Smoking habits and gallbladder disease: a systematic review and meta-analysis study

Background: It has been claimed that smoking is linked with an increased risk for gallbladder disease (GBD); however, related issues need further consolidation and clarification. The present systematic review and meta-analysis aimed to further investigate the potent correlation between GBD and smoking.

Methods: We conducted a comprehensive literature review to identify every study published from January 1989 to December 2019, reporting risk estimates regarding GBD and smoking. The random-effect, generic inverse variance method, according to description by DerSimonian and Laird, was used to compute pooled estimates. We used the Newcastle-Ottawa quality assessment scale to appraise the included studies' quality.

Results: Thirty published case-control, cross-sectional, and cohort studies including 4,623,435 individuals met the eligibility criteria and were considered for data synthesis. Compared to the non-smokers, ever smokers had 1.25 times higher odds of developing GBD [95 % confidence interval (CI): 1.09-1.44]; however, increased heterogeneity was observed (I² =96 %, 95 % CI: 62-100 %, p <0.001). Publication bias was non-significant (Eggers' regression p =0.072). The main sources of heterogeneity, as detected by meta-regression analyzing study characteristics, biases and confounders, were non-adjustment for family history (p =0.007) and alcohol (p =0.020), respectively. Subgroup analysis indicated a comparable risk for GBD as far as current, former and ever smokers are concerned (p =0.520). Quantitative analysis suggested a dose-effect for current smoking and GBD (p =0.010).

Conclusions: Non-smokers were demonstrated to be at a lower risk of presenting GBD when compared with ever smokers; all relevant risk estimates necessitate adjustment for family history and alcohol intake. HIPPOKRATIA 2020, 24(4): 147-156.