Table.

Main characteristics of the studies included in this meta-analysis

Study	Zein et al14	Corpechot et al12	Mantaka et al13
Country	USA	France	Greece
Study design	Cross-sectional	Cross-sectional	Cross-sectional
Year	2006	2010	2018
Total participants	First cohort: 77 patients with PBC	164 patients with PBC	148 patients with PBC
	Second cohort: 155 patients with PBC
Participants	First cohort: Patients with PBC who were seen at one of the three teaching hospitals of Case Western Reserve University (University Hospital, Veteran Affair Medical left and MetroHealth Medical Center) in Cleveland, Ohio, from 1 January 1998 to 31 October 2005 were identified from the databases of the hospitals. Only patients who had liver histopathology available in the system were included	Participants were patients with PBC who previously participated in a prospective epidemiological study. Most of them were recruited from Saint-Antoine hospital. Only patients who had liver histopathology available in the system were included. They were re-interviewed for this study in 2008	Participants were patients with PBC who were seen at the University of Crete Medical School hospital, Greece. Only patients who had liver histopathology available in the system were included
	Second cohort: Patients with PBC who were seen at Cleveland Clinic in Cleveland, Ohio, from 1 January 1998 to 30 March 2006 were identified from the database of the hospital. Only patients who had liver histopathology available in the system were included
Diagnosis of PBC	First cohort: Presence of ICD-9 code for PBC in the database plus 1. Detectable AMA, 2. Cholestatic biochemical profile ≥six months and 3. Compatible liver histology	Presence of at least two of the following criteria; 1. Cholestatic biochemical profile ≥six months, 2. presence of AMA or anti-gp210 ANA (titer ≥1:40 and detectable on ELISA) and 3. compatible liver histology	Based on standard biochemical, immunological, and histological criteria
	Second cohort: Same as the first cohort
Determination of smoking status	First cohort: Data on smoking status were retrieved from health questionnaire filled by the patients during visits with healthcare providers of those hospitals. Second cohort: Same as the first cohort	Smoking status was determined through health questionnaires answered by the patients for this study.	Smoking status was determined through health questionnaires answered by the patients for this study.
Definition of advanced fibrosis	First cohort: Stage of liver fibrosis was defined based on liver biopsy using Ludwig’s classification. Stage 3 and 4 were considered advanced fibrosis	Stage of liver fibrosis was defined based on liver biopsy using Ludwig’s classification. Stage 3 and 4 were considered advanced fibrosis	Stage of liver fibrosis was defined based on liver biopsy using Metavir-based classification system. F3 and F4 were considered advanced fibrosis
	Second cohort: Same as the first cohort
Females (%)	First cohort: 87.6	90.2	86.5
	Second cohort: 91.3
Average age (yr)	First cohort: 53.0	50.0	65.6
	Second cohort: 52.0
Race (%)	First cohort: Caucasian (91.8)	NA	NA
	Second cohort: Caucasian (95.7)
History of smoking (%)	First cohort: 51.0	26.0	32.7
	Second cohort: 50.3
Patients with advanced liver fibrosis (%)	First cohort: 49.4	20.5	17.5
	Second cohort: 51.5
Confounder adjusted in multivariate analysis	None	Sex and significant alcohol consumption	Sex and significant alcohol consumption
Newcastle-Ottawa score	Selection: 3	Selection: 3	Selection: 3
	Comparability: 1	Comparability: 2	Comparability: 2
	Exposure: 3	Exposure: 3	Exposure: 3

PBC, primary biliary cirrhosis; AMA, antimitochondrial antibody; ICD-9, international classification of diseases-9; ANA, antinuclear antibody; ELISA, enzyme-linked immunosorbent assay; BMI, body mass index; NA, not available