Case Control Study
Copyright ©The Author(s) 2022.
World J Hepatol. Sep 27, 2022; 14(9): 1747-1756
Published online Sep 27, 2022. doi: 10.4254/wjh.v14.i9.1747
Table 1 Cohort characteristics of cases and controls

Controls (n = 200)
Cases (n = 200)
Test for difference
Age, yr [mean (SD; range)]61.5 (11.6; 29.1-95.1)63.6 (11.6; 28.1-94.3)P = 0.073
Sex
Male18 (9.0)17 (8.5)
Female182 (91.0)183 (91.5)P = 0.86
Country of birth
Australia157 (78.5)122 (61.0)
Overseas43 (21.5)78 (39.0)P < 0.001
Self-reported ethnicity
Caucasian180 (90.0)175 (87.5)
Asian11 (5.5)14 (7.0)
Other3 (1.5)4 (2.0)
Mixed race1 (0.5)0 (0)
Unspecified5 (2.5)7 (3.5)P = 0.75
Education completed
Up to some secondary3 (1.5)18 (9.0)
Yr 10/1133 (16.5)56 (28.0)
Yr 1221 (10.5)26 (13.0)
TAFE/Trade32 (16.0)43 (21.5)
University111 (55.5)57 (28.5)P < 0.001
Family history of PBC?
No 200 (100.0)194 (97.0)
Yes0 (0)6 (3.0)
BMI (kg/m2) mean26.8 27.1 P = 0.49
Table 2 Odds ratios for primary biliary cholangitis and alcohol intake (frequency per week, drinks per session, drinker per week) for different age spans

Controls, n (%)
Cases, n (%)
Univariable
Adjusted1
Further adjusted for current alcohol consumption
16-20 yr2
Frequency per week
Didn’t drink70 (35.5)91 (46.2)1.34 (0.84, 2.13)1.36 (0.79, 2.35)1.32 (0.74, 2.36)
< 1 d per week71 (36.0)68 (34.5)1.00 [Reference]1.00 [Reference]1.00 [Reference]
≥ 1 d per week56 (28.4) 38 (19.3)0.65 (0.37, 1.15)0.59 (0.31, 1.15)0.71 (0.36, 1.43)
TrendP = 0.015P = 0.022P = 0.088
Drinks per session
Didn’t drink68 (35.4)89 (46.1)1.34 (0.81, 2.22)1.28 (0.71, 2.31)1.04 (0.55, 1.95)
1-2 drinks67 (34.9)63 (32.6)1.00 [Reference]1.00 [Reference]1.00 [Reference]
≥ 3 drinks57 (29.7)41 (21.2)0.61 (0.33, 1.15)0.54 (0.26, 1.09)0.46 (0.21, 0.99)
TrendP = 0.010P = 0.023P = 0.055
Drinks per week
Didn’t drink68 (35.4)89 (46.1)1.50 (0.95, 2.37)1.53 (0.89, 2.62)1.35 (0.76, 2.41)
1-5 drinks per week87 (45.3)79 (40.9)1.00 [Reference]1.00 [Reference]1.00 [Reference]
≥ 6 drinks per week37 (19.3)25 (13.0)0.67 (0.35, 1.27)0.71 (0.35, 1.48)0.85 (0.40, 1.82)
TrendP = 0.014P = 0.065P = 0.26
21-30 yr2
Frequency per week
Didn’t drink19 (9.9)64 (33.5)3.11 (1.59, 6.08)3.11 (1.42, 6.79)2.81 (1.26, 6.29)
< 1 day per week65 (33.9)69 (36.1)1.00 [Reference]1.00 [Reference]1.00 [Reference]
1-2 days per week69 (35.9)43 (22.5)0.49 (0.27, 0.86)0.48 (0.25, 0.92)0.51 (0.26, 1.00)
≥ 3 days per week39 (20.3)15 (7.9)0.26 (0.11, 0.57)0.18 (0.07, 0.47)0.22 (0.09, 0.57)
TrendP < 0.001P < 0.001P < 0.001
Drinks per session
Didn’t drink18 (9.6)63 (33.9)5.57 (2.76, 11.22)4.81 (2.18, 10.65)3.99 (1.76, 9.01)
1-2 drinks102 (54.6)67 (36.0)1.00 [Reference]1.00 [Reference]1.00 [Reference]
≥ 3 drinks67 (35.8)56 (30.1)1.03 (0.61, 1.77)0.78 (0.41, 1.46)0.89 (0.46, 1.71)
TrendP < 0.001P < 0.001P = 0.003
Drinks per week
Didn’t drink18 (9.6)63 (33.9)5.05 (2.53, 10.09)4.77 (2.16, 10.53)3.89 (1.73, 8.76)
1-5 drinks per week98 (52.4)75 (40.3)1.00 [Reference]1.00 [Reference]1.00 [Reference]
6-10 drinks per week47 (25.1)37 (19.9)0.86 (0.49, 1.53)0.82 (0.42, 1.58)0.84 (0.43, 1.65)
≥ 11 drinks per week24 (12.8)11 (5.9)0.52 (0.23, 1.18)0.31 (0.12, 0.83)0.42 (0.15, 1.14)
TrendP < 0.001P < 0.001P = 0.001
31-40 yr2
Frequency per week
Didn’t drink14 (9.2)47 (31.1)3.60 (1.28, 10.11)3.60 (1.10, 11.81)3.57 (1.09, 11.72)
< 1 day per week49 (32.2)52 (34.4)1.00 [Reference]1.00 [Reference]1.00 [Reference]
1-2 days per week53 (34.9)35 (23.2)0.56 (0.27, 1.18)0.64 (0.28, 1.47)0.69 (0.30, 1.60)
≥ 3 days per week36 (23.7)17 (11.3)0.28 (0.11, 0.70)0.29 (0.10, 0.84)0.36 (0.12, 1.08)
TrendP < 0.001P < 0.001P = 0.002
Drinks per session
Didn’t drink13 (8.8)46 (31.1)5.12 (1.92, 13.67)4.48 (1.48, 13.59)3.94 (1.27, 12.27)
1-2 drinks94 (64.0)71 (48.0)1.00 [Reference]1.00 [Reference]1.00 [Reference]
≥ 3 drinks40 (27.2)31 (21.0)0.85 (0.42, 1.73)0.71 (0.33, 1.55)0.81 (0.36, 1.81)
TrendP = 0.002P = 0.006P = 0.034
Drinks per week
Didn’t drink13 (8.8)46 (31.1)3.65 (1.34, 9.91)3.51 (1.13, 10.93)3.00 (0.95, 9.54)
1-5 drinks per week78 (53.1)72 (48.7)1.00 [Reference]1.00 [Reference]1.00 [Reference]
6-10 drinks per week38 (25.9)18 (12.2)0.37 (0.15, 0.89)0.38 (0.14, 1.01)0.39 (0.15, 1.03)
≥ 11 drinks per week18 (12.2)12 (8.1)0.51 (0.19, 1.38)0.48 (0.16, 1.40)0.66 (0.20, 2.15)
TrendP < 0.001P = 0.001P = 0.008
Table 3 Odds ratios for the association between tobacco and marijuana intake and primary biliary cholangitis development

