Abstract: Objective To examine the association between CagA-antibody-positive helicobacter pylori (Hp) infection and carotid atherosclerosis (CAS) in middle-aged asymptomatic population. 
Methods A total of 578 CAS patients treated in our hospital were selected for this study, and 578 patients without CAS were selected as the control group. CagA-antibody-positive Hp infection was compared between two groups, and logistic regression analysis was conducted. Carotid intima-media thickness(CIMT) was compared between patients with CagA-antibody-positive Hp infection and those with CagA-antibody-negative Hp infection. 
Results The CAS group had significantly higher frequency of CagA-antibody-positive Hp infection than the controls (P＜0.05). CagA-antibody-positive Hp infection was an independent risk factors for CAS (OR=1.813, 95% CI: 1.379-2.384, P＜0.05). CIMT was significantly greater in patients with CagA-antibody-positive Hp infection than in those with CagA-antibody-negative Hp infection (t=28.046, P＜0.05). 
Conclusion In middle-aged asymptomatic population， CagA-antibody-negative Hp infection is an independent risk factor for CAS. The levels of CIMT in patients with CagA-antibody-positive Hp infection are significantly higher than those of patients with CagA-antibody-negative Hp infection. Thus, CagA-antibody-positive Hp infection has been implicated in the development and progression of CAS. 

Key words: helicobacter pylori, carotid atherosclerosis, cytotoxin-associated protein A