Systematic review with meta‐analysis: coffee consumption and the risk of gallstone disease

Summary Background Epidemiologic evidence on coffee consumption reducing the risk of gallstone disease has been contradictory. Aim To perform a meta‐analysis of observational studies, to investigate an association and dose–response of coffee consumption with gallstone disease. Methods We used PubMed and EMBASE databases to identify all published studies before June 2015. A random‐effects model was used to compute a pooled relative risk (RR) and corresponding 95% confidence intervals (CIs). Results One case–control study and five prospective cohort studies (with seven cohorts) involving 227 749 participants and 11 477 gallstone disease cases were included. Coffee consumption was significantly associated with a reduced risk of gallstone disease (RR, 0.83; 95% CI, 0.76 to 0.89; I2 = 35.9%), based on prospective studies; specifically, we observed an inverse relation in females, but not in males. The case–control study did not reveal any association between coffee and gallstone disease (OR, 0.99; 95% CI, 0.64 to 1.53). In a dose–response analysis, the RR of gallstone disease was 0.95 (95% CI, 0.91 to 1.00; P = 0.049) per 1 cup/day of coffee consumption. A significant nonlinear dose–response association was also identified (P for nonlinearity = 0.0106). For people who drank 2, 4 and 6 cups of coffee per day, the estimated RRs of gallstone disease were 0.89 (95% CI, 0.79 to 0.99), 0.81 (95% CI, 0.72 to 0.92) and 0.75 (95% CI, 0.64 to 0.88), respectively, compared with the lowest level drinkers. Conclusion This study suggests that coffee consumption is related to a significantly decreased risk of gallstone disease.