pneumoniae antibodies and coronary heart disease events did not markedly change after controlling for other risk factors for coronary heart disease (OR 2.44, P = 0.055) in non-diabetic subjects living in eastern Finland. In diabetic patients we did not find any association between chlamydial antibodies and coronary heart disease events.
Conclusion: We found an association between C. pneumoniae antibodies and coronary heart disease events in non-diabetics living in eastern Finland. This association remained strong even after controlling for the other risk factors for coronary heart disease. In diabetic patients with high risk for coronary heart disease, C. pneumoniae was not a risk factor for coronary heart disease.