Association between Chlamydia pneumoniae antibodies and intimal calcification in femoral arteries of nondiabetic patients.

BACKGROUND Chlamydia pneumoniae, a gram-negative bacterium, has been suggested to be a risk factor for atherosclerosis. Calcium is a well-known component of atherosclerotic plaques, but it is uncertain whether infectious agents play a role in the calcification process of the arteries. PATIENTS To address this issue we investigated the association of Chlamydia antibodies with intimal arterial calcification as assessed by soft tissue radiograms from the thigh region of 1373 nondiabetic Finnish individuals aged 45 to 64 years. RESULTS At baseline, radiologically detectable intimal calcification in femoral arteries was found in 172 (27%) of 638 men and 43 (6%) of 735 women (P<.001). The presence of intimal artery calcifications was strongly related to conventional atherosclerotic risk factors and to Chlamydia antibodies. In Cox regression analysis, association of Chlamydia antibodies with intimal artery calcification persisted after extensive adjustment for other cardiovascular risk factors (P =.04). A dose-response relationship was observed between Chlamydia antibodies and intimal femoral artery calcification (P =.006). The presence of intimal artery calcification was strongly associated with an increased risk of future coronary heart disease mortality (P<.001). CONCLUSION Chlamydia antibodies are strongly associated with intimal calcification of the femoral arteries.