Table 3. Cox proportional hazards regression analysis for interaction effects of pyogenic liver abscess and comorbidity on risk of acute pancreatitis.

Variable		Person-years	Event	Adjusted HRa (95% CI)
Pyogenic liver abscess	Comorbidityb
No	No	548 045	562	1 (Reference)
No	Yes	45 543	143	2.39 (1.99, 2.88)
Yes	No	53 807	188	3.62 (3.07, 4.28)
Yes	Yes	65 435	362	5.09 (4.46, 5.81)
Pyogenic liver abscess	Diabetes mellitus
No	No	560 767	621	1 (Reference)
No	Yes	32 821	84	1.75 (1.39, 2.21)
Yes	No	71 188	331	4.32 (3.78, 4.94)
Yes	Yes	48 053	219	3.94 (3.38, 4.60)
Pyogenic liver abscess	Hypertriglyceridemia
No	No	591 209	699	1 (Reference)
No	Yes	2380	6	1.77 (0.79, 3.96)
Yes	No	117 984	542	3.95 (3.53, 4.42)
Yes	Yes	1259	8	5.31 (2.65, 10.66)
Pyogenic liver abscess	Biliary stones
No	No	582 496	654	1 (Reference)
No	Yes	11 092	51	3.19 (2.40, 4.25)
Yes	No	96 325	359	3.46 (3.04, 3.93)
Yes	Yes	22 918	191	6.65 (5.65, 7.81)
Pyogenic liver abscess	Alcoholism
No	No	592 198	697	1 (Reference)
No	Yes	1391	8	5.08 (2.53, 10.22)
Yes	No	118 149	542	3.96 (3.54, 4.43)
Yes	Yes	1094	8	7.92 (3.94, 15.93)
Pyogenic liver abscess	Hepatitis C
No	No	591 159	691	1 (Reference)
No	Yes	2430	14	4.09 (2.41, 6.95)
Yes	No	116 667	528	3.95 (3.53, 4.42)
Yes	Yes	2576	22	6.47 (4.23, 9.90)

CI, confidence interval; HR, hazard ratio.

^aAdjusted HR: Adjusted for age and sex.

^bPatients with any one of the comorbidities (diabetes mellitus, hypertriglyceridemia, biliary stone, alcoholism and hepatitis C) were classified as the comorbidity group.