American Journal of Epidemiology Advance Access originally published online on February 18, 2009
American Journal of Epidemiology 2009 169(8):990-995; doi:10.1093/aje/kwn418
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ORIGINAL CONTRIBUTIONS |
Sex-Modified Effect of Hepatitis B Virus Infection on Mortality From Primary Liver Cancer
Correspondence to Prof. Yue Chen, Department of Epidemiology and Community Medicine, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada (e-mail: ychen{at}uottawa.ca) or Prof. Qingwu Jiang, Department of Epidemiology, School of Public Health, Fudan University, 130 Dong'an Road, Shanghai 200032, People's Republic of China (e-mail: jiangqu{at}fudan.edu.cn).
Received for publication April 3, 2008. Accepted for publication December 19, 2008.
Sex and hepatitis B virus (HBV) infection are both important risk factors for primary liver cancer. However, their possible biologic interaction has not been well studied. The authors examined data from 89,789 subjects aged 25–69 years who participated in a 14-year cohort study (1992–2006) conducted in Haimen, China. An age-stratified Cox proportional hazards model was used for multivariate analysis. The authors assessed the combined effect of sex and HBV infection on liver cancer mortality by calculating 3 interaction measures: the relative risk due to interaction, the attributable proportion of interaction, and the synergy index. There was a greater risk difference between hepatitis B surface antigen carriers and noncarriers among men than among women. After adjustment for potential confounders, the relative risk due to interaction, the attributable proportion of interaction, and the synergy index were 33.27 (95% confidence interval (CI): 22.54, 43.99), 0.59 (95% CI: 0.55, 0.63), and 2.49 (95% CI: 2.13, 2.90), respectively, suggesting a significant synergistic effect of the interaction between sex and HBV infection on liver cancer mortality. HBV infection had a larger impact on liver cancer mortality in men than in women, which may explain at least part of the sex difference in liver cancer risk.
China; cohort studies; hepatitis B virus; liver neoplasms; mortality; risk factors; sex
Abbreviations: CI, confidence interval; HBsAg, hepatitis B surface antigen; HBV, hepatitis B virus; RERI, relative risk due to interaction