Meta-Analysis
Copyright ©2013 Baishideng Publishing Group Co.
World J Gastroenterol. Dec 14, 2013; 19(46): 8780-8788
Published online Dec 14, 2013. doi: 10.3748/wjg.v19.i46.8780
Table 1 Characteristics of the 12 studies that reported an association between smoking or alcohol consumption and the risk of extrahepatic cholangiocarcinoma
Author and yearCountryDesignSourceNumber of casesNumber of controlsRisk factor assessmentECC ascertainmentSmoking RR (95% CI)Alcohol RR (95% CI)Adjustments
Ghadirian et al[18] 1993CanadaCase-controlPopulation24239QuestionnaireNA2.820 (1.010-7.860)-Age, sex, other smoking habits, alcohol consumption, schooling, respondent status
Chow et al[19] 1994United StatesCase-controlPopulation64255QuestionnairePathological1.630 (0.900-2.970)10.600 (0.290-1.220)1Age, ethnic origin, smoking status (adjusted for alcohol consumption)
Khan et al[20] 1999United StatesCase-controlHospital31138Medical recordsPathological0.630 (0.210-1.880)-Age, female gender, ethnicity, cholelithiasis, socioeconomic status
Zhang et al[21] 2004ChinaCase-controlPopulation99373QuestionnaireCancer registry1.490 (0.870-2.560)21.290 (0.780-2.170)2Age, total energy, cholelithiasis, hypertension, history of salty food intake, smoking status (adjusted for alcohol consumption)
Welzel et al[11] 2007United StatesCase-controlPopulation549102782Medical recordsCancer registry1.700 (1.000-3.000)-Age, sex, race, geographic location, state buy-in status
Shaib et al[10] 2007United StatesCase-controlHospital163236Medical recordsPathological + imaging1.300 (0.800-1.900)31.290 (0.190-8.910)1Race, age, gender, HBV, HCV markers (adjusted for alcohol consumption)
El-Serag et al[22] 2009United StatesCohort---RegistryCancer registry-1.060 (0.600-1.870)Age, sex, baseline visit date, type of visit, a preceding visit
Tao et al[23] 2010ChinaCase-controlHospital129380Medical recordsPathological + imaging0.900 (0.500-1.300)31.200 (0.800-1.900)3-
Cai et al[24] 20114ChinaCase-controlHospital313608Medical recordsPathological0.900 (0.640-1.248)3--
Onal et al[25] 2012TurkeyCase-controlHospital8948QuestionnairePathological + imaging1.900 (0.900-4.200)34.010 (0.480-33.62)3-
Brandi et al[26] 2013ItalyCase-controlPopulation59212QuestionnairePathological0.780 (0.400-1.500)-Age, sex, region of residence
Zhou et al[27] 2013ChinaCase-controlHospital239478Medical recordsPathological + imaging1.301 (0.863-1.962)1.053 (0.670-1.655)Age, sex, cirrhosis, cholelithiasis, cholecystectomy, DM, family history of other cancer
Table 2 Quality of the studies used in this analysis
Author and yearQuality indicators of Newcastle-Ottawa quality assessment scale
Score
Selection
Comparability
Exposure/outcome
IaIbIcIdIIaIIbIIIaIIIbIIIc
Ghadirian et al[18] 1993NoYesYesYesYesYesYesNoNo6
Chow et al[19] 1994YesYesYesYesYesYesYesNoNo7
Khan et al[20] 1999YesYesNoYesYesYesYesYesNo7
Zhang et al[21] 2004YesYesYesYesYesYesYesNoNo7
Welzel et al[11] 2007NoYesYesYesYesYesYesYesNo7
Shaib et al[10] 2007YesYesNoYesYesYesYesYesYes7
El-Serag et al[22] 2009YesYesYesYesYesNoYesYesYes8
Tao et al[23] 2010YesYesNoYesYesYesYesYesNo7
Cai et al[24] 2011YesYesNoYesYesYesYesYesNo7
Onal et al[25] 2012YesYesNoYesYesNoYesYesNo7
Brandi et al[26] 2013YesYesYesYesYesYesNoNoNo6
Zhou et al[27] 2013YesYesNoYesYesNoYesYesNo7
Table 3 Subgroup analyses of the association between smoking and extrahepatic cholangiocarcinoma and alcohol consumption and extrahepatic cholangiocarcinoma
No. of studiesRR (95%CI)Tests for heterogeneity
QPI2
Smoking
Geographical region
Non-Asia71.39 (1.03-1.87)8.2800.21827.5%
Asia41.08 (0.85-1.38)3.8500.27822.1%
Study design
Population-based51.47 (1.06-2.05)5.4700.24326.8%
Hospital-based61.10 (0.88-1.37)6.1900.28819.2%
Adjustment for cholelithiasis31.28 (0.94-1.76)1.9170.3830.0%
Alcohol drinking
Geographical region
Non-Asia40.94 (0.56-1.56)3.5600.31315.7%
Asia31.17 (0.90-1.53)0.3600.8350.0%
Study design
Population-based20.92 (0.44-1.94)2.8900.08965.4%
Hospital-based41.16 (0.86-1.58)1.5200.6780.0%
Case-control61.10 (0.86-1.41)4.7500.4470.0%
Cohort11.06 (0.60-1.87)---