Chlamydia pneumoniae Seropositivity is Associated with Cardiovascular Events in the General Population: The Nagahama Study

AIMS: Persistent Chlamydia pneumoniae (C. pneumoniae) infection has been suggested to be a risk factor for cardiovascular events; however, only findings from studies on small populations are available so far. This study investigated this hypothesis in a large general population through a longitudinal analysis. METHODS: We included 9,064 community residents who participated in the Nagahama study (mean age: 52.8 years). C. pneumoniae infection (seropositivity) was determined by serum levels of immunoglobulin A and immunoglobulin G assessed by enzyme-linked immunoassay. The incidence rates of cardiovascular diseases (CVDs), including stroke and coronary artery diseases, were determined by reviewing participants' hospital records and death certificates. Basic clinical parameters were obtained using the baseline survey of the Nagahama study. RESULTS: During a mean follow-up duration of 4,390 days, we observed 323 cases of CVDs. The incidence rates of CVDs were 45.0 and 24.5 per 10,000 person-years in the seropositive and seronegative groups, respectively (log-rank test: p＜0.001). The results of the Cox proportional hazard model analysis indicated that C. pneumoniae seropositivity was remarkably associated with CVDs (1.30, 95% confidence interval: 1.04-1.64) after adjusting for established risk factors, including arterial stiffness (p = 0.023). The hazard ratio was higher in the subpopulation aged ≤ 55 years (2.62, 95% confidence interval: 1.45-4.75, p = 0.001) and reached 3.66 (95% confidence interval: 1.39-9.65, p = 0.009) in the subpopulation aged ≤ 45 years. CONCLUSION: C. pneumoniae seropositivity was significantly associated with CVDs incidence, especially in adolescents and middle-aged individuals.