Hepatitis B virus infection, diabetes mellitus, and their synergism for cholangiocarcinoma development: A case-control study in Korea

Table 4 Interaction between diabetes mellitus and hepatitis B virus infection for cholangiocarcinoma: logistic regression analysis with adjusted odds ratio

Interaction variables		n	βCoefficient (± SE)	P value	AOR1 (95%CI)	S (95%CI)2
DM	HBV
Negative	Negative	658			1
Positive	Negative	124	0.909 (0.22)	< 0.001	2.5 (1.6-3.8)
Negative	Positive	36	1.259 (0.39)	0.001	3.5 (1.6-7.6)
Positive	Positive	10	2.502 (0.96)	0.009	12.2 (1.9-80.1)	2.80 (1.54-5.08)
Complicated DM	HBV
Negative	Negative	740			1
Positive	Negative	42	0.967 (0.34)	0.005	2.6 (1.3-5.1)
Negative	Positive	37	1.107 (0.38)	0.004	3.0 (1.4-6.4)
Positive	Positive	9	3.423 (1.32)	0.009	30.7 (2.3-403.4)	8.12 (4.92-13.38)

¹AOR: Odds ratio adjusted for the other significant risk factors for cholangiocarcinoma;

²S = Synergy index described by Rothman = (OR₁₁ - 1)/(OR₀₁ + OR₁₀ - 2), where OR₁₁ = OR of the joint effect of 2 risk factors; OR₀₁ and OR₁₀ = OR of each risk factor in the absence of the other. DM: Diabetes mellitus; HBV: Hepatitis B virus; AOR: Adjusted odds ratio.