(Circulation. 2002;105:1028.)
© 2002 American Heart Association, Inc.
Brief Rapid Communications |
From the Department of Cardiovascular Medicine, University of Tokyo Graduate School of Medicine (N.I., M.O., R.N.); Center for Multiphasic Health Testing and Services, Mitsui Memorial Hospital (Y.I., E.T., E-i.T., M.Y.); and Department of Hygiene and Public Health, Teikyo University School of Medicine (H.H.), Tokyo, Japan.
Correspondence to Nobukazu Ishizaka, MD, PhD, Department of Cardiovascular Medicine, University of Tokyo, Graduate School of Medicine, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8655, Japan. E-mail nobuishizka-tky{at}umin.ac.jp
| Abstract |
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Methods and Results In this cross-sectional cohort study, we analyzed data from subjects undergoing general health-screening tests, including both high-resolution B-mode carotid ultrasound and assessment of HBsAg status, between 1994 and 2001 at our institute. Of the 4686 study subjects (3137 men and 1549 women; age 22 to 88 years), 1294 (28%) had carotid artery plaque and 40 (0.9%) were positive for HBsAg, indicating they were hepatitis B virus carriers. No HBsAg-positive subjects were positive either for antibodies against the hepatitis C virus (HCV) or for HCV core proteins. Univariate analysis revealed HBsAg positivity was associated with carotid plaque with an odds ratio of 1.58 (95% CI, 1.14 to 2.19, P<0.05). When other confounding risk factors for atherosclerosis were included as covariates in the statistical analysis, HBsAg positivity was still positively associated with carotid plaque with an odds ratio of 1.57 (95% CI, 1.10 to 2.24, P<0.05).
Conclusions These findings suggest a possible role of chronic hepatitis B infection in the pathogenesis of carotid arteriosclerosis.
Key Words: infection plaque ultrasonics atherosclerosis
| Introduction |
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We recently have reported5 that seropositivity for the hepatitis C virus (HCV) has a positive association with carotid atherosclerosis. In the present study, we investigated the possible association between hepatitis B virus surface antigen (HBsAg) positivity and carotid arteriosclerosis. We analyzed the data of subjects undergoing general health screening tests. In Japan, a regular health check-up for employees is legally mandated to employers, and the service is available in check-up laboratories affiliated with medical institutes such as ours. Thus, the majority of the study subjects of this large cohort were considered to be healthy.
| Methods |
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Carotid Ultrasound
The status of the carotid arteries was studied by high-resolution B-mode ultrasonography (Sonolayer SSA270A) equipped with a 7.5 MHz transducer (PLF-703ST, Toshiba) as described previously.6 Plaque was defined as a focal thickening of the intimal-medial layer
1.3 mm of thickness.
Risk Factors
Hypertension was defined as systolic blood pressure >140 mm Hg and/or diastolic blood pressure >90 mm Hg. Body mass index (BMI) was calculated as weight (kg)/height (m2). Hypercholesterolemia, hypo-HDL-cholesterolemia, and hypertriglyceridemia were defined as a total cholesterol (TC) level of >5.68 mmol/L, an HDL-cholesterol (HDL-C) level of <1.03 mmol/L, and a triglyceride (TG) level of >1.69 mmol/L, respectively. A high hemoglobin A1C level was defined as
5.9%.
Laboratory Tests
Subjects fasted overnight before blood samples were obtained. TC, HDL-C, and TG levels were determined enzymatically; HBsAg and hemoglobin A1C levels were determined by latex agglutination immunoassay. Measurement of C-reactive protein (CRP) was performed using a latex-enhanced turbidimetric immunoassay (LPIAACE CRP-L, Dia-iatron).
Statistical Analysis
Statistical analyses were performed using unpaired t tests,
2 tests, and univariate and multivariate logistic regression analyses using computer software, Statistica version 5J (StatSoft Inc). P values <0.05 were considered to be statistically significant.
| Results |
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2 test).
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Relationship Between HBsAg Positivity and Carotid Plaque
Results of the univariate logistic regression analysis are described in Table 2. In addition to conventional risk factors for atherosclerosis (male sex, age, hypertension, hypercholesterolemia hypo-HDL-cholesterolemia, hypertriglyceridemia, increased hemoglobin A1C, and prior smoking), HBsAg positivity was found to be associated with carotid plaque with an odds ratio of 1.58 (95% CI, 1.14 to 2.19, P<0.05). In addition, a CRP level >0.4 mg/dL was also positively associated with carotid plaque, as we and others have previously reported.5,7 A multivariate logistic regression analysis revealed that HBsAg positivity was a statistically significant predictor for carotid plaque with an odds ratio of 1.57 (95% CI, 1.10 to 2.24, P<0.05) that was independent of other confounding risk factors for atherosclerosis (Table 2).
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| Discussion |
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In general, the clinical course of chronic HBV infection is characterized by a series of exacerbations and remissions, but it may lead to hepatic decompensation, progression of liver disease, and the development of cirrhosis. Liver cirrhosis appears to be associated with a decreased risk of atherosclerosis, which may be explained by the decreased coagulation status and the reduction of some of the conventional risk factors for atherosclerosis, such as high TC and lipoprotein(a) (Lp[a]).9 Therefore, the positive correlation between HBsAg positivity and carotid atherosclerosis observed in the present study was rather unexpected. In the present study, however, TC levels were not significantly different between HBsAg-positive and HBsAg-negative subjects. In addition, Lp(a) data for >90% of the study subjects were available, and Lp(a) levels in the HBsAg-positive (n=39) and HBsAg-negative (n=4317) subjects were 13.9±16.1 mg/dL and 16.5±15.4 mg/dL, respectively, and did not differ significantly. These observations may be explained by the fact that liver dysfunction in the majority of the HBsAg-positive subjects was minor, a possibility that is supported by the finding that serum levels of aspartate transaminase and alanine transaminase were not different between HBsAg-positive and HBsAg-negative subjects. Kiechl et al3 found no significant association between chronic hepatitis and the carotid atheromatous plaque, although whether each subject had hepatitis B or C was not specified. The different conclusions may be obtained because they analyzed the possible link between chronic active hepatitis and atherosclerosis,3 whereas most subjects were generally healthy in our study.
Several previous studies have suggested that some microorganisms may contribute to the pathogenesis of atherosclerosis; including Chlamydia pneumoniae,10 cytomegarovirus,11 Helicobacter pylori,12 and herpes simplex virus.13 They may cause vascular injury by direct colonization1 and activation of inflammatory response, which may play a role in the progression and destabilization of atherosclerotic plaques. Similarly, several possible mechanisms may exist to explain the relationship between HBV infection and atherosclerosis. First, HBV may colonize in the vascular tissues,14 leading to vascular damage. Second, HBV infection occasionally is associated with vasculitis.15 Third, chronic HBV infection may be associated with increased levels of oxidative stress,16 which may accelerate atherogenesis. Finally, chronic HBV infection may stimulate inflammatory and immune-mediated responses.
It recently has been recognized that HBV might be detectable in some HBsAg-negative subjects by a more sensitive assay, the HBV DNA detection test.17 Although this technique is not practical for general health-screening tests from an economic standpoint, the link between HBV DNA-positivity and atherosclerosis should be clarified in future studies.
In conclusion, a general population-based cohort study showed HBsAg positivity to be a risk factor for carotid atherosclerosis that was independent from other confounding risk factors. Whether this association can be observed in other countries where prevalence of HBsAg carrier is greater18 is a disputed issue.
Received December 7, 2001; revision received January 14, 2002; accepted January 14, 2002.
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