Controls (n = 200), n (%)
Cases (n = 200), n (%)
Univariable
Adjusted1
Adjusted2
Ever smoked tobacco prior to PBC diagnosis
No116 (58.0)89 (44.5)1.00 [Reference]1.00 [Reference]
Yes84 (42.0)111 (55.5)1.73 (1.15, 2.59)1.42 (0.88, 2.30)
P = 0.008P = 0.15
Age started smoking tobacco
Never smoker115 (57.8)88 (44.2)1.00 [Reference]1.00 [Reference]
10-1519 (9.6)24 (12.1)1.66 (0.79, 3.47)1.16 (0.49, 2.74)
> 15-1730 (15.1)35 (17.6)1.59 (0.87, 2.91)1.15 (0.57, 2.31)
> 17-1919 (9.6)26 (13.1)1.66 (0.87, 3.16)1.72 (0.79, 3.73)
> 19-3816 (8.0)26 (13.1)2.23 (1.10, 4.53)2.16 (0.97, 4.83)
TrendP = 0.008P = 0.022
Years smoking tobacco prior to PBC diagnosis
Never smoker115 (57.8)88 (44.2)1.00 [Reference]1.00 [Reference]
0-1028 (14.1)23 (11.6)1.15 (0.63, 2.09)1.07 (0.54, 2.13)
> 10-2026 (13.1)32 (16.1)1.63 (0.89, 3.00)1.18 (0.58, 2.38)
> 20-3522 (11.1)41 (20.6)2.46 (1.33, 4.55)2.27 (1.12, 4.62)
> 35-59.98 (4.0)15 (7.5)2.47 (1.01, 6.06)1.90 (0.68, 5.30)
TrendP = 0.001P = 0.018
Ever smoked marijuana prior to PBC diagnosis
No184 (92.0)179 (89.5)1.00 [Reference]1.00 [Reference]1.00 [Reference]
Yes16 (8.0)21 (10.5)1.36 (0.68, 2.71)1.45 (0.66, 3.20)1.27 (0.56, 2.87)
P = 0.39P = 0.36P = 0.56
Marijuana smoking status (constrained to starting smoking marijuana prior to PBC diagnosis)
Never smoker184 (92.0)179 (89.5)1.00 [Reference]1.00 [Reference]1.00 [Reference]
Ex-smoker16 (8.0)19 (9.5)1.21 (0.60, 2.46)1.23 (0.55, 2.79)1.10 (0.48, 2.55)
Current smoker0 (0)2 (1.0)---