Objective To systematically evaluate the association between smoking and the risk of primary biliary cirrhosis( PBC) from the perspective of evidence- based medicine. Methods A literature search was performed in Pub Med,EMBASE,CBM,CNKI,Wanfang Data,and VIP database to collect the case- control studies on the association between smoking and the risk of PBC published in the last two decades. Chinese search words were “吸烟”,“香烟”,“原发性胆汁性肝硬化”,“危险因素”,“队列研究”,and “病例对照研究”,and English search words were “smoking”,“cigarette”,“tobacco”,“risk factors”,“primary biliary cirrhosis”,“cohort studies”,and“case- control studies”. And then a meta- analysis was performed using Review Manager 5. 2. The pooled odds ratio( OR) and 95% confidence interval( CI) were calculated,and the publication bias was analyzed by funnel plots. Results A total of 7 case- control studies involving 5459 subjects( 2652 patients with PBC vs 2807 controls) were included in the meta- analysis. The analysis results showed that smokers had a significantly higher risk of PBC compared with non- smokers( OR = 1. 49,95% CI: 1. 11- 2. 00,P = 0. 009). The geographical subgroup analysis results showed that there was a significant difference in the risk of PBC between non- smokers and smokers in North America( OR = 1. 57,95% CI: 1. 20- 2. 04,P = 0. 0008). However,there was no significant difference in the risk of PBC between non- smokers and smokers in Europe( OR = 1. 41,95% CI: 0. 73- 2. 73,P = 0. 31). Conclusion Smoking can increase the risk of PBC. However,it needs to be confirmed in high- quality prospective studies with larger samples because of the heterogeneity of current included studies.
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