Department of Biomedical Sciences, Humanitas University, Milan, Italy.
IRCCS Humanitas Research Hospital, Milan, Italy.
J Crohns Colitis. 2021 Oct 7;15(10):1658-1678. doi: 10.1093/ecco-jcc/jjab047.
The association between smoking and inflammatory bowel disease [IBD] relies on old meta-analyses including exclusively non-Jewish White populations. Uncertainty persists regarding the role of smoking in other ethnicities.
We systematically searched Medline/PubMed, Embase, and Scopus for studies examining tobacco smoking and the risk of developing IBD, ie, Crohn's disease [CD] or ulcerative colitis [UC]. Two authors independently extracted study data and assessed each study's risk of bias. We examined heterogeneity and small-study effect, and calculated summary estimates using random-effects models. Stratified analyses and meta-regression were employed to study the association between study-level characteristics and effect estimates. The strength of epidemiological evidence was assessed through prespecified criteria.
We synthesised 57 studies examining the smoking-related risk of developing CD and UC. Non-Jewish White smokers were at increased risk of CD (29 studies; relative risk [RR]: 1.95, 95% confidence interval [CI]: 1.69‒2.24; moderate evidence). No association was observed in Asian, Jewish. and Latin-American populations [11 studies; RR: 0.97; 95% CI: 0.83-1.13], with no evidence of heterogeneity across these ethnicities. Smokers were at reduced risk of UC [51 studies; RR: 0.55, 95% CI: 0.48-0.64; weak evidence] irrespectively of ethnicity; however, cohort studies, large studies, and those recently published showed attenuated associations.
This meta-analysis did not identify any increased risk of CD in smokers in ethnicities other than non-Jewish Whites, and confirmed the protective effect of smoking on UC occurrence. Future research should characterise the genetic background of CD patients across different ethnicities to improve our understanding of the role of smoking in CD pathogenesis.
吸烟与炎症性肠病[IBD]之间的关联基于仅包括非犹太裔白人群体的旧荟萃分析。关于吸烟在其他种族中的作用仍存在不确定性。
我们系统地检索了 Medline/PubMed、Embase 和 Scopus 中的研究，这些研究检查了吸烟与 IBD（即克罗恩病[CD]或溃疡性结肠炎[UC]）发展风险之间的关系。两位作者独立提取了研究数据，并评估了每个研究的偏倚风险。我们检查了异质性和小样本效应，并使用随机效应模型计算了汇总估计值。进行分层分析和荟萃回归以研究研究水平特征与效应估计值之间的关系。通过预设标准评估了流行病学证据的强度。
我们综合了 57 项研究，这些研究检查了吸烟与 CD 和 UC 发病风险之间的关系。非犹太裔白种烟民患 CD 的风险增加（29 项研究；相对风险[RR]：1.95，95%置信区间[CI]：1.69-2.24；中等质量证据）。在亚洲、犹太人和拉丁裔人群中没有观察到关联[11 项研究；RR：0.97；95% CI：0.83-1.13]，这些种族之间没有异质性的证据。吸烟与 UC 的风险降低相关[51 项研究；RR：0.55，95% CI：0.48-0.64；低质量证据]，与种族无关；然而，队列研究、大型研究和最近发表的研究显示出关联减弱。
这项荟萃分析未发现非犹太裔白种人以外的其他种族中吸烟与 CD 风险增加之间的任何关联，并证实了吸烟对 UC 发生的保护作用。未来的研究应描述不同种族中 CD 患者的遗传背景，以提高我们对吸烟在 CD 发病机制中的作用的理解。
