Body mass index and biliary tract disease: A systematic review and meta-analysis of prospective studies

• Body mass index is associated with a higher risk of biliary tract disease.
• This association is stronger for non-cancer biliary tract disease than cancers in biliary tract.
• The association of body fat with non-cancer biliary tract disease is stronger for women than men.

ObjectiveTo evaluate the association between body mass index (BMI, kg/m2) and incidence of biliary tract disease.MethodsWe performed a systematic review and a meta-analysis of prospective studies by searching the database of PubMed and EMBASE published up to December 31, 2013. Outcome of interest was disease of biliary tract system (gallbladder, extrahepatic bile duct and Ampullar of Vater). We used a random-effects model to combine the study-specific relative risks (RRs) and 95% confidence intervals (95% CIs) from 22 prospective studies. We examined whether BMI was associated with a higher risk of biliary tract disease in a combined analysis.ResultsThe positive association was stronger for non-cancer biliary tract disease than biliary tract cancer; combined RRs (95% CIs) comparing the top with bottom categories were 1.40 (1.15–1.65) for biliary tract cancer and 2.75 (2.35–3.15) for non-cancer biliary tract disease (P for difference < 0.001). For non-cancer biliary tract disease, combined RRs (95% CIs) comparing the top with bottom categories were 3.21 (2.48–3.93) for women and 2.01 (1.66–2.37) for men (P for difference = 0.04).ConclusionObesity is associated with higher risks of biliary tract cancer and, to a greater extent, non-cancer biliary tract disease.