PAST INFECTION BY CHLAMYDIA-PNEUMONIAE STRAIN TWAR AND ASYMPTOMATIC CAROTID ATHEROSCLEROSIS

PURPOSE: To determine whether past infection by Chlamydia pneumoniae s train TWAR is associated with asymptomatic atherosclerosis. Previous s tudies have linked this organism with symptomatic coronary heart disea se. SUBJECTS AND METHODS: Between 1986 and 1989, 15,800 men and women aged 45 to 64 years were examined as part of the Atherosclerosis Risk in Communities Study, a prospective cohort study of atherosclerosis be ing conducted in 4 United States communities. The examination included B-mode ultrasonography of the carotid arteries and an assessment of c ardiovascular disease risk factors. Carotid wall thickening (blood-int ima to medial-adventitial interface) in the absence of clinical cardio vascular disease was considered evidence of asymptomatic atheroscleros is. In 1991, IgG antibody titers to TWAR were assayed by microimmunofl uorescence in stored sera from 326 case-control pairs matched by age g roup, race, sex, examination period, and field center. A titer of -1:8 or higher was considered a positive TWAR antibody response. RESULTS: Seventy-three percent of atherosclerosis cases had serologic evidence of past TWAR infection versus 63% of controls (matched odds ratio 1.76 ; 95% confidence interval, 121 to 2.57). After adjustment for age, hyp ertension, diabetes, cigarette smoking, low-density lipoprotein choles terol, high-density lipoprotein cholesterol, and education, the odds r atio for atherosclerosis was essentially unchanged at 2.00 (95% confid ence interval, 1.19 to 3.35). The association was stronger for individ uals aged 45 to 54 years than for those aged 55 to 64 years. CONCLUSIO N: There was a significant cross-sectional association between past TW AR infection and asymptomatic atherosclerosis. This organism may be a contributor to the pathogenesis of atherosclerosis.