Multiplicative synergistic risk of hepatocellular carcinoma development among hepatitis B and C co-infected subjects in HBV endemic area: a community-based cohort study

Table 3 Hazard Ratios (HRs) and 95% confidence intervals (CIs) of hepatocellular carcinoma (HCC) according to hepatitis B and C virus infection status

Infection status	No. of subjects	Person-years	No. of HCC	HR^a (95% CI)
HBsAg(−) / anti-HCV(−)	5744	53,504	16	1.0 (reference)
HBsAg(+) / anti-HCV(−)	335	2,981	15	17.1 (8.4-34.8)
HBsAg(−) / anti-HCV(+)	360	3,731	12	10.4 (4.9-22.1)
HBsAg(+) / anti-HCV(+)	14	133	3	115.0 (32.5-407.3)
				SI and 95% CI: 4.5 (1.3-15.5)^b

HBsAg, hepatitis B surface antigen; anti-HCV, antibodies against hepatitis C virus. ^aHR: age- and sex-adjusted. ^bSI: synergy index=(RR₁₁-1)/(RR₀₁+RR₁₀-2), in which RR₁₁=relative risk of the joint effect of two risk factors; RR₀₁ and RR₁₀=relative risk of each risk factor in the absence of the other. Two hundred and forty-one subjects including 4 HCC cases had no information on HBsAg or anti-HCV, and were excluded from the analysis.

ISSN: 1471-2407